Anatomical Record 9 (1915)

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THE ANATOMICAL RECORD

EDITORIAL BOARD

Irving Hardesty

Tulane University

Clarence M. Jackson

University of Minnesota

Thomas G. Lee

University of Minnesota

Frederic T. Lewis

Harvard University

Warren H. Lewis

Johns Hopkins University

Charles F. W. McClure

Princeton University

William S. Miller

University of Wisconsin

Florence R. Sarin

Johns Hopkins University

George L. Streeter

University of Michigan

G. Carl Huber, Managing Editor

1330 Hill Street. Ann Arbor. Michigan


VOLUME 9 1915

PHILADELPHIA THE WISTAR institute OF ANATOMY AND BIOLOGY

COMPOSED AND PRINTED AT THE

WAVERLY PRESS

By THE WlLLIA-MS & WiLKINS COMPANY

Baltimore, Md., U. S. A.

Contents

No. 1. JANUARY

Shixkishi Hatai. The growth of the body and organs in albino rats fed with a lipoidiree ration

Frederick S. Hammett. The source of the hydrochloric acid found in the stomach 21

stropping machine for microtome knives (M. J. G.). Three figures 26

Daxiel Davjs. a simple apparatus for microscopic and macroscopic 'ph'ot'ography'.

Ihree ngures

Journals Announcement ~

Proceedings of the American Association of Anatomists. Thirty-first session. 35

Proceedings of the American Association of Anatomists. Abstracts 45

Proceedings of the American Association of Anatomists. Demonstrations. 138

List of officers and members 145

Xo. 2. FEBRUARY

W. B. Kirkham and H. W. Haggard. A comparative study of the shoulder region of the normal and of a wingless fowl. Eleven figures (three plates) 159

H. Ryerson Decker. Report of the anomalies in a subject with a supernumerary lumbar vertebra. Six figures loi

Arnold H. Eggerth. On the anlage of the bulbo-urethral (Cowper's) and major vestibular (Bartholin's) glands in the human embryo. Four figures 191

F. C.^ockeray. Volumetric determinations of the parts of the brain in a human fetus 156 mm. long (crown-rump) 207

Xo. 3 MARCH

Helen DeaxV King. On the weight of the albino rat at birth and the factors that influence it r,lo

A. R. RixXGOEN. Observations on the origin of the mast leucocytes of the adult rabbit. 233 RoLLo E. McCotter. a note on the course and distribution of the nervus terminalis

in man. Two figures 243

Richard E. Scammon. On Weber's method of reconstruction and its application to curved surfaces. Five figures 247

Charles D. Cipp. On the structure of the erythrocj'te. Four figures 259

No. 4. APRIL Charles F. W. McClure. On the provisional arrangement of the embryonic lymphatic system. An arrangement by means of w-hich a centripetal lymph flow toward the venous circulation is controlled and regulated in an orderly and uniform manner, from the time lymph begins to collect in the intercellular spaces until it is forwarded to the venous circulation. Six figures 281

Ida L. Revelet. The pyramidal tract in the guinea-pig. (Cavia aperea.) Ten figures. 297 Gilbert Horrax. A study of the afferent fibers of the body wall and of the hind legs to the cerebellum of the dog by the method of degeneration. Seven figures 807

Ralph Edward Sheldon. Some new receptacles for cadavers and gross preparations. Eight figures 323

Franklin Pearce Reagan. Vascularization phenomena in fragments of embryonic

bodies completely isolated from yolk-sac blastoderm. Ten figures .329

No. 5. MAY

E. D. CoNGDON. The identification of tissues in artificial cultures. Ten figures 343

W. M. Baldwin. The action of ultra-violet raj's upon the frog's egg. I. The artificial production of spina bifida. Sixteen figures 365

T. B. Reeves. On the presence of interstitial cells in the chicken's testis. Three figures 383

Paul E. Lineback. A simple method of brain dissection. Five figures 387

No. 6. JUNE

Davenport Hooker. The roles of nucleus and cytoplasm in melanin elaboration. One figure 393

Helen Dean King and J. M. Stotsenbtjrg. On the normal sex ratio and the size of the litter in the albino rat (Mus norvegicus albinus). One figure 403

Ivan E. Wallin. An instance of acidophilic chromosomes and chromatin particles. One plate (twelve figures) 421

Henry Laurens. The connecting systems of the reptile heart. Eight figures (two plates) 427

Thesle T. Job. The adult anatomy of the lymphatic system in the common rat (Epimys norvegicus) . Four figures 447

Frederic Pomeroy Lord. Some anatomical deductions from a pathological temporomandibular articulation. Three figures 459

Arthur W. Meyer. Laboratory and technical miscellany. Six figures 465

W. B. Martin. Neutral stains as applied to the granules of the pancreatic islet cells. . 475

No. 7. JULY

Arthur William Meyer. Spolia anatomica addenda I. Twenty-seven figures 483

E. I. Werber. Experimental studies aiming at the control of defective and monstrous development. A survey of recorded monstrosities with special attention to the ophthalmic defects. Twenty-nine figures 529

Charles F. W. McClure. The development of the lymphatic system in the light of the more recent investigations in the field of vasculogenesis 563

H. D. Reed. The sound-transmitting apparatus in Necturus. Six figures 581

No. 8. AUGUST

R. W. SiiUFELDT. On the comparative osteology of the limpkin (Aramus vociferus; and its place in the system. Sixteen figures 591

B. W. KuNKEL. The paraphysis and pineal reszion of the garter snake. Forty-one figures 607

H. M. Helm. The gastric vasa brevia. Thirty-seven figures 637

Shinkishi Hatai. On the influence of exercise on the growth of organs in the albino rat. 647

J M. Stotsenburg. The growth of the fetus of the albino rat from the thirteenth to the twenty-second day of gestation. Two figures 667

No. 9. SEPTEMBER

A. R. RiNGOEN. Observations on the differentiation of the granules in the eosinophilic leucocytes of the bone-marrow of the adult rabbit 683

James Crawford Watt. An abnormal frog's heart with persisting dorsal mesocardium. Six figures 703

Raphael Isaacs. A mechanical device to simplify drawing with the microscope. Three figures 711

Alexander S. Begg. A simple form of drawing apparatus. One figure 715

Warren H. Lewis. The use of guide planes and plaster of paris for reconstructions from serial sections: some points on reconstruction. Five figures 719 No. 10. OCTOBER

R. W. Shufeldt. Comparative osteology of certain rails and cranes, and the systematic positions of the super-suborders gruiformes and ralliformes. Nine figures 731

Helen Dean King. The growth and variability in the body weight of the albino rat. Five figures 751

George Bevier. An anomalous origin of the subclavian artery. Three figures 777

Sara B. Conrow. Taillessness in the rat. Three figures 783

Edward F. Malone. Application of the Cajal method to tissue previously sectioned. . . 791


The Growth Of The Body And Organs In Albino Rats Fed With A Lipoid-Free Ration

Shinkishi Hatai

The Wistar Institute of Anatomy and Biology

Nearly seven years ago the wriler attempted to raise stunted albino rats with the hope that a forced retardation of growth would induce some disturbance in the firm relation which normally exists between the weight of the body and of the central nervous system. The stunted rats w^ere produced by feeding them with a minimum amount of nitrogenous food. It was found, however, that in this instance the artificial stunting did not modify the weight relation between the body and the central nervous system (Hatai '08). Although it was highly desirable to pursue this investigation further, yet on account of inconstancy and uncertainty of the outcome in raising stunted rats by the method employed, the investigation was postponed.

In 1911 Professors Osborne and Mendel pubhshed a series of remarkable papers in which the results of maintenance experiments by means of various isolated proteins were fully described. According to these investigators, albino rats about one-third grown can maintain their body weight for a considerable period without revealing any sign of nutritional or physical deterioration. This satisfactory and constant procedure for producing undersized rats renewed my interest in the problem mentioned.

During the past two years I have been so fortunate as to receive a number of stunted rats with their controls for examination. ■ These came through the courtesy of Dr. McCoUum, who raised the rats by feeding them with a 'lipoid-free ration.' These rats fall into two series: the series of 1913 and the series of 1914. The present paper contains the results of the anatomical examination of these interesting rats, and I take this opportunity to thank Dr. McCoUiun for his courtesy in putting these animals at my disposal.

The rats used were from those bred in the colonj^ at The Wistar Institute in Philadelphia and sent to the University of Wisconsin. In each case rats belonging to the same litter were divided by Dr. IMcCoUum into two lots with nearly identical body weights. The one lot was used for control and received the normal mixed ration, while the other lot, which was used for the experiment, received a specially prepared diet. As to the dietary formula, the following statements were kindly furnished by Dr. McCollum: The ration of the experimented rats which received the lipoid-free food was as follows:

Casein 18 per cent Agar-agar 2 per cent

Lactose 20 per cent Dextrin 56 per cent

The salts were as stated below:

Salt mixture

NaCl

MgSO^ (anhydrous)

NaH2P04Ho6

K2HPO4

CaH4(PO)2H20.

Fe citrate

Ca lactate


Per 100 grams

No. m


of ration No. 185


gm.


gm.


0.808


0.168


0.264


0.264


0.336


0.336


0.936


0.964


0.528


0.528


0.096


0.096


2.000


1.300


The salt mixtures no. 174 and no. 185 were given at different periods in the case of both series.

At the end of the experiment these rats were shipped back to The Wistar Institute for the anatomical examination, where the writer determined the weights of the following organs: Brain and spinal cord, heart, lungs, kidneys, Uver, spleen, alimentary tract, testes and ovaries, suprarenals, thymus, thj^roid, hypophysis and eyeballs. Some of these organs were preserved for further histological examination. Besides the organs mentioned, the bones also were examined.

Although the methods employed in determining the relative amount of alteration in the various organs of the experimented rats, and also the technique for the preparation of the bones and separation of the encephalon into the four parts can be found in my papers recently published (Hatai '13 and '14), I shall briefly restate the essential points. The encephalon was divided into four parts in the following

1. Olfactory bulbs. The protruding portions of the olfactory tract with bulbs were cut from the rest of the encephalon by section of the tract just caudad to the bulb.

2. Cerebrum. The cerebrum is separated from the stem by a cut passing just in front of the dorsal edge of the anterior collicuh and just caudad to the corpus mammiUare on the ventral surface.

3. Cerebellum. The cerebellum is separated by severing the peduncles.

4. Stem. The structure which is left after removal of these three parts mentioned above, is called the stem.

The bones were prepared as follows: The bones are freed from the main bulk of muscles and placed in a hot aqueous solution of 2 per cent 'gold dust washing powder.' After maceration for several hours at nearly 90°C., the remaining soft parts are removed. The bones thus prepared are gently wiped with blotting paper and are weighed. . This gives the 'fresh weight.' These weighed bones are then dried at 9o°C. for one week and the amount of moisture determined from the weight of the dried residue.

In order to determine the amount of modification following the experimental ration, we have employed our usual method of comparing the observed values with those found in a series of reference tables that have been compiled in this laboratory. These tables present for normal rats adequate data on all the organs and characters under consideration and in each case the graph representing the table can be expressed by a mathematical formula (Hatai '13; Hatai '14).

In making the comparison between the observed values and those in the tables— the body length is always used as the basal measurement and the weight of the body or organs as observed compared with the corresponding values given in the reference tables. In this manner comparison is made not only for the experimented rats but also for those used as controls. The departures of the observed values from those in the tables having been observed in each case — the difference between that found for the experimented animals and that for the controls is obtained and this figure is used to indicate the amount by which the experimented animals have been modified.

Two examples will serve to illustrate this procedure. They are taken from table 3 — C, normal males, 1914 series: (1) On the 'mixed ration' the average tail length for the three rats is 172 mm., for the ^iven body length, 196 mm. We expect from the reference tables a tail length of 165 mm. The observed value is therefore plus 4.2 per cent. The two rats on the "lipoid-free diet and egg fat" give a tail length of 151 mm. for a body length of 168 nmi. From the reference tables we should expect a tail length of 139 mm. The observed value for the tail length of the experimented group is therefore plus 8.6 per cent. The difference between these two percentage shows the tail length in the experimented group to be 8.6 — 4.2, or 4.4 per cent greater than that of the controls. This is the value given in table 3. (2) Taking the brain weights for the groups just used we find by following the method employed above for the tail length, that the group on the "mixed ration" has a brain weight 4.8 per cent below the reference table value, while the group on the "hpoid-free ration plus egg-fat" has a brain weight which is 6.4 per cent deficient. Thus the brain weight in the experimented group is — 6.4 less — 4.8 or 1.6 per cent lower than in the controls. This is the value entered in table 2. All the percentage differences in the accompanying tables have been obtained in a manner similar to that illustrated by the two examples just given.

The only modification in procedure to which attention need be drawn is in the cases where the data from two series, 1913 and 1914, have been combined. In those cases the percentage deviation which is given in the table is the mean of the deviations for each series computed separately.


GROWTH OF BODY AND ORGANS


GROWTH OF BODY IN WEIGHT

The modifications of the growth of the body in weight due to the lipoid-free ration are shown in tables 1 and 2. Table 1 refers to the growth of the albino rats belonging to the 1913 series, while table 2 refers to the growth of the 1914 series. We note in both tables that the rats fed with the mixed ration made nearly normal growth in respect to their ages (see Donaldson '06). The spring

TABLE 1

Showing the weight of the body as modified by the lipoid-free ration compared with that of the rats raised on the mixed ration {1913 series)



MALES


FEMALES


DATE


Mixed ration (3)


I Lipoid-free 1 ration (4)


Mixed ration (4)


Lipoid-free ration (5)


1913

April 16


94.7

129.7 137.7 153.7 149.3 159.7 166.3 173.3 185.0 196.7 209.7 223.3 222.7 229.0 243.3 249.7


93.8

122.7

127.8

134.8

136.5

1 139.0

140.7

i 131.5

1 124.8

134.2

139.7

143.2

1 149.2

i 151.0

155.0

153.5


85.0 112.0 125.7 146.7

litters

<( « 

129.0 140.7 143.3 151.0 156.7 161.0 166.0 167.7 172.7


76.2


30


92.4


Maj' 7


98 6


14


108.4


21


107.4


28


108.4


June 4


108.4


11


103.8


23


107.8


30


109.0


July 7


111.6


14


111.0


21


107.2


28

August 15

September 1


111.8 118.6 125.2


rats in 1913 made much better growth than the autumn rats in 1914. On the other hand, the experimented rats in both series made a noticeably poor growth when contrasted with the controls. In the 1913 series we notice that the experimented rats made continuous and steady growth throughout the period of experimentation, although the total amount of growth in weight was very slight. Curiously enough the experimented rats belonging to 1914 made a still smaller growth, and indeed in some cases the final body weight is no higher than the body weight at the beginning of the experiment. This difference in growth in the two series may probably be due to the different physiological condition of the rats in these two series, combined with slight differences in the preparation of the ration. One point is clear, however: that the rats cannot continue the normal rate of growth on the lipoid-free ration in combination with the salt mixture which was used.

In table 2 we have also the data on the growth of the body of the albino rats which were fed first with the lipoid-free ration and later with the same ration to which a minute quantity of the egg-fat had been added. For convenience, these last mentioned rats will be designated simply as 'egg-fat series.'

It was found by McCollum and Davis ('13) that the rats whose body growth had ceased for a long period as the result of the lipoid-free ration, could be made to grow by the addition of a minute quantity of the extract of egg to the experimental ration. In order to see whether or not the rats thus treated would show any modifications other than those shown by the rats fed with the simple experimental ration, a small series was carried on. As will be seen from table 2, the 1914 rats given the extract of egg did not show the improvement in the growth of the body which was to be anticipated.^ Thus the growth of the body is nearly identical in both the lipoid-free series and in the egg-fat series. Why in the present experiment the egg-fat series did not show a noticeable improvement in the growth of the body is not clear. However, from the fact that the control rats belonging to the 1914 series did not make satisfactory^ growth when contrasted wdth the 1913 series, we conclude that the failure to grow was

1 Our experience in feeding synthetic rations in this laboratory has convinced us that there exists a great variation in the vitality of individual rats as indicated by their ability to gro-^*^ on such rations. It is unfortunate that practically all of the animals employed in the work here reported were not sufficiently vigorous to grow for a time in a nearly normal manner on the experimental ration, or to respond by a period of active growth when the ration was supplemented with egg yolk fats. We have individual rats in our colony at the present time which have been on the diet employed in the lipoid-free period with egg j'olk fats added, during more than six hundred days, and which compare favorably with our stock rats in size and well-being." — E. V. McCollum.


8 SHINKISHI HATAI

probablj' due to a peculiarity of the rats rather than a pecuHarity of the experimental ration.

Osborne and Mendel ('12) obtained normal growth of the rats with the ration from which the lipoid had been almost entirely removed. They carried the experiment for a considerable length of time by beginning with albino rats slightly over 30 days in age. In one series the experiment lasted for nearly 160 days. In every instance, so far as one can judge from the graphs, the body weight of the experimented rats was nearly identical with that of the control rats, while McCollum and Da\ds' rats, fed with the lipoid-free ration, did not grow at any period to the size of the controls (]McCollmii and Da\ds ' 13 ; see also present series) .

This difference in growth between the rats of Osborne and Mendel, on the one hand, and those of McCollum and Davis on the other, was undoubtedly due to the nature of the inorganic salts and some extracts still contained in the food. The Osborne and Mendel rats received the inorganic salts from protein-free milk, while those of JMcCollum and Davis received the salts which were a laboratory mixture of pm"e chem.icals. In reference to the varying effects of different salt mixtures McCollum and Davis state ('13) that

"Yoimg rats have been found to be very sensitive to variations in the character of the salt mixtures supplied, but with certain mixtures we have been able to obtain practically' normal growth for periods varying from 70 to 120 days. Beyond that time little or no increase in body weight can be induced with such ra^tions. The rats may remain in an apparent!}' good nutritional condition on those rations for man}^ weeks after growth ceases."

ANATOMICAL ANALYSIS

We now wish to present the results of the anatomical examination of these interesting rats reared by McCollum at the University of Wisconsin.

Although the growth rate was dissimilar in the two consecutive years, nevertheless it was found that the alterations shown by the various characters are nearly identical in the two series oi exper ments, and on account of this uniformity in the results, as well as to avoid unnecessary complication by presenting the two series of data separately, I have combined the results. Consequently, unless otherwise stated, the figures given in the tables represent the averages of the two sets of data belonging to the 1913 and the 1914 series combined.

CENTRAL NERVOUS SYSTEM

If the hpoid-free ration is able to produce any alterations in the lipoid content of the organs, the central nervous system would naturally be expected to indicate such effects, since the central nervous system of the albino rat at about 200 days of age normally contains some 60 per cent of lipoid in the dried residue (Koch '13). This lipoid content is certainly greater in the nervous system than in any other organ (Koch '11). The weights of the central nervous systems of the experimented and of the control rats are shown in table 3 (see also page 16). As will be seen from this table, the weight of the brain with respect to the body length is generally slightly smaller in both the lipoidfree and egg-fat series. Only one exception is found in the female rats (B) fed with the lipoid-free ration in which the experimented rats show a slight over weight of 0.7 per cent. This slight increase is probably due to the abnormally small brain weight of the control rats, thus raising the relative weight of the central nervous system of the experimented rats. Indeed the nonnal brain weight of the female rats corresponding to the body length of 189 mm. should be 1.80 grams as against the observed weight of 1.73 grams, i.e., the observed weight of the control is nearly 4 per cent less than the normal brain weight. Without making any correction, however, we find on the average that the experimented rats show about 2 per cent less brain weight than the controls.

Similarly we find a reduction of 2.1 per cent in the weight of the spinal cord when compared with that of the control rats. This reduction of 2 per cent in weight in both the brain and spinal cord is somewhat greater than what we might expect from the normal fluctuation, nevertheless it is certainly far smaller than one might anticipate from the nature of the experunent. It seems reasonable, therefore, to conclude that the central nervous


PER CENT WATER

Brain Sp. cord


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GROWTH OF BODY AND ORGANS 11

system is adequately supplied with the necessary amount of the lipoids from the body and this fact in turn leads us to assume that the body has the ability to synthesize the lipoids from the non-lipoid materials. McCollum ('12) has demonstrated that the phosphorus needed by the animal for phosphatid formation can be drawn from inorganic phosphates, and that phosphatids can be synthesized anew in the animal body. Further investigation of McCollum ('12) indicates that certain complex lipoids of the lecithin type can be synthesized in large amounts by birds.

The percentage of water found in the central nervous system indicates also that the chemical composition has not been noticeably altered since the difference between the control and experimented rats is only 0.2 per cent in the brain and 0.5 per cent in the spinal cord; both in favor of the controls. It is to be noted, however, that a small reduction appears in all the experimented series, thus indicating a strong tendency to a slight modification.

To determine whether or not the reduction of 2 per cent in the weight of the central nervous system was mainly caused by the alteration in the white substance, in which the lipoids are predominant, the brain was divided into four parts and the weights and water content of those parts were found separately. The results of the investigation are shown in table 4. We notice from the table that although the percentage of water tends to be smaller in the experimented rats in all four parts, nevertheless the greatest relative reduction appears in the olfactory bulbs, the cerebellum comes next and the cerebrum and stem come in the order named. Thus the stem where the lipoid constituent is greatest is least modified and the olfactory bulbs and cerebellum, where the lipoid constituent is least, are most affected. From this we infer that the gray substance is most affected, and the white substance, in which one might anticipate the largest alteration, is least modified.

This fact of greater change of the gray matter is interesting, since it is found that during partial starvation with non-nitrogenous food for three weeks, the total brain weight shows a reduction of 5 per cent (Hatai '04) but the amount of myelin, as can be seen from the normalitv in the amount of alcohol and ether extract as well as from the Weigert preparations, is not altered (Donaldson '11). We conclude therefore that the absence of lipoids from the ration does not affect the amount of the lipoids in the central nervous system, but on the contrary, the gray substance is affected. This alteration of the gray substance is similar to the effect of partial starvation on the brain of the albino rat.

SKELETAL SYSTEM

The skeletal system is naturally looked on as another structure which might show some alteration owing to the use of the artificial mixture of the pure chemicals contained in the ration in place of the salts normally present. For this purpose the following bones were examined: femur, tibia and fibula, humerus, radius and ulna. The results of the investigation are given in table 5. We note from this table that the ratio between body length and bone length and the ratio between body weight and bone weight are not altered. However, the water content found in these bones shows a distinct alteration in the experimented rats. The difference amounts to as much as 5.5 per cent in the case of the lipoid-free ration and 5.3 per cent in the case of the egg fat series; both in favor of the experimented rats. This difference of over 5 per cent is far greater than the usual incidental fluctuations. Furthermore, its constancy in direction in all these cases indicates that the chemical composition of the bones must be affected as the result of the experimental ration.

SEX GLANDS

The alterations thus far recorded are all of small magnitude, but we now come to the consideration of the one very obvious alteration. This is manifested by the testes and ovaries.

TESTES

We notice from table 3 that the experimented male has considerably smaller testes than the control. The difference amounts to as much as 44 per cent against the experimented. We notice also that the initial body weight of the experimented male rat was 87 grams; this body weight calls for nearly 1.09 grams of testes, while the observed final weight is but 0.83 grams, thus showing a difference of nearly 23 per cent. We conclude therefore that the testes not only failed to grow during nearly six months of the special diet, but that there is a clear indication of an actual loss in weight.

OVARIES

In the case of the ovaries the difference between the controls and experimented is less than one-half of that found in the case of testes. The difference amounts to 17.4 per cent against the experimented. The initial body weight of the female rat was 80 grams; this body weight calls for nearly 0.015 grams of ovaries, while the observed final weight is 0.028 grams, thus showing an increment of more than 80 per cent during the experimental period of nearly six months. Thus it is clear that although the weight of the ovaries was 17 per cent smaller than that of the controls, nevertheless the ovaries of the experimented rats made steady growth, and indeed the final weight of the ovaries was nearly double the initial weight. The functional normality of the ovaries in the lipoid-free series is demonstrated by the fact that some of the females raised on the lipoid-free ration produced litters (McCoUum and Davis '13).

EFFECT OF LIPOID-FREE RATION ON CASTRATED MALE RATS

The reduction of the testes in weight as the result of the experimental ration (1913 series) suggested that the same experimental ration when given to castrated male rats might produce a diff'erent alteration. To determine tliis point a series of castrated rats was sent to Dr. McCollum. Five of these castrated rats were fed with a mixed ration and six others were fed with the lipoid-free ration, to which latter a small amount of the egg-fat was added occasionally. The results of the investigation are given in tables 2, 3, 4 and 5. As is seen from table 2, the growth of the body in weight in castrates fed with the lipoid-free ration is similar to that of the intact rats fed in the same way. Thus castration, plus the lipoid-free ration, does not produce any other alterations, the testis excepted, than those shown by the intact rats fed in the same way.

We further note from tables 3 (E) and 4 that the central nervous system of the castrates fed with the experimental ration is not different from that of the intact rats fed in the same way Thus it is clear that the effect of the ration is not modified by castration. This conclusion applies also to the ratio between body length and bone length and the ratio between body weight and bone weight. The only difference is found in the percentage of water in bones of those castrates fed with lipoid-free ration.

We note that the difference in the water content of the bones between the castrates fed with the mixed ration and the castrates fed with the experimental ration, amounts to 13 per cent, which is much more than the difference between the intact rats on a mixed ration and those on the experimental ration. This greater difference of water content is found also in all individual cases. We conclude, therefore, that castration followed by the lipoid-free ration produces no further alteration than is found in the non-castrated rats fed with the same experimental ration, except in the water content in the bones. No explanation is possible for this singular result until further experiments have been made.

THE VISCERAL ORGANS AND DUCTLESS GLANDS

As has already been stated, the visceral organs and ductless glands, together with the eyeballs of these rats, were also examined. However, in ^dew of the greater variability of these organs as well as the relatively small number of rats examined, I have decided not to attempt at this moment to interpret the alterations recorded by these organs. Nevertheless, for the reader who may wish to know the weight relations between the controls and the experimented rats shown by these organs, table 6 is given, where the results of the investigation are presented.

It may be important to add one word concerning the weight of the lungs. As will be seen from table 6, the weights of the lungs belonging to the experimented rats are always considerably smaller than those of the controls. This means that the lungs of the experimented rats were in a healthy condition and that the greater weights found in the controls were due not to sound lungs of larger size, but to a diseased condition. This fact must be considered when interpreting the weight relations given by various other organs whose weights vary with the condition of the hmgs (Hatai '13).

CONCLUSIONS

1. The lipoid-free ration diminishes the normal rate of the growth of the body.

2. The weight of the central nervous system shows a reduction (^f about 2 per cent as the result of the experimental ration. The percentage of water found in the central nervous system shows a verj^ slight diminution.

3. The different parts of the encephalon are differently altered. In general, the parts where the gray substance is predominant are more affected than the parts where the white substance is predominant.

4. The weight and length of the longer bones with respect to body weight and body length are not modified. The percentage of water found in these bones, however, is constantly greater (5 per cent) in the experimented rats. This indicates that the chemical composition of the skeletal system has been somewhat altered.

5. The testes of the experimented rats showed not only a deficiency of 44 per cent as a result of six months of the lipoidfree diet, but there is a clear indication of actual loss in weight (23 per cent).

6. The ovaries of the experimented rats were smaller in weight by 17.4 per cent but no loss of the gland has occurred and growth was continuous.

7. The reactions shown by the hpoid-free ration and egg fat series are similar to those produced by partial starvation, especially with respect to the responses by the central nervous system and b}' the sex glands.

8. Although the lipoid-free ration causes a marked atrophy of the testes, yet in castrates on the lipoid-free ration no special alteration occurs which can be referred to castration, save the diminution of the solids in the bones.

9. Two incidental observations call for comment: (a) The loss of solids in the bones of the rats receiving a lipoid-free diet is of interest owing to the possible use of the phosphorus of the bone in the formation of lipoids, (b) On the Upoid-free diet, as well as in various forms of underfeeding, and after longcontinued exercise, the rats become remarkably resistant to the lung infection which appears in the controls.

LITERATURE CITED

DoxALDSOX, H. H. 1906 A comparison of the white rat with man in respect to the growth of the entire bod}^ Boas Anniversary N'olmne, New York. 1911 Tlie effect of underfeeding on the percentage of water, on the ether-alcohol extract and on medullation in the central nervous sj'stem of the albino rat. Jour. Comp. Xeur., vol. 21, no. 2, pp. 139-145.

1911 a An interpretation of some differences in the percentage of water found in the central nervous system of the albino rat and due to conditions other than age. Jour. Comp. Xeur., vol. 21, no. 2, pp. 161-176.

Hatai, S. 1904 The effect of partial starvation on the brain of the white rat. Amer. Jour. Physiol., vol. 12, no. 1, pp. 116-127.

1908 Preliminary note on the size and condition of the central nervous system in albino rats experimentally stunted. Jour. Comp. Xeur., vol. 18, no. 2, pp. 151-155.

1913 On the weights of the abdominal and the thoracic viscera, the sex glands, ductless glands and the eyeballs of the albino rat (Mus norvegicus albinus) according to body weight. Am. Jour. Anat., vol. 15, no. 1, pp. 87-119.

1914 On the weight of the thymus gland of the albino rat (Mus norvegicus albinus) according to age. Am. Jour. Anat., vol. 16, no. 2, pp. 251-257.

1915 The growth of organs in the albino rat as affected by gonadectomy. Jour. Exp. Zool., vol. 18, no. 1, pp. 1-68.

Koch, W. 1911 Recent studies on lipoids. Jour. Amer. ^led. Assoc, vol. 56, pp. 799-801.

1913 Contributions to the chemical differentiation of the central nervous system. III. The chemical differentiation of the brain of the albino rat during growth. Jour. Biol, (^hem., vol. 15, no. 3, pp. 423448.

McCoLLTj.M, E. v., and Davis, ^Iarguerite 1913 The necessity of certain lipins in the diet during growth. Jour. Biol. Chem., vol. 15, no. 1, pp. 167-175.

1914 Further observations on the physiological properties of the lipins of the egg yolk. Proc. Soc. Exp. Biol, and ]\led., vol. 11, no. 3, pp. 101-102.

McCoLLUM, E. v., Halpix, J. G., and Drescheh, A. H. 1912 Synthesis of

lecithin in the hen and the character of lecithins produced. Jour.

Biol. Chem., vol. 13, no. 2, pp. 219-224. Osborne, T. B., and Mendel, L. B. 1911 Feeding experiments with isolated

food substances. Carnegie Institution of Washington, Publication

Xo. 156.

1912 Feeding experiments with fat-frcc food mixtures. .Jour. Biol. Chem., vol. 12, no. 1, pp. 81-89.


The Source Of The Hydrochloric Acid Found in The Stomach

Frederick S. Hammett

From the Departments uf Anatomy and Biochemistry of the Harvard Medical School,

Boston, Mass.

At the present time two opinions exist as to the source of the hydrochloric acid found in the stomach. The work of ]\Iiss Fitzgerald (1910) tends to show that the parietal cells of the gastric glands are the seat of the direct formation of the acid. Harvej^ and Bensley (1912), on the contrar}-, report that their experiments demonstrate that while these cells may form precursors of the acid, they do not produce the acid itself. Previous to these. publications, Frankel (1891) as well as Edinger (1880), by using d^'es, had demonstrated an acid reaction below the surface epithelium of the gastric mucosa; but they could not accurately localize the source of the acid.

The disagreement between the conclusions of I\liss Fitzgerald and of Harvey and Bensley appears to call for a critical review of their work, such as is here undertaken. In preparing it, I must thank both Dr. Frederic T. Lewis and Dr. Otto Folin for generous assistance.

Miss Fitzgerald found direct proof of the presence of acid in the Imiiina of the gastric glands, in the canaliculi of the parietal cells, and even in the parietal cells themselves. She found in these places a deposit of Prussian blue after injecting a ferrocyanide and a ferric salt into the ears of the animals experimented upon. This precipitate is formed in the presence of hydrochloric acid and the two salts mentioned. She found the precipitate in no other place than the immediate vicinity of the parietal cells. From her findings she ch'aws the conclusion that the parietal cells of the gastric glands produce the hj^di'ochloric acid found in the stomach.

Harvey and Bensley consider that ]Miss Fitzgerald's conclusions are unjustified, for reasons which are discussed Seriatim in the following paragraphs.

1. The reaction is not constant. In some of ]\Iiss Fitzgerald's experiments the Prussian blue reaction was not obtained, and Harvey and Bensley, who repeated her work, likewise report unsuccessful experiments. Xo explanation, other than mere conjecture, is offered to account for these failures.

2. When present, the reaction is restricted to limited areas. Regional activity of the glands, decreased blood supply, and inhibition of secretory function due to the toxic effects of the injected salts, are all sufficient to explain this effect; the actual cause is unknown.

3. Within the areas which respond, the reaction occurs in only a few cells. The non-reacting cells can be considered either as resting cells, or as those which have already discharged their acid and are prevented from further activity by the toxic effect of the injected salts. It is to be noted that the parietal cells of the deeper third of the gland tubules, that is, the third farthest from the free surface, never contained the Prussian blue." This may be correlated with the fact that the upper end or neck of the tubules is the source of new cells, as indicated by the presence of mitotic figures. And further, as stated by Kolliker Q902, p. 158), "the parietal cells are infrequent at the bottom of the glands, where they may be entirely absent; they increase in the body of the gland and are most frequent in the region of its neck." Thus the Prussian blue reaction appears to occur where the parietal cells are most active and most numerous.

4. The reaction occurs in other places than the gastric glands. Miss Fitzgerald did not find the Prussian blue precipitate in any tissues but those of the stomach wall. As a result of che toxic action of the injected salts a marked inflammation occurred. This would signify an increased permeability of the cell walls, and the secreted acid of the parietal cells could escape into the neighboring tissues as well as into the natural pathway. That only traces of the precipitate were found outside of the glands proper is fairly convincing evidence of its intensive localization.

Although Harvey and Bensley found a precipitate in the liver, spleen, and blood vessels of the cardiac muscle, yet this precipitate may indeed not have been typical Prussian blue. We find, for example, that lactic acid, when added to a mixtm-e of the salts in question, causes an atypical precipitate. This may explain Harvey and Bensley 's apparently contradictory results of finding no precipitate in the heart's blood but finding it in the vessels of the heart muscle. In all probability it was precipitated there by the liberation of lactic acid from the dead muscle. Moreover we find that blood serum, blood plasma, and various salts which occur in the blood (sodium bicarbonate, sodium carbonate, sodiiun chloride, di-sodimii phosphate, and monosodium phosphate, each in 0.1 per cent solution) may be added to a mixture of potassium ferrocynnide and iron and ammonium citrate without causing a precipitate. This is contrary to Harvey and Bensley's conclusion that '^the Prussian blue is precipitated in the blood stream when solutions of these salts (sodimn ferrocyanide and iron and ammonium citrate) are injected into it." At least there is no precipitate of Prussian blue when the salts are added to fresh normal blood in vitro.

Some of Harvey and Bensley's results with the Prussian blue reaction afford interesting evidence in support of Miss Fitzgerald's ideas. For instance, they find the Prussian blue precipitate on the mucous surface of the stomach, and prove that there is no backing up of the precipitate into the lumina of the glands; but occasionally they find the Prussian blue precipitate in these Imnina. Therefore the Prussian blue must have been formed in the lumina of the glands. This necessitates acid, yet Harvey and Bensley deny the presence of acid in this situation. It seems as if they had furnished evidence of the presence of acid in the lumina of the glands of the gastric mucosa.

Furthermore, as might be expected on physiological grounds, they find that poisons and a decreased or restricted blood supply do not increase the formation of the Prussian blue precipitate. These influences would be expected to decrease the liabihty of precipitate formation, so that only the favored locations would be able to respond. Both by their criticisms and their own work wdth the Prussian blue reaction, Harvey and Bensley appear to have strengthened greatly the conclusions of Aliss Fitzgerald. After summarizing her experimental findings they state — Our own results have confinned these facts entirely." To prove that the cells of the gastric glands do not produce hydrochloric acid as such, Harvey and Bensley attempted injection experiments with various dyes; but this line of work did not yield satisfactory results

The next form of attack was to immerse portions of the gastric mucous membrane from a freshly killed animal in a solution of the dye cyanamin in normal sodium chloride solution. This dye yields distinctive colors for acid, akaline, and neutral solutions. With this method they found the contents of the gland cells to be alkaline. The acid reaction occurred on the surface of the mucosa and extended inward as far as the bottom of the gastric pits or foveolae. There it changed rapidh^ thi'ough neutral to alkaline, and so it extended through the Imnina of the glands and into the secretory canaliculi of the parietal cells, which were thus strikingly demonstrated.

^^'e have prepared cyanamin according to the directions given b}' Witt (1890) and have repeated Harvey and Bensley 's experiment, obtaining similar results; but we draw different conclusions from these results.

Harvey and Bensley found that the concentration of the gland secretion is quite different from that of normal saline solutions. This being so, the laws of osmosis and diffusion come into play and we can not go on the supposition that the addition of the dye to the normal saline solution renders it isosmotic with the cell contents. Apparently no attempt was made to determine the relative concentrations of the reacting substances, e.g., dye and hydrochloric acid.

In order to determine for ourselves whether the dye oi" the hydrochloric acid diffused the more rapidl}, experiments were conducted to that end. As might be expected, it was found that the acid diffused with by far the greater rapidity under conditions


SOURCE OF HYDROCHLORIC ACID IN STOMACH 25

approximating those in which the tissue was used. Having estabHshed this fact we have the following mechanical process as an explanation of Harvey and Bensley's results.

The hydrochloric acid secreted by the gland cells diffuses out of the cells, through the canaliculi and into the lumina towards the free surface, faster than the dj'^e diffuses inward along the same path. Consequently the mucous surface of the tissue and the foveolar contents show acidity. The tissue, after removal from the organ, does not continue to perform its secretory function, nor does it excrete save by diffusion. This then leaves the cell contents alkaline, as is shown by the fact that the slOwly moving dye stains the cells with the alkaline reaction. Supposing we have hydrogen weakly bound to protein and ionizing in the cell to (H)+ and protein. We know we have sodium ions and chlorine ions present. NaCl = (Na) + + (CI)-. Removing the hydrogen ions and the chlorine ions we have an excess of sodium ions, thus making the cell contents alkaline.

The localization of the reaction between the dye and the acid is dependent upon the relative velocitj'^ of the participating constituents. Inasmuch as the acid has the higher velocity, we get the recorded results and a stable confirmation of Miss Fitzgerald's experiments and conclusions.

LITERATURE CITED

Edinger, L. ISSO Zur Kenntniss der Driisenzellen des Magens, besonders beim ^Menschen. Arch. mikr. Anat., Bd. 17, pp. 193-211.

Fitzgerald, M. P. 1910 The origin of the hydrochloric acid in the gastric tubules. Proc. Roy. Soc. London, Ser. B, vol. 83, pp. 56-94.

Frankel, S. 1891 Beitriige zur Physiologic der Magendriisen. Arch, gesammte Physiol., Bd. 48, pp. 63-74.

Harvey, B. "c. H., and Bensley, R. R. 1912 Upon the fonnation of hydrochloric acid in the foveolae and on the surface of the gastric mucous membrane and the non-acid character of the gland cells and lumina. Biol. Bull., vol. 23, pp. 225-249.

KoLLiKER, A. 1902 Handbuch der Gewebelehre des :Menschen. 6te Auflage, Bd. 3, herausgegeben von V. von Ebner. Leipzig.

Witt, O. N. 1890 Ueber die Cyanamine, eine neue Gruppe von Farbstoffen. Ber. deutsch. chem. Gesell., Bd. 23, pp. 2247-2252.


STROPPING MACHINE FOR MICROTOME KNIVES

M. J. G.

The Wisiar Instiiuie of Anatomy and Biology

This machine consists of two reciprocating carriers moving at right angles to each other, one (A) bearing the knife with the reversing mechanism and the other (B) carrying the strop. These carriers are actuated by cranks of unhke speeds (C, D) geared together (at E) and driven by a belt from a motor (F). The entire apparatus is constructed on an angle iron (2 inches X 2 mches) frame. Carrier B (fig. 2) is a hea\'y brass plate 19 inches long, 3| inches wide, and designed to carry a strop (H) 15 inches long and 2j inches wide. This carrier is grooved and accurately fitted to a base casting (G) upon which it travels. At each end of the carrier is a pillar (/). A f inch steel rod (J) connects the tops of these pillars and carries a lug (K) at each end.

Carrier ^ is 12 inches long and is designed to carry a knife of any length from 3| inches to 7 inches. This carrier is mounted and moves in a base L secured at right angles to the base G.

and are vertical pillars carrj^ing | inch steel rods M, M, which move freely in a direction vertical to the plane of the strop. To the rods {M, M,) are attached by universal joints, the axis Q carrying the reversing mechanism R and the gear wheels T, T. Axis S (in which the knife forms the central portion) is also attached by universal joints to the vertical rods, M, M. It has also a gear wheel at each end meshing with the gear wheel T of the corresponding end of axis Q. The supporting pillar may be adjusted upon carrier A to accomodate a longer or shorter knife. Axis S is made up of the knife X and the gear wheels Y, Y, with their hollow spmdles as shown in figure 3. By means of pm Z the shank of the knife is prevented from turning in the hollow spindle of the gear wheel Y.

The gear wheel Y carries a wrist pin XX (fig. 3), to which is attached the lower end of the dash-pot DP (fig. 2); the upper member of the dash-pot is attached to axis Q. The dash-pot consists of an outer steel cylinder having an air outlet at the top (the size of which outlet may be changed by a screw) and an inner brass plunger with an air inlet at the bottom controlled by a valve. The springs on each side of the dash-pot tend to force the plunger into the cylinder by driving the air through the outlet at the top. The dash-pot springs, acting upon the wrist pin of the axis S, tend to tilt the knife edge downwards. The

2G



27


28 STROPPING MACHINE FOR MICROTOME KNIVES

dash-pot prevents the knife from striking too hard upon the strop when reversed.

The machine operates as follows: Carrier B moves to the left (fig. 2) while carrier A moves at right angles to carrier B. The knife is thus moved from end to end of the strop, and at the same time it moves part way across the strop. The gear ratio is such that the knife traverses the same path only once in every 137 strokes, thus bringing every portion of the knife edge in contact with every portion of strop surface. As carrier B passes to the end of its stroke to the left, the rod R comes in contact with lug K, and axis Q, with gear wheels T, T, is turned slightly anti-clock-wise. This movement gives the axis S a half turn clock-wise, thus throwing the knife edge to the right, at which instant the carrier B begins its stroke to the right. This process is repeated at each end of the stroke. The dash-pot springs pull the knife over firmly but slowly into its new position at each stroke. The knives used with this machine have a short shank at each end (fig. 3). The vertical rods M, M, move freely upward and downward carr}dng with them the knife and all the reversing mechanism. This permits the knife to follow over the sm'face of the strop and to conform to any irregularities which the strop may present.

The strop consists of a piece of Russia leather stretched over a piece of wood and secured at the ends. The strop is secured to the carrier by dowel pins and may be easily removed; the flesh side of the leather comes in contact with the knife. Any abrasive material may be smeared upon the strop, but experience proves that the best results are obtained by using castor oil in small quantities. The resulting edge is one free from the saw-toothed appearance and may be described as a polished line.

This machine was designed and constructed to do both honing and stropping. In actual use, however, it is found in most cases that a few moments on the honing stone is all that is necessary to prepare the knife for stropping. The practice followed at The Wistar Institute, where the machine has been in constant use for two years, is to give a knife about 10 or 15 minutes hand treatment on the honing stone, and then place it in the stropping machine for 10 to 30 iiours.

Where any considerable amount of section cutting is done the time saved in sharpening microtome knives is a very considerable item. The machine was built at The Wistar Institute^ and may be duplicated ])y any good machinist. A (juarter horse power motor running at 800 r.f).!!!. is used to drive the ma(^hin(\ The strop makes 25 complete strokes i)er minute.


A SIMPLE APPARATUS FOR MICROSCOPIC AND .MACROSCOPIC PHOTOGRAPHY

DANIEL DAVIS

From the Physiological Laboratory, Johns Hopkins University

THREE FIGURES

One of the pioneers in photomicrography was Leon Foucoult,' who in 1844 was the first to make daguerreotypes with the microscope by means of electric light. Since that time many forms of photomicrographic instruments have been designed. All of these cameras, however, can be divided into three types, the horizontal, the vertical, and the convertible, each type possessing advantages peculiar to itself.

Of these three classes of apparatus the horizontal is certainly the oldest and perhaps still the most popular. Its chief advantage is that it allows unlimited l^ellows extension. This was at first of primary consideration, for in the early days of photomicrography the water and xhe oil immersion objectives, to say nothing of the apochromat, were unknown. Consequently, the only way of obtaining high magnifications was by means of a comparativeh' low-power objective used without any ocular, the image l^eing projected a considerable distance onto the plate. This method is still of value when great depth of field is desired. Furthermore, it is somewhat easier to obtain critical illumination with the horizontal camera, since the beam of light can be projected directly into the microscope, obviating the use of the mirror. A simple and efficient camera of this type has been constructed by Parker,^ while very complete and ingenious machines have heea described b}^ Barnard^ and Buxton.^

Owing to its greater compactness the vertical camera is often preferred. With the modern highly perfected lenses great bellows extension is no longer essential for high-i:)ower work. This is due to the fact that the image formed by an apochromatic objective can be very greatlv enlarged bv means of a compensating or projection ocular without losing" anv of its original sharpness. The vertical camera is of course the onlv tvpe to be^ used in photographing specimens in liquid. Perhaps the best camera of this type is the Xim Heurck, but a very snnjMe

1 E. J. Spitta: Jour. Quekett Micr. Club, London, 1907-08, n. s. x, 5L ■' H. B. Parker: Bulletin Xo. 7, of the Hygienic Laboratory, ^\ashington, 1902, p. 7.

3 J. E. Barnard: Tr. Jenner Inst. Prevent. -Med.. London, 1899, 2 s, )). 24S.

B. H. Buxton: Jour. Applied Micr., Rochester, 1901, vol. 4, p. 1366. 29


30 DANIEL DAVIS

outfit has been described by Borden/' while Terras^ has designed a vertical camera resting on the floor in vvhich the microscope is carried on a very low shelf, thus making possible the convenient use of long bellows extensions. The simplest upright camera is a light box fitting directly on the tube of the microscope. The description of an aluminum camera of this character has recently been given by Wilson."

It is to possess the advantages peculiar to each of the above types that the numerous forms of convertible cameras have been designed, and it is to this type that the machine which I wish to describe belongs. It is obvious, however, that such an instrument can not also possess the many little refinements peculiar to either the horizontal or the vertical form. This machme is the result of three years' experimentation. If it merits a description it is because it is so easily and so cheaply built, and because it is so simple and accurate of manipulation.

The stand consists of two parts, the optical bench, and the camera rest. Each is of the same width, length, and thickness. The optical bench is formed from two pieces of | inch poplai 3 feet long and 3 inches wide. These strips are screwed and glued to two cross-pieces, one at each end, each piece measuring | x 3 x 8| inches. There are two other cross-pieces only 2 inches wide, equally spaced across the bottom. In order to make the bench still more rigid, a batten measurmg 3 feet x | X If niches is fastened along either side. These prevent the bench from sagging. On the top of this bench is a track on which the various auxiliary condeiisers slide. This track is formed of two similar brass tubes, 3 feet long, | inch outside diameter, and j\ inch thick. The distance between the centers of these tubes is o| inches.

The camera lest is formed of four poplar strips, all of which are 3 feet long and | inch thick. Two of the strips are 1 inch while the others are 2 inches in width. Only two cross-pieces are used, one at each end. These supports are of exactly the same dimensions as the end crosspieces fitted to the optical bench. Battens are similarly fastened to the sides, the 1 inch strips coming next to them, the 2 inch strips then being fastened in place with a space of 1 inch between them and the narrower pieces. This will leave just enough room l)etween the center pieces for the bolts holding the camera on the rest, while the tubes on the optical bench fit into the spaces on either side when the stand is folded up. The stand complete is shown in figure 3. It will be seen that the parts are fastened together with bracket hinges, while the camera rest can be clamped in a vertical position by means of oak side braces held m place by small bolts fitted with thumlj nuts. The exact dimensions and position of these braces are immaterial, depending somewhat on the size and type of camera used, but the pieces should be slotted at one end as shown, so that to lower the rest to the horizontal position it will be necessary only to loosen the thumb nuts.

^ W. C. Borden: Am. :M()nth. Micr. Jour., Washington, 1S9G, vol. 17, p. 193. 6 J. A. Terras:- Proc. Scot. Micr. Soc, London and Edinburgh, 1899-1903, vol. 3. p. 210.

" L. B. Wilson: Aniorican photogra|)hy, Boston, 1914, vol. 8, p. 204.


APPARATUS FOR MICROSCOPIC PHOTOGRAPHY

Furthermore, it is important to arrange the braces so that the camera may be clamped to either side of the rest. This rest will accommodate nearly any style of plate camera not larger than the G*- x 8* inch size with a bellows extension of not more than 3 feet.

The lamp and the various auxiliary condensers are supported on the track of the optical bench by means of geometric slides, as described bv Barnard.* The slide is made from a piece of | inch poplar 3| inches wide and 10| inches long. Four inches from one end across the bottom of this piece is cut a V-shaped groove h inch deep. The sides of this groove are at 90° to each other; one of the tubes of the track fits into this groove, and it is by this means that the slide is kept m alignment.



Fig. 1 Camera in horizontal position. The U-shaped frame on the microscope table is used to support the ray filter. The condensing lenses, a planoconvex and the meniscus, are arranged for high-power work.


The other end of the support resting on the other tube is cut away till the sHde sits level upon the track. There is, of course, one such support for each lens that is to lie carried on the optical bench, the lens being attached to an upright rod of convenient length fastened to the slide, as shown in figure 2. I liave found it convenient to use three lenses, all 4 inches in diameter. Two are plano-convex of 12 inches focal length, while the other is a double convex lens of 18 inches focal length, thus forming a simple Kohler condensing system, as suggested by Barnard."' These lenses are mounted on i inch sheet iron rings 5| inches in diameter with a 3f inch hole in the center, the lens being supported by three equally spaced machine screws fitted with washers and short spiral spring sleeves. A slotted 6 inch iron rod of the same diameter as the upright on the slide (in this case f inch) is riveted radially to the ring, this rod being fastened to the upright by means of an adjustable clamp.

■'J. E. Barnard: Practical photomicrography, Edward Arnold, London, 1911.


Fig. 2 Camera in vertical position. Ihe two piano-convex condensing lenses arranged for medium-power work. For low-power work the meniscus lens is substituted for the plano-convex lens nearer the light.



Fig. 3 (Camera fitted with a wide angle lens and fastened to the back of the rest for tlie pliotographing of embryos.


Acetylene has proved an excellent illuminant. The light is very actinic, and perfectly steady. A I foot burner is ample, and the gas can readily be made in any simple generator. The gas should be passed through a fairly large bottle before being fed to the burner. This serves to maintain a steady pressure as well as cooling the acetylene and allowing the condensation of water. Such a light used with the condensers just described has proved ample for magnifications of over 1000 diameters.

The microscope is supported on a table, the legs of which just straddle the track on the optical bench to which this table is clamped. Having been properly centered, the microscope is fastened in posit'on by means of an oak stiip extending across the horseshoe base. This strip is bolted to the microscope table. Two small blocks are attached to the table, as shown in figure 1. These fit snugly against the side of the horseshoe base, serving as guides to the correct position of the microscope should it be removed from the stand. All fastenings used on this table should of course be fitted with thumb nuts. The height of the table must be such as to cause the optical axes of the microscope and of the camera to coincide. The condensing lenses and burner are then adjusted. When the camera is placed vertically another table is used of such a height as to make the optical axis of the condensing system center upon the microscope mirror. The condensers thus need no readjustment when changing the camera from the horizontal io the vertical position.

In use this outfit has proved very satisfactory. When in the horizontal position the field can be examined by sliding back the camera fiont, or perhaps more conveniently by removing the microscope from the stand. By means of the guide blocks the microscope can readily be replaced in correct alignment. When using the greatest bellows extension, focusing is accomplished b}^ means of a waxed silk cord passing around a little pulley fitted to the knob of the fine adjustment. When used vertically the microscope, once haviag been adjusted, is not moved. If it is desired to examine the field it is but necessary to raise the camera front a few inches and then lowei the camera rest out of the way into the horizontal position. When ready to photograph the camera can quickly be swung up over the microscope. Finally, by clamping the camera to the back of the stand, as shown m figure 3, and using a photographic lens of short focal length, a most couvenient arrangement is obtained for copying drawings, or photographing embryos or other macroscopic specimens.


INCREASE IN PRICE OF JOURNALS

In order to extend and improve the journals published by The Wistar Institute, a Finance Committee, consisting of editors representing each journal, was appointed on December 30th, 1913, to consider the methods of accomplishing this object. The sudden outbreak of European misfortunes interfered seriously with the plans of this conmiittee. It was finally decided, at a meeting held December 28th, 1914, in St. Louis, Mo., that for the present an increase in the price of these periodicals would not be unfavorably received, and that this increase would meet the needs of the journals until some more favorable provision could be made.

This increase brings the price of these journals up to an amount more nearly equal to the cost of similar European publications and is in no sense an excessive charge.

The journals affected are as follows:

THE AMERICAN JOURNAL OF ANATOMY, beginning with Vol. 18, price per volume, $7.50; foreign, $8.00.

THE ANATOMICAL RECORD, beginning with Vol. 9, price per volume, $5.00; foreign, $5.50.

THE JOURNAL OF COMPARATIVE NEUROLOGY, beginning with Vol. 25, price per volume, $7.50; foreign, $8.00.

THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY

36th Street and Woodland Avenue Philadelphia, Pa.


PROCEEDINGS OF THE AMERICAN ASSOCIATION OF ANATOMISTS

THIRTY-FIRST SESSION

At the Washington University Medical School, St. Louis, Mo., December 28, 29 and SO, 1914

Monday, December 28, 9.30 a.m.

The thirty-first session of the American Association of Anatomists was called to order by President G. Carl Huber, who appointed the following committees:

Committee on Nominations: G. S. Huntington, chairman; Irving Hardesty, Florence R. Sabin.

Auditing Committee: T. G. Lee, chairman; A. T. Kerr.

President G. Carl Huber, in recognition of the great loss the Association had sustained in the death of Professor Minot, suggested that some arrangement be made for expression from the Association. Prof. F. T. Lewis moved that the following committee be appointed to draw up appropriate resolutions: Chairman, Prof. George S. Huntington; Members, Professors G. Carl Huber and R. J. Terry, the resolutions to be presented at a future meeting of the Society.

Tuesday, December 29, 12.00 m. Association business MEETING, President G. Carl Huber, presiding.

The Secretary reported that the minutes of the Thirtieth Session were prifited in full in The Anatomical Record, volume 8, number 2, pages 69 to 145, and asked whether the Association desired to have the minutes read as prmted. On motion, seconded and carried, the minutes of the Thirtieth Session were approved by the Association as printed in The Anatomical Record.

Prof. T. G. Lee reported for the Auditing Committee as follows: The undersigned Auditing Committee has examined the accounts of Dr. Charles R. Stockard, Secretary-Treasurer of the American Association of Anatomists, and finds the same to be correct, with proper vouchers for expenditures, and bank balance on December 23 of 1285.85. (Signed) T. G. Lee, A. T. Kerr; St. Louis, Mo., December 29, 1914.

The Treasurer made the following report for the year 1914:

Account of G. Carl Huber, former Secretary-Treasurer, closed January, 10, 1914 Balance on hand December 26, 1913, when accounts were last

audited S213.03

Collections made from December 26 to January 10, 1914 55 .00

Total deposit S268.03 S268.03

Expenses of Secretary-Treasurer attending Philadelphia Meeting, December 29-31, 1913 S49.00 49.00

Balance sent by draft to Charles R. Stockard, SecretaryTreasurer $219.03

Amount of draft §219.03

Receipts for dues, 1914 1520.20

Total deposits for 1914 S1739.23 $1739.23

Expenditures for 1914:

Postage (S45.42), printing (834.00) 879.42

To 305 subscriptions to 1 volume of the American Journal

Anatomy and 1 volume of the Anatomical Record @ $4.50 1372.50 To collections and exchange on foreign and domestic drafts 1 .46

total expenditures 814.53.38 S1453.38

Balance 8285.85

Balance on hand, deposited in the name of the American Association of Anatomists in the Corn Exchange Bank, New York City, December 23, 1914.

On motion the reports of the Auditing Committee and the Treasurer were accepted and adopted.

The Committee on Nominations, through its Chairman, Prof. George S. Huntington placed before the Association the following names for members on the Executive Committee for terms expiring in 1918: J. L. Bremer and H. von W. Schulte.

On motion the Secretary was instructed to cast a ballot for the election of the above named officers.

The Secretary presented the following names recommended' by the Executive Committee for election to membership in the American Association of Anatomists:

Wayne Jason Atwell, A.B., Instructor in Histology, 1335 Geddes Avenue, Ann Arbor, Michigan.

Hexry K. Davis, A.B., A.M., Instructor in Anatomj', Cornell University Medical College, Ithaca, New York.

Arnold Henry Eggerth, Assistant in Histology, University of Michigan, Ann Arbor, Michigan.

J. F. GuDERNATscH, Ph.D., Instructor in Anatomy, Cornell University Medical College, New York City.

Elmer R. Hoskins, A.B., A.M., Instructor in Anatomy, University o J Minnesota, Mi-nneapolis, Minnesota.

Charles Eugene Johnson, Ph.D., Instructor in Comparative Anatomy, Department of Animal Biology, University of Minnesota, Minneapolis, Minnesota.

Beverly Waugh Kunkel, Ph.B., Ph.D., Professor of Zoology, Beloit College, Beloit, Wisconsin.

Paul Eugene Lineback, A.B., IM.D., Teaching Fellow in Histology and Embryology, Harvard Medical School, Boston, Massachusetts.

C. C. Macklin, M.D., Assistant in Anatomy, Johns Hopkins Medical School,

Baltimore, Maryland. William Eli McCormack, M.D., Instructor in Embryologj' and Histology, University of Louisville, Louisville, Kentucky.

D. Gregg Metheny, M.D., Jefferson Medical College, Philadelphia, Pa.

Roy L. Moodie, A.B., Ph.D., Assistant Professor of Anatomy, University of

Illinois, Chicago, Illinois. Henry R. Muller, M.D., Assistant in Anatomy, Johns Hopkins Medical School,

Baltimore, Maryland, Jay a. Myers, A.B., Ph.D., Instructor in Anatomy, University of Minnesota,

Minneapolis, Minnesota. H. W. Norris, B.S., A.M., Professor of Zoology, Grinnell College, Grinnell, Iowa. James Wenceslas Papez, B.A., M.D., Professor of Anatomy, Atlanta Medical

College, Atlanta, Georgia. Franklin P. Reagan, A.B., Princeton University, Princeton, New Jersey. Randolph Tucker Shields, A.B., M.D., Dean, University of Nanking, Medical

School, Nanking, China. P. A. West, B.A., Johns Hopkitis Medical School, Baltimore, Maryland. Harry Oscar White, M.D., Professor of Anatomy, Histology and Embryology,

Medical Department, University of Southern California, Los Angeles, California . John Locke Worcester, M.D., Instructor in Anatomy, University of Michigan,

ISI4 Willard, A7i7i Arbor, Michigan.

On motion the Secretary was instructed to cast a ballot for the election of all the candidates proposed by the Executive Committee. Carried.

The following proposed amendment, having been a matter of record at the last meeting, was presented for action by the Association. These officers shall be elected by a ballot at the annual meeting of the Association and their official term shall commence with the close of the annual meeting."


At the annual meeting next preceding an election, the President shall name a nominating committee of three members. This Committee shall make its nominations to the Secretary not less than two months before the annual meeting at which the election is to take place. It shall be the duty of the Secretary to mail the list to all members of the Association at least one month before the annual meeting. Additional names for any office may be made in writing to the Secretary by any five members at any time previous to balloting."

The Association voted the adoption of this amendment.

The following proposed amendment, also recorded at the last meeting, was presented for action by the Association: Amendment of Article VI of the Constitution. The first sentence of the article the annual dues shall be $5.00,'.' it is proposed to amend to read "the annual dues shall be $7.00."

The Association voted the adoption of this amendment.

It was pointed out by Dr. M. J. Greenman, Director of The Wistar Institute, that since the dues of the Anatomists were now adv9.nced to .$7.00 per year, the members of the Association would receive all numbers of The American Journal of Anatomy and The Anatomical Record, six numbers of the Journal of Anatomy and twelve numbers of the Record yearly.

The special Committee on Pre-Medical \A^ork in Biology presented through its chairman. Dr. H. McE. Knower, the following report:

Your Committee was appointed to confer with the Zoologists to ascertain what cooperation may be expected toward standardizing work in Biology required of students looking forward to the stud}- of medicine; and to formulate the considerations which would seem practical to incorporate in plans for such courses.

The Zoological Society promptly appointed a committee for this conference, and the following questions were discussed, not only with this committee, but with a number of other representative members of the Zoological Society. Besides this, published statements of courses and of discussions on this subject were examined.

The following questions seemed to be most important :

Question 1 . Is the work given in different colleges in the elementary, general course in Biology adapted to satisfy the requirements of premedical training in this subject?


Question 2. Is it possible to so select and standardize the work of the first year in Biology in different colleges as to make it uniform, and to include, here, all needed to make it an adequate course?

Question 3. If an ideal course, including sufficient preliminary work can not be secured within the one year period advocated, what principles should be urged to govern the planning of the biological work of students looking forward to the study of medicine, so that they will profit most by the training of the first year, and be best prepared to follow this up in special departments of Biology more directly related to medicine.

Question 4. What additional work is to be advised, which is not to be obtained in the first year's general course?

Both committees agree that it is of the first importance to urge the selection of only thoroughly trained scientifi.c men as teachers for this work. Such men can be trusted to insist on real scientif].c methods and to select the best material and treatment to give the beginner a practical introduction and basis for further work.

Beyond this point, however, the committees were unable to proceed. The Zoologists suggested that the Anatomists should draw up a statement of what they desire the Zoologists to do, in preparing students for anatomy. After this has been done, the Zoologists are ready to consider how far it is practical to meet these needs. Several attempts have been made in this direction, and j^our conmiittee submits the following statement to the Association for its approval and transmission to the Zoologists.

At the present time a one-year's course in biology is generally required as a preparation for the work of the medical school. This study of biology must serve as a preparation for medical work in physiology, pathology, bacteriology and parasitologj-, as well as anatomy, and it may fairly be questioned whether a single college course is adequate for this purpose. The study of botany alone is obviously insufficient, and the domain of zoology is so vast that much care should be exercised in the choice of the phases of the science to be presented to young students. Courses which are primarily experimental and deal with the functions and reactions of animals, although excellent in preparation for the physiological work of the medical school, are not the proper basis for the study of human anatomy. It is the purpose of this report to point out only those features of the college preparation which experience has shown to be desirable, and in fact essential, for the successful study of gross and microscopic anatomy.

No uniform or stereotyped preparatory course is recommended, for it is recognized that every teacher should give special attention to those subjects and groups in which he is particularly interested, and to the knowledge of which he has contributed by his own researches. Success depends in large part upon the abihty of the teacher, but the following purposes of instruction should not be forgotten if the preparatory work is to satisfy the requirements of anatomy.

1. Students frequently begin the study of human anatomy with an insufficient knowledge of the lower forms of animal life. The broad knowledge of the various classes of animals and of invertebrate and lower-vertebrate morphology, which was the inspiration of the great anatomists of the past, is now too often replaced by vague considerations of the method of science and ideals of observation. A return to the study of animals, as objects of interest in themselves, apart from theoretical considerations and possible relations to human society, is therefore recommended. The student should obtain a synoptic knowledge of the animal kingdom, and should be able to classify in a general way, and to describe the life histories of the common forms of animals, aquatic and terrestrial, which may be collected in his locality. A beginning in such work may well be made by the student independently, or perhaps in high-school courses, but such fragmentary and elementary studies should be supplemented by a thorough college course. The first-hand familiarity with animals thus obtained should serve as the basis for all further work.

2. As a result of the knowledge of genera and species which the student should have obtained directly for himself, by studying some group of animals or plants; questions of the origin of species and of the relation of the great classes of animals to one another are inevitably before him as philosophical problems. Collateral reading then becomes as necessary for the biologist as for the man of learning in any other branch of knowledge. Selected works of Lamarck, Darwin, Huxley, Mendel, and others should be freely consulted. This literature, which in its influence upon human thought has far outspread the bounds of biology, should not be nelgected by the student of zoology, whose particular heritage it is. Since the idea that science cannot be read, and that there is no knowledge in books, is often taught as a cardinal principle, it has come about that students of zoology have little knowledge of, or respect for, the writings of the makers of their science.

3. Before beginning the study of human histology, every student may reasonably be expected to be familiar with the use of the microscope and with the simpler methods of preparing specimens for microscopic examination. This technique can be leai-ned in connection with various courses, perhaps the most useful of which is a general study of the cell with a comparative study of the elementary tissues. The maturation of the germ cells and the processes of fertilization and segmentation cannot be properly presented in the medical curriculum, and these fundamental biological phenomena should therefore be observed in college courses. The development of the chick, which was studied primarily by physicians to explain the growth of the human embryo, can likewise receive little attention in the medical school. These subjects ai-e all very desirable in themselves, and if studied by laboratory methods, will supply the requisite skill in the use of the microscope.

4. In preparing for human dissection, comparative anatomy should be studied with the same standards of thoroughness which obtain in the dissecting room. The student should learn to dissect rapidly and well, and to record with careful drawings and brief descriptions the forms and relations of the structures which he has disclosed. But such studies are not useful merely for their methods. A knowledge of comparative anatomy, including especially the anatomy of the lower vertebrates, is indispensable for understanding the structure of the human body. For other reasons also, human anatomy must be treated as an advanced study. The State does not provide bodies for dissection in order that untrained students may learn from them those elementary facts, which may be understood equally well by dissecting cats or rabbits. It is absurd," says President Eliot, "to begin with the human body the practice of dissection. " And the value of dissection is so great in relation both to medicine and surgery, that an adequate preparation should be required. For the study of anatomy, in the words of Lord Macaulay, "is not a mere question of science; it is not the unprofitable exercise of an ingenious mind ; it is a question between health and sickness, between ease and torment, between life and death."

5. Finally', these recommendations may be summarized as a plea for a more thorough study of zoology on the part of those planning to enter the medical schools. The zoological courses should not be abridged and popularized in order that time may be saved for other pursuits, or that the science may seem more attractive to college youth. Courses in anatomy and phj^siology which duplicate the work of the medical school, and courses in "medical zoology," ought not to be substituted for the strictly zoological university courses. The science of zoology is of such great service to students of medicine that it deserves a large place in their undergraduate studies. With medical anatomy, it constitutes "a subject essentially one and indivisible;" and the penalty for its neglect is inadequate preparation for medical practice.

St. Louis, Missouri Committee: H. McE. Knower, Chairman

December 29, 1914 F. T. Lewis

W. H. Lewis

In the following summary, the Chairman of the Committee has rearranged the main points of the above report in groups, to correspond to the four questions proposed at the beginning; so that a more definite idea may be secured of the manner in which these are answered. In assembling the answers to the different questions the exact sense of the report itself has been retained. In answering questions 3 and 4 an effort has been made to indicate what we may reasonably expect to include in the first vear, and what should be advised in addition.

•1 and 2. The first two questions formulated by the Committee are answered in the negative; that is, a one-year's course is not regarded as sufficient, and a uniform, standardized course seems undesirable. An introduction to the subject through special courses in selected medical zoology" is also disapproved.

3. (a). In regard to the third question, it has seemed necessary to urge a more thorough knowledge of the morphology of lower forms of animals and their life histories. While the Anatomists in adopting this statement as given in the report, undoubtedly, expect the physiological aspects of these mechanisms to be -considered as necessary accompaniments of such first hand famiharity with animals; it is urged in the report that the introductory college course shall not be "primarily physiological." It is earnestly desired that the work should involve a rigorous grounding in comparative morphology', especially of lower forms, which furnishes not only the best basis for human anatomy, but is a very essential preliminary for comparative and human physiology, (b). It is urged that the theoretical and philosophical considerations which accompany the course shall foUow a practical acquaintance with animals; rather than that special animal structures should serve chiefly as illustrative material for lectures on general biological theories, with a neglect of a thorough study of a series of animal forms, (c). The additional principles which should govern the planning of the introductorj^ course, bej'ond those just stated, are: The selection of suitable teachers; The undesirability of attempting to establish a uniform preparatory course, or courses especially limited to applications to medicine ; The acquirement of skill in the use of the microscope, and of correct scientific method of work in connection with the work of the course; The beginnings of embryology and cytology.

4. As to the last question, number 4, the report does not attempt to decide what proportion of the recommended preparation for anatomy can be obtained by a student in the fi.rst year's course. This must be indicated by the zoologists. It seems evident to a student of present conditions, however, that most of the work desired in cytology and comparative, general histology; comparative anatomy of vertebrates; or systematic zoology will have to be elected by students looking forward to medicine, after they have taken the introductory course. It is to be hoped that the elements of vertebrate embryology will be included in that course. Some of this work may well be done in one of the excellent Summer Laboratories.

5. Finally, the importance of collateral reading in the masterpieces of biological literature is strongly emphasized.

H. McE. Knower, Chairman

On motion, the report as presented was adopted and the Committee was continued and instructed to confer with the Committee of the Zoologists on the basis of the report.

At the final session the Committee for ' Resolutions on the death of Professor Minot presented through its chairman, Prof. George S. Huntington, the following:

The American Association of Anatomists, assembled in the ThirtyFirst Session at St. Louis, record their profound sense of sorrow and their deep feeling of loss sustained by the death of Prof. Charles Sedgwick ^Nlinot of Harvard Universit3^ For manj^ years Doctor Minot has stood for the best development of science and medical education both in this country and abroad. He has been particularly identified with the progress of the American Anatomical Association. In his official connections as President and ]\Iember of the Executive Committee his brilhant and constructive mind guided the affairs of the Society with marked success. ]Much of the progress of The "Wistar Institute of Anatomy originated in his keen executive abihty as Chairman of its Advisory Board. He was one of the founders of The Ameiican Journal of Anatomy and of its offspring, The Anatomical Record. His colleagues reahze that these first American anatomical publications owed their success during their earty and experimental years largely to his judgment and -wisdom. Later he became most active in establishing and maintaining the eminently valuable relations now existing between the journals and the Publication Department of The Wistar Institute. These are mere outlines of a few of the more formal points of contact between Doctor Minot and the Anatomical Association. Important and far-reaching as these have been, and lasting as their impress will prove in the future development of the Society, they are fully equalled in value by the influence of his marked personality on the individual life and work of the members with whom he came in closer contact. Keen and yet considerate judgment, kindly help, both with advice and material, were freely extended by him. The Association, in mourning the loss of a stimulating leader, of a wise counsellor and of a personal force which has always directed forward the lone advance of national science, directs the following resolutions:

1. That the foregoing minute be pubhshed in the Proceedings of the Thirty-First Session and that the Secretary be requested to forward a copy to Doctor ^Nlinot's family.

2. That Prof. Frederick T. Lewis of Harvard L^niversity be requested to prepare, on behalf of the Association, a memorial of Doctor ^Nlinot's personal and academic hfe, with full consideration of his educational and scientific achievements, for publication in The Anatomical Record.

Before adjournment it was voted: That this Association extend a vote of thanks to Washington University, Professor Terry and his Staff, our hosts at this session, and of congratulations to them on the completion of their carefully planned and admirably equipped Institute of Anatomy. Charles R. Stoce„\rd,

Secretarj- of the Thirty-First Session, of the American Association of Anatomists


ABSTRACTS OF PAPERS

1. The rhinencephalon of the dolphin [Delphinus delphis] William H.

F. Addison, University of Pennsylvania.

In the adult dolphin, the olfactory bulbs and tracts are lacking, and that portion of the mesethmoid, which corresponds to the cribriform plate of the ethmoid of the ordinary mammal is imperforate. Thus the dolphin is entirely anasmotic, and it has been interesting to study the more centrally placed parts of the rhinencephalon, to see in them the extent of the regression which has accompanied the disappearance of the olfactory tracts and bulbs.

During the past summer, I had the opportunity of examining thin sections of the brain of an adult dolphin in the Frankfurt Neurological Institute, under the direction of Professor Edinger, to whom I am greatly indebted.

In addition to the lack of olfactory bulbs and tracts, the olfactory cortex of the basal surface of the frontal lobe is also wanting. At this region the corpus striatum of each side comes to the surface and protrudes as a convex oval area. This area, smooth and free from fissures, was named lobe desert by Broca. The parolfactory cortex is also niuch reduced, but at least some definite remains of it are seen. This is interesting in the light of Edinger's view, that the tuberculum olfactorium is not a part of the olfactory system, but is the end-station of tracts conveying impulses by way of the fifth nerve from specialized sensory structures in the snout region. To the sense, which this mechanism serves, he has given the name of 'oral sense.'

Of the several connections of the olfactory and parolfactory cortical cells with the hippocampus, only Zuckerkandl's bundle is definitely present. The fimbria is a slender band of fibers arising from the hippocampus. True fornix fibers are not seen, and in the usual region of the corpora mammillaria there are no well-developed rounded protuberances, and in the gray tissue of this region are seen no medullated nerve fibers. This would indicate that the tractus cortico-mammillaris is very small or perhaps lacking. There is the usual arrangement of a psalterium or crossing of fibers between the two hippocampi. Indeed, the psalterium is so well developed that the possibility is suggested that it may contain other fibers in addition to the commissural hippocampal fibers. The anterior commissure is much reduced, evidently the olfactory portion being entirelv lacking.

Of the other possible connections of the olfactory and parolfactory cortical cells, both the taenia thalami and the taenia semicirculans are seen, as are their respective end-stations, the ganglion habenulae and the nucleus amj^gdalae. The hippocampi are very degenerate small structures, and it is with difficulty that one sees the analogy with even the microsmatic type of hippocampus.

Thus, in the brain of the dolphin, accompanying the loss of the olfactory bulbs and tracts, there is found a recession of the frontal cortex, exposing the corpus striatum over a considerable area; loss of the olfactory portion of the anterior commissure ; great diminution of the hippocampus, and reduction or loss of the uncrossed fibers from it to the corpora mammillaria (tractus cortico-mammillaris or true fornix); also, the usual connections between the olfactory cortex and the hippocampi are lacking except Zuckerkandl's bundle, and the corpora mammillaria are greatly reduced.

2. The artificial -production of spina bifida by m.eans of ultra-violet rays.

W. M. Baldwin, Department of Anatomv, Cornell Medical College,

New York City.

The purpose in presenting this paper is two-fold: first, by reason of the method employed the condition of spina bifida in tadpoles may be produced at will and the level of the bifurcation of the neural tube predetermined; second, the method gives considerable insight into the developmental potentials of the various portions of the ovum, and, in this instance, of the nature and location of the neural tube formative substances. This method consists in the illumination of small surface areas of the fertilized ovum of the frog by means of ultra-violet light of intensity sufficient to kill the area exposed in from 10 to 30 seconds.

It was found that in the undivided ovum the chemical organ-building substances, 'ferments,' or proanlagen, of the neural tube are neither located in any portion of the yolk hemisphere, nor along the equator. These proanlagen occupy a superficial position well up on the surface of the pigmented hemisphere of the egg and attain their definitive extent and position by a process of backward migration or differentiation, keeping pace in this migration with the corresponding shifting of the dorsal lip of the blastopore. These two processes occur synchronously, so that when the rate of the latter is interfered with (as from the presence of an area of dead yolk), the neural tube proanlagen differentiate into half anlagen and then half tubes at approximately their former rate of backward progression, but now along a line corresponding to the equator of the egg and not, as is usual, along the median plane of the egg. The yolk mass is finalty completely drawn into the body of the embryo, and as a result the two neural-tube halves are approximated to a greater or less degree. Subsequent fusion of the tu})e-halves does not, however, occur. Each half-tube by a later shifting of its cell becomes a whole tube.

The expeiiments add one more fact towai'ds the establishment of the conception of the egg as a composite structure containing, from the first, the organ-building substances of the various body systems, restricted to more or less definitely localized areas in the egg substance (mosaic theory of Roux). Furthermore, the conclusion seems justifiable, tenatively, at least, that the various chemicals such as salts of sodium and of lithium, which have been used bj^ Morgan, Hertwig.

Herbst, Jenkinson and others in the production of this malformation, have, at least, produced their effect by acting upon portions of the yolk hemisphere and not necessarily upon the proanlagen restricted to the pigmented hemisphere.

C. R. Bardeen, see abstract 57, page 137.

3. Some effects of mammalian thyroid and thymus-glands upon the development of Amphibian larvae. G. W. Bartelmez, Department of T^natomy, The University of Chicago.

The following data are taken from some attempts made with a view to analyzing the reactions reported in the feeding experiments of Gudernatsch and others. They are based on experiments upon larvae of Amblystoma tigrinum and Rana catesbiana treated with sheep's thyroid and thymus in three different ways, appropriately controlled. (1) Using the glands as food. (2) Feeding normally but adding saline extracts of the glands to the water of the culture dishes. (3) Injecting strong extracts into the coelom or dorsal musculature.

Experiments icith thyroid gland. Amblystoma: Effects of feeding {spring, 1913). Aml^lystoma is a favorable form in that the larvae can be hatched and reared in the laboratory, that they are fairly hard}", more especially that they are carnivorous and the effects of feeding can be studied separately from those resulting from suspensions of the glands in the culture w\ater. When exclusive thyroid feeding was begun soon after hatching (12 to 15 mm. larvae) there was a high mortality but the survivors showed only the effects of a meagre diet such as was obtained by feeding egg albumen or by starving. Thej^ grew little or not at all and the limbs did not differentiate as rapidlj^ as in the controls. No clear cut results were obtained unless the larvae were at least 30 mm. long, had three or four fingers and leg buds. In these cases a few individuals survived to undergo partial metamorphosis. Still older larvae, if they were well nourished, after two or three feedings of thyroid underwent metamorphosis in the course of eleven to sixteen days. Fairly normally constituted adults were thus obtained from 35 to 80 mm., long whereas the normal in this vicinity at the time of metamorphosis is from 130 to 150 mm. long. My conclusions from these obsfervations are that the thyroid feeding does not stimulate differentiation in Amblystoma since the differentiation of the limbs is not accelerated but it does bring about certain changes in the gut which in turn induce other changes characteristic of metamorphosis.

Amblystoma: Effects of thyroid extracts {spring and summer, 1914). In these experiments the evil effects of an unnatural food were elimmated by giving the larvae first entomostraca and then anuran tadpoles as food and between the feedings adding the extract to the water m which they were living. Starting with larvae 15 to 17 mm. long, after six treatments in the course of sLx weeks no differences were noted as pompared with the controls. During this time they grew and differentiated normallv, reaching a length of from 20 to 40 mm. Continuing the treatment for two and a half months, small, adults were obtained. Beginning with older larvae the process was somewhat more rapid. The chief differences between these and the feeding experunents lie in the lowered mortahtj^ and the more complete metamorphoses in the former set. Both agree in that the thyroid has no specific effect until the larva has reached a definite minimal stage in development and in that the metamorphosis is not wholly normal.

Amhlystoma: Effects of hijpodennic injections {summer, 1914). The results of injecting small doses of strong extracts of thyroid were somewhat variable, largel}^ no doubt because in different cases different proportions of the injection oozed from the wound. Animals under 50 mm, in length gave no signs of metamorphosis before death. In older ones two doses were sometimes necessary to start the process and then it began within four to seven days and was completed in fourteen to thirty days; a period somewhat longer than normal.

Rana catesbiana: Experiments ivith thyroid gland. The results with bull frog tadpoles were complicated by various factors and only a few experiments can be summarized here. The reaction varied according to the stage of development of the larva, its age (1st, 2nd or 3rd season), the length of previous confinement in the laboratory and the season of the year in which the treatment was begun. The indi\ddual resistance was also variable and this was a factor as the supply of material was limited and each tadpole was measured and observed until its death.

Effects of feeding. Larvae fed only twice with thyroid and the rest of the time with hmiph node reacted like those fed exclusively on thyroid and as the death rate was lower, the former treatment was used in most cases. In larvae of all ages five or six days after the first feeding the body became more slim than in the protein fed controls. This was due to the marked reduction in the length and in the position of the spiral gut. After this differences were noted which depended upon the stage of development reached .by the animal at the time thyroid feeding was begun. If the legs had developed so far that the toes were differentiated at time of first feeding, the legs grew as they do shortly before metamorphosis, but true metamorphosis did not set in until after six or seven weeks. Some of this group, however, developed a marked resistance to the thyroid. To cite a single case: An individual which had been accustomed to a Ij-mph node diet and then to thyroid by six feedings between January 19 and April 7, was fed weekly with th^-roid until May 21 (seven times) then on alternate days twelve times, died half way through metamorphosis on June 16. In this and the cases mentioned above the gut reduced at a faster rate than it does normally. This fact is accentuated by the following class of cases. When thyroid feeding was begun before the larva had gone Ijeyond the stage of leg buds a peculiar kind of metamorphisis was brought about. The gut shortened and assumed practically the adult condition, the head showed some signs of metamorphosis l)ut there was no reduction of gills, little reduction of the tail and no more development of the leg buds than in the control.


The results of treatment with thyroid extract and the injection of thyroid suspensions in general confirmed these results with feeding.

Upon the assumption that lymph node tissue is similar as a food to thymus, but that it has no internal secretion, some series of experiments were made with these two tissues using them both as foods and as extracts in the culture dishes. In Amblystoma they gave practically identical results in all feeding expermients — ^and there was no proof of a retardation of development. Larvae treated wdth thymus extract metamorphosed normally but sooner and when the animals were smaller than the controls. Furthermore, the hypodermic injection of thymus extract did not retard or inhibit metamorphosis in the larger larvae. In Rana the feeding of both thymus and lymph node produced more rapid development than was observed in the plant fed control.

4 The develojmientof the sympathetic nervous system in Elasmohranchs-.

Geo. a. Bates, Tufts College Medical School, Boston, Mass.

The first appearance of the sympathetic in Squalus is in the form of a series of ganglia lateral to the aorta in. 15 mm. embiyos. At the time of its formation the dorsal and ventral roots of the somatic spinal nerves, in their ventral growth, have reached this level. The ganglion of the sympathetic is formed in immediate connection with the dorsal root, from cells that arise from this source. It appears as a cluster of cells attached to the dorsal root and embedded in a protoplasmic mass quite distinct from the surrounding mesenchymal cells.

In embryos of from 7 to 8 mm. cells of the ventro-lateral wall of the neural tube have begun to migrate into the space between the tube and myotome. At the same time mesenchjmiatous cells from the dismtegrating sclerotome migrate dorsallv into the same region. The medullary ceUs are easily distinguishable from the sclerotomic cells m sections prepared by the vom Rath method. These cells arrange themselves along the margin of the myotome and are distinctly marked off from the surroundmg cells. „ ^ , , u

There are no medullary cells among the cells of the mesenchyma. In the latter, however, two varieties of cells are present; one reacting to the basic stain quite intensely, the other less so. These tacts are demonstrated in sublimate fixed, hematoxylm stained sections, and particularly in sections stained with iron hematoxyhn.

Such cells are present throughout the mesenchyma and at pomts where neither the ventral root cells nor cells from the dorsal crest have begun their migration. , . , ,

The claim that the deeply stainmg ceUs in the mesenchyma are medullary cells which subsequently will become incorporated into the sympathetic ganghon, seems unwarranted for the following reasons:

At this stage, 7 to 8 mm. there is no sign of the formation of the sympathetic ganglion. At the level of the aorta and lateral to it a mass of sclerotomic cells may be seen and it is here that the two sorts of cells, above mentioned, are found.

The dijfference in staining property seems to be the result of the presence or absence of chromatin due, probably, to the state of activity of the cell. Such conditions have frequentlj^ been observed in mesodermic cells in the formation of the liver, and also by various observers in other regions. In other words, the difference in staining properties of cells in the region of the dorsal aorta affords no foundation for the inference that the more deeply staining cells are destined to become sympathetic cells. On the contrary, they are mosodermal in their origin and are not genetically related to the sympathetic.

As above stated, the sympathetic ganglion is developed directly from the dorsal root of the somatic spinal nerve at a stage of about 35 to 17 mm. At the time of development there are relatively few cells present in the motor root, and the question of contribution to the ganglion of cells from that source, while not improbable, is doubtful.

5. The growth of the head and face in American (white), German-American, and Filijiino children {lantern and photos). Robert Bennett Bean, The Tulane University of Louisiana.

Materials :

579 Filipino boys } Manila, PhiHppine Islands


309 German girls 324 German boys 412 American gir 415 American boys


324 German boys I . . , at- u412 American girls f Ann Arbor, Michigan


2185, total

The growth of the head diameters {length, breadth and height). Between the ages of 6 and 16 the head grows in length least, 0.9 cm., in the American girls, and most, 1.6 cm., in the Filipino boys; in breadth least, 0.5 cm., in the American girls, and most, 1.1 cm., in the German boys; and in height least, 0.5 cm. in the German and American girls, and most 1.1 cm. in the Filipino boys. The heads of the Filipinos grow more rapidly in length between 6 and 11 years of age than between 11 and 16 3^ears of age, whereas the heads of the Germans and Americans grow more rapidly in the latter than in the former period. What is true of the Germans and Americans in relation to the Filipinos is also true of the boys in relation to the girls.

The head size as represented by the module (length plus breadth plus height) increases least, 19 points, in the American girls and most 35 points in the Filipino boys.

At 6 years of age the heads of the Americans of both sexes are the largest, the heads of the Filipinos are the smallest, and the heads of the Germans are nearly as large as those of the Americans. At 16 years of age the heads of the Filipinos are the smallest, and the heads of the Americans are nearly as large as those of the Germans.

The cephalic index decreases with age for the length-breadth index least, 0.0, for the Filipino girls, and most, 3.3, for the Filipino boys; and for the length-height index least, 0.4, for the Filipino boys, and most, 2.7, for the German girls.

Growth of head circumferences (frontal, forehead, parietal and occipital.) The forehead and occipital regions are large in the boys and in the Americans, the frontal and parietal regions are large in the girls and in the Germans and Filipinos. The forehead and frontal regions together are large in the girls and in the older children, and the occipital and parietal regions together are large in the boys and in the younger children.

From 6 to 16 years of age, the forehead, frontal, and parietal regions grow most in the Filipinos, less in the Germans, and least in the Americans, but the reverse is true of the occipital region. The forehead, frontal and occipital regions grow more in the boys than in the girls, and this is especially true of the occipital region, whereas the parietal region grows more in the girls than in the boys.

It is notable that, in relation to each of the other regions, the forehead increases in size and the parietal region decreases with age.

The large size and greater growth of the parietal region are characteristic of the girls and of the young children, and the large size and greater growth of the occipital region are characteristic of the boys and of the older children. The Filipinos resemble the girls in this respect, and the Americans resemble the boys, whereas the Germans are more or less intermediate.

The Hypo-types are like the Filipinos, the Hyper-types are like the Americans and the Meso-types are like the Germans.

The growth of the face (length, breadth and facial angle) : The growth of the face as a whole vndiy be considered by taking the product of the length and breadth. From this standpoint the growth from 6 to 16 years is least in the Filipino girls, greatest in the American boys, with the others in between, the boys greater than the girls. The face increases about 33 per cent in the girls and about 50 per cent in the boys during the ten year period.

The face length increases with age about 2 cm. in 10 years. The girl's face grows more from 6 to 11 years and the boy's from 11 to 16 years. The face of the Filipino is shorter than that of the German and American, about 1 cm. at 16 years and about 0.3 cm. at 6 years. The face of the Filipino grows less in length than that of the German and American from 6 to 16 years.

The face breadth increases with age from 11.3 cm. at 6 years to 13.1 at 16 years. The face breadth of the girls grows more rapidly from 6 to 11 and that of the boys from 11 to 16. The face of the Filipino is as broad as that of the German and broader than that of the American, and the growth of face is about the same in breadth for the three peoples.

The face index increases with age, the face becomes longer relative to its width, and this increase is greatest in the Americans, less in the Germans, and least in the Filipinos. The increase in the Germans is greatest from 6 to 11 years and in the Americans it is greatest from 11 to 16 years.

The facial angle represents the projection of the maxilla, and with increase of age this is greater in the American boys aind less in the Fihpino boys than is apparent in the German and American girls and the German boys. The Filipino girls have no records made of the facial angle.

Cephalo-facial index (originated by the author). This represents the size of the face in terms of the head, the latter always 100. The face grows relatively more than the head from 6 to 16 years, relatively more from 6 to 11 in the Germans and Americans and relatively more from 11 to 16 in the Filipinos. At 6 years the Filipinos have relatively the largest faces, and the Americans relatively the smallest, with the Germans in between, at 11 this is reversed, and at 16 all are about the same.

The cephalic index decreases with age, and it decreases from the Filipinos through the Germans to the Americans. The face index increases with age, and it increases from the Filipinos through the Germans to the Americans. If the process of development recapitulates the progress of evolution then the Americans represent in evolution what the adult represents in development, and the Germans and Filipinos are less mature stages. The Filipinos represent what I have called Hypophylo-morphs, the Germans Meso-phylo-morphs (?) and the Americans Hyper-phylo-morphs. In each group may be found adult individuals with varying degrees of development in head and face form, and these I would classifj^ as Hypo-onto-morph, ]\Ieso-onto-morph, and Hyper-onto-morph, depending upon the extent of development. Crossing of races has introduced the phjdo- types into nearly all peoples, therefore the six forms may be distinguished among almost all mixed races. Among the white peoples the Hypo- types are rare, but among the Filipinos the Hyper- types are abundant. ]\Iore white peoples have mixed wdth the Filipinos than Filipinos with the white peoples.

6. Some ears and types of men. {Lantern and photos). Robert Bennett Bean, The Tulane University of Louisiana, New Orleans, La. Materials :

1325 American whites 2039 American negroes 73 American Indians 171 Alaskan Eskimos _^4 Manila Filipinos 3702 Total The present study is a continuation of those made previoush' on the external ear and physical form of man, and it is more detailed and specific than former studies. It corroborates them in general and in particular, and adds racial distinctions to type differences.

The most important result is the segregation of the Hj-per-, ]\Ieso-, and Hypo- types from each group, both by the car form and by other anatomical characteristics. The other result of importance is the differentiation of the races by their ear form. Incidentally skin lines were discovered on all ears, lines that represent the folded over skin tip of the ear, the sldn tip which should overlie the cartilaginous tip (Darwin's tubercle) but does not alwaj^s do so.

The segregation of the types, Hyper-, Meso-, and Hypo-, is acconiphshed by determining for each ear whether the helix is prominent or not, whether the anthelix is depressed or not, whether the lower helix and lobule turn towards the head or away from it, and whether the tragus and antitragus are everted or depressed. After having determined to w^hich type the ear belongs, then the cephalic index, nasal index and facial index of the individual are calculated. The results are found below.

Type differences. Hyper-: In this type of ear the helix is depressed toward the head, the anthelix is prominent — projects beyond the helix — the lower helix and lobule turn toward the head, and the tragus and antitragus are everted and prominent — project bej^ond their surroundings. The nasal index, facial index and cephalic index indicate that the type of individual associated with this type of ear has a long, narrow nose, a long, narrow face, and a long narrow head as a rule.

Hypo-: In this type of ear the helix is prominent, the anthelix depressed, the lower helix and lobule turn out from the head in the form of a shelf, and the tragus and antitragus are depressed below their surroundings. The nasal index, facial index, and cephalic index indicate that the type of individual associated with this type of ear has as a rule a short, broad nose, a short broad face, and a short broad head.

Meso-: In this type of ear the helix and anthelix are both prominent, thus forming a double roll near the dorsal margin of the ear, the lower helix and lobule turn out from the head in the form of a shelf, but not to the same extent as in the Hypo- ear, and the shelf, instead of being horizontal, has a gentle slope forward or may be precipitous, and finally the tragus and antitragus have an intermediate position, are neither prominent nor depressed. The nasal index, facial index, and cephalic index indicate that the type of individual associated with this type of ear has a nose, face, and head of intermediate form between the Hyper- and the Hypo-, although the face is larger than either of the two.

Each of the three types may be subdi\dded into onto and phylo forms, the phylo, the primordial form, and the onto, the derived form. The Hyper-onto-morph, the Meso-onto-morph, and very rarely the Hypo-onto-morph are European, or white, types; whereas the Hypophylo-morph, the Meso-phylo-morph, and rarely the Hyper-phylomorph are types of the negroes, Indians, Eskimos, Filipinos, and other primitive peoples.

At birth the white child is a Hypo-phjdo-morph, and as the child develops it passes consecutivelv through the stages of the Hypo-ontomorph, Meso-phvlo-morph, Meso-onto-morph, Hyper-phylo-morph and Hyper-onto-morph, unless development stops at or between one or the other of the types.

There is little doubt that the Hj'per-ontc-morph is th? end product of a hyperactive thyroid gland, the result of rapid differentiation, with slight growth, resulting in a small, active, nervous individual. The Hypo-phylo-morph is probabty the end product of great thjaiius activit}^ resulting in a more or less complete retention of the infantile condition, whereas the Meso-phylo-morph has great activity of the gonads. The other types are variants of the three mentioned, composites, mixtures, blends or mosaics.

Race differences. The race differences are of two kinds, measured and descriptive. Only the racial differences of the ear will be considered here.

^Measured differences: These are divided into differences in the living and differences in the dead. The ears of only three groups of dead people were measured, American negroes, American whites and Filipinos. B}^ measurements of the total ear length, total ear breadth.


TABLE


1





GBOUP


EAR LENGTH


EAR INDEX



Male


Female


Male


Female


Dead \inerican white


64.18 58.58 58.80

63.9 66.9 72.3 73.8 60.8


58.32 57.43

61.3

67.1 58.0


58.0

64.0 56.8

57.4 55.9 52.6 54.4 60.9



American negro


60.8


Manila Filipino


57.5


Living Xew Orleans student



■Vnierican "old" wKite^


56.0


•American Indian



\laskan Eskimo


53.0


American negro


60.2




1 'Old' whites are those who have been in this country for 3 generations or more.


Foetuses, new-born and young infants, male and female :

Ear index white 68 .8

Ear index negro 64.5

ear base, true ear length (Schwalbe), concha length and concha breadth, it is found that the negro ear is short and broad, the white ear is long and narrow, and the Filipino ear is relatively longer and narrower than the white ear. The ear length and the index of the ear of both the living and the dead are shown in table 1.

No other measurements are given because racial differences are more pronounced in the ear length and the ear index. The Indian and Eskimo have long ears, the negro and Filipino have short ears and the ears of the white people are intermediate. This accounts in part for the fact that the ear index of the negro is high, that of the Indian and Eskimo is low, and that of the white is intermediate, but it does not account for the low index of the FiUpino. The reason for this is that ear of the Fihpino is short and also narrow, it is a small ear. The negro ear is not onlj- short, but it is also broad.

The ear increases in size with age, to 70 years or later, but the increase in length is greater than that in breadth, therefore the index decreases with age.

Descriptive Differences: The true negro ear is small, ahnost flat, close to the head, and the helix is broad as if much folded over. The upper part of the helix is almost horizontal and passes directly backward from the upper end of the ear base to join the vertical dorsal portion of the helix at a right or acute angle in a rounded point at the upper outer extremity of the ear. The superior and dorsal borders of the hehx are separated by a depression above Darwin's tubercle, where the helix is thin or absent. The dorsal border passes downward and turns forward at an obtuse angle to form the inferior border of the ear which enters the cheek almost at right angles, with no lobule or a very small one which is nearh' flat. The Satyr tubercle is well marked and Darwin's tubercle is small or absent. The skin lines formed by the overfolding of the helix are less distinct on the negro ear than on the white, and thej' usuallj' converge on the negro ear over Darwin's tubercle. The true negro ear is not seen in great numbers among American negroes. It occurred 245 times among 1478 Xew Orleans negroes (16.6 per cent), men, women and children, chiefly of the laboring classes.

There is another form of ear that is found frequently among the negroes, but it is also found not rarely among other peoples, even among the whites, and I have called this the involuted ear, because it seems to represent an advanced stage in retrograde development and evolution. It has a gnarled appearance, as if the ear had been burned around the border and had contracted irregularly in healing, leaving a thick, irregular helix. This ear type was at first thought to be due to accidental causes, but the presence of the skin lines of the ear tip in regular order proved the ear to be a true type. It was found 601 times in 1478 New Orleans negroes (40.7 per cent) and 52 times among 857 Xew Orleans whites (6.1 per cent).

The details of the ears of the negro and white are different as follows: The negro ears are glabrous, the white ears are hirsute; the Satyr tubercle is large in the negro ear, small in the white; Darwin's tubercle is more difficult to find in the negro ear than in the white; the skin lines converge about Darwin's tubercle in the negro ear, and between Darwin's tubercle and the Satyr tubercle in the white; the helix is broad in the negro ear, narrow in the white; the anthelix is more prominent in the white ear than in the negro; the posterior auricular sulcus is deeper in the negro ear than in the white, and m the negro ear the sulcus dips into the concha, whereas in the white it turns out over the helix or lobule.

I wish to thank Dr. Hrdlicka for some of the records of the American whites and negroes and for the records of the Alaskan Eskimo and American Indians.


7. Abse7ice of the vena cava inferior in a 12 ni?n. pig embryo, associated icith the drainage of the portal system into the cardinal system. Alexander S. Begg, Harvard Medical School.

In a 12 mm. pig embryo which appeared normal before being sectioned, I found very radical anomalies of the abdominal veins. The vena cava inferior, which arises through anastomosis of the right subcardinal vein with the sinusoids of the liver in pig embr3'os of about 6 mm. and which is verj" large in 12 mm. embryos, had failed to develox. Thus this embryo presented a young stage of the interesting and well-known anomaly of the adult, described as 'absence of the vena cava inferior.'

Moreover, the portal system did not empty into the liver by the usual large venous trunk, but only through capillary comiections, very difficult to follow. On the other hand, the connection between the portal system and the cardinal system, which is ordinarilj' insignificant at this stage, is an important, if not the chief, outlet of the portal vein. Thus this embryo shows in an early stage the rather rare anomaly of the adult in which a large vein passes from the splenic vein to the left renal vein.

In order to show accurately these features, models have been made of the vessels in the abnormal pig and also in a normal specimen for comparison. Except for the decrease in the size of the portal vein as it enters the liver, the abnormalities are a persistence of earlier normal conditions.

8. Notes on the endocranial casts of Okapia, Giraffa. and Samotherium Davidson Black, Anatomical Laboratory, Western Reserve University, Medical School.

The superficial convolutional pattern of the convex surface of the cerebrum in the lower gj'rencephalous mammalia, more especially in the Ungulates and Carnivores, is quite- accurate^ reproduced bj^ the corresponding irregularities of the internal surface of the skull. The major portion of the lateral surface of the neopallium is exposed in these forms — more especialty in the Ungulata. In other words, no very extensive operculae are present to obscure the fmidamental fissura' pattern, which maj' thus be accurately studied in the endocranial cast.

One endocranial cast of an adult Okapia and one of an adult Giraffa camelopardalis were obtained in INlanchester through the courtesy of Prof. G. Elliot Smith. The second specimen of an adult Okapia, together with that of Samotherium, was obtained through the courtesy of Dr. Smith Woodward from the Museum of Natural Histor}-, at South Kensington, Uondon. I am also indebted to Prof. Arthur Keith for the opportunity of studjnng the giraffe brams in the collection of the Royal College of Surgeons, and to Dr. C. U. Ariens Kappers for the privilege of studving the Ungulate and other material in the collection of the Central Dutch Institute for Brain Research in Amsterdam.

These notes, together with the illustrations here shown as lantern slides, will form the basis of a more extensive paper in the near future.

Giraffa: The convolutional pattern in the giraffe is well known from the study of actual specimens of the brain, and may be readily outlined upon the surface of the cast. Dorsally the lateral sulci and suprasylvian arc are well marked. The coronal sulcus shows a caudal connection with the ansate sulcus, which is a common ungulate condition. This 'ansata' is in no waj- to be compared with the somewhat similarly placed cruciate sulcus peculiar to the carnivores. The olfactory bulbs are onh^ seen in this view as small swellings projecting very slightl}^ from beneath the frontal pole.

The whole course of the suprasylvian sulcus is shown in the lateral view of the cast. In addition to the post, horizontal limb common in Cervidae and other forms, a posterior descending ramus of the suprasylvian sulcus is to be noted. This sulcus is probabh' not homologous with the postsylvian sulcus of the carnivores. The posterior rhinal fissure is well marked and above it can be seen the bulging of the ' post, sylvian operculum,' the edges of which are indented by a series of small sulci.

The Ungulate sylvian, or pseudosylvian, fissure aj pears as a short ascending ramus from the diverging ectosylvian sulci. Between the summit of this pseudosjdvian fossa and the suprasylvian sulcus there is seen a well marked arcuate fissure. This 'arcuate' constellation is in no way homologous with the ectos^dvian group so evident in Canis, FeHs, etc., but appears to be a characteristic feature of the giraffidae, and when present together with the posterior descending ramus of the suprasylvian, is a distinct diagnostic feature.

The anterior rhinal fissure, together with the orbital and paraorbital sulci present no peculiarities. There is a typical triradiate diagonal sulcus. Posteriori}', the area behind the descending ramus of the suprasylvian sulcus is marked by several irregular sulci, as is the case in the corresponding area behind the oblique sulcus in Cervus.

The cast is one of a typically macrosmatic mammal of the Ungulate type. The olfactory bulbs are very large and sessile and, together with the tractus olfactorius and tuberculum, are best seen in the ventral view. Here, as also in the lateral view, the enormous size of the combined ophthalmic and maxillary divisions and also the large mandibular divisions of the trigeminal nerve is at once evident, the optic nerves being small in comparison. The large size of the N. V. is directly related to a highty developed so-called 'oral sense.'

Okapia: This animal is a hornless member of the family Giraffidae, and was first discovered in the Belgian Congo in 1899 by Sir Harry Johnston. No material other than the skin and skeleton has as yet been available for scientific stud}'.

The arrangement of the sulci appearmg on the dorso-lateral surface of this cast gives evidence of a close relationship between the Okapia and the Giraffe. The 'arcuate' constellation, the descending ramus of the suprasylvian and the position occupied by the lateral group of sulci are essentially similar to those obtaining in the giraffe.

There are, however, numerous specific differences. The descending ramus of the suprasylvian fissure cuts the post, rhinal fissure m Okapia.


In Cervus dama and many other forms, an 'oblique' sulcus occupies the area in which this descending ramus is found in the Giraffidae. This oblique sulcus in Cervidae in many cases cuts the rhinal fissure, and it may be that this sulcus is the homologue of the descending ramus of the suprasylvian. Thus the cutting of the post, rhinal fissure by the latter sulcus may be a premature feature conmion to Okapia and Cervus, but absent in the more specialized giraffe.

The pseudosylvian fissure is very short and the relation of the anterior ectosylvian sulcus to the anterior rhinal fissure is obscure. The irregular sulci in the area behind the ram. desc. of the suprasylvian sulcus present essentially similar relations to those in the giraffe.

The relations of the coronal, ansate and suprasylvian sulci together with the diagonal are quite different to the conditions obtaining in the giraffe. The suprasylvian is joined to the corono-ansate sulci, as is the case in the Cervidae and often in the other Ungulates. The absence of this condition in the giraffe may thus be considered as another evidence of specialization in this form.

A constellation apparently representing the 'diagonal' sulcus of EUiot Smith appears continuous with the suprasylvian (on the right side in the specimen illustrated). On the left side of the same specimen the diagonal sulcus occupies its usual position in front of and below the coronal sulcus.

The olfactory bulbs are large and pedunculated, and project a considerable distance beyond the frontal pole, so that the olfactory stalks are visible in the dorsal view. The olfactory tracts and tubercule, together with the pyriform lobe, are well seen in the ventral view. The tuberculum is especially prominent and occupies a special little fossa on the skull floor. The total amount of neopallium as compared with the rhinencephalon appears less than in the case of the giraffe.

Bamoiheriuwi: This animal was an Okapi-Hke form found in the upper Miocene deposits in the island of Samos. The cast shows evidence of considerable compression during fossilization, resulting in marked asymmetry. Notwithstanding this unfavorable condition, it is possible to trace the course of the principal sulci with but little difficulty.

The entolateral sulcus occupies its usual position, but the lateral sulcus takes a very unusual course and becomes joined to the coronal as well as with the suprasylvian, through the intermediation of the ansate sulcus. This junction of lateral and coronal is found nowhere else in the Ungulata except in the primitive hippopotamus. In other orders, however, as for example in the Carnivora,this junction between coronal and lateral sulci is a common feature. Elliot Smith has shown this feature to be a very primitive character and present in such Eocene Carnivores as Stenoplesicites and Gynohyacnodon as well as in ancestral Ungulates.

The continuity of the suprasylvian and coronal by way of the ansate sulcus is, as has been already noted, a common feature in Ungulates, but is practically never present in Carnivores.

The coronal sulcus is placed far forward, and is comparatively small as in Hyrax, while the ansate sulcus is well developed. In front of the coronal sulcus a triradiate diagonal fissure is evident in its usual position.

The orbital sulcus emerges from the anterior rhinal fossa and is placed far forward, as in many of the Cervidae and Suidae.

A sulcus recalling the Carnivore 'cruciatus,' but not to be homologized, appears emerging from the sagittal furrow and probably represents the upturned termination of the splenial.

The ramus descendens of the suprasylvian sulcus cuts the posterior rhinal fissure as in Okapia. The pseudosylvian sulcus on the left side is represented by a series of small vertical notches, the whole being related to a typical 'arcuate' sulcus, such as obtains in Okapia and Giraffa. The pseudosylvian sulcus on the right side more nearly approaches the condition obtaining in Giraffa.

Summary: From a study of the limited amount of material at my disposal it appears that of the three Artiodactyl forms of the family Giraffidae under discussion, the brain of Samotherium shows undoubtedly the most primitive arrangement of sulci, presenting as it does certain features common both to the Carnivora and the Ungulata. In other words this form is evidently most closely related to that hypothetical 'co-mammal' from which both the Carnivora and Ungulata were specialised.

In addition to this primitive feature, Samotherium presents certain generalized characters, common and peculiar to the Ungulata such for example as (a) the relation of the descending ramus of the suprasylvian sulcus to the post, rhinal fissure (provided the former sulcus be the homologue of the ' oblique' sulcus of EUiot Smith) and (b) the arrangement of the coronal, ansate, suprasylvian complex anteriorly. In these generalized characters Okapia resembles Samotherium and the two differ from Giraffa.

All these forms show a certain fundamental similarity in fissural pattern. These specialized characters are seen in the arrangement in the ' intrasylvian arcuate' complex which, taken in conjunction with the descending ramus of the suprasylvian sulcus is apparently peculiar to Giraffidae.

And finally, Giraffa differs from both Samotherium and Okapia in the possession of certain specialized features, such, for example, as the complete separation of the corono-ansate group from the suprasylvian sulcus.

9. Explanation of variations of the renal artery. J. L. Beemer, Harvard Medical School, Boston.

Vessels mentioned in the text-books of anatomy as either anomalous roots or anomalous branches of the renal artery may be placed m three groups: (1) those to the mesonephros and its adjacent organs, ventrolateral branches of the aorta; (2) those to the intestinal tract and its derivatives, ventral branches; and (3) those to the body wall and dia


60 AMERICAN ASSOCIATION OF ANATOMISTS

phragm, dorso-lateral branches. Group 1 includes the spermatic and adrenal arteries, and branches of the iliacs and middle sacral; group 2, the coeliac axis and its branches to liver, pancreas, and colon, and the superior and inferior mesenteric arteries; and group 3, the lumbar arteries and the inferior phrenic. If horizontal anastomoses between members of the different groups can be found, and if in addition longitudinal or vertical anastomoses between members of the same group exist, any of the variations are explicable.

At the outset it was found that, whereas in man the renal artery is normally a branch of a mesonephric artery, in pig and sheep the new vessel is derived from body wall (or lateral body) vessels.

The origin of the renal arterj- in man from the iliacs or the middle sacral is due to the original pehdc position of the kidnej^ in the immediate vicinity of the vessels mentioned. Branches from them, similar to mesonephric arteries, may run to the kidney, and may continue in activity as the kidnej^ migrates, instead of being lost or becoming ureteric arteries, as is more usual. Spermatic and adrenal branches of the renal artery are not uncommon, and are due to the fact that all are derivatives of the mesonephric arteries. Vertical anastomoses of mesonephric arteries are common, and since now one root, now another, is kept, such anastomoses account readily for the frequent asymmetrical origin of the renals from the aorta. Vertical anastomoses between dorso-latei'al aortic branches are also common in the abdominal, as well as in the cervical, region.

Horizontal connections, rarer than the vertical, are found oftenest between the ventral and the ventro-lateral group, and account for the origin of the renal artery from the coeliac axis or the mesenteric arteries, and for the branches of the renal to liver, pancreas, and colon. A double anastomosis between one of the early ventral arteries and a mesonephric artery on each side, with the subsequent loss of the ventral artery and of any two of the three roots to such an anastomosis, would result in the origin of the renals from a common stem.

Horizontal anastomoses between vertebral, or dorsal, and lateral body arteries can hardly be considered anomalies, as in most animals the two sets of vessels soon come from a common stem, as in adult man. Horizontal anastomoses between lateral body and mesonephric arteries are ver}^ rare, but serve to explain the origin of the renal artery in man from a lumbar artery, or the presence of a phrenic branch of the renal.

The various anastomoses found may be so close to the aorta, when it is only an endothelial tube, that they become incorporated in its wall by the development of the muscular layer.

It will thus be seen that all the variations of origin or anomalous Iji'anches of the renal artery can be explained by the presence, in different embryos, of pieces of a periaortic anastomoses, joining the various aortic branches, verticall}'- and horizontally. If these pieces were all developed in one individual, it would be capable of transferring the blood stream from a dorsal vessel to a ventral one, and vice versa. In this connection it is interesting to note that the mesonephric arteries of adult selachians are said to spring normally from the segmental body wall vessels, and that in Bdellostoma the mesenteric arteries arise from the dorsal wall of the aorta.

10. Comparative size of nucleus and cytoplasm in old and regenerating

tissues. E. L. Brezee, Cornell University Medical School, New

York City. (Introduced by C. R. Stockard.)

The species used for this expermient were Fundulus heteroclitus, tadpoles of Rana sylvatica, and two species of salamander, Diemyctylus viridens adults and Amblystoma punctatum larvae.

Old and regenerating tissue from both adult and larval annuals were studied. The tails and arms were cut off about one-third or one-half way from the body. These parts after a few days had regenerated and the organisms were then preservd in Bouin's fluid, sectioned and stained with hamatein and eosin.

Sections were cut in such a plane as would pass through both old and regenerating tissue. Two sections of each specimen were studied and camera lucida drawings made of the nuclear outlines of portions of epithehum and mesenchyme from the old and new tissue of each section. The cell outlines could not be traced as they did not show distinctly enough. In the epithehum the cells were so closely packed that all the substance which was not nucleus could be considered as cytoplasm. In the mesenchyme, however, the cells were so scattered and the intercellular spaces so numerous that the amount of cytoplasm could not be determined m this way; hence no relation between the amount of nuclear material and of cytoplasm could be calculated, . but merely the size of nuclei in old and new tissue compared.

The purpose of the experiment was three-fold: (a) to determine whether the nuclei of the old or of the new tissue were larger; (b) to determine in both old and new tissue whether the amounts of nuclear or of cytoplasmic material were greater; and _(c) to compare the relative amounts of nuclear and cytoplasmic material in old and new tissue. In each case the areas traced from the old and new tissue of the same section were compared, and the results noted.

(a) By comparing the tracings from each portion of new tissue with the corresponding portion of old it was possible to determine without actual measurement in which the nuclei were larger. The results are shown in table 1 .

In the mesenchvme there is a slight advantage in nuclear size sho\yn in the old tissue; this is true also of the epithehum of the larvae but m the adult annuals the size of the nuclei of the new epithelium is more often greater.

(b) The actual areas of nuclear and cytoplasmic material were found by the followmg method: a rectangular portion was outlmed and its area found ; the mean diameter of each nucleus within this portion was determined and its area found by use of the formula t r^, letting tt =


62


AMERICAN ASSOCIATION OF ANATOMISTS


3 Y. The sum of these areas gave the total area of the nuclei and by subtractmg this from the area of the rectangle, the area of the cytoplasm was found. Then, using the ratio

Area of nucleus : Area of cytoplasm : : 1 : X the number of parts of cytoplasm to one part of nuclear material was found for each specimen. In the majority of all cases the area of cytoplasm was greater than of nuclear material; i. e., in the ratios X was found to be greater than 1. Table 2 shows the number of cases which were exceptions :

TABLE 1


NUCLEI LARGEB IN OLD TISSUE AS COMFABED WITH NEW 1


NUCLEI LABGEB IN

NEW TISSUE AS COM PABED WITH OLD


Mesenchyme Adult

Fundulus heteroclitus tail

Diemyctylus tail

Diemyctylus arm

Total

Average

Larval

B,ana sylvatica tail

Amblystoma punctatum tail.

Total

Average

Adult and larval

Total

Average

Epithelium Adult

Fundulus heteroclitus tail

Diemyctylus tail

Diemyctylus arm

Total

Average

Larval

Rana sylvatica tail

Ambylstoma punctatum tail.

Total

Average

Adult and Larval

Total

Average


2 cases 31 cases

5 cases 38 cases

40 per cent

6 cases 10 cases 16 cases

40 per cent

54 cases 40 per cent


7 cases 21 cases

2 cases 30 cases 32 per cent

4 cases 12 cases 16 cases 40 per cent

46 cases 34 per cent


4 cases 18 cases

3 cases 25 cases 27 per cent

2 cases 13 cases 15 cases 37| per cent

40 cases 30 per cent


No cases

12 cases

2 cases

14 cases

15 per cent

2 cases

9 cases 11 cases 27| per cent

25 cases 19 per cent


4 cases 15 cases 12 cases 31 cases 33 per cent

2 cases 7 cases 9 cases 22| per cent

40 cases 30 per cent


3 cases 31 cases 16 cases 50 cases 53 per cent

4 cases 9 cases

13 cases 32^ per cent

63 cases 47 per cent


The cytoplasmic area was greater than the nuclear in 86 per cent of all cases, the percentage of exceptions being considerably less in the larval than in the adult animals.


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63


TABLE 2


Adult

Fundulus heteroclitus tail

Diemyctylus tail

Diemyctylus arm

Total

Larval

Rana sylvatica tail

Amblystoma punctatum tail. Total


No exceptions 12 exceptions 2 exceptions 15 per cent

No exceptions 5 exceptions 12| per cent


No exceptions 9 exceptions 7 exceptions

17 per cent

1 exception

2 exceptions 7i per cent


Total number of tracings of epithelium 268

Total number of exceptions 38


(c) In a small majority of the cases, 57| per cent, the number of parts of cytoplasm to one part of nuclear material was found to be greater in the old tissue than in the new. Table 3 shows the summary of the ratios as found for each paii" of tracings, the numbers representing X in the ratio

TABLE 3

Summary of tables of areas of cytoplas?n to areas of nuclei


NUMBER OF SECTIONS


AVERAGE OP PARTS OF CTTOPLASM TO 1 PART NUCLEUS




Old


New


Adult






10


6.041


6.533


Fundulus heteroclitus tail



64


1.381


1.302


Diemyctylus tail



20


1.428


1.204


Diemyctylus arm



Larval






10


2.694


2.266


Rana sylvatica tail



30


1.808


1.628


Amblystoma punctatum tail



Total Average .


2.585


2.587




Area of nucleus : Area of cytoplasm : : 1 : X. Table 4 shows the percentage of cases for each species in which there is more cytoplasmic material in the old than in the new, as compared with the same amount of nuclear material:

TABLE i Adult S

Fundulus heteroclitus tail ^"

Diemyctylus tail ^^

Diemyctylus arm '

Average ^^


64 AMERICAN ASSOCIATION OF ANATOMISTS

TABLE 4— Continued.

Larval

Rana sylvatica tail. 70

Amblystoma punctatum tail 57

Average 63|

Total Average o7|

Summary: From the total number of 536 tracings in this experiment the following conclusions may be drawn: (a) In the mesenchyme of both larval and adult animals and in the epithelium of the larval animals the nuclei are larger in the old tissue than in the new; but in the epithelium of the adult animals the nuclei are larger in the new tissue. (b) In 86 per cent of the tracings of epithelium the cytoplasmic area is greater than the nuclear; the larval tissues show fewer exceptions to this rule than the adult, (c) The amount of cytoplasmic material as compared with nuclear is found to be slightly greater in the old than in the new tissue in 57^ per cent of the cases.

In general then it would seem that in the epithelium of the larval animal the whole cell in the old tissue is larger than the cell in the regenerating tissue, the cytoplasm, however, being larger in greater proportion than the nucleus. In the epithelium of the adult animal the nucleus of the old cell is smaller than that of the .cell in the regenerating tissue but the amount of cytoplasm is greater per nuclear area.

11. A7i aUejnpted analysis of growth. Montrose T. Burrows, Anatomical Laboratorj^ Cornell University Medical College, Xew York City.

The study of the growth of different tissues during their development, the study of regeneration, the study of animal behavior, as w^ell as the study of cancer and the effect of phj^sical and chemical conditions on growth and development has showm that the environment is very important in development. Further these studies have given evidence to show that the various forms of cell activity are dependent upon conditions in the environment aside from food and oxygen. Little is known, however, as to the nature of the changes brought about in the cells through this effect of environment nor has sufficient evidence been given to any one theory to cause its general acceptance.

Two years ago I made the observation that growth, division, migratory, movements, rhythmical contractions and latency could be observed in heart muscle cells migrating from the same, piece of tissue into the same media and in a more recent study I have found that each of these activities is associated with a particular environment. These environmental differences consisted not only in differences in the chemical composition of the medium brought about ])y the active cell metabolism but also in differences in the mechanical support given these cells, which in plasma clots was altered not only by the concentration and nature of the substances coming from the tissue fragment but also by the shape of the clot and the support given to the clot and the tissue


PROCEEDINGS 65

fragment. The facts in this last statement I have been able to show by direct experiment, as well as to show further that the conditions of the particular environment were necessary for the particular activity shown by the cell. By altering the environment of a cell showing one activity this cell showed the form and activity of one occupying this new environment.

In the paper to be presented before the society I wish not only to describe these observations in greater detail but to give evidence to show that the movement of tissue cells may be interpreted in terms of surface tension. In the same manner I have been able to find a relation between surface tension changes and growth and evidence to show that the organization peculiar to the contracting cells may be interpreted by similar changes.

12. Observations of the lymph-flow and the associated morphological changes in the early superficial lymphatics of chick embryos. Eleanor Linton Clark, Anatomical Laboratory of the University of Missouri.

The present investigation is concerned with a few of the physiological and morphological changes which take place in the developing lymphatic system, after its first appearance. Early superficial lymphatics were studied in living chicks and experiments performed to test the direction and character of the lymph-flow at various stages. The same embryos were then injected and the extent and character of the l3Tnphatic system studied in cleared specimens. Thus an attempt has been made to correlate the structure and function of the early lymphatic system, and to determine, if possible, some of the factors which regulate a few of the phases of its development.

Eggs are opened in a warm chamber, left at incubator temperature, in a manner which has already been described. Under the binocular microscope the lymph circulation is tested by injecting a few India ink granules directly into a lymphatic capillary or duct. The fine glass canula is withdrawn carefully, so as to prevent leakage and the movement of the granules is observed through the binocular microscope. After testing the direction and character of the lymph-flow m various regions, the Ivmphatic system is injected and the embryo cleared by the Spalteholz method. Chicks of 5^ to 9 days were studied m this manner.

(1) In its primary condition (in chicks of approximately 5 to 6 days) the superficial lymphatic svstem is a rapidly growing, richly anastomosing plexus. A lymphatic plexus gradually extends posteriorly, from its venous connections in the neck, through the axillary region and down the side. At the same time another plexus is extending anteriorly from the coccygeal veins in the tail. It spreads out over the pelvis and eventually the two plexuses meet and anastomose oyer the hip. During this period of rapid extension there is no circulation m the superficial lymphatics. The side pressure in the veins with which the lymphatics connect, is higher than the pressure in the lymphatics and con THE ANATOMICAL RECORD, VOL. 9 NO. 1


66 AMERICAN ASSOCIATION OF ANATOMISTS

sequently blood is continually forced out into the extending lymphatic plexus. The plexus covers a wide area and is irregular and indifferent in character.

(2) The next period in the developing superficial lymphatics is characterized by the begmning of lymph-flow, accompanied by the differentiation of definite ducts or channels in the irregular prunary plexus. The flow starts in the side plexus and follows a definite path anteriorly, through the axillary region and the deep plexus, into the veins near the duet of Cuvier. Somewhat later the circulation over the pelvis begins. The flow in this region is instigated bj^ the first pulsations of the lymph heart (still in the form of a plexus). In the earliest stage of circulation the granules move slowly and follow a narrow wmding path. Injections show that the first channels are small and somewhat tortuous but quite distinct from the surrounding plexus. On this stage the blood is gradually washed out of the lymphatic system: first from the side region and later from the lymphatics of the pelvis.

(3) The development of the superficial l3miphatics in chicks of 7 to 8 days is characterized by increased pressure in the lymphatics, stronger pulsations of the lymph heart, a more rapid lymph-flow and associated with this, the formation of new channels in the lymphatic plexus and the enlargement of those already formed. The exact position of a channel is not predetermined, since variations in the number and position of the main ducts are frequent at aU stages.

(4) In chicks of 8 to 9 days, the pressure in the superficial lymphatics is very high. The great increase in the flow of lymph from the allantois and from the deep body lymphatics appears to interfere with the outlet of the fluid from the superficial Ijmiphatics. At this stage the flow is rapid in certain portions of the superficial lymphatic system and very sluggish in others. Injections show that ducts or channels are present in the former regions and large sacs or lakes in the latter. The sacs always occur at a point where there are two conflicting pressures. Because of the looseness of the subcutaneous tissue at this stage, the lymphatic system encounters very little resistance from without and so expands in response to the increased pressure within the lymphatics. The sacs may be formed by the enlargement of two or more neighboring ducts and the brealdng clown of the walls between them, or by the enlargement of a single duct. At this stage the lymph heart first assumes the form of a sac. Its muscular walls offer an obstacle to its distension and hence it remains much smaller than some of the other sacs or reservoirs. Except for the development of muscles in its wall, the h^mph heart does not differ in its mode of formation from other portions of the early lymphatic system.

In addition to the differences in pressure at various stages, the flow of lymph is influenced and altered by (a) the movements of the embryo, (b) the beating of the lymph heart, (c) changes in the blood circulation (d) development of valves at the entrance to the veins, (e) the formation of new lymphatic capillaries and ducts, and (f) by the shifting of the I'clationship of various organs.


PROCEEDINGS 67

In chicks older than 9 days the mcreased thickness of the sldn and the development of feathers prevented further observation of the circulation of granules in the superficial hinphatics.

13. Studies of the growth of blood vessels, by observation of living tadpoles

and by experiments on chick embryos. Eliot R. Clark, University

of Missouri, Anatomical Department.

There are two views each claiming the support of active workers as to the mode of development of the main arteries and veins. According to one view, which has been largely developed by Hochstetter and recently championed by his pupil Elze, the main arteries and veins develop in definite predetermined places, and the growth of each represents merely the steady extension of a single vessel along its inherited path. The second view, which has been mainly developed bj' Thoma, and which has found support recently in the works of E. Miiller, C. G. Sabin, H. Rabl, Mall and Evans, is that each artery and vein is preceded by an indifferent capillary plexus, any part of which is capable of developing into artery or vein, and that the selection of one or another capillary depends upon mechanical conditions inside and outside the capillary.

The studies here presented are in favor of the second view. The observations on which this view has rested have consisted of studies made by injection or reconstruction, of vessels in a selected region in embryos of different ages. In the present study the development was watched in its various stages in the same embryo. The region selected was the transparent fin expansion of the tail of the frog larva. Drawings were made while the tadpole was immobihzed by chloretone, with the aid of an apparatus previously described. By alternating the periods of observation with periods in which the tadpole was returned to fresh water, it was possible to make many successive observations on the same animal, as it increased in size. The records made consisted not only of camera lucida drawings of the vessels, with records as to direction of flow, but also notes as to the comparative rate and amount of flow in each.

It was found that arterioles and venules develop from an indifferent capillary plexus, in which, at any stage, it is impossible to predict which capillary will be incorporated as a part of the advancing arteriole or venule. Thus a vessel which, at one stage, is the mam channel between artery and vein, may in later stages either remain the same size, or may even become solid, and disappear by retraction of the endothelium. The factor which determines the selection, of a capillary as part of the developing arteriole or venule is the relation in which it is placed with reference to the new capillaries which develop more peripherally. If favorably placed the flow of blood through it increases and its diameter increases, until it becomes a part of the arteriole or venule.

That the development of the main vessels is due to favormg mechanical factors, and not to heredit\ , is indicated also by the results of experiments on chick embrvos. These consisted of the removal of the an


68 . AMERICAN ASSOCIATION OF ANATOMISTS

terior cardinal vein of one side in chicks approximately two days old. This was accomplished by injecting into the vessel Berhn blue — which clumps on contact with the blood and sticks to the endothelium — and removing with forceps and needle the vein and surrounding tissue. The ear vesicle was removed along with the vein as the vein passes under it. In all the chicks in which the operation was successful, examined three or four days after the operation, there was found a well developed vein in the place usually occupied by the internal jugular. In one case this vein was larger than the vein on the unoperated side; in most cases it was slightly smaller, but in all cases it was well developed.

This would seem to show that there exist in the side of the neck mechanical conditions favoring the development of a large vein — ■ since, after the normal vein had been removed, its place was taken by another, which could in no waj'" be considered as inherited.

14- Salient features of the medulla oblongata of Aniblystoma embryos of

definite physiological stages in development. George E. Coghill.

In the stage of development designated by me (Jour. Comp. Neur., vol. 24, p. 163) as non-motile, root fibers of the trigeminal and lateral line ganglia of Amblystoma enter the medulla oblongata. In the early flexure stage the descending trigeminal tract extends to the auditory region and there is a perceptible ascending division of the root; while, in the coiled-reaction stage, the trigeminal tract becomes continuous with the spinal sensory tract, which is composed of fibers from the Rohon-Beard cells. Dorsally of the trigeminal tract in the auditor}^ region of the coiled-reaction stage are recognized the auditory root bundle, the fasciculus communis (solitarius) and two lateral line root bundles, the fasciculus communis laying between the auditory and lateral line root bundles. In the early swimming stage the lateral line root bundles of the seventh and tenth nerves overlap and the fasciculus communis has almost if not quite become continuous with the visceral sensory root bundle of the ninth and tenth nerves. There are no longitudinal association bundles corresponding to tracts a and b of Herrick (Jour. Comp. Neur., vol. 24, no. 4).

Very large tangential neurones are arranged along the mesial aspect of the root bundles as if functionally related to all of them in common, though smaller cells, located farther dorsad, appear to be especially related to the lateral line components. The axones of the large tangential cells pass mesially of the latero-ventral motor tract to the ventral commissure. This motor tract is the only longitudinal tract in the ventral part of the medulla oblongata until about the time swimming begins, when there appears a suggestion of a slightly more dorsal bundle, presumably the bulbo-spinal tract.

The functional significance of the sensory centers of the medulla oblongata in Amblystoma of this period can not be judged by the degree of development of the sensory root bundles alone, for these are developed entirely out of proportion to the corresponding peripheral nerves,


PROCEEDINGS 69

this being particularly true of the visceral sensory system. Also, experiments show that, in the earlier periods under consideration, the sensibility of the preauditory region to tactile stimulation is much lower than is that of the rostral portion of the trunk.

15. On the develo-pment of^ the lymphatics in the lungs of the pig. R. S.

Cunningham, Anatomical Laboratory, Johns Hopkins University.

The lymphatics of the lungs are derived from three sources, the right and left thoracic ducts and the retroperitoneal sac.

In embryos 2.6 to 3 cm. long vessels bud off from the thoracic duct and grow across to the lateral wall of the trachea and form there a plexus that gradually extends over the ventral surface of the trachea and especially down over the bifurcation. From this plexus yessels pass into both lungs and into the pleura.

The right tho]-acic duct divides, in embryo 2.5 to 2.6 cm., one branch passes to the heart while the other breaks up to form a plexus on the right lateral wall of the trachea; some vessels from this plexus pass down into the hilum of the right luna: and others anastomose with the plexus that extends up over the trachea from the other side. The development of the lymphatics within the lung depends upon the division of the vessels into two groups — those accompanying the veins and those accompanying the bronchi and arteries.

Each of the principal branches of the pulmonary vein is accompanied by a group of lymphatic vessels that anastomose freely with the plexus around the adjacent bronchus. These lymphatics grow more rapidly than those associated with the bronchi, and, after following the veins almost to the capillary bed, they pass to the pleura. In the early stages the terminal veins lie about midway between the adjacent bronchi and in this plane a sheet of lymphatic vessels develops from the vessels accompanying the vein and passes to the pleura, marking out the boundaries of the distribution of each bronchus. The first vessels to reach the pleura thus follow the veins, and they anastomose with the vessels that grow to the pleura from the hilum. These vessels reach the pleura when the embryo is about 3.6 cm. long. The bronchial vessels grow more slowly and at first are only to be found around the larger bronchi. As these structures multiply and the lung increases in size the lymphatics accompanying the main bronchi send vessels to the smaller ones, these vessels form a plexus around each bronchus— so that the bronchial tree is surrounded by a continuous series of branching tubes made up of lymphatic vessels. From every point of division of the bronchi lymphatics pass to joui those folio wmg the veins, and those around the terminal bronchus leave it, near where it ends in the primitive atria, and join those of the veins, septa, or— more rarely— those of the pleura. Lymphatics also arise from the retroperitoneal sac and grow up posterior to the stomach and the diaphragm to enter the lower pole of the lower lobe of the lung. These vessels form a plexus on the median surface of the lower lobe and send branches both to the other surfaces of the pleura of the lower lobe and


70 AMERICAN ASSOCIATION OF ANATOMISTS

into the lung along the veins, where plexuses develop similar to those above and soon the two groups anastomose (embryos 3.9 to 4.1 cm. long).

The further development consists in the multiplication oi the plexuses ■ on the bronchi and blood vessels, following the further development of these structures. As the lung increases in vokime the larger veins become more closely approximated to the bronchi and only the terminal ones are separated from them, these lie in the periphery of the lobule. Thus the vessels around the veins and bronchi become closely associated, except those accompanjang the terminal branches where the veins still lie in the connective tissue septa. These septa develop along the course marked out by the sheets of tymphatic vessels.

The common plexus surrounding the artery and bronchus becomes separated into two plexuses, incident to the increase in the size of the artery, they continue to have many anastomoses however. The vessels of the pleura mark out the early connective tissue septa, but later there develops a fine meshed plexus between these larger divisions, this plexus is not connected with the deep lymphatics. The valves begin to form in embryos about 6 cm. long and practically all point away from the pleura, so that the pleura is drained separately from the remamder of the lung.

In the adult there are Ijrmphatic vessels accompanj-ing the bronchi, the arteries, and the veins — ^these anastomose freely. There are also vessels in the connective tissue septa that drain chiefly into those around the veins and to some extent into those around the bronchi, near the point where the vein separates from the other structures to take its peripheral position in the lobule. All the deep vessels, together with most of the pleural vessels, drain into large trunks that end in the nodes at the hilum, but the lower half of the pleura of the lower lobe drains by a group of 4 to 6 vessels to the preaortic nodes that develop from the cephalic portion of the retroperitoneal sac. These vessels pass down through the ligament that connects the lower and median surface of the lower lobe with the tissue surrounding the aorta.

16. The morphology of the mammalian seminiferous tubule. George

M. Curtis, Anatomical Laboratory, Vanderbilt University Medical

School.

The problems here considered may be divided into two phases: (1), dealing mainly with the purely morphologic aspects of the tubule and (2), considering more the relation of the process of spermatogenesis to the tubule.

1 . The seminiferous tubule: (a) Blind ends. Since their descriptiorr and delineation by J. Miiller ('30), in the testis of the squirrel, the presence of blind ends in the course of the seminiferous tubules has been repeatedly affirmed and denied. In this work as thus far completed none of these structures have been disclosed. This statement is based upon the following evidence:

Adult albino mouse: Two complete tubules.


PROCEEDINGS 71

One isolated and reconstructed graphically and in wax. One isolated and reconstructed graphically. Adult rabbit: Six complete and one incomplete, tubules and tubule complexes.

Five isolated by teasing by Huber (Huber and Curtis '13). One isolated and reconstructed graphical^.

One incomplete complex isolated and partially reconstructed graphically and in wax. Three-week dog: Two complete tubules.

Both isolated and reconstructed in wax. From the above eleven tubules and the careful study of the material necessary to isolate them it is concluded that blind ends are not present in these three forms.

(b) Ampullae. These structures described and figured by Sappey ('88) have not been met with in any of the three above forms.

(c) Lobules. These are present in the albino mouse structurally as evidenced by the tubule modelled and by the tubule graphically reconstructed. However, no apparent lobulation is visible in examining the sections. In the rabbit and dog lobules are visible with the naked eye, each lobule being found to contain the coils of a portion of a single tubule or tubule complex.

(d) Branches and anastomoses. These were found to be infrequent in the mouse testis, more frequent in the dog and most frequent in the rabbit.

(e) Embryonic ends. In the mouse tubule, between the cessation of the active process of spermatogenesis and the flattened epithelium of the tubules rectus, was found a region where the tubule retained its embrj-onic structure, disclosing the sexual and sustentacular cells around an irregular lumen. It suggests itself that this may be a possible region of reserve to be used in growth or regeneration.

2. The spermatogenic wave : F^specially through the work of v. Ebner it has been shown that the development of mammalian spermatozoa proceeds in a wave-like process along the course of the seminiferous tubules. V. Ebner ('88) states that in the rat these waves ascend from the rete and vary in length from 25 mm. to 38 mm. averaging 32 nmi. Benda ('87) intimates their variabiHty.

A study of these waves has been made in the two complete seminiferous tubules of the adult mouse, and in one complete and in a portion of an incomplete tubule complex in the rabbit. In determining the relations between w^ave and tubule it first became necessary to arbitrarily choose a series of eight successive stages of spermatogenesis. These were obtained from v.'Ebner's figures and a study of the series. The above tubules were then reconstructed graphically, their loops corresponding to the numbered tubule sections in the serial drawings. By observing the stages of spermatogenesis present in each tubule section at definite intervals and applying them to theii- proper loop m the graphic reconstruction, the continuity of the stages was_ determined.

By comparing and numbering alike all the loops of the serial drawmgs,


72 AMERICAN ASSOCIATION OF ANATOMISTS

graphic reconstruction and model, the relations of the waves to the model were determined and their actual lengths computed. Their succession was shown by plotting the successive stages occurring along the course of the tubules. By this method the following results have been obtained.

(a) Wave length. From a study of seven waves in the mouse this was computed as averaging 1.83 cm. From a study of one complete wave and a comparison of eight wave portions the average wave length in the rabbit is estimated 1.4 cm.

(b) Wave variability. In the mouse and rabbit the waves vary in length, direction of course, uniformity, and in that single stages may be out of order in a successive series.

(c) Wave reversibility. In both forms the waves may reverse their direction, often frequently in a single portion of a tulDule or tubule complex.

(d) Wave direction. In the mouse the waves of five rete ends all descend from the rete. In the rabbit the waves vary, three waves ascending and two descending from the rete.

The above work was completed under Dr. Huber's direction at the . Histological Laboratory of the University of Michigan, and I desire to express here my thanks for his courtesies and assistance.

17. The structural relations of anterior hepatic anteries. C. H. Dan FORTH, Washington University Medical School.

In an earlier paper (.Jour. Morph., vol. 23, no. 3, 1912) the writer published a brief description of the anterior hepatic arteries of Polj'-odon. These vessels, which arise from the same trunk as the posterior coronary arteries, were found to be of constant occurrence and of fairly uniform distribution. Thej^ were often equal to, or even more extensive than the posterior (ordinarjO hepatic arteries, with which they anastomose.

At the time the above mentioned paper was published, it was supposed that anterior hepatic arteries were peculiar to Polyodon. Further observations, however, have revealed them in several other forms. Their general relations, so far as gross methods reveal, seem to be essentially the same in all cases.

It is now possible to record a few recent observations on the development and finer relations of the anterior hepatic arteries of Polyodon. In this fish the connective tissue about the hepatic veins is unusually extensive. Associated with 'these veins, as well as with the branches of the portal system, there are considerable accumulations of Ijmiplioid tissue. In general there is a branch of the artery running through each of these lymphoid aggregations. In young fish, less than 100 mm. in length, the thickened connective tissue sheath about the vein is not apparent and in such specimens anterior hepatic arteries have not been detected. At 123 mm. the connective tissue about the veins shows a slight thickening and the arteries may be traced in sections. But even at this stage there is no noticeable accumulation of lymphocytes.


PROCEEDINGS 73

In the adult the ramifications of the artery are usually found associated with the tributaries of the hepatic vein. Nevertheless, they are not confined to the connective tissue about the veins, but branches of considerable size may pass out into the liver parenchyma where they are for the most part surrounded by lymphocytes. Some of their branches may again become associated with vems.

These observations indicate that the anterior hepatic arteries arc not to be regarded as of the nature of vasa vasorum in connection with the hepatic veins, but as independent vessels, probably of considerable functional importance.

18. The so-called " endothelioid" cells. Hal Downey.

Pathologic conditions affecting primarily the hematopoietic organs are frequently characterized by the presence of large protoplasmic cells which are usually designated as epithelioid" or endothelioid" cells. Such cells are seen in generalized granulomata of the lymph nodes (tubercular lymph nodes, Hodgkin's disease), in Gaucher's disease, Banti's disease, in lymph nodes from typhoid fever patients, etc. Although these cells may show structural variations of considerable degree, most pathologists, especially American pathologists, do not hesitate to group them together under the heading of " endothelioid cells" or 'endothelial leucocytes.' They are given this name, because it is believed that they are derived from the endothelium which is supposed to line the lymph sinuses and cover the strands of reticulum of lymph nodes, or from the "endothehal" lining of the venous sinuses of the spleen, or from that which lines the blood and lymph vessels, primarily the latter.

Mallory calls all these cells 'endothelial leucocytes,' and he beKeves that they correspond to the so-called "large mononuclear leucocytes" of the circulating blood. Of the latter he says (Principles of Pathologic Histology, p. 21): "They are derived from the endothelial cells lining blood, and to a less extent lymph, vessels by proliferation and desquamation. They also multiply by mitosis after emigration from the vessels into the lesions." In this connection Mallory's idea of the structure of a lymph node is of interest. On page 616 he states: "Next to the cells of the lymphocyte series the most important cells of the lymph nodes are the endothelial cells. They line the blood vessels, the lymph sinuses and the reticulum of the parenchyma. Those lining the sinuses and the reticulum play a much more important part in pathologic conditions than those lining the blood vessels. They may increase greatly in number, desquamate from the walls of the sinuses and from the reticulum and form endothelial leucocytes. As a rule they exhibit marked phagocytic properties for other cells The capsule and trabeculae are composed of fibroblasts, among which are occasional smooth muscle cells. Fibroblasts also form the reticulum in the lymph sinuses and in the parenchA^ma and strengthen the walls of the vessels."

From this we see that Mallory believes the entire reticulum of a lymph node to be covered by a distuict endothelium which is independ


74 AMERICAN ASSOCIATION OF ANATOMISTS

ent of the reticular cell, which he describes as fibroblasts. This endothelium not only lines the sinuses but also covers the reticular strands of the parenchyme. Mallory is quoted so extensively because, in the main, his views coincide with those of most American pathologists.

The writer became interested in this problem while working over the lymphoid tissue of a fish (Folia Haem., Bd. 8). Here it was found that the blood and lymph spaces of the lymphoid tissue were not lined by a distinct endothelium, and that cells which might be mistaken for endothelial cells were merely portions of the general reticulum, in many cases with fibrils running through their protoplasm. The reticulum was partly fibrous and partly protoplasmic; where the fibers were present they were always embedded in the protoplasm of the reticular cells. The question was investigated again in connection with a problem on the origin of the lymphocj^tes in lymph nodes and spleen (Arch. f. mikr. Anat., Bd. 80), and latety in connection with a study of the histology of the spleen and lymph nodes in Gaucher's disease.

The conclusions from this study of the reticulum and its supposed relations to endothelial cells are very different from those of such anatomists as v. Ebner and Stohr, and the greater number of pathologists. Even with ordinary methods it is evident that the strands of the reticulum are composed of branched, anastomosing cells which are closely associated with the fibers. Nothing can be seen of a continuous epithelial covering. Associated with these strands, especially where the reticulum forms the wall of a sinus, are varying numbers of larger and more rounded protoplasmic cells whose connection with the fibers of the reticulum is not so evident with ordinary methods. Such cells, especially where they project out into the lumen of a sinus, might well be mistaken for hypertrophied endothelial cells. However, the use of any one of the numerous specific stains for reticular fibers (Krause's iodo-iodide of potassium — gold chloride method, the Maresch-Bielschowsky, or the older formula of Mallory's hematoxylin as used by Thome) shows clearly that these cells are frequently traversed by fibers, and that even the large rounded cells resembling large mononuclear leucocytes are frequently attached to the reticulum and have fibers embedded in their peripheral portions. These latter cells show great phagocytic activity, especially for red corpuscles, and their nuclei are large and indented. If these cells were not attached we would not hesitate to pronounce them as large mononuclear leucocytes. Frequently large numbers of similar cells are seen free in the sinuses and in the meshes of the reticular network. It is no difficult matter to show that they have been derived from the reticulum. These same cells are very numerous in the lymph of the thoracic duct and in the lymph of the lymph vessels beyond the lymph nodes. It therefore seems proven that large mononuclear leucocytes, or at least cells which cannot be distinguished from them morphologically, may be derived from the reticulum of the lymph nodes; in fact it is possible to demonstrate all intermediate stages between ordinary reticular cells and these larger cells. These cells


PROCEEDINGS 75

are frequently seen to be dividing by mitosis both within the lymph nodes and within the thoracic duct. The resulting daughter cells will be smaller cells resembling lymphocytes in structure.

The specific stains for reticular fibers, especialh^ when followed by a good counterstain, show further, that the reticular fibers of the strands within the parenchyme are embedded in the protoplasm of the cells. With these methods it is impossible to see an eadothelial covering to these strands. Since there is no endothelium covering the reticular strands or lining the sinuses we are hardly justified in naming the .large cells which are cut off from the reticulum 'endothelial leucocytes.' Whether such cells may also be derived from the endothelial cells lining lymph and blood vessels, as claimed by Mallory, still remams to be demonstrated. Theoretically there is nothmg against such a view, since numerous investigators, including the writer, have sho^\'n that similar cells may be derived from the covering cells of the omentum and serous laj-ers generally. However, Weidenreich and Schott believe that these covering cells are merely flattened surface fibroblasts (see also experiments of W. C. Clarke, Anat. Rec, vol. 8, no. 2, p. 95). If this view is correct these covering fibroblasts would not be very different from the reticulum cells of the lymph nodes.

There is nothing new about the results obtained from this study of normal animals, since Thome, Weidenreich and others reached the same conclusions. The pathologists Rossle and Yoshida, working with the Maresch-Bielschowsky method, also concluded that it is impossible to distinguish between endothelial cells and cells of the reticulum, and Ferguson, using the same method, fomid that the fibers of the reticulum are largely embedded in the protoplasm of the reticular cells. This literature, however, is almost unknowai to pathologists; consequently statements like those quoted from Mallory are constantly reappearing in the pathological literature, and to some extent in the anatomical literature also (Evans, Anat. Rec, vol. 8, no. 2, p. 101).

Gaucher's. disease has already been mentioned as one of those diseases which are characterized by the presence of large numbers of the so-called 'endothelioid' cells in the spleen, lymph nodes, liver, and bone marrow. The writer was fortunate in obtaining some of this material from Dr. F. S. Mandlebaum (Pathologist, Mount Sinai Hospital, New York City). The fixation of the material is unusually good, and so it is ideal material for working out the origin of the ' endothelioid' cells. In this case these cells are large clear cells characterized by the presence of exceedingly fine fibrils. in their cytoplasm. American pathologists have claimed that they were derived from the endothelium, especiallv from that lining the venous sinuses of the spleen, and the lymph sinuses of the lymph nodes. Several German pathologists have suspected that the reticulum was concerned m the formation of these cells, but none of them were able to prove this positively, as they could not find the necessary intermediate stages between reticular cells and the large cells of the disease. Mandlebaum's material.


76 AMERICAN ASSOCIATION OF ANATOMISTS

however, shows the early stages in the disease, and it is not difficult to find all of the necessary intermediate stages between the characteristic cells of the disease and the cells of the reticulum, as I hope to be able to prove with the demonstrations. In the liver, in the walls of the vessels, etc., they seem to be derived from fibroblasts. From this material it was impossible to prove the origin of these cells from the ' endothelium' of the venous sinuses of the spleen. However, if such were the case it would in no way invalidate the above findings, as it is now generally conceded by anatomists that this ' endothelium' is mereh' a specially modified portion of the reticulum.

In Hodgkin's disease we again have cells which have been called ' endothelioid' cells. They are very different in character from the large eel's seen in Gaucher's disease, nevertheless, their origin from the reticulum of the lymph nodes is easily demonstrated. Reticular fibers may be seen penetrating their protoplasm, and the same is true of the Gaucher cells while they are still attached to the reticulum.

These facts, and the results obtained from a study of normal tymph nodes, show that the large cells which are characteristic of mam^ pathologic processes, and which are numerous in the sinuses of normal lymph nodes, in the lymph of the thoracic duct, etc., are in most cases not derived from endothelial cells. There is, therefore, no reason for nammg them 'endothelial leucocytes' or 'endothelioid' cells. In most cases they could be designated as "reticular" cells. However, this would not do for a general term, because Dominici, Weidenreich and Downe}^ among others have shown that large mononuclear leucocytes may also be derived from lymphocytes. The intermediate stages in this process are shown in one of the lantern slides. One of the slides will also show that the reverse may be true, i.e., that lymphoc3^tes may be derived from large mononuclear leucocytes.

Those investigators (Goldmann, Evans a ad Schulemann, Aschoff, Kiyono, etc.) who have recently been engaged in the study of the results of vital staming by means of lithium carmine and the dyes belonging to the benzidine group will not agree with the view of the relationships between cells of the reticulum and large mononuclear leucocytes and lymphocytes expressed above. However, it must be remembered that they have not yet succeeded in showing that the cells which are able to store the d^^es in the form of granules (a process related to phagocytosis — Evans and Schulemann) are genetically different from those which do not take up the dye. Their results are equally well explained if we assume that those lymphoid cells which are located in the tissues or which have recently been cut off from the reticulum are in a condition which is especially favorable for phagocytosis, a fact which was known long ])ofore the modem investigations with vital staining were begun. We know that reticular cells, while they are still attached to the reticulum, show special phagocytic activity, and that this activity may be increased after the cells have separated from the reticulum. This can easily be proven by an examination of the large reticular cells in the sinuses of any lymph node


PROCEEDINGS 77

which contams free red corpuscles. In the lymph of the thoracic duct or in the peritoneal fluid the phagocytic activity of these cells is still very pronounced, l3ut it is greatly dimini?hed as soon as they reach the blood stream. In the tissues the phagocytic activity is again very pronounced. The function, and to some extent the morphological appearance, of a lymphoid or 'endothelioid' cell depends, therefore, on the conditions under which it finds itself. It is not necessary to assume the existence of a special line of 'histiocytes' which differ genetically from the other lymphoid cells.

19. On the anlage of the bulbo-urethral and rnajor vestibular glands in the human embryo. (Lantern). Arnold H. Eggerth, Department of Anatomv, University of Michigan. (Presented by G. Carl Huber.)

For this investigation, the urogenital systems of four human embryos of critical ages from the collection of Dr. Huber were reconstructed. In each of the models, the urogenital sinus presents three pair of symmetrically placed lateral epithelial folds. The cephalic ends of the middle of these lateral folds bear short epithehal buds, the anlagen of the bulbo-urethral and major vestibular glands. The measurements given are for crowii breech length. The model of a 32 mm. female embryo presents a short epithelial bud, 15 ^i in length, on the left side only. The model of a male embryo of 30 mm. presents gland buds on both sides, whose respective lengths are 50 m and 60 n. A female embryo of 45 mm. shows gland buds having a length of 120 iJL and 150 fx, and a female embryo of 60 mm. presents gland buds with termiaal branching, having a length of 200 /x and 240 fj.. The relative positions for the gland anlagen in both male and female embryos for the varying ages as reconstructed, is essentially the same.

20. The cell clusters in the dorsal aorta of the pig embryo. V E. Emmel, Department of Anatomy, Washington University Medical School. In the course of a study of hematogenesis in several regions of the

mammalian vascular system, the following observations were made on the dorsal aorta of the pig embryo. The material studied consisted of about seventeen embryos varying from 6 to 25 mm. in length, together with several mouse and rabbit embryos. In the dorsal aorta of the 6 to 15 mm. specimens there occur rounded cell masses or clusters, the cytological characteristics of which identify the component cells as belonging to the mesamoeboids of Minot or the primitive lymphocytes of Maximow. Their constant occurrence at certain stages of development, their evident more or less firm attachment to the vascular surface, and their restriction, apparently without exception, to the ventral wall of the aorta, appear to necessitate relegating to these clusters a significance greater than that of agglutinated cell masses merely incidentally resting upon the aortic wall. The absence, in many cases, of evident endothelial continuity at the basal regions of these clusters, the transitional cytological characteristics from the


78 AMERICAN ASSOCIATION OF ANATOMISTS

basal to the more peripheral cells, the changes in form and increase in number and size of the adjacent endothelial nuclei, together with the frequent occurrence of mitotic figures within the masses, is evidence strongly indicative of their active proliferation and origin in situ from the aortic endothelium. At the 15 mm. stage the clusters have become greatly reduced in number and are no longer to be observed in the 25 mm. embryo. During this 6 to 20 mm. period of development, there occurs in the ventral region of the aorta, in contrast to the dorsal region, an extensive degeneration of the medial and lateral intersegmental aortic arteries and a remarkable 'caudal wandering' of the coeliac and mesenteric arteries upon the aortic wall. The simultaneous appearance of these phenomena in the ontogeny of the embryo and the morphological interrelationships of the structures under consideration in the ventral aortic wall are of such a character as to be suggestive of some significant correlation between the formation of these clusters and the development of the permanent visceral arteries of the adult.

21. Feeding experiments on rats. J. F. Gudernatsch, Department of

Anatomy, Cornell University Medical College, New York City.

Based upon the results obtained by feeding the internally secreting glands to amphibians, these experiments are being continued, this time with mammals. The glands are given to white rats in stated • portions, at regular intervals. A prelimmary account of some observations on the thyroid-treated animals may here be given.

Beef thyroid was fed in portions small enough to keep the animals in fairly good health; 1 gram a week was given, in some experiments 1 gram in 5 daj-s. The application of even so small doses of thyroid sometimes produced slight symptoms of hyperthyroidism; however, the animals kept well enough to have offspring.

The following enumeration gives the records of 8 successful matings; in the first 4 cases the offspring are still living, while in the remaining 4 the young died, at stated dates.

Case I: d' tX 9 t.^ (a) While under treatment the father was bred to 3 treated 9 ; no result, (b) After discontinuation of the thyroid treatment the father was bred to a non-treated 9 ; 10 young were born after 26 days, all so frail that they died within a week, (c) One month after thyroid treatment of the father and immediately after thyroid treatment of the mother the two were mated; 3 young were born 54 days after the father and 29 days after the mother had received their last dose of th5^roid. The young are much smaller than the normal rats of equal age.

Ca.se II. d' t X 9 n. After discontinuation of the thyroid treatment the father was bred to the non-treated mother; 4 young were bom 30 days later; 2 died very soon, 2 undersized ones are living.

Case III: 9 t X d n. (a) While under treatment the mother was

^ t = treated ; n = normal.


PROCEEDINGS 79

bred to a treated cf ; no result, (b) Immediately after thyroid treatment the mother was bred to the non-treated father; 6 young were bom 113 days later; 4 undersized ones are living. The mother required 3 months to recover from the thja-oid influence.

Case IV: & t X 9 n. (a) While mider treatment the father was bred to a treated 9 ; no result, (b) The normal mother was bred to 2 normal &; 2 litters, (c) After discontinuation of thyroid treatment the father was bred to the normal mother; 3 young were born 117 days later; they are undersized. The father required 3 months to recover from the thyroid influence.

Case V: cf ^ X '9 n. (a) While under treatment the father was bred to a non-treated 9 ; no result, (b) While imder treatment the father was bred to the non-treated mother; 5 young were born 24 da3^s later; 1 died 9 days old, 4 very frail and undersized lived about 7 months. When 3 months old they weighed 57, 58, 60 and 66 grams respectively; (65 to 70 grams is the average weight of a rat about 60 days old).

Case VI: d' t X 9 t (a) While under treatment the father was bred to the treated mother; no result, (b) While under treatment the father was bred to a non-treated 9 ; 5 young (see Case V). (c) The treated father and treated mother (under a) were again mated; thyroid treatment ceased 31 days later; 7 yomig were born 81 days later; very frail and undersized; lived 2 months. The parents required 2 months to recover from the tlwroid influence.

Case VII: & t X 9 n. (a) While under treatment the father was bred to 3 treated 9 ; no result, (b) After discontinuation of the thyroid treatment the father was mated to the non-treated mother. Ten young were born 26 daj^s later; all died within 2 weeks.

Case VIII: 9 t X 9 n. (a) The non-treated father was bred to 2 non-treated 9 ; 2 litters, (b) Before thyroid treatment the mother was bred to a non-treated cf ; 1 litter, (c) While under treatment the mother was bred to a treated d^ ; no result, (d) After discontinuation of the thyroid treatment the mother was bred to the non-treated father; 5 yomig were born 151 daj^s later; all died within 5 days. The mother required 4 months to recover from the thyroid influence.

The history of these cases shows that the feeding of thyroid to rats greatly interferes with their breedmg qu alities. Twenty-four matings, in which both parents were treated, resulted m failure, 2 in which the female alone had been treated and 4 m which the female alone received thyroid food, in all 30 matings. Yet out of these 14 males 7 had been tested and given offspring previously to the treatment, and out of the 16 females 9 had been tested and were found fertile.

Table 1 gives the enumeration of several matings, which will show that pregnancy did not set in mitil several weeks after the discontmuation of the thyroid treatment, except when the female was nontreated. The number of days is given that elapsed between the placing together of the parents and the birth of a live litter (or death of the female). The gestation period of the rat is from 21 to 24 days.


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AMERICAN ASSOCIATION OF ANATOMISTS


> Thyroid given after mating


Thus under no circumstances will pregnaticy set in during the thyroid treatment (cases 3 to 7, 15); after discontinuation of the thvroid treatment, the ammals usuaJIy required several weeks to recover from the thjToid influence (cases 11 to 18).

TABLE 1

(1) 9 dies after 2 days

(2) 9 dies after 2 days

(3) 9 dies after 7 days

(4) 9 dies after 19 days

(5) 9 dies after 21 days [ No pregnancy

(6) 9 dies after 21 days

(7) 9 dies after 3S days.

(8) 9 normal; young born after 24 days; all die

early

(9) 9 normal; young born after 26 days ; all die

within two weeks

(10) 9 normal; young born after 28 days; 2 die

within a week

(11) 9 dies after 57 daj-s; 6 fetuses

(12) 9 dies after 67 days ; 7 fetuses

(13) 9 dies after 107 days; pregnant

(14) 9 dies after 112 days; pregnant

(15) young born after 110 days, 87 days after thy roid treatment

(16) cf normal; young born after 113 days

(17) 9 normal; young born after 117 days

(18) cT normal; young born after 151 days


No thyroid given after mating


Thyroid feeding continued for 33 days after mating.

No thyroid given after mating


Only one mating of both parents previously treated gave offspring after 29 days. However, the treatment of the father had ceased one month before the mating time.

The feeding to rats of fresh thyroid tissue shows its effect in three different ways:

1. Whenthe dose is too large, all the well-known symptoms of hyperthyroidization become evident, viz.: emaciation, diarrhoea, muscular weakness and finally cachexia leading to death. The hair becomes yellowish, stands erect, sometimes falls out in patches, in short the entire coat looks ragged.

2. When the dose is so regulated, as to keep the animals in approximately good health — the fur will always become shabby — then the animals do not breed. Not one mating of both parents treated , after the animals had been placed together, gave any result. Pregnancy was always delayed, since fertilization did not occur until several weeks after the application of the thyroid had been discontinued.

3. Did pregnancy finally occur, it resulted (a) in abortus; (b) the young died soon after birth ; (c) in very late pregnancies, the young show a diminished tendency to grow\ Although they are not especially frail, they keep in relative size behind the young of normally fed rats.


PROCEEDINGS 81

22. The development of reflex mechanisym in Amblydoma. C. Judson

Hekrick and George E. Coghill.

The results of neurological studies of Amblystoma by the authors and others now afford a tolerably sound basis for the interpretation of some features of the mechanism of functional differentiation of the central nervous system of the individual and may also contribute something to the knowledge of the factors involved in the phylogenetic differentiation of the nervous system.

]Most of the observations on the nervous system of Amblystoma and other urodeles from which these conclusions have been deduced are recorded in the following papers:

Coghill, George E. 1902 The cranial nerves of Amblystoma tigrinum. Jour' Comp. Xeur., vol. 12, pp. 205-289.

1909 The reaction to tactile stimuli and the development of the swimming movement in embryos of Diemyctylus torosus Eschscholtz. Jour. Comp. Neur., vol. 19, pp. 83-105.

1913 The primary ventral roots and somatic motor column of Amblystoma. Jour. Comp. Neur., vol. 23, pp. 121-143.

1914 Correlated anatomical and physiological studies of the growth of the nervous system of Amphibia. I. The afferent sj^stem of the trunk of Amblystoma. Jour. Comp. Neur., vol. 24, pp. 161-233.

Herrick, C. Jtjdsgx. 1914 The medulla oblongata of larval Amblystoma. Jour. Comp. Neur., vol. 24, pp. 343-427.

The sicim^mng reflex. The reflex mechanism essential to swimming in Amblystoma embryos of the youngest age m which this reflex is possible consists of three groups of neurones: (1) sensorj' peripheral neurones lying within the spinal cord (the transitor\' Eohon-Beard cells) which send their dendrites to the skin and myotomes, while their axones ascend in a dorso-lateral sensory tract of the cord; (2) commissural neurones which pass from the sensorj^ cells of one side to the motor cells of the other through the ventral commissure; the decussation of these fibers occurring only in the upper spinal cord and lower medulla oblongata; (3) motor cells, which form a descending, ventrolateral motor tract and innervate the myotomes by means of collaterals. It should be noted particularly that all responses of such embr^^os are 'total reactions," and of the same sort regardless of the place' and kind of excitation; that the peripheral sensory fibers are not specific with reference to exteroceptive and proprioceptive stimuli; that the sensors^ and motor peripheral neurones are not differentiated away from ceritral neurones of longitudinal columns, and that the first' central paths to appear are long and made up of chains of numerous relativelv short neurones.

Spinal reflexes in half-grown larvae. The spinal ganglion cells and ventral horn cells are at this age fully matured, and crossed as well as uncrossed reflexes have become possible at all levels m the spinal cord. Both correlation neurones and ventral horn cells send dendrites into ah parts of the cross section of the white substance, some even

THE ANATOMICAL RECORD, VOL. 0. KO. 1


82 AMERICAN ASSOCIATION OF ANATOMISTS

crossing in the ventral commissure. The responses are still in large measure simple and 'total reactions,' but they are brought under the influence of a much greater variety of excitations than are those of young embryos, in consequence of the introduction of longitudinal tracts that are actuated by special sense organs, especially those of the head.

The mammalian spinal cord. Here the correlation neurones are organized into an elaborate system of distinct reflex circuits, and there is a corresponding specialization and refinement of motor functions.

The medulla oblongata of larval Amblystoma. Each physiological type of end organ has its own distmct ganglion or ganglia and nerve roots. Each root fiber from the several types of end organs, immediately upon entering the medulla, divides into ascending and descending branches which pass upward and dowoiward for practically the entire length of the medulla oblongata. These bundles of root fibers constitute nearly all of the substantia alba of the dorsal half of the medulla, with the exception of two large, longitudinal correlation paths on either side. The ventral half of the white substance contains the motor roots and numerous long correlation tracts. In contrast with the sharp physiological differentiation of the sensory neurones of the first order, those of the second order are not functionally specific, for the dendrites of anj' one of them may establish sj^naptic relations with several or all of the peripheral sensory root bundles. The primary sensory centers, therefore, serve, not only as receptive centers, but also as correlation centers.

The medulla oblongata of mammals. The arrangement of the peripheral sensory neurones in the mammalian medulla oblongata is essentially the same as in the amphibian. The sensory neurones of the second order, however, are segregated into definite primary^ receptive centers, each related specifically to one peripheral system, and the secondary paths leading from these primary centers may be as specific functionally as are the peripheral root bundles themselves. The correlation of these elements into particular reflex systems is effected in centers farther removed from the first sensory neurone of the arc.

Conclusion. It is the prevailing belief that every form of central nervous system has arisen by the concentration of an original diffuse and relatively equipotential peripheral ganglionic plexus. Out of such a primordial nervous matrix there has been a progressive individuation of centers and pathways and a parallel progressive differentiation of specific reflexes away from the primitive type of 'total reaction.' The reflex mechanisms of embry^onic and larval Amblystoma are in many respects primitive; and their forms suggest that they represent different stages in this process of mdividuation of specific reflexes. The 'typical' two-neurone, short circuit comiection between dorsal and ventral root fibers is, theiefore, not to be regarded as primitive. During such processes of individuation of parts of the nervous system its integrative action has been preserved through the development of correlation centers farther removed from the receptors and effectors. Thus arose such supra-segmental apparatuses as


PROCEEDINGS 83

the cerebellum and cerebral cortex. Finally, we would urge that the factors operating in either the^ ontogenetic or the phylogenetic differentiation of the functional mechanisms of the brain cannot profitably be investigated without a precise knowledge in each stage investigated of the peripheral relations of each of these functional systems and of the interrelations of the neurones involved at every step in the progress of the nervous impulse from periphery to center and back to the effector organs during the normal course of functional activity.

23. The development of fibrous tissues in peritoneal adhesions. Arthur

E. Hertzler, Kansas City, Mo.

The material used in this study was obtained by causing adhesions of intestines by suture or by irritants and by attaching foreign bodies to the mesentery or omentum.

When a suture of adjacent loops of mlestine is placed, the space between the guts is filled with an amorphous exudate. In 10 to 30 minutes this exudate coagulates formhig fibrinous bands which extend from one gut surface to the other. These bands stain specifically with Weigert and Mallory stains. By comparing series it can be noted that the bands first lose the specificity for Weigert while retaining it for Mallory\ This occurs in 24 to 48 hours. In 4 days they no longer accept the Mallorj^ stain for fibrm but do accept the Mallory fibril stam. Bands may be seen which stain in part red and in part blue with the Mallory stam. W'ith picro-f uchsin the same transition attains.

When a disc of foreign material is sewed to the mesentery it is covered at once with an exudate. This coagulates over the entire surface and its conversion into fibrous tissue takes place simultaneously over the entire disc and does not proceed from the edges toward the center.

These fibrin bands may form in the exudate before the advent of cellular elements and the transition above noted may take place without the advent of cells.

An\ process which prevents the exudate from coagulating into fibrin prevents wound healing. This is true irrespective of the means employed. Infections produce this effect permanently and peptonization of the animal prevents it temporarily.

If wound healing has been delayed by any means which prevents the formation of fibrin in the primary' exudate then healing must await the advent of new^ exudate. This takes place only when cells find their wav mto the mifriendly exudate. The formation of fibrous tissue then takes place according to the methods described m the literature. The healing of wounds as described in the literature is in fact healing by second intention.

24- On the development of the digitiform gland in Squalus acanthias.

E. R. HosKiNS, Institute of Anatomy, University of Minnesota.

The digitifoim gland in Aqualus is evidenced first by a slight thickening of the entoderm of the dorso-lateral border of the gut just pos


84 AMERICAN ASSOCIATION OF ANATOMISTS

terior to the spiral valve. This may be seen in embryos 15 mm. in length, especially in those sectioned longituclinall3^ The thickening soon pushes lateral^ to form a hollow bud which turns and grows anteriorly along the gut. The form of the curved portion at the point of emergence from the gut always persists so that in older stages and in the adult this portion which becomes the duct of the gland enters both the intestine and the digitiform gland anteriorly.

In the stage of 28 mm. it may be seen that from the main part of the gland small buds resembling the original form of the gland grow laterally on all sides. These buds become tubules extending laterally and slightly posteriorly. They in turn give rise to secondary tubules which in time form irregular groups opening into the primary tubules. This condition is to be found throughout development, the gland becoming a compound tubular structure, the secondary tubules arising from the primary, close to the main lumen of the gland.

As the gland develops, it carries the mesentery of the intestine with it and is thus supported from the dorsal wall of the body cavity.

The entoderm of the digitiform gland is composed at first of four layers of low columnar or cuboidal cells with elongated nuclei, being similar to the entoderm of the gut from which it develops. As the gland increases in length, the epithelium is gradually reduced to one layer \a thickness. Its primaiy and secondary tubules both arise as structures of an epithelium of one layer of cells. At the points of greatest growth, namely, at the distal ends of the tubules the nuclei are wider and shorter than along the main lumen, often being spherical.

The epithehum lining the main or central lumen later thickens giving us a structure of two layers of columnar cells with rounded nuclei in the full-term fetus and of four layers in the adult.

So. The development of the albino rat, from the end of the first to the tenth

day after insemination. G. Gael Huber, Department of Anatomy,

University of Michigan.

The material on which this investigation is based was collected while the writer was stationed at The Wistar Institute of Anatomy. For the trustworthiness of the records pertaining to the time of insemination of the female rats used, he is greatly indebted to Dr. J. M. Stotsenburg. The age of the stages as given in this account is reckoned from the time when copulation was first observed, thus from the time of insemination. Garnoy's fluid ^\as used as a fixative; paraffin embedding and staining in hemalum and Gongo red was the general procedure. The process of ovulation, maturation and fertilizatbn having been carefully studied by Sobotta and Burckhard, their account carrying the development to the pronuclear stage, mj^ own studies of the development of the albino rat begin with this stage.

The pronuclear stage extends through a relatively long period, perhaps 12 to 15 hours. All ova obtained 24 hours after insemination present the pronuclear stage, this period presenting about the middle of the pronuclear phase. Of the two pronuclei, the female


PEOCEEDINGS 85

pronucleus is sHghtly the larger. The nuclei lie near the centre of the ovum, are distinctly membranated, and do not fuse prior to the formation of the first segmentation spindle. By the end of the first day, the fertilized ova have travelled about one-fourth the length of the oviduct, and are found lying free in its lumen. The formation of the first segmentation spindle, and the first segmentation occur during the early part of the second day after msemination. The resulting 2 cell stage extends for a period of about 24 hours, since 2 eel) stages were found in material obtained 1 day, 18 hours to 2 days, 22 hours after insemination. The first two blastomeres are equivalent cells. By the end of the second day after insemination, all the fertilized ova are in the 2 cell stage, having traversed a little over one-half the length of the oviduct. One of the cells of the first two blastomeres divides before the other resulting in a three cell stage; such a stage was obtamed 2 days, 19 hours, and 2 days, 22 hours after insemmation. The division of the other of the first two blastomeres soon follows, so that by the end of the third day all tubes examined contained ova in the 4 cell stage, they having traversed by this time about -^^ of the length of the oviduct.

An 8 cell stage is reached toward the end of the fourth day after insemination (3 days, 17 hours) and by the end of the fourth day, the segmenting ova, in a 12 cell to 16 cell stage, pass from the oviducts to the uterine horns.

It will be observed that begmning with the pronuciear stage, found 24 hours after insemination, there occur three successive segmentations, spaced at intervals of about 18 hours and resulting in 2, 4, and 8 cell stages durmg transit of the ova through the oviducts. During the fourth segmentation, the ova pass from the oviducts into the uterine horns. Weighings of the water displaced bj^ a series of madels made of early segmentation stages indicate that during the first 4 days of the development of the albino rat there is only very slight increase of the size of the egg mass as against the unsegmented ovum with two pronuclei.

Durmg the early hours of the fifth day after insemination all of the segmenting ova of the albmo rat are to be found lying free in the lumen of the uterus, spaced as in later stages of development, the fifth series of segmentations having been completed by this time, the resulting morula mass having an ovoid form and consisting of 24 to 32 cells and measuring approximately 80 m by 50 m- During the middle of the fifth day after insemmation, the. early stages of blastodermic vesicle or blastocele formation may be found. The segmentation cavity or blastocele begins as a single, u-iegularly crescentic space, arishig between cells, and is excentrically placed. The early stages of blastocele formation are thus observed in morula masses composed of 30 to 32 cells, these Ivmg free in the cavity of the uterus. The enlargement of the blastocele, after its anlage, is obtamed by a flattening of the border or roof cells; to a lesser extent, by anmcrease m the number of these cells. By the end of the fifth day after msemmation,


86 AMERICAN ASSOCIATION OF ANATOMISTS

all the ova are found in the blastoderm vesicle stage, one pole of each vesicle, designated its floor, consisting of a rela.tiveh' thick mass of cells; the other pole, its roof, consisting of a single layer of flattened cells bordering and enclosing the segmentation cavity. Cell differentiation into a layer of covering cells, a layer of ectoclermal and entodermal cells, such as described by Selenka, is not to be observed at this stage. During the sixth day after insemination, at which time the ova still lie free in the lumen of the uterine horn, the blastodermic vesicles increase in size, partly as a result of further flattening of the roof cells, partly as a result of rearrangement and flattening of the cells constituting the floor of the vesicle, this portion of the vesicle now consisting of about three layers of cells, the imiermost layer having differentiated to form the yolk entoderm. By the end of the sixth day the blastodermic vesicle consists of a discoidal area, the germ disc, comprising about i to ^ of the wall of the vesicle, and consisting of two to three laj^ers of cells, of which the inner is differentiated to form the yolk entoderm, the remainder of the vesicle wall consisting of a single layer of very much flattened cells.

During the seventh day after msemination, the blastodermic vesicles become definite^ oriented in the decidual crypts, the thicker portion of the vesicle wall, its floor, being directed toward the mesom^etrial border. Durmg the early hours of the seventh day, cell proliferation, cell rearrangement, and enlargement of cells takes place in the region of the germinal disc, resulting in a marked thickening of this portion of the wall of the vesicle, manifested by an outward gro"SAi;h, as also a growth inward into the cavity of the vesicle, initiating the phenomena known as 'inversion of the germ layers,' or 'entypy of the germ layers.' In this thickening of the germ disc, there may be recognized on the one hand the anlage of the ectoplacental cone or 'Trager,' on the other hand, in the cell mass which extends into the cavity of the blastodermic vesicle, the anlage of the egg-plug or egg-cylinder. In the anlage of the egg-cylinder there may be recognized early a circumscribed compact mass of cells, staining somewhat more deeply, which mass of cells I have designated the ectodermal node, since it is the anlage of the primary^ embrs^onic ectoderm of the future embryo. This ectodermal node, so far as it extends into the blastocele, is covered by the single layer of j'olk entoderm, or as it is now knoT\ai, the visceral layer of the entoderm. The ectodermal node is readily differentiated from the cells of the ectoplacental cone, with the base of which it is in close relation.

The more complete development and differentiation of the eggcylinder, the anlage of which was noted during the seventh day, ma}^ be observed during the eighth day after insemination. The thin walled portion of the vesicle, its roof or antimesometrial portion, enlarges, assuming a distinctly cylindric form. The ectodermal node with covering of the layer of visceral entoderm is forced into the cavity of the vesicle, this bj^ reason of proliferation of the cells at the base of the ectoplacental cone, this resulting in the formation of a nearly


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cylindrical I}- formed column of compactly arranged, polyhedral cells, interposed between the ectodermal node and the base of the ectoplacental cone, but merguig into the latter without sharp, demarkation. To this colunni of cells, the name of extraembryonic ectoderm is given. The ectodermal node and the extraembryonic ectoderm together form a cylindric structure, surromided by a single layer of visceral entoderm, which reaches from the base of the ectoplacental cone to nearly the mesometrial end of the origmal segmentation cavity. During the latter half of the eighth day, a small cavity appears in the ectodermal node. This is the anlage of the mesometrial portion of the proamniotic cavity. The cells bomiding this cavity, derived from the cells of the ectodermal node,- constitute the primary embryonic ectoderm. Soon after the anlage of the mesometrial portion of the proarmiiotic cavity, several discrete spaces become evident in the extraembryonic ectoderm of the egg-cylinder, constituting the anlage of the antimesometrial portion of the proamniotic cavity, these discrete spaces quickh' joining to form a smgle space, the antimesometrial portion of the proarmiiotic cavity, lined by a single layer of cells of the extraembiyonic ectoderm. Toward the end of the eighth day the mesometrial portion of the proarmiiotic cavity, arising in the ectodermal node, and the antimesometrial portion of the proamniotic cavity, arising in the entraembryonic ectoderm, fuse to form a single proamniotic cavity, the mesometrial portion of which is lined by primary embrj^onic ectoderm, the antimesometrial portion of which is lined by extraembiyonic ectoderm, the two types of ectoderm forming a continuous layer, their line of union, however, being readily distinguishable. This hollow ectodermal cylinder, attached to the base of the ectoplacental cone and extending to the antimesometrial end of the segmentation cavit}^, is surrounded by a single layer of visceral entoderm in the meantime differentiated into a portion which surromids the primary embryonic ectoderm, which consists of flattened cells and is now known as the primary embryonic entoderm, and a portion surrounding the extraembryonic portion of the egg-cylinder, consisting of tall columnar cells -oath vacualated protoplasm containing hemoglobin granules, and constituting an embryotrophic layer.

This cylindrical structure presents durmg the early part of the ninth day after insemmation no evident bilateral sj-mmetry, so that longitudinal sections, cut in planes at right angles to each other, present identical pictures. This is also evident in cross sections of the vesicles.

During the middle and latter part of the ninth day, active cell proliferation in the embrvonic ectoderm in the region of the future caudal end of the embrvo, leads to a distinct thickening of the embrv'onic ectoderm of this region. This thickening constitutes the primitive streak region. In it, there is developed a short axial groove, the primitive gi-oove. From the edges of this groove, cells derived from the embr>^onic ectoderm, wander between ectoderm and embryonic entoderm. This constitutes the anlage of the mesoderm. There is no evidence of the participation of the embryonic entoderm in the anlage of the


88 AMERICAN ASSOCIATION OF ANATOMISTS

f

mesoderm. Toward the end of the nmth day, and beginnmg of the tenth day after insemination, as a result of proUferation of the cells of the mesodermal anlage and further outwandering of cells from the embryonic ectoderm in the region of the primitive groove, the mesoderm extends so as to form a distinct layer situated between the two primary- germ layers.

26. The development of the lymphatic drainage of the anterior limb in

embryos of the cat. Lantern. George S. Huntington, Columbia

University.

Two phases of the functional adaptation of early mammalian lymphatics are considered:

1. Since Miller's discovery in 1913 (Am. Jour. Anat., vol. 15, pp. 131-198) of the haemophoric function of the avian thoracic ducts in the early stages of their development, attention has been directed toward the determination of homologous conditions during lymphatic ontogeny in embryos of the other amniote classes. In the mammal (cat) the area of the jugular lymphsac and of some of its tributaries offers in the early stages conditions corresponding to those of the bird, although they are more obscure by reason of the close association with the adjacent sj^stemic veins, a difficulty not encountered in the avian axial lymphatic line. The interpretation of mammalian lymphatic ontogeny gained from the viewpoint of the functional adaptation of early lymphatic channels serves to clarify some heretofore doubtful points in the mutual relations of developing lymphatic and venous channels in the mammalian embryo.

The vessel which offers the least complicated and clearest view of the genetic processes involved is the primitive ulnar lymphatic, draining the lateral body wall and the anterior limb bud, and accompanying the primitive ulnar vein during the period of the latter's functional activity, prior to the establishment of the definite subclavian venous line.

The first anlages of the developing primitive ulnar lymphatic are found in embryos between 7 mm. and 8 mm. as a disconnected series of intercellular mesenchymal spaces which form dorsal to the primitive ulnar vein and to the lower cervical nerve trunks. At first these spaces are irregular and communicate with smaller intercellular clefts in the surrounding mesenchyme. Later, in embryos of 8 mm. to 8.5 mm., they become distended and in part bounded by flattened mesenchjnne cells. In embryos of 8.5 mm. to 9 mm. the originally separate individual spaces have united to form a continuous channel whose cephalic extremity effects a secondaiy^ junction with the dorsal division of the jugular lymphsac. This stage is usually completed in the 9 ram. embryo in which the primitive ulnar vein is paralleled at a little distance along its dorsal or dorso-lateral aspect by the distinct channel of the primitive ulnar lymphatic. The mesenchyme surrounding this vessel exhibits at numerous points groups of developing bloodcells. In the 9.5 mm. embryo this local haemopoesis attains its fullest develop


PROCEEDINGS • 89

ineiit and the red bloodcells begin to crowd the previously clear lumen of the primitive ulnar lymphatic channel. The walls of the latter appear to be formed still m part by undifferentiated mesenchymal cells, in part by flattened cells assuming distinct endothelial characters! At numerous points the lumen of the lymphatic channel is still in open communication with smaller intercellular clefts in the surrounding haemopoetic mesenchyme. Some of these enlarge to include groups of bloodcells and become added to the main lymph channel. The majority of red cells appear to gain access to the latter through these avenues. It is of course possible that some of the blood-contents of the ulnar lymphatic are due to reflux from the jugular lyraphsac, but the conditions in the 9.5 mm. embryo seem to point clearly to the inclusion of the cells in situ in the manner described.

In the 10 mm. and 11 mm. embryos the primitive ulnar lymphatic appears enlarged, lined by a definite and closed endothelium and the lumen densely crowded with red blood-cells. This is the fully developed haemophoric stage of the vessel.

In embryos of 11.5 mm. evacuation of the blood contents of the primitive ulnar lymphatic into the jugular sac and through the same into the precardinal vein occurs. This process is usually completed in the 12 mm. and 12.5 mm. stages. The proximal segment of the primitive ulnar lymphatic rapidly narrows after evacuation is completed and in embryos of 13 mm. to 14 mm. the continuity of the channel becomes interrupted a short distance caudad to its point of entrance into the jugular sac. The endothelial cells lining the lumen become larger, more rounded, stain deepl}^ and appear to revert to the indifferent mesenchymal type, obliterating finally all trace of the former channel at this point. This may occur as early as the 13 mm. stage or be deferred to the 14 mm. or even the 15 mm. stage.

2. After the interruption of the primitive ulnar lymphatic at the level stated above, the distal segment of the channel enlarges rapidly by distension with clear fluid and by the addition of numerous new intercellular spaces forming in the surrounding mesenchyme. In this way a vast lymphatic reservoir, the axillary lymphsac, is formed which for a time receives and stores the lymph drained from the limb-bud and body wall. The former path of lymphatic drainage of this area via the primitive ulnar lymphatic dorsal to the nerve trunks of the anterior limb into the jugular Ijmiphsac having been interrupted, as above described, a new ventral 'lymphatic line is now established by the concrescence of numerous originally separate lymph spaces developed along the course of the recently estabMshed subclavian vem. The resulting channel connects cephalad with the ventral process extending caudad from the subclavian approach of the jugular lymphsac over the ventral face of the jugulo-subclavian venous angle. Distally it opens into and drains the axillary sac which subsequently becomes reduced in extent and incorporated in the permanent thoraco-appendicular lymphatic system. The axillarv sac thus functions as a tempoi-ary storage reservoir for the lymph pending the completion of the change trom


90 AMERICAN ASSOCIATION OF ANATOMISTS

the dorsal primitive ulnar to the ventral permalnent subclavian line of lymphatic drainage of the anterior limb and lateral body wall.

The definition of stages given above is based on observations covering a large number of closely graded embryos of the cat and represent the average. Considerable individual chronological variation is encountered. The material used comprises the following series of the Columbia University Embryological Collection in transverse section:

Serial No. 105, 108, 119, 121, 135, 137, 138, 266, 281, 487, 488, 752

Serial No. 282, 284, 486, 567, 595

Serial No. 89, 102, 485, 596, 597, 703

Serial No. 285, 466, 490, 704

Serial No. 106, 136, 265, 268, 421, 458, 459, 462, 467, 468, 489, 491,

492, 589 Serial No. 132, 133, 239, 269, 273, 461, 497, 499, .501, 598, 599 Serial No. 79, 101, 111, 112, 113, 114, 140, 237, 272, 274, 474, 477,

478, 496, 498, 500, 707 Serial No. 81, 118, 120, 479, 480, 720 Serial No. 77, 98, 213, 473, 566, 718, 719 Serial No. 251, 256, 472 Serial No. 78, 97, 100, 217, 263, 471, 744 Serial No. 264, 590, 591, 592 Serial No. 92, 107, 262 Serial No. 76, 189, 223 Serial No. 122, 127, 210, 211.. 212, 214, 747

The paper is illustrated by photomicrographs of the sections and Lumiere lantern slides of the reconstructions.

27. Effect of acute and chronic inanition upon the relative weights of the various organs and systems of adult albino rats. C. M. Jackson, Institute of Anatomy, University of Minnesota, Minneapolis. Twenty-one well-nourished adult rats were used, initial body weights varying from 182 to 367 grams. Fifteen rats were used for acute inanition, being allowed water but no food. They were killed after 6 to 12 days, the loss in body weight varying from 25 to 39 per cent (average loss, 36 per cent). Six rats were subjected to chronic inanition, being underfed so as to reduce the body weight slowly through a period of about five weeks, and were killed when the loss in bocjy weight reached about 36 per cent. The results below stated apply in general to both acute and chronic inanition, unless otherwise specified. The published data of Donaldson, Hatai, Jackson and Lowrey are taken ap normal for comparison. On account of the great variability of some organs and the relatively small number of observations, final conclusions are in some cases uncertain.

The head and fore-limbs lose relatively less than the body as a whole. Their relative (percentage) weight therefore increases. Of the systems — integument, skeleton, musculature, viscera and 'remainder'- — the in


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tegument loses relatively nearly the same as the whole body, and therefore nearly maintains its original relative (percentage) weight. The same is true of the musculature, which however undergoes a somewhat greater loss in relative weight during chronic inanition. The visceral group, as a whole, undergoes little change in relative weight, decreasing slightly in acute inanition. The uidividual organs, however, vary greatly, as indicated below. The skeleton retains nearly its original absolute weight, and therefore increases greatly in relative weight. There is a corresponding decrease in the 'remamder,' due chiefly to loss of fat. The individual viscera may be classified in three groups:

(1) The brain, spinal cord and eyeballs show little or no loss in absolute weight, compared with the normal at the initial body weight, hence their relative (percentage) weight has markedly increased with the diminution in body weight during inanition. The same is apparently true for the thyroid gland in acute inanition, but in chronic inanition there is apparently a loss, though relatively less than in the body as a whole. The suprarenal glands also apparently lose less in absolute weight than the body as a whole, hence their relative (percentage) weight increases.

(2) The heart, lungs, kidneys, testis, epididymis and hypophysis undergo nearly the same relative loss in weight as the bod}^ as a whole, therefore their relative (percentage) weight remains nearly the same. The thymus has already undergone age mvolution, and is therefore not materially affected by inanition.

(3) The Hver and the alimentaiy canal (both empty and including contents) usually decrease in weight relatively more than the body as a whole. The spleen is exceedingly variable; in acute inanition it usually shows a marked decrease in relative weight (although averaging higher in chronic inanition).

S8. Changes in young albino rats held at constant body weight by underfeeding for various periods. CM. Jackson, Institute of Anatomy, University of jNIinnesota, Minneapolis.

Ten litters, including 65 rats, were used. Twentj^-five rats were used as controls, including 11 at 3 weeks of age, 2 at 6 weeks, 6 at 10 weeks, 3 at 32 weeks, and 3 at 35 weeks. In addition, data previously gathered by observations upon several hundred normal rats were available for comparison. Forty rats were held at constant body weight by underfeeding for various"^ periods, 8 rats from age of 3 weeks to age of 6 weeks; 3 rals from 3 weeks to 8 weeks; 22 rats from 3 weeks to 10 weeks; 1 rat from 3 weeks to 13 weeks; 1 rat from 3 weeks to 16 weeks; 2 rats from 6 weeks to 32 weeks; and 3 rats from 10 weeks to 35 weeks. On account of the great variabiHty of some organs, the number of observations in some cases is insufficient for final conclusions.

As to body proportions, the relative weights of the head, trunk and

extremities remain practically unchanged in young albmo rats held at

constant body weights. . ,

Of the systems— integmnent, skeleton, musculature, viscera and


92 AMERICAN ASSOCIATION OF ANATOMISTS

'remainder' — there is but little change in the weight of the musculature, visceral group (as a whole) and ' remainder. ' There is, however, usually a marked decrease in the integument, counter-balanced by a marked increase in the skeleton. Thus under these conditions the growth capacity appears weakest in the skin and strongest in the skeletal system. This is in striking contrast with the normal growth process, during which the musculature shows the greatest increase and the skeleton lags behind relatively.

The increase in the skeleton during constant body weight appears to involve the ligaments and cartilages as well as the bony skeleton. The skeletal grow^th tends to proceed along the lines of normal development, as indicated by changes in water content, by formation and union of epiphyses, and bj' relative elongation of the tail (compared with trunk length) . The teeth also continue to develop normally (eruption of third mars).

The individual viscera may be classified in three groups.

(1) There is during the maintenance of constant bodj' weight a wellmarked increase in the weights of the spinal cord and eyeballs; usually also of the tetis alimentary canal (both empty and including contents) and hypophysis.

(2) There is no marked change in the weights of the brain, heart, lungs, suprarenal glands, kidneys and epididymi. The hver is variable, with, apparently a slight tendency to increase in the younger rats and to decrease in the older.

(3) There is always a marked decrease in the weight of the thymus ('hunger involution'); usually also of the spleen (earlier stages) and probabty to a slight extent of the lungs and thja-oid gland.

29. Haemopoiesis in the yolk-sac of the pig embryo. H. E. Jordan,

University of Virginia, Va.

The yolk-sac of the 10 mm. pig embryo was found to be especially favorable for a study of the early stages in blood-cell formation. _ It is still sufficiently young to show the earliest steps (with the exception of the initial origin of the angioblast) and sufficiently advanced to include the more important of the later stages. For these reasons it seems desirable to limit the present description to this stage of development. It need simply be added that the haemopoietic phenomena are essentially the same in the yolk-sacs of specimens ranging from 4 to 12 mm. Still younger and older specimens have not yet been examined.

This description pertains chiefly to a specimen fixed in Zenker's fluid and stained in toto with Delafield's hematoxylin and counterstained with eosin. The specimen is exceptional only in its unusually good preservation. IVIitotic figures are abundantly present in all oi the tissues of the embryo and the sac; and the mitochondrial content of cells of the liver and the entoderm of the sac are clearly shown. It would seem that the specimen may therefore be confidently regarded as perfectly normal and well preserved.

The point of special importance pertains to the evidence for the origin of primitive blood cells or haemoblasts, from the mesenchyma. This


PROCEEDINGS 93

is the link in the nionophyletic view of haemopoiesis as urged notably by Saxer, Bryce, Maximow and Dantschakoff concerning which there remains perhaps the greatest doubt. In the belief that the yolk-sac offered the best material for an investigation of this particular point, this study was undertaken. Both direct and indirect evidence strongly indicates that the mesenchyma of the young yolk-sac does differentiate into blood-vascular tissue, or so-called angioblast.

Regarding the origin of the initial angioblast in the yolk-sac of the pig this material yields no data. To identify angioblast with mesenchyma, at least in part, in the yolk-sac of this stage may seem to beg the entire question. Against this objection can be brought the observation that in certain portions the entire extra-entodermal layer forms a continuous tissue, or syncytium. The continuity is complete only in the location of early blood-islands; where blood vessels appear the continuity pertains to the endothelium. Moreover, there is apparently no difference, either from the standpoint of cytoplasmic or nuclear structure or form, between endothelial cells, mesenchymal cells, and the surface mesothelial cells. And in certain regions the three are seen to be continuous. The criteria which Clark (Anat. Rec, vol. 8, no. 2; 1914) used with success in the chick embryo for the differentiation of endothelial from mesenchjTiial cells are not applicable to this material. On the other hand, the angioblast is everywhere sharply delimited from the entoderm. The morphologic evidence seems to force the conclusion that endothelium (angioblast), mesenchyma, and mesothelium are at this stage composed of the same cell, slight^ modified along different lines by chiefly mechanical factors. In mesothelium and endothelium these factors include predominantly the element of pressure forcing an elongation and flattening of the cells. This accounts for the close similarity, amounting apparently to an identity, between the endothelial and the mesothelial cell.

Since it can be readily proved, as will be shown below, that haemoblasts differentiate from the endothelium of these early blood-vessels, these observations regarding the similarity and continuity of endothehum and mesenchyma constitute the indirect evidence for the mesenchjanal origin of primitive blood cells. That mesothelium and endothelium, in spite of their histologic close similarity, are however functionally different at this stage must be admitted from the fact that no evidence appears of a direct origin of haemoblasts from mesothelium. But the continuity of mesothelium and mesenchyma must again be emphasized, as well a^ the proUferative capacity of the mesothelium. Moreover, that mesothelium mav function haemopoietically is shown in Bremer's description of mesothehal ingrowths (angioblast-cords and angiocysts) into the body-stalk of a voung human embryo (Amer. Jour. Anat., vol. 16, no. 4, 1914).

The direct evidence for the origin of haemoblasts (prmiitive lymphocytes— IMaximow ; mesamoeboid cells— Minot) from mesenchyma appears chiefivinthe presence of certain cells in the mesenchymal syncytnmi with the cvtoplasmic and nuclear features of true intra-vascular haemo


94 AMERICAN ASSOCIATION OF ANATOMISTS

blasts and megaloblasts. There can be no doubt regarding their identity. What needs to be estabUshed is their true relationship to the mesenchymal cells. It is possible that they may have wandered into the mesenchyma from the blood vessels. This is Minot's suggestion regarding the ' lymphocytes ' which Maximow has described as arising in the bodymesenchyme of the young rabbit embryo; and he bases his conclusion upon the observation that such cells frequently show certain nuclear and cjd:oplasmic features which he interprets as degenerative (Keibel and Mall's Human Embr>^ologA^, p. 511, vol. 3). The cells in question in the yolk-sac of the pig show no nuclear or essential cytopla,smic differences which seem, to warrant the interpretation that they are degenerating cells.

But neither these facts nor the additional one, namely, that they appear to be continuous through numerous processes with the mesenchyma, prove that they have arisen in situ. The processes may be of the nature of those described by Kite (Journ. Infect. Dis., vol. 15, no. 2, 1914) for pohTnorpho-nuclear leucocytes under certain conditions; and these pseudopodia of a possible wandering cell may have become so intimately fused with the mesenchymal syncytium as to simulate continuity. The following observation, however, seems to estabhsh the in situ origin of these haemoblasts in the mesenchyma: In the case of certain undoubted haemoblasts which are still in continuity with an undoubted mesenchymal cell, a delicate chromatic thread attached to the haemoblast nucleus extends for a considerable distance through the connecting bridge of protoplasm towards the nucleus of the mesenchymal cell. In a few instances the connection was apparently complete. This chromatic bridge is always most conspicuous at its haemoblast terminal, and looks like an evagination from the haemoblast nucleus. That this chromatic bridge indicates amitotic division is doubtful, since many of the mesenchymal cells are seen in mitosis. But whatever its interpretation in terms of cell division, it would seem to show a haemoblast origin from mescench3rme. In some instances the e\ddence indicates that the mesenchyme becomes arranged in the form of endothelium about such forming haemoblasts. Haemoblasts are occasionally seen in process of transit between mesenchyma and blood vessel, the direction being probably either way. Certain spaces in the mesenchyme are lined by flattened endotheliod (mesothelial) cells.

It remains to describe blood cell origin and differentiation within the blood vessels. The blood vessels are at the start simply endothelial tubes of irregular caliber. The blood cells within the vessel include haemoblasts, cyrthroblasts (megaloblasts and normoblasts) and giant cells. No evidence appears of leucocytes except in so far as the smaller basophilic haemoblasts simulate lymphocytes. All of these cells are capable of intense proliferative activity.

The haemoblast (mesomoeboid stage of INIinot) is a relatively small spherical cell with a relatively large nucleus, and a narrow shell of slightly basophilic cytoplasm. The nucleus contains a delicate widemeshed chromatic reticulum with generally several larger spheroidal


PROCEEDINGS 95

chromatic masses. Occasional cells answering to this description are of much greater size.

The megaloblast (ichthyoid stage of Minot) phase of the developing eiythroblast is a relatively much larger cell. Its nucleus, however, is approximately of the same size and structure as that of the hacmoblast. Its considerable cytoplasmic body reacts to the eosin stain. It thus has a bright pink color, due presumably to the presence of a small amount of haemoglobin. These cells divide extensively; they present a large series of size variations; moreover, the larger parent cells are frequently of lenticular or bluntly fusiform shape. This peculiar shape is interpreted in terms of an endothehal origin, as will be described below. Again, certain cells of this type possess a number of blunt pseudopodia. Certain cells with bilobed nuclei suggest that the nuclei of certain of these cells may also occasionally divide bj^ amitosis.

The mormoblast (saunoid stage of Minot) is also a relatively large cell, with a relatively smaller, denser, more chromatic granular nucleus. This is the most abundant type of cell. It is veiy uniform from the view-point both of size and structure. Verj^ many of these cells are seen in mitosis. The cytoplasm of this cell is peculiar; apparently the technic employed extracted the haemoglobin; the cytoplasm appears clear, with a very wide-meshed dehcate reticulum. A smaller number of cells are present very similar to the normoblasts, except that the nucleus is still smaller and more chromatic. This is the erythrocyte in early stage of metamorphosis into an erythroplastid. This involves the extrusion of the nucleus together with an enveloping sheU of cytoplasm, as described by Emmel (Am. Jour. Anat., vol. 16, no. 2, iai4). This stage is extremely rare, but in view of Emmel's careful work can be properly interpreted.

The giant cells are relatively enormous cells, and very variable from the standpoint of the number, size and chromaticity of the nuclei. The larger varieties have a more deeply staining apparently cytoplasm. A graded series can be traced from the megaloblast with one nucleus, through one with two nuclei still retaining a pmk-stauiing cytoplasm, to cells with more nuclei (or a larger, more chromatic nucleus) and a deep-brown-staining cytoplasm. This indicates the origm of the giant cells, namely, through growth (frequently accompanied by endogenous multiphcation of the nucleus) of a megaloblast (or haemoblast).

From the standpoint of nuclear material giant cells have relatively little cytoplasm. From this \aewpomt they represent young or 'rejuvenated' cells. There is some evidence to indicate amitotic division of the nuclei; but mitotic figures also appear, frequently with tn-and multipolar spindles. All the evidence indicates veiy rapid growth ot these cells. They are of two types, mono- and multinucleate. As to their function the evidence seems clear in the case of the multmucleate type. The megakai"v-ocytes most probably subsequently become multinucleate through division of the nucleus, and thus partake ot the same function. About one or several of the nuclei appear clearer courts


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identical m structure with that described for the normoblast The nuclei meanwhile also assume the features of the normoblast type W here m a bmucleate eel one of the nuclei and its surrounding cytoplasm is thus moclified, T^•hlle the remainder of the cell retains the features of the megaloblast, the appearance might be interpreted in terms of the ingestion of a normoblast by a megaloblast. But where both nuclei ot the same cell, as is frequently the case, and their adjacent cytopasmic areas are similarly differentiated, the interpretation is in applicable. The polykaryocytes of the yolk-sac undoubtedly have at least as a partial functional role that of the formation of normoblasts as here aescriDed.

In the human yolk-sac Spee (Anat. Anz., Bd. 14, 1896) described the giant cells (to which he also attributed a haemogenic function) as arising from the entodermal cells. This yiew is untenable for the yolk-sac of the pig. Giant cells and the entodermal cells lining the sac have no features m common except their general staining reaction. Ihe cytoplasm of the entodermal cells contains distinct basal filaments (mitochondria). Such are absent in the giant cells. Also, the entodermal cells contam a single relatively small nucleus, with coarse chromatic net, and usually two large spherical chromatic nucleoli I^Ioreover, there is never an intimate spatial relationship between entodermal and giant cells, and nothing appears in the nature of transition stages

In passing may be noted the very close similarity between the entodermal cells of the yolk-sac and those of the liver. ■" Graf v Spee ('96) and also Paladmo ('03) have attributed to the entoderm of the yolksac an hepatic function on the basis of a general morphologic similarity I his similarity m the pig pertains even to the finer cytoplasmic structure and content, namely apparently identical mitochondrial threads It shoulG be noted that no other tissues in this specimen showed distinctly any mitochondrial elements. This statement is not meant to imply that they were not present- there is sufficient recorded evidence to prove that they are— but only that this technic did not preserve them while It reveals very^ beautifully the special threads in the entodermal cells ot the sac and the hver cells.

Similar deep-staining filament were described by myself (Anat ^nz Bd. 31, 00, 11, 1907, and Bd. 39, 00, 1, 1910) in theVolk-sac of a 9.2 mm' tiuman embryo as 'mucinous masses,' and subsequently by Branca (Ann. de Gyiiec. et d'Obst., tome 2, 1908) in yolk-sac of about\he same age as functional protoplasm' (ergastoplasm). They are very similar to the ergastoplasmic filaments of certain secretory cells as, for example those ot the pancreas, where they have been described as segmenting distally into secretory granules." No such segmentation is discernible in these cells from the yolk-sac of the pig. In the human yolk-sac the entodermal cell contained a generous irregular granular content but the granules showed no direct relationship to the filaments and they were tentatively interpreted as debris incidental to degenerative changes. Mislawsky (Arch. Micr. Anat., Bd. 81. 00 4 1913) has recently shown by aid of delicate differential staining methods that the


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basal filaments of the pancreas cell are in reality condrioconts, and have nothing dii'ectly to do with foiTaation of secretion granules. These filaments of the yolk entoderm and hepatic cells are more probably of the nature of mitochondria and give evidence of the metabolic \dnlity of these cells.

It is of importance also to note that all the types of blood cells described for the yolk-sac are present also in the liver, only the nonnoblasts are relatively much more abundant. Elsewhere in the embryo (including especially the heart) normoblasts and later er\nhrocytes are exclusively to be seen.

Finally, as to the role of the endothehum of the yolk-sac vessels in haemopoiesis: the matter may be summed up by simply stating that endothehal cells differentiate into haemoblasts, both intravascularly and to a sHght extent also extravascularly. This involves a rounding up of the cytoplasm about an endothehal cell nucleus and a subsequent abstraction of the forming cell from the wall of the vessel. Such process is probably commonly preceded by proliferation of the endothehal cell involved. ]\litosis of endothehal cells are fairh' abundant. Occasional endothehal cells are binucleated. The haemoblast need not necessarily at once separate from the endothehal wall. It may retain its coimection through the succeeding stages of development including the fully differentiated megaloblast: and there is some e\'idence to show that even a giant cell may thus remain connected. The evidence for this, not however quite complete in the case of the giant cell, consists in a graded series of developmental stages from the true endothehal cell to the megaloblast. The megaloblast of this series is of lenticular form, its pointed terminals passing into a thread of protoplasm continuous in both directions with the endothehal wall.

30. Morphological endences of intracellular dedructio?} of red bloodcorpuscles. Prestox Kyes, from the University of Chicago. The intracellular destruction of red blood-corpuscles by vascular endothehum although recognized as of frequent occurrence under pathological conditions, has not been estabhshed as a physiological process taking place under normal conditions.

It is the purpose of this communication to give morphological evidences that in the case of the pigeon, among other species, there is a constant noimal phagoc>i:osis of red blood-cells by speciaHzed vascular endothelium in the hver and spleen.

Sections of suitablv fixed tissue from the hver and spleen of pigeons displav when subjected to Perl's test for u-on, a distmctly differentiated type of cell marked by the Prussian blue tone of the cj^oplasm due to a positive iron reaction. Combmed with count er-stains,_ therefore. Perl's method afi'ords a favorable technique for microscopic study of the cells in question, which cells will be uiterpreted later as phagocytic endothehal cells whose iron content is due to mgested red blood-corpuscles. In detail, the histological technique which I have employed in stud^■ing the tissues of eighteen nomial pigeons, is as follows:

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Fix thin slices of tissue for 18 to 24 hours in Muller's fluid plus 5 per cent mercuric sublimate. Imbed in paraffin and section to 4 microns. Fix sections to slide and stain 20 to 40 minutes with acid carmine. Wash, and transfer to equal parts of a 2 per cent aqueous solution of potassium ferrocj^anide and of a 2 per cent aqueous solution of hj^drochloric acid. Remove after from 3 to 10 minutes, wash in distilled water and pass quickly through a 0.5 per cent aqueous eiythrosin solution. Dehydrate in alcohol, clear in xylol and mount in Canada balsam.

Specimens of normal pigeon's liver and spleen prepared according to the above method, display an extensive content of cells possessing the distinct blue tone of the Prussian-blue iron reaction. These cells are distributed rather evenly throughout both organs but more numerously in the liver. Under low powers of the microscope their general morphology indicates that the iron-containing cells are of the same type in the two organs, and as will be seen later this is supported by a correspondence in their finer structure and physiologJ^ Inasmuch as the relation of these cells to other structures is much more evident, however, in the liver, their first description is limited to that organ.

In liver specimens observed under medium magnification, the cells referred to above appear as blue patches sharply differentiated from the red-stained parenchyma. These cells are larger in their greatest dimension than the liver cells proper, vary much in size and form, and are often seen to contain two or three carmine — or eosin-stained bodies. In their distribution they display a constant relation to the venous capillaries, often appearing to occupy the lumen of these vessels. Under the higher powers of the microscope, it is seen that each cell is an integral part of the endothelial intima lining the capillaries; in other words a fixed tissue cell engaged by one of its surfaces upon the reticulum of the vessel wall and with a free surface bulging to a greater or less degree into the vessel lumen. The attached surface of the cell follows strictly the line of the vessel-wall be it straight or curved, often continuing around an angle of bifurcation. No processes are seen extending between the liver cells: in fact I have not seen evidence that these cells possess processes extending in any direction. The cells under discussion are clearly those described in the liver of mammals by v. Kupffer first as perivascular connective-tissue cells and finally as intimal cells. To these cells the terms ' Sternzellen, ' 'stellate cells,' 'Kupffer cells,' have been applied in reference to the liver; but to include the same cell as also seen in the spleen and where not, I employ the term hemophage.

The nucleus displayed by the hemophage stains a deep garnet with the carmine used in the given technique and contains two or three very distinct and intensely stained nucleoli. In the hemophages which are more nearlj^ flat, the nucleus appears as those of the typical endothelial cell, whereas in the protruding cells of greater bulk, the nucleus is more vesicular and is irregularly pyramidal in form. Two nuclei may be found within a single cell. This but rarely, however.

The most striking characteristic of the hemophage is the morphology of its cell-bodv. This is determined by the fact that within vascuoles


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of the cytoplasm, are contained red blood-corpuscles taken from the circulating blood stream. It is not meant that here and there may occasionally be found a hemophage which has taken up an erythrocyte, but rather,' that the occurrence is general and that approximately onethird of the total intimal cells are active hemophages and that each . hemophage displays e\ddence of containing, or having recently contained, one or more erythrocytes. The fact that the red blood-corpuscles of birds are nucleated, have a definite ovoid outline, and are of relatively large size, allows clear observation as to their actual inclusion and ultimate intracellular fate. The cell-body of the hemophage has no fixed morphology but changes from time to time according to the phase of its phagocytic activity. Within a single field of the microscope may be seen all intermediate stages between the hemophage whose cell-body is greatly distended by an intact erythrocyte recently ingested and the hemophage which has so far completed the destruction of the erv^throcvte as to again appear as a flat endothelial cell except for the presence' of the traces of the end-products of the digestion. In the first instance the cell-body of the hemophage bulges markedly into the capillary lumen and its nucleus is crowded to one side. The included erythrocyte in this earliest stage appears in all ways the same as those of the blood-stream and displays the normal staining reaction; namely, by the technique given, its nucleus stains a deep red-brown, while its cytoplasm stains an even yellow bronze tone. In hemophages which represent the subsequent stages, the included erythrocytes are seen m various stages of disintegration and digestion while the cytoplasm of the including cell gives a constant iron reaction. The first marked change in the erythrocyte is hemolysis, the hemoglobin escaping into vacuoles of the cytoplasm of the phagocytic cell and leaving the nucleuscontaining stroma distinctly outhned. Gradually both the stroma and nucleus lose their staining reaction, until finally the vacuole contracts about a small indistinct remnant of the nucleus which in its turn ultimately disappears. ■.

Meanwhile the hemoglobin which has escaped into the cytoplasm of the hemophage is seen to undergo a series of changes. At hrst tne greater part of the pigment does not give the iron reaction but retains its yellow-bronze tone with erythrosin and occupies vacuoles of various sizes. In hemophages representing a later stage, however the contents of the vacuoles also give the iron reaction and with great intensity contrasting with the lighter blue of the surrounding cytoplasm buch cells finally show no content of unmodified hemoglobin. With tne disappearance of the native hemoglobin, therefore, there is a parallel increase in the iron-reacting pigment. In untreated specimens this pigment is golden-yellow and is presumably hemosiderm. ^^e hemophages which represent the last stages in the phagocytosis and digestion, appear less and less bulky, with a fainter iron reaction and a less vesK> ular nucleus. The last observable stage is represented by ^ cell which contains no yellow pigment but which in all ways ^PPf^f-.f^^.^yP^'^ endotheUal cell of the vascular intima except, however, that its cytoplasm gives a faint and diffuse iron reaction.


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As stated above, examples of the stages just outlined are readily seen in a single microscopic field and the interpretation of the sequence of events which they represent leads to the conclusion that the cells of the vascular endothelium of the venous capillaries of the liver of birds in performing a normal physiological function, ingest intact red-blood corpuscles, hemolyse the same, destroy the stroma and nucleus, split the hemoglobin with a freeing of the iron, and finally return to their original form.

In the spleen, the hemophages are seen in distinctly fewer numbers than in the liver. For the most part they are confined to the pulp cords in contrast to the Malpighian follicles and have no such evident relation to a vessel-wall or lumen as in the liver. The hemophage, however, is morphologically in all of its details of the same type as that of the liver, and the phases of ingestion and digestion of erythrocytes form the same cycle giving the same iron reaction at corresponding points.

With the recognition of a constant normal phagocytosis of erythrocytes by the intimal cells of the venous capillaries of the liver and corresponding cells in the spleen, the question arises as to how far these cells differ from vascular endothelium in general; in other words, the extent of their specialization. In reference to this point, the evidence shows that the phagocytosis is normally accomplished by endothelium in certain locations only. Thus in the liver, the hemophages are confined to the intuna of the venous capillaries, while the intima of the larger vessels displaj^s no such phagocytic action.

In applying the same technique in a study of the livers of the frog (Rana pipiens), toad (Bufo lentiginosus), turtle (Chiysemys marginata), crocodile (Alligator mississipiensis), and opossum (Didelphys virginiana), I have foimd a similar cycle of intracellular blood destruction in the corresponding cells of the reptiles, amphibia and mammals.

It would appear, therefore, that the application of a trustworthy differential histological method, shows that the liver and spleen of many species, do contain specialized endothelial cells which have as a normal phj^siological function the destruction of red blood-corpuscles with a liberation of the contained iron.

31. 071 the implantation and placentatio7i in the Sciuroid rodents (lantern) .

Thomas G. Lee, Institute of Anatomy, Universitj^ of Minnesota.

In 1902 and 1903 the writer published descriptions of the implantation of the ovum in Spermophilus. In this work attention was called to a method of implantation and a series of structural changes preceding the formation of the true placenta which were unlike those of any other previously described mammal, and at the same time were the first account of the implantation in any of the Sciuroidae. These observations were confirmed on the European Spermophilus by Rejsek, In 1905 Miiller found similar conditions in the European red squirrel, Sciurus. In 1910 the writer described the early stages of Cynomys at the International Anatomical Congress in Brussels. Since 1902 the writer has been engaged in collecting early stages of various genera of


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American Sciuroid rodents to determine if the peculiar conditions found in Spermophilus (or 'Citellus' as the taxonomists have since decided upon as the proper generic name) were characteristic of this large group of rodents. The collection of very early stages of wild rodents which breed for the most part but once a year, and whose genera are widely separated over the United States, is an extremely tedious and very expensive undertaking, but sufficient material has been secured to date of the following genera of the Sciuroidae to determine that the general method of implantation and placentation as previously described for Citellus (Spermophilus) hold true for the larger division. The genera studied include Citellus, 3 species, Ammospermophilus, Tamias, Cynomys, and Sciurus. The writer is preparing a more complete description and illustration of the early developmental conditions characteristic of these Sciruoidae than was possible before with the quite limited material. The greater variety of material now available enables one to pomt out the interesting slight divergences among the several genera.

32. On the relationship of the endocardium to entoderm in Citellus. Thomas

G. Lee, Institute of Anatomy, University of Minnesota.

In studying the early development of the sciuroid rodent Citellus the writer noted the following described conditions which may be of mterest to investigators working on that yet unsolved problem of the origin of the vascular system.

With the folding over and fusion of the entodermal walls of the foregut to form the pharynx region, there is to be noted a dorso-lateral angle on either side formed by the dorsal wall on either side of the chorda and the lateral wall of the pharynx and a somewhat less prominent ventro-lateral angle or groove, which will be designated in this paper as the cardiac sulcus.

Each cardiac sulcus is a groove or furrow in the free surface of the entoderm which follows the course of the lateral hearts. It begins in the lateral wall of the mid gut region and extends forwards to enter the closed pharynx region at the ventro-lateral angle and then continues along the ventral wall of the pharnyx convergmg to unite with the opposite sulcus in the mid ventral line just above the point of fusion of the lateral hearts.

The entoderm in the line of the cardiac sulcus is considerably thicker than that on either side. This thickening, however, is not uniform; it is more pronounced in certain areas than others. There is thus produced a corresponding elevation or ridge of the entoderm in the direction of the lateral heart. This thickened entoderm constitutes the walls of the sulcus. The groove, while easily recogmzable throughout its course, varies in its shape; in places it is narrow and deep, in other places it becomes widened out and quite shallow. In embryos of this stage of development, the fold of splanchnic mesoderm which will form the myocardium does not completely envelope the endothelial tube of the lateral heart, the interval behag completed by the entoderm of the foregut. It is this portion of the entoderm that forms the


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cardiac sulcus. The above described sulcus is not peculiar to Citellus but is figured b}^ many investigators, as Koliiker in the rabbit, Fleischman in the cat. Bonnet in the dog. It is a transitoiy structure but is probably to be found in all mammals at the proper stage of development. While this region has been figured, almost no reference has been made to it as far as I am at present familiar with the literature.

In a number of series of Citellus I have found interesting examples of an intimate relationship between the entoderm of the cardiac sulcus and the endocardium of the lateral heart as shown by the reconstructions and drawings that illustrate this paper.

In the Citellus embryo here modelled, the primary impla.ntation attachment (previously described by the writer) is just separating while the trophoblastic attachment for the allantoic placenta is beginning at the mesometrial portion of the uterine cavity; the amnion is not yet quite complete; the foregut is closed, the ectoderm of the oral plate is fused with the entoderm but not broken through ; the pharynx does not yet show the evagination of the pouches ; the endocardium of the lateral heart is beginning to fuse at the anterior end; the two dorsal aortae are well outlined, the first aortic arch is not yet completed. In an embryo at this stage the endocardium of the lateral heart on either side, in the region between the junctions of foregut and midgut and the point of beginning union of the two lateral hearts, shows an intimate relationship to the thickened entoderm of the cardiac sulcus. The endocardial tube is free and separate from the myocardial fold of splanchnic mesoderm in the sections, the contour of the tube is either oval or pear-shaped vrith a portion of the endotheUal wall extended out as a thin fold or strand of cells toward the sulcus. Examining the series section by section it will be seen that while in each there is the extension of the fold or strand of cells toward the sulcus, in certain sections there is a short interval and in others verA^ close contact; in certain sections there is distinct continuity with the entoderm of the sulcus walls. This intimate relationship is lost in the region of the fusion of the lateral heart.

33. The comparative embryology of the mammalian stomxich. Frederic

T. Lewis, Harvard ]\Iedical School.

The study here reported has been carried out in large part by Dr. C. H. Heuser of The Wistar Institute of Anatomy, and a preliminary report of it was presented by him at the last meeting of the Anatomists. The work has now been carried further, and is nearly finished. Four animals have Vjeen studied, the cat, rat, pig, and sheep. The simple lenticular stomach from which the very diverse adult forms proceed, has been modelled as a starting point (cat, 6.2 mm.; rat, 5.4. mm.; pig, 7.8 mm.; sheep, 7.2 mm.). Even at this stage there are some significant differences, notably in the decidedl}^ convex lesser curvature in the sheep.

In the human stomach, the later development has been the subject of a paper already published by the writer. The effort is now made to obtain the stages of these other mammals most suitable for comparison. From a considerable number modelled, four stomachs of each species


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have been chosen, ending with the rather definite stage in which the smooth epithelial lining has become corrugated.

In the cat, the simple carnivorous type of stomach is early manifest. There is a well-marked angular incisure separating the elongated cardiac portion from the tubular pars pylorica. The fundus is less prominent than in any of the other mammals chosen, including man, and the gastric canal, following the cardiac part of the lesser curvature, is relatively late in its development. As a whole the stomach is less differentiated than in any of the other forms. In the rat the fundus early becomes elongated, forming a capacious pouch with its tip hooked toward the oesophagus. The gastric canal is short, but well-defined, and ends at a distinct angular incisure. In the pig there is also a large fundus, which soon overhangs toward the right side. The gastric canal ends at an incisure which produces only a shallow indentation of the lesser curvature. Below it, as in the rat, the pars pylorica is at first capacious, apparently representing a pyloric vestibule, and then more tubular, foi-ming the pyloric antrum. The sheep's stomach, at 10 mm., presents a slight angle indicating the lower end of the gastric canal, and a much deeper incisure below the rounded ventral swelling of the lesser curvature, which is the beginning of the future psalterium. The psalterium is an early and prominent subdivision in the sheep, but is scarcely indicated in the other forms. The fundus in the sheep develops into the large rumen. Even though it is lined with stratified epithelium in the adult, it cannot be regarded as a portion of the oesophagus, as some have taught. The reticulum represents the body of the stomach, and the abomasum is the pars pylorica, including both vestibule and antrum. In all of the forms examined the fundus, corpus and gastric canal are readily identified. The subdivisions of the pars pylorica require further study.

SJf. Reversed torsion of the human heart. Frederic T. Lewis, Harvard Medical School, and Maud E. Abbott, McGill University. Presented by Dr. Lewis.

While preparing the chapter on congenital cardiac disease for Osier's "Modern medicine," Dr. Maude E. Abbott, curator of the Medical Museum in Montreal, visited the Warren Aluseuni and examined all the abnormal hearts which it contains. Among them is the heart of a man who died of phthisis in 1838, when twenty-one years of age. Its interventricular septum is so slightly developed that it was overlooked in the contemporary account of the specimen. The most interesting feature of this heart, however, is the large ventrally placed artery which appears to be the pulmonary arteiy, but which in reality i^ the aorta. It passes from the left side of the imperfectly divided ventricle toward the right, crossing the ventral surface of the pulmonary artery. The latter leaves the ventricular cavity like an aorta. Although these vessels have been cut away quite close to the heart, their distal relations as to aortic arch, right and left pulmonary branches and ductus arteriosus were apparently normal. Moreover, the atria and atrio-ventricular valves are normally arranged. In fig. IB this heart is shown beside a normal one (fig. lA) for comparison.


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fV^L/!



Fig. 1. A, ventral view of a normal adult human heart. B, corresponding view of an adult human heart showing reversed torsion. C, model of the heart of a 4.9 human embryo, which in D has been manipulated so as to present reversed torsion. E, model of the normal heart of a 10 mm. human embryo, the torsion of which has been reversed in F.

a, aorta, at. d, right atrium (or auricle), at. s, left atrium (or auricle). p, pulmonary artery, v. d, right ventricle, v. s, left ventricle.


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Dr. Abbott brought this specimen to the writer for embryological interpretation, and he made the suggestion that in the embryo the cardiac tube had bent in the reverse direction to that which is normal, so that the aortic Hmb turned upward on the left side of the common ventricle instead of on the right. In order to verify this supposition, which we found had already been made by Keith, Dr. Abbott and the writer together undertook the following investigation. Normal embryonic hearts of the critical stages were selected and modelled as they occur in the embryo. Second models were then made, in which the ventricular portion of the heart was reversed, section by section. The two models of the heart of a 4.9 mm. embryo, kindly loaned to us by Dr. A. S. Begg, have been completed, and with others which are unfinished they seem to demonstrate the correctness of the interpretation. The distal part of the aortic trunk, including the roots of the pulmonary and fourth aortic arches, remains undisturbed in all its relations, and the atria and atrio-ventricular orifices are also in essentially normal position. But the reversal of the primary torsion causes the aorta to be split off from the truncus arteriosus ventral to the pulmonary artery, around the front of which it swings to the left ventricle. By manipulating the embryonic hearts in this way, the conditions in the abnormal adult specimen can be produced verv satisfactorily, as shown in fig. 1 C-F.

35. Variations in the early development of the kidney in pig embryos

with special reference to the production of anomalies. Frederic T.

Lewis, Harvard IVIedical School, and James W. Papez, Atlanta

Medical College. Presented by Professor Papez.

In the summer of 1914, the collection of 165 series of 10 to 12 mm. pig embryos used for class instruction at the Harvard JMedical School, was carefully examined to detect anomalies in the region of the developing kidneys. Although fused kidneys of the horse-shoe type are said to occur not infrequently in adult hogs, the proportion of cases is not such that a kidney of this type might be expected in the number of series examined, and none was found. However, the normal relations of the kidneys to one another varied in such a way that we may offer a new explanation of this anomaly, namely that it is due to the relation of the kidneys to the bifurcation of the aorta into the umbiUcal or common iliac arteries. This bifurcation forms a U-shaped crotch in which the kidneys are lodged, and from which they escape by migrating upward. The arteries, as a mechanical obstruction, tend to bring the right and left renal blastemas close together, so that fusion may readily take place. A fusion at the upper poles, making a horse-shoe kidney convex superiorly, would probably arise earher than the fusion at the lower poles, in which case the horse-shoe would be convex inferiorly. The relations of the kidneys which seem to justify this interpretation have been demonstrated in a series of models.

The anomahes actually observed consist chiefly of diverticula of the Wolffian duct, perhaps^ representing abortive ureters. Eighteen of these were found, most of which are on the part of the Wofffian duct


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distal to the orifice of the ureter. One is detached, forming an epithehal cyst. Two diverticula were found springing from the ureter itself. One of these which is shghtly elongated, ending blindly near the renal blastema, might give rise to a di\dded ureter, but inasmuch as it does not enter the blastema, no renal tubules would empty into it. On the proximal side of the orifice of the ureter in the Wolffian duct, there were six diverticula, generally close to the ureter. Thus a portion of the Wolffian duct immediately below the lowest and typically rudimentary tubules of the Wolffian body is generally free from diverticula. In one case, however, an elongated diverticulum in this region extended toward the Wolffian body and ended in relation with a blastemal cyst, such as produces the glomerular end of a renal tubule. In position and structure this formation is intermediate between the Wolffian body and kidney. In the anterior end of the Wolffian body, the elongating cysts open directly into the Wolffian duct, but below, as is well shown in this instance, the Wolffian duct sends out tubules, comparable with the ureter and collecting tubules of the kidney, to join with the portion of the tubule derived from the cyst. This specimen shows also a second and much smaller outgrowth of the Wolffian duct, nearer the ureter, which brings the Wolffian body into still closer relation with the permanent kidney.

36. Some anatomical deductions from a 'pathological temporo-mandih ular articulation. Frederic Pomeroy Lord, Department of

Anatomy and Histologj^, Dartmouth Medical School.

In a previous paper, Observations on the temporo-mandibular articulation," certain reasons, based largely on the study of a working model of the jaw-joint, were given to prove that the mouth is opened by the combined pull of the external pteiygoid muscles. It was also shown that, during opening, each condyle of the jaw moved forward nearly in a straight line, which is almost parallel to the plane of pull of the two external pteiygoid muscles; and that the depth of the bony glenoid fossa is practically obliterated b}^ the inter-articular cartilage.

Further proof of these facts has been noted in a singular skull, found in the Peabody INIuseum at Harvard, whose Director, Professor Putnam, kindly gave me access to its large collection of skulls.

In this specimen the left jaw-joint is virtually normal; the right has suffered from an attack of osteo-arthritis, apparently recovered from, later. During the attack the whole of the joint surfaces had been remodelled along entirely new lines, without a meniscus, and yet it gave, it would seem, equally good function with that of the other side, representing the usual condition.

The new joint shows the course taken by the advancmg condyle, permanently recorded in bone, and the evidence as to the character and direction of the condylar path, thus disclosed, corroborates that previously adduced.

The joint surfaces show, also, better than those of a normal specimen, how well adapted thej are to resist lateral or mesial displacement of the


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condyles, in closing the mouth, either by the pull of the masseter or the internal pteiygoid, and in proper proportion to the direction of their pull.

By making an artificial meniscus, exactly fitted to that especial skull, in the case of a normal specimen, the same adaptation of the joint surfaces can be demonstrated.

37. Distribution of nervus terminalis in man (lantern). Rollo E. McCoTTER, Department of Anatomy, University of Michigan. Johnston and Brookover were the first to observe the presence of the

nervus terminalis in man. Apparently, the material used by them permitted only of the examination of a portion of its intracranial course. By means of gross dissections of the heads of several human fetuses the writer is able to demonstrate the intracranial course and nasal distribution of the nervus terminahs. The nerve appears on the cortex in the region of the olfactory trigone, courses as a single trunk over the medial surface of the olfactory tract and breaks up into a plexus on the medial surface of the olfactory bulb where it is associated with the vomero-nasal and olfactoiy nerves. From the plexus on the medial surface of the olfactory bulb the fibers of the nervus terminalis collect into several communicating filaments and course over the lateral surface of the crista galli and pass through the cribriform plate well forward. The nervus-terminalis reaches the nasal cavity as a single bundle and is distributed to the septal mucosa anterior to the path of the vomeronasal nerves.

This article will be published, with figures, in volume 9 of the Anatomical Record.

38. On the anatomy of the brain and ear of a fish from the coal measures of Kansas. Roy L. Moodie, Department of Anatomy, University of Illinois, Chicago.

The preservation of the soft parts of extinct animals has alwaj's been a matter of great interest to students of paleontology and a number of papers have appeared on this subject. There are now known from the studies of various paleontologists muscle and kidney tissues from the Devonian, aUmentary canals and muscle tissues from the Carboniferous and from the succeeding formations a variety of the softer organs have been preserved in different waj's. They may be mummified, carbonized or changed into mineral substances, or the form of the part may be preserved as a cast of the cavity which the organ occupied. The latter is the usual mode of formation of fossil reptilian and mammalian brains. The casts are, however, always dural casts which never repeat the exact topography of the organ, and the smaller convolutions of the brain are not represented in the average brain cast.

A study of the brain cast of a mammal would give a more accurate idea of the form of the brain than would the cast of the brain case of a reptile, since the mammalian brain more nearly fills its cavity than does the brain of a reptile, as noted by Dendy (Phil. Trans., Royal Soc.


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London, Ser. B, vol. 291, pp. 227-331) for Sphenodon. The brain case of all recent selachians and teleosts is much larger in proportion to the size of the brain than among the reptiles, so that a cast of the cranial cavity of a fish would give no idea of the detailed anatomy of the brain. We may be sure that the organs which are described herewith are not casts but are, apparently, a transformation of brain substance, before decomposition, into some mineral, probably calcium phosphate. The walls of the brain are not shrunken but preserve a rounded contour as they probably had in life, resembling greatly, so far as details are concerned, the brain of a recently dissected and well-preserved fish. There are also preserved in their proper relations nerves and blood vessels, somewhat enlarged by the segregation of mineral matter and the subsequent formation of crystals but still preserving the normal relations. It is hard to conceive of this method of replacement of the brain by mineral matter in view of the chemical analysis of the brain which shows such a high percentage of water and soluble substances, and such a small percentage of resistant substances such as neurokeratin.

The little fossils with which we are at present concerned were collected in shales above the Kickapoo limestone in the Coal Measures near Lawrence, Kansas. The nodules containing the brains are all small, the specimens of brains themselves measuring only 15 mm. in length. The skeletal parts of the fishes have largely disappeared, so far in fact that it is not possible to determine the nature of the skull. Identification of the form being thus impossible, we are forced to use the characters of the brain to locate our form. Fortunately for this purpose Eastman has described a small brain from the Waverly of Kentucky, Iowa Geol. Surv., vol. 18, 1908, p. 267, pi. 13, very similar in many ways to the brains from Kansas. He was fortunate enough to identify the species of the fish to which the brain belonged, naming it Rhadinichthys deani and placing it among the Chondrostei or ganoids. The fish described by Eastman was collected in the Mississippian of Kentucky, but the character of the brain is so similar to those from the Coal Measures of Kansas that we will be quite safe in locating our fish near the Chondrostei, to which certain characters of the brain ally it independent of any comparison.

The brain itself is very completely shown in a series of specimens and we are able to study all sides of the brain in a few cases. The spinal cord is only partly represented, if at all, by a very small portion on the edge of the nodules. The vagal lobe is single and lies far back over the region of the fourth ventricle. There are no indications of separation of the lobe into subdivisions as is so common among existing fishes. Its complete form is preserved but the one best preserved has the upper surface abraded, since it projected slightly through the surface of the nodule. The facial lobe is smaller in the fish from Kansas than it is in the Mississippian brain described by Eastman. It is separated from the vagal and cerebellar lobes by slight constrictions and from its anterior aspect thei-e arises a tubular structure which is apparently connected with the pineal organ. This may be a vessel of some description or it


PROCEEDINGS 109

may be a fold of membrane which has been preserved. The cerebellar lobes are most unusual in being entirely lateral. If the median portion of this organ has become involuted below the surface of the huge optic lobes it is not possible to determine this. A study of the internal construction of the brain is not possible with the material at hand, if it will ever be; the formation of large crystals having obUterated all structural characters. Between the medial tips of the cerebellar lobes lies a structure which may be the pineal body. It is not present in all of the specimens, being entirely absent in one well-preserved l)rain. From the anterior, ventral portion of this organ runs a rounded elevation which may be either the stalk of the epiphj^sis or a plexiform vessel. Its morpholog}^ is uncertain. This is a very constant structure among the specimens at hand. The optic lobes are very large and indicate, apparently, a teleostean character for the fish. They occupy onethird the full length of the brain and constitute fully one-half its bulk. The eye was large as is indicated by an impression of the orbit and the optic stalk short. The optic chiasm is e\ddent in one specimen but the details of its nature are uncertain. The structure just anterior to the optic lobes is probabh^ the thalamus or praethalamus. It, like the vagal lobe, has its dorsal surface somewhat abraded but other specimens show that its full form was not greatly different from that shown in the figures. The olfactory lobes are distinct and relative^ large, being separated by a slight groove. The base of the olfactory tract is preserved and shows a strong olfactory development. The horizontal semicircular canal is well preserved on the right side of one specimen and on both sides of another nodule. The ampulla is large and the utriculus nearly double its size. The base of the vertical semicircular canal is preserved on the upper aspect of the utriculus. The base of the hypophysis is large and well preserved.

My thanks are due Doctor Herrick and Doctor Johnston for assistance in the determination of the characters of this little Paleozoic brain. A fuller discussion with illustrations and a review of other fossil brains will appear shortly in the Journal of Comparative Neurolog^^

39. The growth of the vascular system as it is correlated ivith the development of function, in the embryos of amblystoma. Julia S. Moore, (introduced by George E. Coghill).

Embryos of Amblystoma punctatum and microstomum in the physiological stages of development described by Coghill (Jour. Comp. Neur., vol. 24, p. 163) as (1) non-motile, (2) early flexure, (3) coiled-reaction, (4) early swimming stage, were used in this study of the vascular system in its correlation with other organ systems and with the growth of the embryo as a physiological unit. The following correlations are made upon the .basis of a close study of serial sections and of li\dng embrj'os.

As in other vertebrate embryos, rhythmic contractions of the heart begin before there is anj- connection with the nervous system and before there is any histological evidence of the muscular nature of the myocardium. The first cardiac movements do not occur until after


110 AMERICAN ASSOCIATION OF ANATOMISTS

the body movements, as represented by the early flexure stage, are well established. The rate of heart-beat averages in the early flexure stage 29 per minute; in the coiled-reaction stage, 49. In the early swimming stage it varied from 49 to 72. At the time that rhythmical contraction begins there is no perceptible connection between the arteries and the veins. In the coiled-reaction stage communication is estabUshed between the branchial vessels of the first gill and between the internal carotid arteiy and the ophthalmic vein, and a circulation of plasma may begm at this time. But corpuscles in Uving embryos were seen to circulate first in the late coiled-reaction or the early swimming stage, though they are found in the heart and venous system earlier in the microscopic sections. It is evident that circulation of corpuscles in the gills is started about the time that definite swimming begins, circulation in the balancer follows very soon afterwards. The evidence obtained concerning the aerating function of the corpuscles is not conclusive. From all observations thus far made it would seem that the corpuscles carry no haemoglobin until a later period than that considered in this paper.

Up to the early swimming stage no blood vessels could be seen to enter the myotomes, and no vascular connection has been made with the digestive system, which is differentiated even less than the myotomes at this time. Circulation could be seen in the vessels between the myotomes only at a later period. The mouth of the embryo does not open until some two weeks after swimming begins. At the non motile stage the cells of the ectoderm and the nervous system already show a greater degree of differentiation than those of other organ systems, as signified by the diminution of the yolk content of the cells. A similar diminution of yolk is marked m the blood corpuscle about the time that it comes into circulation. By the time that the corpuscles have used up their yolk they have approximately attained their adult size and form. The cells of the pronephros show a similar differentiation and diminution of yolk about the same time or a little earlier. The entodermal and mesodermal cells are still crowded with yolk up to a later period. A characteristic relation seems to exist in all cells between the nuclei and the yolk, which suggests a process of digestion within the cell. The relative amount of yolk thus seems to hold a definite relation to the degree of differentiation in the various parts of the embryo. The facts observed in connection with the rate of differentiation and the disappearance of yolk in the various parts of the embryo would indicate that the blood performs little or no nutritive function, as each cell of the })ody seems to be able to supply its own needs both for differentiation and for function, until swimming is well established.

In the early swimming stage no blood vessels are yet found in the nervous system, but the anterior cerebral vein is very closely applied to the surface of the brain, while the segmental vessels, developing later in the trunk come into close contact with the spinal cord. This close relation in development of the anterior cerebral vein with the most highly differentiated parts of the brain would indicate a correlation of the


PROCEEDINGS HI

vascular system with the esLvly processes of function and differentiation in the nervous system. The tetanic condition of the embrj^o in the coiled-reaction necessitates a violent metaboUsm whose products must be ren'ioved. The nerve centers controlhng this muscular activit}^ must also undergo considerable metabolism. Hence it may be supposed that the early differentiation and function of these parts have stimulated the development of the vascular system, and that the vascular system has an excretory function in relation to these parts. The presence of the sacculated outgrowth of the dorsal aorta at the level of the pronephros, the ciliated nephrostome, the opening of the pronephric duct into the cloaca, and the close relation of the posterior cardmal vein to the pronephros indicate that the vascular system in conjunction with the pronephros is functional as an excretory system in the coiled-reaction stage. The communication of afferent and eft'erent vessels in the gills, permitting a circulation of plasma, makes possible the excretion of carbon dioxide through the blood in the coiled-reaction stage, while a distinctive aerating function can appear only later with the development of haemoglobin.

4-0. A preliminary note on the septum secundum in the pig. C. V. Morrill, Department of Anatomy, University and Bellevue Hospital, ]\Iedical College.

In the course of a paper devoted chiefly to the development of the Purkinje fibers of the heart, Retzer (some results of recent investigations on the mammalian heart; Anat. Rec, vol. 2, no. 4, 1908) briefly discusses the formation of the atrial septum in the pig. He states that the accounts of His and Born though accepted by most embiyologists are incorrect on this point. In the pig Retzer considers that septum II in Born's sense does not exist and that this supposed septum is merety a fold in the atrial wall produced by the growth of the auricles around the conus arteriosus as a fixed point; and further that it never attains sufficient size to justify its bemg called a septum.

Since, as Retzer says, Born's account has been followed to a large extent bj^ other writers as evidenced by the descriptions of Hochstetter in Hertwig's Handbuch and Tandler in Keibel and jNIall's Manual, it seemed worth while to re-examine the development of the atrial septum in the light of Retzer's criticism.

The study of this point is based on serial sections of pig embryos of 6.8, 7.9, 8.5, 12.3, 15.2 and 21.0 mm. total length. Of these, the heart regions of the 7.9 and 15.2 mm. embryos have been reconstructed in wax and that of the 21.0 mm. is in process of reconstruction.

In the 6.8 mm. stage, the earliest examined, septum I forms an incomplete interatrial curtain. Both ostia are present. The caudal (inferior) border of septum I meets and fuses with the corresponding wall of the atria. At the ventral end of the line of fusion, a slight thickening projects into the right atrium and with this the caudal extremity of the left sinus valve blends. In the 7.9 mm. emb.rj^o, septum i has fused with the endocardial cushions for the most part.


112 AMERICAN ASSOCIATION OF ANATOMISTS

but a narrow slit, the remains of ostium I, still connects the two atrial chambers. Ostium II has enlarged and its borders are fimbriated. The thickening in the caudal wall of the right atrium close to the ventral extremity of septum I, which was noticed in the earlier embryo, has developed into a distinct spur which extends cephalad (upward) a short distance in the ventral border of septum I, just dorsal to the still-persisting ostium I. This, I believe, represents the earliest appearance of the septum II of Born (he did not describe the earlier stages). With it, the caudal end of the left sinus valve blends. The corresponding end of the right sinus valve is lost in the caudal wall of the right atrium, close to this point. In the 12.3 mm. embryo, the spur has thickened and extends further cephalad. In the 15.2 mm. stage, it has lengthened out into a definite ridge extending from its place of origin in the caudal wall of the right atrium, first cephalad, then dorsally, arching over ostium II to reach the dorsal atrial wall, where it fades out. Its caudal end is thick and up-standing; its cephalic end narrow, pointed and not sharply marked off from the atrial wall. The caudal ends of both sinus valves are now fused with it. In this stage ostium I has entirely closed and ostium II considerably enlarged dorso-ventrally, so that the free border of septum I bordering the latter opening, now faces almost entirely cephalad (upward). In the 21.0 mm. stage, the oldest examined, septum II has become thicker and more sharply defined near its caudal extremity. Its narrow, pointed end extends cephalad and dorsally, bordering ostium II, then caudally for some distance along the dorsal wall of the right atrium in the region of the spatium intersepto-valvulare and close to the left sinus valve.

It does not seem probable that this very definite thickening is merely a fold in the atrial wall produced by the growth of the auricles around the conus, as Retzer clauns. It is true that in the middle of its course it does conform to the curve of the conus, but at its caudal extremity where it is thickest and at its pointed extremity which lies in the dorsal atrial wall, it is entirely unrelated to that structure. Thyng (the anatomy of a 17.8 mm. human embryo; Am. Jour. Anat., vol. 17, no. 1, 1914), has recently recorded the presence of a 'ridge or tubercle' in the caudal part of the right atrium which he considers to be the caudal end of the future septum secundum in the human heart.

A more detailed account of this structure and nearly related parts will be given in a subsequent paper.

41. Studies on the syrinx of Gallus domesticus. J. A. Myers, Institute

of Anatomy, University of Minnesota, Minneapolis.

The results of this work may be summarized as follows:

Structure. (1) The syrinx of the domestic chicken belongs to the

tracheo-bronchiaUs type, and is quite simple when compared with the

voice organ of song birds. (2) No intrinsic muscles are present in the

sjTinx of Gallus domesticus. The extrinsic paired sterno-trachealis

with its caudal prolongations constitute the entire musculature of the

syrinx. (3) The rigid skeleton is very highly modified. The first


PROCEEDINGS 113

four tracheal rings are imperfectly fused to form the tympanum. The four intermediate syringeal cartilages are continuous ventrally with the ventral pyramid of the pessulus, ' while dorsally they end unattached. The first bronchial half-rings are large and in adults are attached and fused at both ends of the pessulus. The pessulus is the largest of all skeletal parts and lies dorso-ventrally at the junction of the bronchi in a plane transverse to the long axis of the trachea. The tracheal rings, the pessulus, and the ventral ends of the first half-rings become ossified, while all other skeletal parts remain cartilaginous. (4) The external tympanic membranes appear between the fourth intermediate syringeal cartilages and the first half-rings while the internal tympanic membranes extend from the caudal borders of the pessulus to the bronchidesmus and represent merely a modified part of the medial bronchial walls. (5) The syrinx is lined with stratified ciliated columnar epithelium containing numerous simple alveolar glands. Upon approaching the tympanic membranes this columnar epithelium is transformed into a stratified squamous epithelium which becomes a single layer of flattened cells over the membranes proper. (6) The tympanum is attached to the remainder of the syrinx only by elastic membranes.

Development. (1) The first indication of the respiratory system was observed in a 68 hour embrj'O in which the laryngeo-tracheal groove and the bronchi were represented. At first the trachea is much shorter than the bronchi, but with the development of the neck, it becomes, after the 140 hour stage, relatively much longer than the bronchi. The walls of the trachea and the bronchi are at first composed only of epithelium which contains two or three rows of nuclei. (2) The mesenchymal condensation common to the entire epithelial tube first becomes markedly prominent at the tracheal bifurcation in an embiyo of 152 hours. (3) The anlagen of the first bronchial half-rings appear in a 176 hour embryo, those of the fourth intermediate syringeal cartilages appear 12 hours later. The anlagen of tlie third intermediate syringeal cartilages and the anlage of the pessulus are present at 200 hours. (4) Distinct cartilage cells were first observed in the first bronchial half-rings. (5) The first four tracheal rings have not united to form the tympanum at hatching, nor have the other skeletal elements taken the shape of those found in the adult. No bone is present at the time of hatching. (6) Ciliated cells are present in stages beyond 248 hours but were not observed in the region of the future tympanic membranes. (7) ^Mucous cells were first observed in 332 hour embiyos and only in later stages were they found arranged in the form of simple alveolar glands. (8) Muscular tissue is differentiated in the 176 hour stage. Muscle fibers showing faint cross striations appear at 296 hours. At 452 hours the muscles are well developed. (9) At the time of hatching the tympanic membranes are thick. They are covered, however, as in the adult, with a single layer of epithelial cells.

Function. (1) That the syrinx is the true voice organ of the chicken is evident from the following deductions: First, structurally it is the only part of the respiratory tract capable of producing sound; Second,

THE ANATOMICAL RECOBD, VOL. 9, NO. 1


114 AMERICAN ASSOCIATION OF ANATOMISTS

when the trachea is divided and the cephalic portion tightly tied off, the chicken is still able to crow; Third, after division of the trachea, voice can be reproduced artificially by forcing air into the air sacs. (2) The upper larynx serves only to modulate the voice. (3) The sterno-tracheal muscles by their contraction shorten the trachea and modify pitch. They also draw the tympanum cephalad, thus indirectly varying the tenseness of the tympanic membranes. (4) The air sacs are necessarj^ in voice production, for voice could not be reproduced artificially after puncturing the cervical sacs.

Ji.2. On the presence of elastic ligaments in the middle ear region of birds.

A. G. PoHLMAN, St. I;Ouis University.

Recent work by otologists, notably Kreidl and Mangold, has demonstrated that our knowledge of the anatomy and physiologj^ of the middle ear region is imperfect. The Tensor tympani and Stapedius muscles are regarded as synergists rather than opponents and even the facial nerve innervation to the Stapedius is denied on an experimental basis. The problem of what these two muscles really work against is of interest not only to the physiologists but to the anatomists as well and that they may have some function relative to respiratory and atmospheric changes in the air content of the middle ear is not to be denied. The bird because of its single columella and single Tensor tympani presents a condition where the physiology may be more easily determined but Denker's work on the parrot does not consider the details of the middle ear and Breuer's article, while it takes into account the functions of the single muscle, quite avoids all mention of the ligamentous apparatus. The most recent work on ligaments is that by Smith who describes the position of Platner's ligament and the two accessory drum ligaments in the chicken cjuite accurately.

It was assumed that the Tensor tympani in birds must pull against elastic ligaments, and the following points were developed: (1) That the attachment of the stapedial plate to the oval window and the membrane of the Fenestra cochleae were elastic in nature. (2) That Platner's ligam.ent, placed in direct opposition to the pull of the Tensor tympani, is also elastic and draws the columella forward to its position of rest when the muscle relaxes. (3) That the drum attachment itself is rich in elastic fibers. (4) That in some birds elastic fibers and even ligaments reach from the extra-columella over the drum into the Eustachian tube. The conditions in the mammal remain to be investigated.

43. A genetic interpretation of the stapes, based on a study of avian embryos in which the development of the cartilaginous otic capsides has been experimentally inhibited. Franklin P. Reagan, Department of Compara ' tive Anatomy, Princeton University. (Introduced by C. F. W. McClure.)

The chondro-crania of all vertebrate embryos possess one essential ground plan. Around the anterior end of the notochord, is formed the parachordal cartilage, anterior to this the trabeculae. Following the


PROCEEDINGS 115

formation (invagination) of the epithelia of the three bilaterally symmetrical sense organs, the latter become more or less surromided by prechondral cytoblastemae, later by cartilages, that surrounding the otocj'st being the anlage of the otic capsule or cartilaginous labyrinth.

It occurred to the writer that this cartilage of the otic capsule evident!}^ arises in response to the presence of the auditory epithelium, and that if this be true, an excision of the epithelium at an early stage would inhibit the stimulus to the development of an otic capsule, and that further, if this also be true, it would be possible to test to what extent the stapes can develop in the absence of a cartilaginous otic capsule, or in the absence of the stimulus which produces the latter.

Fortunately it was found that the removal of the otocyst from one side of chick embryos from five to sixty hours incubation resulted in the complete inhibition of the development of the cartilaginous otic capsules, as revealed by a study of operated embiyos which were allowed to incubate from six to fifteen days.

On the operated side, the staff-like portion of the stapes resembles in shape, size and position the same portion on the uninjured side, seemingly complete except lacking the flange-like ring of cartilage which completes the stapedial plate.

It seems that the central portion of the stapedial plate is actualty formed by cartilage of the hyoid arch while its periphery arises as an independent chondrification in the fenestra ovalis, distinct from the otic capsule but incapable of developing under conditions in which the latter fails to form. Both the otic capsule and the periphery of stapedial plate appear to have as their exciting stimulus the auditory epithelium.

I have reason to believe that my evidence is not merelj' of a negative sort, resulting from injury to the mesenchymatous anlage of the otic capsule.

44- On the origin of the duct of Cuvier and the cardinal veins. Florence R. Sabin, Anatomical Laboratory, Johns Hopkms Universit}'. Certain injections of young embrj^onic pigs brought out clearly the fact that the posterior and mesial or sub-cardinal veins arise as longitudinal anastomoses of direct lateral branches of the aorta. These lateral branches are distinct from the dorsal segmental branches which pass directly to the spinal cord. The lateral branches on the other hand alternate with the nephritic tubules and are two or three to a segment according to the number of tubules. The mesial cardinal vein in the pig forms at the same time as the posterior cardinal, but it is the posterior cardinal vein which connects with the duct of Cuvier. The specimens of injected pigs will be demonstrated at this meeting.

These studies in the pig led to taking up the subject of the origin of the cardinal veins in the chick since the material is so much easier controlled. In the chick of 36 hours incubation I injected a little India ink into the marginal vein and watched it circulate through the embryo. All of the ink smiply passed through the heart and the double aorta back into the capillaries of the membranes so that there was no capil


116 AMERICAN ASSOCIATION OF ANATOMISTS

lary circulation within the embryo. In chiel<:s a little older, however, from 38 to 42 hours of incubation I saw a little of the ink pass through a tiny branch from the lateral surface of the aorta opposite the venous end of the heart around to the vitelline veins on either side. As soon as this connection between the aorta and the venous end of the heart is established the embryo itself as distinct from the membranes may be said to have a circulation. This tiny vessel which is the first part of the duct of Cuvier to develop grows from the aorta just cephalic to the first cervical myotome. Subsequently direct branches from the aorta opposite about three segments grow around to the vitelline veins and these primitive branches at once show anastomoses.

At the same time that this venous return for the blood of the embryo is formed, sprouts grow to the brain from the arch of the aorta. In the early chick the arch of the aorta is just at the root of the optic vesicle and it is at this point that the brain first receives capillaries. At first these capillaries have no circulation since they have no connection with the venous end of the heart. Gradually the capillaries to the brain spread out around the base of the optic cup and over the mid-brain. From this plexus a single vessel grows caudalward along the side of the medulla ventral to the otic vesicle and just at the caudal end of the medulla turns sharply ventralward almost at a right angle and joins the cephalic part of the duct of Cuvier. I have one specimen in which the branch of the duct of Cuvier comiects both with the aorta and with this vessel from the brain. Soon, however, the direct connection between the aorta and the heart is broken and the primitive head vein is established. Thus the composite nature of the head vein, suggested by Salzer in 1895 and more fully described by Grosser in 1907, is explained. The part of the head vein which lies close to the neural tube arises from the arch of the aorta and is a part of the vascular system of the central nervous system ; the caudal part of the head vein arises directly from the aorta just cephalic to the first cervical mj^otome, it lies in the lateral groove and is analogous to the posterior cardinal vein. The part of the head vein cephalic to the first myotome may well be called the vena capitis as was done by Grosser while the caudal part which becomes the internal jugular vein is a true anterior cardinal vein in the sense of being analogous to the posterior cardinal vein. This caudal part of the vein is much the shorter portion of the head vein in the early chick. It should be noted that it is the entire head vein which is usually termed the anterior cardinal vein. In this use of the name it must be emphasized that the head vein has a double origin.

The posterior cardinal vein in the chick is likewise formed from direct branches of the aorta which grow lateralward to the Wolffian body and there form a longitudinal vein. In contrast to the pig these branches are for the most part segmental arteries that is they arise between the myotomes. A few lateral branches opposite the myotomes are involved in the formation of the posterior cardinal veins in the chick but they are always less numerous than the segmental vessels. The position of origin of the segmental vessels along the aortic wall varies


PROCEEDINGS 117

in the different segments and seems to follow a line corresponding to the lateral surface of the spinal cord, but the vessels grow directly lateralward to the groove just ventral to the myotomes. Moreover, when the nephritic tubule is present the longitudinal vein lies closer to it than to the myotome. The difference in the development of the posterior cardinal vein in the pig and in the chick seems to correspond to a relative difference in the time of development of the nephritic tubules. Thus to sum up the origin of the venous system, the first vein of the embryo is the duct of Cuvier which is a direct connection between the aorta and the vitelline veins. The cardinal sj^stem in general arises as a longitudinal system of veins from direct branches of the aorta. The cardinal system proper extends throughout the zone of the myotomes and lies in the Wolffian groove ventral to the myotomes. In the chick the direct connection between the aorta and the heart occupies the zone •of the first three or four myotomes. Eventually the plexus of vessels representing the duct of Cuvier in the chick covers the zone of the first seven myotomes. In the pig the posterior cardinal vein develops from lateral branches at the same time as the nephritic tubules and these lateral branches alternate with the nephritic tubules. In the chick the posterior cardinal vein develops more rapidly than the tubules and comes in part from lateral branches of the aorta which are intersegmental but mainly from dorsal segmental branches which however do not grow first to the spinal cord but rather directly lateralward to the Wolffian groove where thej^ anastomose to make a longitudinal vein.

45. The technique of Weher^s method of reconstruction. Richard E. ScAMMON, Institute of Anatomy, Universitj^ of Minnesota. (Lantern slides.)

This method as used by its author was applied mainly to surfaces which were almost flat. Its extension to the stud}' of rounded surfaces requires that a method of curvature elimination be adopted. In dealing with the surfaces of cylinders or cones this is easily done by correcting for vertical curvature alone, but where segments of spherical surfaces are involved corrections for horizontal curvature are also necessary. Vertical and horizontal corrections can l^e made so that the finished plat will give an approximately true representation of both the area and shape of a given outline upon a curved surface.

The method of making a finished reconstruction from the reconstruction plat has been considerably simplified by the introduction of color by means of 'Herring' papers and by building up the final reconstruction in strata.

The entire process involves the following steps: (a) Correcting section drawings for vertical curvature; (b) Scaling drawings for thickness; (c) Laying out reconstruction plat with corrections for vertical and horizontal curvature; (d) Plotting gauge lines; (e) Building up the finished reconstruction from the plat.


118 AMERICAN ASSOCIATION OF ANATOMISTS

Jf6. Nasolacrimal duct diverticula and their genetic significance (a preliminary note). J. Parsons Schaeffer, The Daniel Baugh Institute of Anatom}' and Biolog}' of the Jefferson Medical College. It is generally iDelieved that the wall of the nasolacrimal duct are regular and that the lumen of the duct represents a more or less uniform cylinder. Indeed, this is what one gatliers from many text-books and from the average gross dissection of the channel. The common practice of passing the lacrimal probe would also lead one to think that the nasolacrimal duct has even or regular walls.



^n^


Oculus



J)llCtl7S

n(zsoIacri7?ialis


Cojic7iu nasaJls iiiferior 2 3

Fig. I Outlines of the hunen of the ductus nasolacrimalis at various levels. What appears to be two ductus nasolacrimales lying side by side at one level turns out to be the main duct and a diverticulum from it. From an adult.

Fig 2 Frontal section through the nasal fossa of a forty-day human embryo. The anlage of the nasolacrimal passages is indicated in solid black. Note its complete isolation from its former surface connection. Note a few lateral buds from the mother cord of ceils, presumably the proton of diverticula. At the ocular end of the cord the lacrimal ducts are beginning to sprout.

Fig. 3 Showing the irregular canalization of the ductus nasolacrimalis, from a term child.

Admittedly, such a condition does obtain in a certain percentage of cases and represents one of the anatomic types of the nasolacrimal duct (fig. 4). On the other hand, recent investigations by the writer indicate that many nasolacrimal ducts present lumina of very irregular contour, some even more or less tortuous in course. The irregularity and complexity of the lumen of the nasolacrimal duct is at times carried to a marked degree (fig. 4).


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119


Minor irregularities are at times due to mere folds in the mucous membrane. In many instances, they are of little moment, again, they ma}^ form definite bridges along the walls of the duct.

In some instances two parts of the nasolacrimal duct are not in exact line and the connection between the parts a somewhat deviating crosschannel. Finally, many nasolacrimal ducts present very irregular lumina due to diverticula.

These diverticula vary from those of an insignificant size to those with relatively large dimensions. The diverticula are obviously direct extensions of the walls of the duct proper. Thej^ are lined with a mucosa



Fig. 4 Showing outline of reconstructions of lumina of mid-portion of two adult nasolacrimal ducts, one is very regular, the other every irregular and with diverticulsi.

similar to that lining the main duct, and at the ostia of the diverticula the mucosae of the main duct and diverticula are directly continuous, both grossly and histologically.

In studying cross-sections of the nasolacrimal duct, one is at times puzzled to explain what are apparently two ducts lying side by side. However, by following the sections serialh' one finds that the one cavity sooner or later communicates with the other, i. e., one turns out to be the nasolacrimal duct proper and the other merelv a diverticulum from it (fig. 1).

These diverticula must be very important clinically and they need further study. Owmg to the irregularity of the lumen in many instances of the nasolacrimal duct, it is ob\nous that false passageways are repeatedly made by operators when they pass the lacrimal probe.

Genetically, nasolacrimal duct diverticula are doubtless the result of irregular canalization in fetal life of the solid cord of epithelial cells from


120 AMERICAN ASSOCIATION OF ANATOMISTS

which the several nasolacrimal channels develop. One must, therefore, return to the embryologic stage of the nasolacrimal duct for a proper genetic interpretation of the nasolacrimal duct diverticula.

After the strand of thickened epithelium (the anlage of the nasolacrimal passages) along the floor of the now rudimentary naso-optic groove becomes entirely isolated from its surface connection it becomes entirely surrounded by mesenchymal tissue and is for a time without a lumen (fig. 2).

This epithelial cord becomes canalized in a very irregular manner. In this canalization, one has direct evidence of the earliest stages of nasolacrimal duct diverticula. Small lateral pouchings from the main channel, due to a re-arrangement of epithelial cells, are early in evidence. Para passu with the growth of the main duct, the diverticula increase in size. At times one finds direct side branches from the mother cord of ■epithelial cells and some of them doubtless represent the proton of •diverticula (fig. 2).

It must, therefore, be concluded from the evidence at hand at present that the diverticula from the ductus nasolacrimalis are of congenital origin and are not acquired in later life.

47. On the gross morphology, topographical relations, and innervation of the human parotid gland. S. S. Schochet, Department of Anatomy, Tulane University. (Introduced by Irving Hardesty.) The parotid gland hardened in situ presents an irregular three-sided inverted pyramid with base uppermost and apex below. The posterior surface of the gland presents a marked concavity with three depressions: an external, middle, and an internal concavity. In addition there a,re in the inferior portion of the mesial surface three grooves caused by the styloid process, the diagastric muscle, and the sterno-cleido-mastoid respectively.

The external carotid arterj^ was not found buried in the gland substance in any of the six specimens so far examined, and the temporomandibular vein lies in a more external and deeper plane. These relations differ from the descriptions given in all the standard text-books. In the illustrations of Testut these vessels are represented as buried in the gland substance.

A small oval or fusiform- thickening of irregular outline of a yellowish white color has been found embedded in the auriculo-temporal nerve. Sections of this show it to contain numerous ganglion cells. Because of the position and the branches of connection of this body, it is here named the "parotid ganglion" (ganglionun parotidis). It measures from 1 to 1.5 cm. in length and from .25 to 0.5 cm. in thiclmess. It is supported by considerable fibrous connective tissue. It is located a short distance from a point where the two roots of the auriculo-temporal nerve fuse after encircling the middle meningeal artery, and in close relation with the temporo-mandibular articulation, the internal axillary and temporal branches of the external carotid artery, thus lying in the plane of the posterior mesial surface of the parotid gland. It should be num


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bered among the sympathetic gangUa of the head, and included, with the ciliary, spheno-palatine, otic, and sub-maxillarj^ ganglia, as a ganglion of the cephalic sympathetic plexus.

The branches of distribution of this ganglion are mainly through the parotid branches of the auriculo-temporal nerve. This ganglion is assumed to serve as a common point of termination of visceral efferent axones from the glosso-palatine nerve (nervus intermedius) which axones reach it by way of the small superficial petrosal nerve, and pass uninterrupted, through the otic gang] ion to terminate about its cells ; these cells in turn send their axones into the substance of the parotid gland. It is also possible that some of the visceral efferent axones of the glossopalatme are incorporated in that part of the facial nerve which passes to the parotid ganglion by the two communicating branches to the auriculo-temporal nerve.

Serial stained sections of the entire human parotid gland are examined to determine the presence of other sympathetic ganglion cells in its capsule and gland substance.

48. Comparative study of certain cranial sutures in the Primates. R. W.

Shufeldt, Washington, D. C.

Early in February, 1914, Doctor Ales Hrdlicka, in charge of the Department of Physical Anthropology- of the United States National Museum, invited my attention to certain variations and peculiarities to be found in the sutures on the lateral aspect of the skull in man, and suggested that I should examine into the matter, with the view of publishing a report upon my subsequent studies of the subject. Doctor Hrdlicka ver^- kindly gave me every facility to examine, compare, and photograph the enormous collection of human skulls of which he has charge at the Museum, or such of them as I intended to employ in my investigations.

Hardly had I gotten into these researches when I came to the conclusion that my work would be a far more useful contribution to anthropology- were I to include in it a similar series of comparisons made with the skulls of various species and genera of apes, monkeys, marmosets, and their allies. To this end I applied to Mr. Gerrit S. Miller, Jr., Curator of the Division of Mammals of the United States National Museum, who kindly permitted me to examine the superb collection of the skulls of these animals mider his charge at the Museura, and to make such photographs as I required for illustrations. In this matter I was very materially assisted by Mr. Ned Hollister, Mr. Miller's aid at the Museum. To all three of these gentlemen I am under great obligations and I have pleasure in thanking them for their assistance in my work, without which it would have been entirely impossible for me to have taken it up in any satisfactory mamier whatever. Data from one or two human skulls in my o^\ti collection are included in this work, as well as those from skulls of certain monkeys and tamarins, presented me bv ]\Ir. Edward S. Schmid, of Washington, D. C.


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The locations of the sutures in the human skulls have been known for a great length of time, as have also the bones between which, in any particular case, they may occur. These sutures have, further, all received names which have been bestowed upon them by the older anatomists, and the majority of these names are still employed in our present-day works on human anatomy.

In examining large series of skulls, it will be found that some of their sutures vary but little, as for example, most of those found between the bones of the face; while on the other hand, a very considerable amount of variation is to be observed in some of the cranial sutures, and especially those at the lateral aspect of the cranium. These sutures are caused to vary in accordance with the mode of articulation of certain of the cranial bones, which later, in their turn, present various differences in their articulations that are responsible for those sutural variations. Again, as is well known, certain sutures present variations which are due to the presence of certain supernumerary or epactal ossifications which are intercalated between the cranial bones in the lines of their sutures, examples of which are the Wormian segments and the epipterics — the former usually occurring in the lambdoid suture connecting the parietal and occipital, as well as in the sutures between the parietal s and other bones. On the other hand, the adventitious epipterics occur in the spaces of the lateral fontanelles, and are subject to marked variations with respect to number, size and position.

It was these epipterics and the sutures among the bones at the lateral aspects of the cranium, as they are found to vary in the various races of man and in the different families, genera and species of the Quadrumana, that I gave my especial attention, and to which my contribution to the subject is devoted, of which this paper is a brief abstract.

In the course of my work I compared several thousand skulls of men, women, and children of all ages, except the very young. The vast majority of these were of prehistoric Peruvians collected by Dr. Hrdlicka, in addition to which there were a sufficient number from other races of the world to satisfy me that I had obtained in my researches all the knoA\Ti sutural variations worthy of record in the aforesaid region of the cranium, and that variations presented on the part of the epipterics were practically endless in nearly every respect. I made a large number of sketches to show this, the majority of which will appear in my paper when it is published. I also made thirty-six photographs of the lateral aspects of skulls of men, women and children, and of various species of the Quadrumana. These, for the most part, are more than half natural size, and show most interesting variations of the sutures at the two sides of the cranium in the Primates, and, taken in connection with my other data, probably present the most extensive study of these sutures and epipterics up to the present time.

Thousands of figures of photographs of the lateral aspect of the human skull, of both sexes and all ages, have been published, and thousands of descriptions of the sutures in that region of the cranium have ap


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peared. There have also been an enormous number of similar illustrations and descriptions given in works upon comparative anatomy for the Quadrumana. In the vast majority of these figures and descriptions the fact is pointed out that the normal articulatory arrangement of the frontal, parietal, temporal (squamous portionj and sphenoid (greater wing) is, apart from the facial articulations, that both the frontal and parietal bones, separated as they are by the coronal suture, articulate in nearty equal proportions with the superior margin or border of the greater wing of the sphenoid, where we find the spheno-parietal and spheno-frontal sutures; that the squamo-parietal suture is the bounding line between the temporal and parietal, and, lastly, that the squamo-sphenoidal suture occurs between the sphenoid and squamous portion of the temporal. These are the only sutures to be considered here and indicate the remaining articulations.

These articulations may or may not be the same on the two sides of the same skull — indeed, they may exhibit verv- considerable variation. Moreover, they are to be fomid in the skulls of all Primates, irrespective of various forms of disease, as hydrocephalus, or in distorted skulls, whether the distortion be congenital or induced.

Craniologists long ago bestowed names on some of the principal points of meeting of certain of these sutures, or where the}' cross prominent ridges, as the stephanion, where the coronal suture crosses the temporal bridge, and pterion, the point where the temporal, frontal, parietal and greater wing of the sphenoid either are in contact or approach each other.

As already pointed out, the squamous portion of the temporal fails to meet the frontal through the intervention of the spheno-parietal articulation. This spheno-parietal suture varies greatty in length, and when it is reduced to zero, all four of the above-named bones are in contact. This Yaay occur upon both sides of the cranium or only upon one. It may be designated by the word 'contact.' and it occurs only in a certain percentage of skulls, whether they be normal, abnormal, or pathological. Contact of these four bones also occurs in the crania of the Primates below man; this is sho^^^^ in one or more of my photographs, and I shall probably meet with others, later on, when this paper is entirely completed.

So far as my studies carry me at present I find, and especial^ among the higher simians, that among the Quadrumana the sutures, at the lateral aspects of the cranium, have all the variations as thej^ occur in man. The occurrence of epipterics of any size in the skulls of the Quadrumana, however, are rare; indeed, up to the present time, I have failed to meet with any such bones in them beyond those of very minute size.

As to the percentage of the occurrence of contacts m the crania of various races of men, I can at this writing only say that it is ver}' small; and how this percentage compares with a similar percentage, taken from the crania of any genus or family of the Quadrumana, I am not, at this time, prepared to say. For the human species, I have prepared


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a great quantity of data on this subject, which can not be well presented in a brief abstract, such as is here submitted.

In man, the true epactal epipterics vary greatly with -respect to number, form, size, and position. With respect to their relation to the pterion, these epipterics, on one or both sides, may be anterior or posterior, or they may be, as I found them to be in the case of an adult male Cinco Cerros Indian (Peru), anterior, posterior, superior, and middle of the left side, while thej^ were multiple also on the right side, but some of the pieces were here lost. An epipteric may be co-extensive with the pterion, in which case it is total. Sometimes the two sides of cranium agree in these respects — that is, there may be an anterior or a posterior epipteric on both aspects of the skull, while they never exactly agree in the matters of form and size. Some epipterics are nearly round, some are triangular, others squarish, while still others are very elongate and narrow. They do not occur anj' more frequently in the skulls of adolescents than they do in adults, and they are very frequently absent entirely in the former.

As to why these adventitious ossifications occur in one skull and not in another, I have, up to the present time, been unable to discover. They occur with equal frequency in small, contracted skulls, as in unusually large crania, or in the skulls of hydrocephalics, where their presence would seem to be more in demand to insure ossific filling in of the lateral fontanelles.

It is still more puzzling to find a reason for from one to four epipterics occurring on one side and none on the opposite side of any particular cranium in man. We see a similar difficulty for solution to account for no Wormian bones in the lambdoid suture of one human skull, and upwards of an hundred in another, witfi no apparent reason for their being there.

When published, my paper will take up all these questions more fully, illustrating my researches by various sketches presenting unusual conditions as to the epipterics and the sutures at the lateral aspect of the skull in the Primate.

49. An experimental study of the origin of blood and vascular endothelium in the Teleost embryo. Charles R. Stockard, Cornell University Medical College, New York City.

The study of the origin and development of the blood and vascular endothelium has proven a difficult problem, mainly on account of the fact that the cir(;ulating fluids of the embryo usually begin to flow before the cellular elements of the blood are completely formed. These early developing cells are thus quickly washed from their places of origin and diffusely scattered throughout the embryonic tissues. All types of corpuscles are therefore found hi intimate association, whcthei' their origins may have been from a common center or from distinctly separate sources. The study of no other tissue presents this obstacle. It has thus seemed highly advantageous to obtain material in which the circulation of the body fluids might be prevented without seriously altering the normal processes of development.


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Several years ago I observed that the eggs of the fish, Funclulus, when treated with weak alcohol, chloroform, ether and other solutions developed embryos in which the blood failed to circulate although the heart pulsated in a feeble manner. During the last three years a systematic study of the origin and development of the blood and vessels in embryos with a heart beat but without a circulation has been conducted. This investigation of the experimental material has at all times been controlled by a study of the blood in the normal embryos.

Such 7natenal permits the analysis of the following propositions: Do blood corpuscles and vascular endothelium have a common origin from definite anlagen, or does the one arise from a localized anlage and the other from widely distributed sources? Does vascular endothelium ever give rise to any type of blood corpusclesf Do all types of blood corpuscles arise from a common anlage? Do certain organs such as the liver have a true hematopoietic function or simply serve as a seat for the midtipUcation of blood cells derived from other sources? What role does circidation and function play in the normal developynent and history of blood corpuscles? Finally, the specific question, is the bony fish an exception to the rule that all eggs with meroblastic cleavage develop blood islands in the yolk-sacf All recent workers claim that there are no blood islands in the Teleost yolk-sac.

In many instances the embryo develops in a fashion closely approximating the normal when the heart beat is fairly strong. The blood fails to circulate, however, on account of the fact that the heart is either blind at one or both ends or fails to connect with the veins. In a normal embryo the plasma begins to flow from the vessels of the embrj^o out into the sinusoids of the yolk-sac, and there establishes a complex vitelline circulation. In individuals in w^hich there is no circulation the plasma accumulates in the pericardial sinus and also in Kupffer's vesicle at the posterior end of the body.

The distended pericardial vesicle forces the head end away from the yolk sphere and thus stretches the heart out into a long straight threadlike structure. These hearts present a great variety of forms depending upon the extent of the pressure in the pericardium. When studied in sections such hearts are in some cases actually solid strings of cells, an inner endothelial string surrounded by a single layer of myocardial cells. In other cases they are slender endothelial lined tubes, while in still others the endothelial cavity is distended and filled with plasma although both ends are closed so that in life the plasma is churned up and down by the pulsation of the heart yet is prevented from escaping or flowing out through the aorta.

The dorsal aortae are in certain specimens almost impossible to identify with high power since their lumina are obliterated — while in other specimens the aortae are well formed endothelial tubes. Yet invariably the aortae never contain any trace of blood corpuscles. The yolk vessels and cardinal veins of such embryos are also distinctly lined with vascular endothelium. It must be concluded from abun


126 AMEEICAN ASSOCIATION OF ANATOMISTS

dant observations that the endotheUal vessel linings are present and may arise in all parts of the embryo and do not arise from a local anlage situated in some limited part of the embrj^o or yolk-sac.

The blood of the Teleost has been found to arise from the so-called 'intermediate cell mass' — Swaen and Brachet, Ziegler, Sobotta and others. These authors differ, however, as to the origin of the cells of the 'intermediate cell mass,' claiming them to be separated from the myotomes, schlerotomes or to be an accumulation of mesenchjmial cells. This cell mass in the material here studied is always found to be distinctly connected with and derived from the mesenchyme. Early workers claimed that the blood of the Teleost arose in blood islands on the j^olk-sac — but more recent investigators have held that the Teleost forms the marked exception to the rule that in all meroblastic types of eggs the blood arises in islands on the yolk-sac. In the Teleost thej^ hold that the entire blood anlage is within the 'intermediate cell mass.' In Fundulus, however, it is found that blood islands do exist in the yolk-sac and continue their development in this position to give rise to well differentiated masses of eiythrocytes when there is no circulation. Normal embryos show these islands distinctly in life and when the circulation is established the corpuscles are swept away in the same fashion as those arising from the intermediate cell mass. The erythrocytes in Fundulus embrj^os have, therefore, two distinct and limited places of origin, first, in the stem vein or conjoined cardinal veins, and, second, from the blood islands of the yolk-sac.

The stem vein may be single or double, separate cardinals. The blood forming portion is posterior, behind the anterior portion of the kidney and extending into the tail. The yolk islands are always on the posterior and ventral j^olk surface and do not extend over the anterior surface.

It is clearly shown by these embryos that the vascular endothelium is of almost universal distribution arising from the mesenchyme, while the blood corpuscles arise from a limited area. The vascular endothelium never gives rise to blood cells. So that the heart, aorta and vessels of the anterior end of the body, although invariably lined with endothelium do not contain a single corpuscle in embryos of any age. Embryos have been studied up to 20 days old; (the normal embrj'O hatches and is free swimmimg after the 12th day).

The crythroblasts developing from the 'intermediate cell mass' and from the splanchnic layer of mesenchyme in the yolk-sac are not at first surrounded by endothelium. As development proceeds the cells surrounding the mass which are of the ordinary eml^ryonic mesenchymal type differentiate or flatten out to form an endothelial layer surrounding the blood cell mass.

All of the corpuscles arising in the stem vein and yolk-sac develop into eiythrocytes. Numerous cells closely resembling poly-morphonuclear and polynuclear leucocytes are found to arise chiefly in the head region and later such cells are found throughout the body. These cells arc often very degenerate in appearance and it cannot be definitely


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stated what their nature actually is. They occur in the tissue and not within the vessels and are abundant in normal embrj^os as well as those without a circulation.

The further development of the erythroblasts is significant in embryos without a circulation. These cells reproduce rapidly by mitosis and finally give rise to well formed erythrocytes, the cytoplasm of which contains a normal amount of haemoglobin. The haemoglobin forms in the cells within the stem vein and in the blood islands and attains a bright red color in life. As the embiyo grows in size the eiythrocytes within the stem vein are further removed from the surface supply of oxygen and after about the eighth day of development they begin to degenerate, and in embryos of sixteen days only a few cells of the eiythrocyte type are present in the stem vein along with numerous more or less degenerate mesenchymal cells. The blood islands are better supplied with oxj^gen and the erythrocytes persist and present a bright red color. When compared with the ery^throcytes of a normal embryo those of the blood islands in an old noncirculating specimen show an interesting condition, instead of the healthy, slightly granular nucleus of the fish corpuscle the nucleus is more compact and darkly stained resembling in a striking way the reptilian tj-pe of corpuscle or 'Sauroid type' of ]\iinot's classification.

Circulation and normal function seem therefore necessary in order to maintain the typical appearance and structure of the red blood cells in these fish, although such cells original^ attain a perfectly tj^pical structure without having circulated.

Finally, these embryos in which the blood cells arise in a normal manner, yet are never permitted to circulate, furnish material for answering in a conclusive way the long contested question — whether the so-called hematopoietic organs such as the liver do actually contain cells which give rise to blood cells, or serve merely to harbor multiplying blood cells in their sinusoids. An examination of the liver of a normal Fundulus embiyo of seven or eight days shows it to be very vascular and numerous eiythroblasts in mitotic division are often seen. The organ presents the usual hematopoietic appearance.

A similar examination of the liver at any stage of development of an embryo in which the blood has not circulated shows a marked contrast to the normal. The organ is perfectly compact scarcely a vessel is to be found with the highest power on thin sections. Such a liver does not contain a single erythrohlast or erythrocyte in any condition. The liver of the bony fish has no true hematopoietic function.

50. Experiments on the amphibian ear vesicle. G. L. Streeter, Carnegie Institution, Johns Hopkins Medical School, Baltunore, Md.

At the last meeting of the Anatomists the results of a series of experiments were shown in which the ear vesicle in amphibian larvae was transplanted in other specimens and intentionally placed in an abnormal posture. It was shown that there is a subsequent spontaneous


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correction of the posture and that the resultmg labyrmth has normal relations to its envu'onment.

Since then the attempt has been made to determine the tune at which this spontaneous rotation of the ear vesicle occurs and lantern slides will be shown representing this period and showing the histological conditions under which the rotation occurs.

51. Comparative studies of the neck muscles of vertebrates. R. M. Strong, Department of Anatomy, The University of jMississippi. During the past five years, I have been engaged in comparative

anatomy studies which have concerned birds especially, but have included Xecturus and the alligator also. Publications are in process of preparation for all of these animals, and a work on the anatomy of the Tubinares (albatrosses, petrels, etc.) is approaching completion.

For this occasion, I have selected one of the sections I found less satisfactorily treated in the literature. I have been especially impressed with the need of work on the neck muscles, and I have been una]:)le to find satisfactoiy illustrations or descriptions of some of these structures. Even the publications of Owen, Gadow% Fiirbringer, and Shufeldt have omitted much, and Fiirbringer has considered the neck muscles only incidentall5^ The present confusion in terminolog>^ has impressed on me more than ever before the great need of action by a conunission to extend the B X A to comparative anatomy.

As the structures described in this paper can not be satisfactorily described without illustrations, no account of them appears in this abstract. Lantern slides and demonstration.

52. Further observations of the origin of melanin pigments. R. ^I. Strong, Department of Anatomy, The University of Mississippi.

In two previous' publications the writer has presented evidence supporting the position maintained by a number of writers that epidermal pigments are produced in situ, i.e., are not of dermal origin. A little over two years ago, I assigned to Miss Katherine Knowlton, a graduate student at The University of Chicago, some work on the pigments of feather germs from Plymouth Rock and Brown Leghorn fowls.

In the course of the studies, some interesting evidence concerning the origin of melanin pigments was obtained. Chromatophores were found in the dermal pulp near its proximal end as well as in their usual location in the epidermal cylinder of the feather germ. We found no evidence, however, that these dermal chromatophores wander into the epidermis. They differ in form and size from the epidermal chromatophores. They were also never seen in positions that would indicate migration into the epidermis, although a few were foujid crowded against the basement membrane which was not penetrated at any point. These dermal chromatophores occur mosth^ at a level lower, i.e., earlier in the development of the feather elements, than the chromatophores w'hich supply the melanin pigment located in the feather elements.


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It seems probable that these chromatophores are comparable to those of the skm dermis. They were fomid m a more or less continuous series leading to the inferior umbilicus, and it is probable that this continuity would have been complete with the chromatophores of the skin if the preparations had mcluded the tissue which surrounds the feather follicle. A more complete account of this work will be pubhshed later. Demonstration of miscroscope slides with sections of feather germs which show dermal pigment.

■53. The date and clinical significance of fusion of the costal element ivith the transverse process in the seventh cervical vertebra. T. Wingate Todd, from the Anatomical Department, Western Reserve University, Cleveland, Ohio.

In a paper presented at a meeting of the Anthropological Society of Paris (Bull, et Mem. de la Soc. Anthrop. de Paris, 1914) on the variations of the transverse process of the seventh cervical vertebra in Homo^ I discussed at length the evidence afforded by the examination of some three hundred vertebral columns regarding the precise disposition of the costal element and its relation to the foramen transversarium (B N A). While many accounts mention the appearance of an ossific centre in the costal element of the transverse process of this vertebra, they do not agree as to the precise date of its appearance, from which we may reasonably- gather that the date varies greatly from individual to individual. Concerning the date of fusion of the costal element with the true transverse process, information seems to be even more scanty. That the matter has some importance, however, is apparent when one considers the confusion existing in the mmds of many clinicians and anatomists regarding the mutual relations of the transverse process of the seventh vertebra and its cervical rib or costal element.

So much more frequently are cervical ribs observed in children than in adults that Dr. Gilbert Scott has been led to state his belief, for which he says he has some evidence and is collecting more, that the osseous tissue of the cervical rib is absorbed as the child grows (Brit. Med. Joum., 1912, vol. 2, pp. 483-84). This extraordinary- statement led me to investigate carefully the date of fusion of the costal element with the transverse process in the belief that such fusion is the explanation of the so-called absorption. Skeletons of suitable age are, however, not readily obtained, but that fusion may be delaj-ed until comparatively late in adolescence is shown by the presence of an unfused costal element, which by no stretch of the imagination could be called a cervical rib, in an Austrian male of 18 3- ears. Fusion is not always delayed so late as this, for in a negro male 17 years of age I found the fusion already complete. In neither of these skeletons had the epiphysis of the spinous processes yet fused with the main part of the bone. The striking difference between the two skeletons is that while the seventh vertebra in the negro approximates the sixth in type, that of the Austrian more nearly resembles the first thoracic. It may be that such a difference in type is closely allied with the date of fusion.

It is plain, however, that fusion may be delayed until the approach of maturity .

Extending my observations to the Primates, I found further evidence in favor of the foregoing conclusions. In a female gorilla .which I estimate to be 14 years old, since the third molars are just being cut, the costal element of the seventh vertebra had fused with the transverse process on the left side, but was still incompletely fused on the right. In a specimen of Ateles belzebuth which I believe to be about five years old, as the permanent dentition is almost completed (i.e., the third molars are emerging from the alveolar process and the canines are not quite fully erupted) while the epiphyses of the limbs are still ununited with the shafts of the bones, the fully ossified costal element of the seventh vertebra is distinct and separate from the true transverse process. Both of these animals were on the verge of maturity.

The examination with the Rontgen rays of fresh skeletons of children, which exhibited distinct costal elements unfused with the transverse process in the seventh vertebra, clearly showed that the skiagram is not to be trusted on the point. Its evidence may be equivocal and too indefinite to decide whether fusion has occurred or not.

Hence one may feel justified in stating that so-called absorption of infantile cervical ribs as the child grows is probably explained by the fusion of the fulty ossified costal element with the transverse process, an occurrence which may be delayed till after puberty, and the date of which cannot be indicated with certainty by the aid of the Rontgen rays.

54. 7s junction and Junctional stimulus a factor in producing and preserving morphological structures? Eduard Uhlenhuth. I propose to show you some preparations of a series of experiments, which I have made with the transplanted eyes of Salamander maculosa. These experiments are designed to show whether or not organs of a typical functional structure, after transplantation to an abnormal site, require function or functional stimulus, in order to be preserved at this new site. In short, I wished to investigate w^hether function and functional stimulus is a factor in preserving functional structures in transplanted organs.

After cutting through the optic nerve the eyes of amphibians undergo considerable degeneration of the retina. Later, however, the optic fibres regenerate and the trunks of the optic nerve unite. At the same time the retina which had undergone disintegration becomes restored to a normal condition.

By transplanting the eye to a place far removed from the normal position such a reunion of the optic nerve with the central nervous system is inhibited and the eye is permanently prevented from functioning. Partly, as might be supposed, the functional stimulus, namely light, which influences the retina even after transplantation, could bring al)out this result. I therefore used two series of larvae with transplanted eyes, both consisting of more than 100 specimens. One of the


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series was kept in ordinary daylight and the other series in a dark room, and in the latter case, no light, not even red light, was admitted Avhile the animals were being cared for, by which means the retina could neither fmictionate nor be affected by functional stimulus. The two series were then compared.

I will show you preparations of these two series. Those of the daylight series, as you will see, clearly show a regular increase in degeneration during the time immediately following upon transplantation, succeeded by a second period of a gradual increase in regeneration. To each preparation of the light series belongs one preparation of a transplanted eye of the same age but kept in darkness, and this is, as you will find, always much more normal than that of the light series. If function or functional stimulus were to favor regeneration the relation would be the reverse.

But I might have selected for each light eye a less normal dark eye of the same age, instead of a more normal one. As in both series the same factor, but in a contrary sense, has equally influenced every transplanted eye, these variations of the eyes of the same age and series cannot be explained as an effect of this factor, but must be the result of another factor which is variable and not controlled and which is perhaps produced by slight variations of the position of the eyes in the new place. Anyway, by having a large number of experiments, one is able to take the average of every age of both series, by means of which I obtained curves of the rapidity of regeneration in every series. Compared witl> the other the}" do not show any differences which can be ascribed to the influence or absence of light.

If the function or functional stimulus does nor influence the rapidity of regeneration it might be impossible to keep the transplanted eyes permanently in a normal condition without these factors; but you will find fairh^ old transplanted eyes, if you will look at the preparations. Some of them were made after the eye had been left for fifteen months in its new position. You will see that even those old e^-es were perfectly normal.

The conclusions, therefore, which we must raise from these facts is the following:

The regeneration of the structures of vision following destruction caused by the transplantation of the eyes can by no means be considered functional regeneration, and even the rapidity of this regeneration is not influenced by functional stimulus. The permanent preservation of the retina, when deprived of all function or functional stimulus and kept in perfectly abnormal conditions, is not a process which is governed by functional adaptation.

55. On the early development of the inguinal region in Mammalia.

John Warren, Haryard Medical School, Boston.

The early development of the gubernaculum and processus vaginalis was studied in the human embryos and in the embryos of the cat, sheep, rabbit, and rat in the Harvard Embrvological Collection. As far as


132 AMERICAN ASSOCIATION OF ANATOMISTS

possible different stages in each form were described so as to show the more important changes in the earty development of this region.

In human embryos the first sign of a connection between the Wolffian body and the abdominal wall can be seen in an embryo of 13.6 mm., transverse series no. 859. From the cells in the wall of the Wolffian duct a fairly distinct mass of cells may be traced dorso-laterall}' immediately beneath the primitive peritoneum covermg the Wolffian body to join the abdominal wall at a slight elevation, the inguinal crest. This cell mass invades later the abdommal wall, and is the anlage of the gubemaculum. A fossa is formed in the peritoneal cavity dorsal to this primitive gubemaculum. In an embryo of 16.6 mm., transverse series no. 1707, the cells in the gubemaculum have become much concentrated, and have begun to invade the ventro-lateral abdominal wall, where as 5'et there is no differentiation of the abdominal musculature. The gubemaculum steadily increases in density and length, and in an embryo of 19. mm., transverse series 819, it extends well through the abdominal wall, where its peripheral end expands and blends with the cellular constituents of the wall. At this stage the musculature ventrally forms a general cell mass, but more dorsally has differentiated into its three layers. In embryos of 22.8 mm., frontal series no. 757, and 24 mm., transverse series no. 38, the musculature is completely formed and grows around the peripheral part of the gubernaculum. An indistinct prolongation of the latter can be traced through the external abdommal ring into the subcutaneous tissue of the abdominal wall, forming a primitive ligamentum scroti. The processus vaginalis appears soon after this stage in embryos of 37 mm., transverse series no. 820, and 42 mm., transverse series no. 838, and develops downward and inward chieflj^ on the mesial side of the subernaculum.

In the Camivora, the primary point of contact between the Wolffian body and the abdominal wall can be distinguished in a cat embryo of 12 mm., transverse series no. 399. Here the anlage of the gubemaculum resembles the earliest form in human embryos, and a shallow fossa is formed also on its dorsal side. In an embryo of 15 mm., transverse series no. 436, the abdominal portion of the gubemaculum has increased in length, while the inguinal or muscular part has already passed through the abdominal musculature into the subcutaneous tissue over the external ring. The musculature is fairly well differentiated, and the external ring can be clearly seen with the peripheral end of the gubernaculum projecting through it. An embryo of 31 mm., transverse series no. 500, gives an excellent view of the whole length of the gubernaculum. The abdominal portion is now very long and slender, and the scrotal part appears as a large oval mass projecting through the external ring. The processus vaginalis has just begun to develop, but is growing downward on the lateral side of the gubemaculum. In an embrj'o of 39 mm., the processus vaginalis ejurrounds the gubemaculum except on its dorsal side, and can be traced well into the large expanded scrotal portion beyond the extemal ring. This represents the most advanced stage of any of the embryos studied.

The sheep embryos offered the best view of the development of the region in unguhites. The earUest appearance of the gubemaculum was seen in an embryo of 18 mm., transverse series no. 1238. It forms a thick connecting bar of tissue, similar to the corresponding stage in the cat and in man. Its extension through the abdominal wall, the development of the abdominal musculature about it, and the earliest trace of the processus vaginalis follow closely the course already described in the cat. The processus vaginalis develops first on the lateral aspect of the gubernaculum and then seems to grow do-^aiward chiefly in its substance. This is rather strikingly shown in the oldest embryo, transverse series no. 1696, 48.4 mm., where the lower end of the processus vaginalis is complete!}' embedded in the large expanded distal end of the gubernaculum, into and about which the cremaster fibers can be seen growing. The relation between the processus and the gubernaculum is different at these stages from any of the other forms.

In rodents, a rabbit embryo of 11 mm., transverse series no. 1327, shovN^s a primary point of contact between the abdommal wall and the Wolffian duct exactly similar to the cat embrj'o of 12 mm. A rat embryo, transverse series no. 1823, 9.3 mm., shows the early gubernaculum at a stage a little further advanced and comparable to that of the human embryo of 16.6 mm., and to the sheep of 18 mm. In all cases the presence of the retro-gubemacular fossa in the peritoneal cavity is striking. The development of the gubemaculum and processus vaginalis is very precocious in rat embryos and seems to advance more rapidly in the earlier stages than in those of the other mammalian embryos studied. A rabbit embryo of 21 mm., transverse series no. 738, gives an excellent view of the whole extent of the gubernaculi of both sides and the three parts — abdommal, mguinal or muscular, and scrotal — are clearly differentiated. There is no sign j-et of the processus vaginalis which can be seen however in a rat embr^'o of 15.2 mm., transverse series no. 1801, appearing on the lateral aspect of the gubernaculum. The processus vaginalis begins to develop in rabbit embryos of between 21 and 29 mm., and in the latter arises from the large funnelshaped fossa dorsal to the gubernaculum and extends downward on the dorso-lateral side of the gubernaculum. This ends in a dense but narrow ligamentum scroti that fuses in the subcutaneous tissue with the one of the opposite side. The cremaster fibers are well marked and arch over and blend -udth the gubernaculum as in the older sheep embrv^os.

56. Is defective and monstrous development due to 'parental metabolic toxaemiaf E. I. Werber, Department of Biolog}', Princeton University.

The problem of the causes underlying defective development has recently received masterly treatment by F. P. Mall. In his extensive study based on 163 pathological ova he supports the conclusion arrived at by the experimental embryologists, namely, that the human monsters are — with the exception of the hereditary 'merosomatous' terata — due to injurious influences of atypical environmental factors. He makes the specific suggestion — which seems justified in the light of evidence brought forth by him as well as by clinical data — that the monstrous development of some ova may be due to their inadequate nuitrition owing to the imperfect implantation in a diseased uterus. It would seem that this hypothesis will hold good at least for manj^ pathologic embryos aborted during the first two months of pregnancy. At any rate, the principle advocated by the hypothesis, viz., the influence of unusual environmental factors, seems to be correct beyond any doubt.

Mall's interpretation could not, however, be applied to monstrous fetusses of the later months of pregnancy or to monsters after full-term births. Some environmental factors must be looked for other than faulty implantation of the ovum, to account for the occurrence of such cases. The results of investigations in experimental embryology and teratology by Dareste, Roux, Hertwng, Fere, Morgan, Tur, Stockard, and others, who obtained monstrous development of ova which had been subjected to the action of physical and chemical modifications of the environment, suggested to me that the human as well as other mammalian monsters may be due to the physical or chemical action of some substances in the blood of one of the parents on either one of the germ cells or on the fertilized ovum respectively. The toxic substances found in the blood of invididuals afflicted with some diseases of metabolism, I think, might be the ones which could be made responsible for the origin of monstrous development.

To test this hypothesis it would be necessary to breed mammals in which certain diseases of metabolism had been produced experimentally, for the spontaneous occurrence of these disturbances in animals is too rare to permit of conclusive breeding experiments. On the other hand, to produce these diseases experimentally, at least as far as this can be done by the present rather inadequate methods of experimental pathology of metabolism, requires some facilities which, so far, are beyond my reach. I have thus had to confine myself to a preliminary step in the investigation.

This consisted in subjecting the eggs of an oviparous vertebral e to the action of solutions of substances found in the circulation of man under certain pathological conditions of metabolism. The eggs of a Fundulus heteroclitus were chosen as the object of experimentation and they were subjected in early (1 to 2 or 2 to 4 cells) cleavage stages to the action of sea-water solutions of various strengths of urea, butyric acid, lactic acid, acetone, sodium glycocholate and ammonium hydroxide, respectively. Positive results permitting of definite conclusions were so far obtained only with butyric acid and acetone.

For butyric acid 10 cc. of a yV ^o yV gram molecular solution, added to 50 cc. of sea water was found to give the best results, that is, the greatest number of monsters, while very much stronger solutions of' acetone, namely, about 35 to 40 cc. in 50 cc. of sea-water were found to be necessary to obtain like numbers of monsters. In the case of butyric acid a long exposure was found to kill most eggs and it was necessary to limit it to 20 hours, while in the case of acetone the eggs could be kept in the solution up to 48 hours, exposures longer than this increasing their mortality. It wtts also found that the eggs were more susceptible to the influence of these chemical modifications "of the environment during the first and second than during the third and fourth cleavages.

The results obtained ^\'ith butyric acid and acetone solutions are ven,' much alike. Great numbers of cj'clopean monsters were found in both these series of experiments. I have recorded in my observations the occurrence of transition from two normal eyes in the typical position in the head all the way down through the more or less closely approximated eyes or eyes of a double composition and through true cyclopia to complete anophthalmia as described by Stockard in his experiments with magnesium chloride and alcohol. Stockard has also described a peculiar change in the form and position of the mouth in the cyclopean embryo. The mouth in such embryos has the appearance of a snout, a proboscis-like structure and is pushed down below the cyclopean eye. This displacement into the ventro-lateral position Stockard attributes to the circumstance that the cyclopean eye, being frontally located, has caused the mouth to mov^ downward. I have observed this occurrence in most of the cyclopean monsters found in my experiments as well as in many cases of dorsal microphthalmia or even in some cases of asymmetric monophthalmia.

Besides the cyclopean, asymmetrically monophthalmic, microphthalmic and anophthalmic embrj-os there was found a very great variety of monstrosities in which practically the entire bodies of the embryo were more or less involved in the malformations. Thus curiously misshapen dwarfs with vestigial eyes or blind or verj' elongate, greatly malformed embryos, often with many waistlike constrictions were of not infrequent occurrence. Eggs in which only an anterior part of the embryo ('meroplastic embrj'os' — Roux), as if the rest of the body had been mechanically removed, were found in great numbers. Of these the ones in which an approximately anterior one-half of the body was present would correspond to the ' hemiembryones anteriores, ' which Roux obtained experimentally in the frog by injuring one of the blastomeres after the first cleavage. These hemiembryos found in mj^ own experiments have defective or sometimes very rudimentary eyes, they often exhibit evidences of oedema and are as a rule extremely misshapen. Eggs were also recorded in considerable numbers in which only a malformed head or small anterior part of it could be observed. These 'meroplasts' are so deformed that only b^^ the presence of rudimentary eyes is it possible to determine that they are heads.

But the most curious and most significant of all meroplasts recorded were eggs in which all that could be observed on the yolk-sac was a very small fragment of brain tissue with a solitary eye, which was sometimes somewhat defective — of the coloboma" type. The fragment of brain tissue is usually smaller than the eye it has given rise to. Since the eggs were fixed by Child's sublimate-acetic method and preserved in formaline, the embr^^os are white while the j^olk-sacs are transparent; yet nothing at all can be seen in the transparent yolksac to indicate that the embrj'o had sunken into it leaving one of its eyes on the surface where it might have beer constricted off. Moreover, in order to establish the fact of the occurence of the solitary eye beyond any possibility of skeptical criticism, I have sectioned one of these eggs on which besides the solitary eye several verj'- small fragments of tissue could be observed in the living as well, as m the fixed specimen in various places, distant from each other, on the j^olk-sac. The interpretation proved to be perfectly correct. For, besides the referred to few, small amorphous fragments of tissue scattered over the yolk-sac there can he seen only an eye typical in all its structures, while nothing can be found, to indicate the presence of an embryo. This is, as far as I am aware, the first cast on record of the independent developmeyit ('self-differentiation ' — Roux) oj the eye.

Another instance of apparently' independent development of the eye in these experiments has occurred in some cases where an e3'e appeared

at a considerable distance from a monophthalmic embryo. The ear vesicles are often involved in the malformations of embryos. This can be readily seen by their sometimes enormous size. Some asymmetrically monophthalmic embryos after hatching could not swim directly forward, dropping to the bottom of the dish in which they were kept, if forced to clo so. They could only move in circular or spiral lines which would indicate some injurj- to the semi-circular canals.

There is a wide range of variation in the deformities of the blood vascular system. The heart is almost perfect in some embryos in which cyclopia is the only superficially noticeable defect. In cases of more extreme malformation the heart may be only a very delicate, straight tube in some embryos while it may be absent altogether in others. In this connection it may be of interest to note that I have found some eggs in which all that was present of the embryo was a functioning heart and some rudimentary blood vessels. The degree of malformation of the blood vessels is subject to a great deal of variation. There may be merely blood-islands scattered on the yolk-sac, rudimentary^ imperfectly comiected, or in some instances more or less normal vessels.

The tendency of butyric acid and acetone solutions to produce twins seems to be only slight for I have observed only a few of such cases. I have only one case comparable to the "Siamese twins" type of the human. In this egg two deformed embryos with a common heart had developed on opposite sides of the egg. Other cases of twin formation found in these experiments belong to the type known as 'duplicitas anterior,' which was produced experimentally by mechanical means by Speemann.

Not infrequent is the occurrence of amorphous embryos or small amorphous fragments of tissue on the yolk-sac as the only evidence of development.

The mechanism involved in the action of butyric acid and acetone in bringing about these effects will have to be taken up as one of the further steps of this investigation. At the present time I can only state that there seems to occur in the eggs when subjected to the action of butyric acid and acetone solutions an elimination of substance of the blastomeres or possibly of the germ-disc. This elimination may be brought about either by precipitation or by tiie solvent effect respectively of the chemicals used in the experiments. Whatever parts of the blastoderm survive that process of destructive elimination, may go on developing to form an isolated organ or a part of the body or a complete embrj'o with defects in some organs.

57. The ileo-jejunal artery. C. R. Bardeen, University of Wisconsin.

From the superior mesenteric artery opposite the origin of the ileocoecal artery there arises a branch which passes to the free small intestine near the junctictn of the upper with the middle third of the gut as measured from the duodenum to the coecum. This branch may be called the ileo-jejunal artery. In a previous article (C. R. Bardeen, "The critical period in the development of the intestines," American Journal of Anatom}', vol. 16, p. 427) I have sho'svTi the probability that the region supplied by this artery represents the junction between that portion of the small intestines the primitive coils of which develop within the umbilical cord, the ileum, and that portion the primitive coils of which develop within the abdominal cavity, the jejunum. A study of the blood supply of the intestines in a number of fetuses and adults has shoA\'n that the portion of the intestines proximal to the center of the region supplied by the ileo-jejunal artery, the 'jejunum,' varies from 26 to 44.1 per cent of the total length of the small intestines as measured on the side opposite the mesentery and from 27.4 to 41.2 per cent measured on the mesenteric border.

In 10 fetuses measuring from 40 to 280 mm. in length (vertex breach) the average proportional length for the jejunum opposite the mesenteric border was 37.1 per cent with extremes of 32.2 and 44.1 per cent. In only two cases was it 40 per cent or over.

In 18 adults varying in age from 14 to 74 years the average proportional length of the jejmium was 33.5 per cent with extremes of from 26 to 40.3 per cent. In five cases it was under 30.7 per cent and in two cases 40 per cent or over. In eleven instances the jejunum as measured in the mesenteric border averaged 33.3 per cent with extremes of from 27.4 per cent to 41.2 per cent. In four instances it was less than 30 per cent; . in two instances 40 per cent or more.

In the adult specimens examined the length of the intestines varied from 138 to 294.5 inches but I have been able to trace no correlation between the length of the free intestines and the proportion between the proximal and distant portions. Aside from the average greater proportional lengt.h of the jejunum in the fetuses examined as compared with the adult I have found no correlation between age and the proportional length of the jejunum and with a greater number of specimens examined this difference might disappear. In 8 women the average length of the gut was shorter than that in 10 men, although I have found no certain correlation between length of gut and length of body. In the 8 women the average length of the jejunum was 31.96 per cent (extremes 26, 40 per cent) and in the 10 men, 35.31 per cent (extremes 27.3, 40.3 per cent). This may indicate a tendency on the part of women to have a longer ileum than men have and may possibly be related to the greater tendency in women to constipation.

The following demonstrations were shown:

1. Certain aspects of hematogenesis in the pig embryo. V. E. Emmel, Department of Anatomy, Washington University Medical School. The microscopical demonstrations and drawings are to illustrate

data relating: (a) to the cytological structure and morphological relations of the cell clusters in the dorsal aorta (cf. also abstract of paper on the same subject) and the macrophags and mesamoeboids in the liver sinusoids and coelomic cavities, with reference to the problem of the relation of endothehal tissue to hematogenesis in these regions, and (b) to certain cytological characteristics of erythrocytes during their cytomorphosis.

2. Sections, models and drawings showing the development of the chondrocranium in Felis domestica. R. J. Terry, Washington University Medical School.

The following points of interest have been selected for demonstration:

(1) Basal plate: the position of the notochord, flexures of the basal plate.

(2) Occipital region: basal and lateral moieties of occipital condyle, hypoglossal canal, dorsal root and ganglion of the hj^poglossal nerve, the occipital hypochordal arch, neural arches of the atlas and atlantal foramen.

(3) Otic region: evidence of independence of chondrification of otic capsule, relations of suprafacial commissure, independent chondrification of the parietal plate, development of the tegmen tympani, course of the facial nerve, formation of the internal acustic meatus, foramen cochleae and aquaductus cochleae, cavum supracochleare, supraganglionic cartilage, chstribution of the acustic nerve.

(4) Orbito-temporal region; hypophyseal cartilage, development of the dorsum sellae, foramen hypophyseos, early relations of the ala orbitalis, primary elements of the ala temporalis, origin of the foramen lacerum, epipteric cave, relations of ocular muscles to chondrocranium.

3. Microscope slides showing feather germs with dermal pigment. R. M. Strong, The University of Mississippi, Oxford.

4. Photographs of plates illustrating the anatomy of the albatross (Diomedea). R. M. Strong, The University of Mississippi, Oxford. The original drawings were made by Mr. Kcnji Toda, artist for the

Department of Zoology at the University of Chicago. About one-third of the plates are represented in the exhibit.

5. Photographs, drawings and charts illustrating (A), the morphology of the mammalian seminiferous tuhule and. (B), the relation of the stages of spermatogenesis to the tuhule. George M. Curtis, Vanderbilt IJniversity Medical School, Nashville.

6. Demonstrations of 'endothelioid' cells, Hal Downey, University of Minnesota, Minneapolis.

1 . Normal lymph node of guinea-pig ; Helly , methyl green and pyronin. The sinuses contain many of the so-called 'endothelioid' cells, both attached and free.

2. " EndotheUoid " cells in lymph node from normal cat; Helly, May-Giemsa. They are large protoplasmic cells which form a part of the reticulum. The wall of the small lymph sinus is in part composed of processes from these cells. One of the cells has almost completely separated from the reticulum. Its nucleus is indented and it has phagocytosed a red corpuscle. This method does not bring out the reticular fibers. The reticulum is not covered by an endothelium; if it were it should be possible to see the nuclei of its cells. The large cells will separate from the rest of the reticulum and form the 'endothelioid' cells of pathologists.

3. Lymph node from normal cat, stained by one of the methods for reticular fibers. The ' endothehoid ' cells contain fibers in their peripheral portion.

4. Spleen from Mandelbaum's case of Gaucher's disease; Orth's fluid, iron-hematoxylin, fuchsin S, orange G, toluidin blue. 'Endothelioid ' cells very numerous in the pulp and venous sinuses.

5. Lymph node from Mandelbaum's case of Gaucher's disease; alcohol fixation, stain as for (4) above. This field shows that the large, characteristic 'endothelioid' cells are derived from the reticulum and not from endothelium. The long strand in the center of the field is a part of the modified reticulum, and the long strand of reticulum approaching the center from the right gradually assumes the character of the protoplasm of the Gaucher cells.

6. Lymph node from a case of Hodgkin's disease; Helty, Weigert's iron-hematoxylin, fuchsin S, orange G, toluidin blue. In many cases the fibers of the reticulum can be seen to penetrate the 'endothelioid' cells.

7. A differential counterstain for vertebrate embryos. W. A. Willard, University of Nebraska, College of Medicine.

Pig embryos designed chiefly for class study of organogenesis are first deeply stained in toto with borax carmine then cut into serial sections 20 mi era or more in thickness and counterstainecl on the slide with a dilute solution of Lyons blue in absolute alcohol which has been rendered a blue-green color by the addition of a few picric acid crystals The strength of the solution and the time required to stain is best determined b}^ experiment with any particular lot of material. The result of the counterstain is to add brilliancj^ and transparency to the whole section slightly decolorizing the carmine and giving a selective stain of light green to the developing nerves and certain portions of the central nervous system Blood cells and to a certain degree epithelial structures are differentiated. By this method short series are made available with a minimum amount of handling, recommending it as a practical laboratory method.

8. A double embryo of the spiny dogfish (Squalus acanthias). W. A. WiLLARD, University of Nebraska, College of Medicine.

This is an example of two normally developed embrj'os attached by separate yolk stalks to a common yolk-sac. The embryos are in the second 3^ ear of theii intra-uterine development, in what is known as the 'pup' stage, one measuring 16 cm., the other 14.5 cm. in length. The larger of the two is supplied from a larger yolk-sac area as indicated by the vascularization by the vitellme vessels. An exposure of the viscera does not disclose any modification of the normal arrangement of organs, such as transposition or reversal of the normal sj-mmetry. As the. embryos had slipped from the cloaca of the female before they were noticed no data were obtainable as to position in the uterus or as to other embrv'os of the same brood.

9. Slides of yolk-sac of 10 mm. pig embryo. H. E. Jordan, University of Virginia, University.

Technic (1): Zenker fixation, hematoxylin-eosin stain; slides of yolksac of 4 mm. pig embryo. Technic (2) : Helly fixation, Giemsa stain.

10. Injections of the lymphatics of the lung. Robert S. Cunningham, Johns Hopkins Medical School, Baltimore.

11. Injections of the vascular system in early pig and chick embryos. Florence R. Sabin, Johns Hopkins Medical School, Baltimore.

12. Cell groups of the hypothalamus iii man. Edward F. Malone, University of Cincinnati, Cincinnati.

(1) Nuclei tuberis laterales; (2) Ganghon opticum basale; (3) Nucleus paraventricularis hypothalami; (4) The three cell groups of the corpus mammillare.

tS. Microscopic preparations showing the reactions of transplanted eyes in Amphibia. Edward Uhlenhuth, Rockefeller Institute, New York City.

Uf. A human embryo of 22 somites {models and figures). Franklin P. Johnson, University of Missouri, Columbia, Mo.

15. Models of the liver veins of pig embryos. Franklin P. Johnson, and T. F. Wheeldon, University of Missouri, Columbia, Mo.

16. Models of the heart of a 20 mm. pig. T. F. Wheeldon, University of Missouri, Columbia, No.

17. Dissections showing origin, course and distribution of nervus terminalis in the human fetus. Rollo E. McCotter, University of IMichigan, Ann Arbor, Mich.

18. Models of the early development of the inguinal region and of the pelvic outlet in human embryos. John Warren, Harvard Medical School, Boston.

19. Demonstration of reconstructions of lateral hearts and foregut in Citellus to show connection of endocardium to entoderm. Thomas G. Lee, Institute of Anatomy, University of Minnesota.

20. Models showing the development of the hypophysis in Squalus acanthias. E. A. Baumgartner, Washington University Medical School, St. Louis.

The study of the hypophysis, begun at the University of Minnesota and completed at Washington L^niversity Medical School, is represented in part by a series of ten models.

A model of a 19 mm. embryo shows Rathke's pouch extending obliquely forward and dorsalward from the mouth. In a 21 mm. embryo a part of the wall of the oral cavity ventral to Rathke's pouch has begun to evaginate to form the anterior end of the hypophysis. From these two out-pouchings are formed the hypoplwsis of the adult. The upper lateral portions of Rathke's pouch are somewhat dilated. In a model of the hypophysis of a 22 mm. embryo, the anterior end is distinctly evaginated; while in a model of the hypophj-sis from a 28 mm. embryo this part is constricted off from the mouth except for a small stalk comiected to its caudal side. Most of the first out-pouching, or Rathke's pouch, wiW form the caudal end of the anterior lobe. The lateral dilated portions are separated from the median part by two furrows which have appeared on the anterior side of the upper part of the hypophysis. The extreme tip of Rathke's pouch is somewhat enlarged, the anlage of the superior lobe of the hypophj^sis. A model of the hypophj^sis of a 33 mm. embryo shows a short anterior end connected by a narrow mid-part to the wider caudal end. A slight ridge, superior to the hypophyseal stalk, connects the lateral portions which, in the adult, form the inferior lobes. In a 48 mm. embryo the model shows that the hypophyseal stalk has disappeared. The superior lobe has two lateral wings extending forward and slightly dorsally. In a model of the hypophysis of a 95 mm. embryo the anterior lobe is very long and the wider anterior and caudal extremities are marked. The inferior lobes project laterally and from their median connection a slender duct comiects them to the caudal extremity of the anterior lobe. In the pup stage ridges indicate the l^egimiing glandular structure. These are present on the ventral wall of the anterior extremity of the anterior lobe and on the roof of the inferior lobe. A model of some of the glands of the anterior lobe shows them connected to the ventral wall. They are short-branched tubular outgrowths showing anastomoses. The lumina may not be continuous throughout the anastomosed tubules.

21. Wax models in verification of the nudeus-'plasma relation of nerve cells. David H. Dolley, University of Missouri (introduced bv E. R. Cl/^rk).

As a result of the averages of measurements, for the most part on the crayfish and the dog, the nucleus-plasma norm of functionally resting nerve cells of the same type has been found to be represented by a close numerical constant in all individuals within any particular species.

For final verification, calculations were made for individual Purkinje cells of several dogs from serial sections at 2 and l/x. From these serials wax models were reconstructed and the data were afforded for the mathematical application of the prismoid formulas. In the case of the wax models, the proportion by weight of wax nucleus to wax plasma is identical within very narrow limits, whatever the size or shape of the cell or whatever the size of the animal or its age between the full development of the relation and senescence. The uniformity of the results after all three methods, with the support of certain collateral evidence, has led to the induction of a law of species identity of the nucleusplasma norm for corresponding nerve cell bodies (Jour. Comp. Neur., vol. 24, October, 1914).

The shifts in absolute and relative size in nucleus and plasma which result from function, as determined by average measurements, are also confirmed by the application of the wax reconstruction and the prismoid formulas to the individual cell.

22. On the use of orcein as a hulk stain for elastic fibers. A. G. Pohlman, University of St. Louis.

Blocks of tissue are run through to 95 per cent alcohol and placed in Unna's orcein solution for 2 to 12 hours according to size. Remove to absolute alcohol shghtly acidulated with HCl for 2 to 3 hours and then into an excess of aT3Solute alcohol for 6 to 12 hours. The tissue may now be handled in the usual way for paraffin and celloidin technique. If tissues are not sufficiently differentiated after sectioning use 5 per cent oxalic acid. The stain is very resistant and will not be affected by ordinary laboratory methods.

Demonstration I. (1) Plain bulk orcein; (2) Paracarmine followed by orcein; (3) Orcein 'followed by hematoxjdin-eosin ; (4) Orcein followed by hcmatoxylin-eosin and orange G. ; (5) Orcein followed by hematox>din and picrofuchsin; (6) Orcein followed ])y picrofuchsin; (7) Differentiation in cleared bulk specimen; (8) Differentiation shown in uncleared bulk specimen.

Demonstration II. (1) Length section of Platner's ligament; (2) Length section through drum ligament in chick; (3) Section through attachment of Stapedial plate and membrane of the Fenestra cochleae; (4) Dissection of the gross relations of the columella in chicken, cluck, goose and turkey. Platner's ligament shows as a delicate fiber running forward from columella to quadrate bone.

SS. Plaster casts of the sphenoid, maxillary and frontal sinuses, the cubical capacity and superficial area of these sinuses. Hanau W. Loeb, St. Louis University.

The casts are made bj' joining together plaster moulds of those portions of the sinuses lying adjacent to one another in serial sections of the head. The casts are then boiled in paraffin and the cubical capacity determined by ascertaining the amount of water displaced by them. To determine the superficial area, the casts are covered with strips from a known amount of adhesive plaster. The difference between the known amount and that remaining gives the superficial, subject to whatever error results from lack of complete approximation of the strips. This is exceedingly small indeed.

2Ji. A method for handling paraffin sections. Irving Hardesty,

Tulane University.

A method for staining and issuing paraffin sections for mounting by the students in large classes in histologj'. Thin sheets of a modified form of celluloid may be obtained under the commercial name, "la cellophane." These sheets are quite thin, perfecth^ transparent and resist the action of water, alcohol of all strengt-hs, ether, chloroform, and all the oils commonly used in clearing and differentiating, including creosote and oil of cloves. La cellophane of thickness No. 253 may be obtained in sheets 17^ by 25 inches. These may be cut into sheets of desired size. The paraffin sections of a specimen, in sufficient number to supply the class may be placed upon the sheets, straightened out and fixed by the usual albumen-water method. After drying, the entire sheet is treated for staining, clearing and mounting, just as is a slide with a single section. After clearing, the sheet is chpped into small pieces each bearing a section and these pieces issued to the class La cellophane No. 253 is sufficiently thin for the purpose; No. 252 however, is, said to be of thinner weight. For work with oil immersion objectives under cover — glasses of ordinary thickness, the student should be ad\ised to mount the pieces with the sections uppermost. The sheets retain practically none or very little of the stain after hematoxjdin and anilin dyes commonly employed.


AMERICAN ASSOCIATION OF ANATOMISTS

OFFICERS AND LIST OF MEMBERS

(January 2d 1915)

Officers

President G. Carl Htjber

Vice-President Frederic T. Leavis

Secretary-Treasurer Charles R. Stockard

Executive Comraittee

For term expiring 1915 Henry McE. Knower, Irving Hardesty

For term expiring 1916 Arthur W. Meyer, Charles F. W. McCltjre

For term expiring 1917 Warren H. Lewis, C. Judson Herrick

For term expiring 1918 Hermann von W. Schulte, John L. Bremer

Committee on International Congress F. P. Mall and G. S. Huntington

Honorary Members

S. Ram6n y Cajal Madrid, Spain

John Cleland Glasgotv, Scotland

Camillo Golgi Pavia, Italy

Oscar Hertwig Berlin, Germany

Alexander MacCallister Cambridge, England

A. Nicholas Paris, France

Moritz Nussbaum ' Bonn, Germany

L. Ranvier Paris, France

Gustav Retzius Stockholm, Sweden

WiLHELM Roux Halle, Germany

Carl Toldt Vienna, Austria

Sir Williajm Turner Edinburgh, Scotland

WiLHELM Waldeyer Berlin, Germany

Members

Addison, William Henry Fitzgerald, B.A., M.B., Assistant Professor of Normal Histology and Embryology, University of Pennsylvania, 3932 Pine Street, Philadelphia, Pa.

1-45


Allen, Bexnet Mills, Ph.D., Professor of Zoology, University of Kansas, 1329

Ohio Street, Lawrence, Kans. Allen, William F., A.M., Instructor of Histology and Embryology, Institute

of Anatomy, University of Minnesota, Minneapolis, Minn. Allis, Edward Phelps, Jr., LL.D., Palais de Carnoles, Mentone, France. Atwell, Wayne Jason, A.B., Instructor in Histology, 1335 Geddes Avenue,

Ann Arbor, Michigan. Baker, Frank, A.M., M.D., Ph.D., (Vice-Pres. '88-'91, Pres. '96-'97), Professor

of Anatomy, University of Georgetown, 1901 Biltmore Street, Washington,

D.C. Baldwin, Wesley Manning, A.B., M.D., Assistant Professor of Anatomy,

Cornell University Medical College, First Avenue and 28th Street, Neiv York,

N. Y. vft^. Bardeen, Charles Russell, A. B., M.D., (Ex. Com. '06-'09), Professor of Anatomy and Dean of Medical School, University of Wisconsin, Science Hall,

Madison, Wis. Badertscher, Jacob A., Ph.M., Ph.D., Instructor in Anatomy, Indiana University School of Medicine, 517 N. Lincoln Street, Bloomington, Ind. Bartelmez, George W., Ph.D., Instructor in Anatomy, Chicago University,

Chicago, III. Bates, George Andrew, M.S., Professor of Histology and Embryology, Tufts

College Medical School, Huntington Avenue, Boston, Mass. V'..#-Baumgartner, Edwin A., A.M., Instructor in Anatomj', Washington University

Medical School, St. Louis, Mo. Baumgartner, William J., A.M., Assistant Professor of Histologj' and Zoology,

University of Kansas, Lawrence, Kans. Bayon, Henry,*B.A., M.D., Associate Professor of Anatomj', Tulane University,

2212 Napoleon Avenue, New Orleans, La. Bean, Robert Bennett, B.S., M.D., Professor of Gross Anatomy, Tulane

University of Louisiana, Station 20, New Orleans, La. Begg, Alexander S., M.D., Instructor in Comparative Anatomj', Harvard

Medical School, Boston, Mass. Bell, Elexious Thompson, B.S., M.D., Assistant Professor of Pathologj', Department of Pathology, University of Minnesota, Minneapolis, Minn. ^__ Bensley, Robert Russell, A.B., M.B., (Second Vice-Pres. '06-'07, Ex. Com.

'08-' 12), Professor of Anatomy, University of Chicago, Chicago, III. Bevan, Arthur Dean, M.D. (Ex. Com. '96-'98), Professor of Surgery, University

of Chicago, 2917 Michigan Avenue, Chicago, III. Bigelow, Robert P., Ph.D., Assistant Professor of Zoology and Parasitology,

Massachusetts Institute of Technology, Boston, Mass. Black, Davidson, B.A., M.B., Assistant Professor of Anatomy, Western Reserve

University, Medical Department, 1353 East 9th Street, Cleveland, Ohio. Blair, Vilray Papix, A.M., M.D., Clinical Professor of Surgery, Medical Department, Washington University, Metropolitan Building, St. Louis, Mo. Blaisdell, Frank Ellsworth, M.D., Assistant Professor of Surgery, Medical

Department of Stanford University, 1520 Lake Street, San Francisco, Calif. Blake, Joseph Augustus, A. B., M.D., American Ambulance Hospital, Boulevard

d'Inkermann, Neully-sur-Seine, Paris, France.

BoYDEN, Edward Allen, Teaching fellow. Histology and Embryology, Harvard

Medical School, Boston, Mass. Bremer, Johx Lewis, M.D., (Ex. Com. '15-), Assistant Professor of Histology,

Harvard Medical School, Boston, Mass. Brodel, Max, Associate Professor of Art as Applied to Medicine, Johns Hopkins

Universit}', Johns Hopkins Hospital, Baltimore, Md. Brooks, Williaii Allex, A.^L, M.D., 167 Beacon Street, Boston, Mass. Brown, A. J., M.D., Demonstrator of Anatomy, Columbia University, 156 Ea^t

64th Street, New York, N. Y. Browning, William, Ph.B., M.D., Professor of Nervous and Mental Diseases,

Long Island College Hospital, 54- Lefferts Place, Brooklyn, N. Y. Bryce, Thomas H., M.A., M.D., Regius Professor of Anatomy, University of

Glasgow, Xo. 2, The University, Glasgow, Scotland. Bullard, H. Hays, A.^L, Ph.D., Instructor in Anatomj^ and Neurology, University of Pittsburgh Medical School, Pittsburgh, Pa. Bunting, Charles Henry, ^I.D., Professor of Pathology, University of Wisconsin, 1804 Madison Street, Madison, Wis. Burrows, Montrose, T., A.B., M.D., Instructor in Anatomy, Cornell University

Medical College, New York, N. Y. Campbell, William Francis, A.B., M.D., Professor of Anatomy and Histology,

Long Island College Hospital, 394 Clinton Avenue, Brooklyn, N. Y. Carpenter, Frederick Walton, Ph.D., Professor of Zoology, Trinity College,

Hartford, Conn. Chase, Martin Rist, M.S., Assistant in Anatomy, Northwestern University

Medical School, 2431 Dearborn Street, Chicago, HI. Cheever, David, M.D., Assistant Professor of Surgical Anatomy, Harvard

Medical School, 355 Marlborough Street, Boston, Mass. Chidester, Floyd E., A.M., Ph.D., Assistant Professor of Zoology, Rutgers

College, New Brunswick, N. J. Chillingworth, Felix P., M.D., Assistant Professor of Physiology and Pharm cology, Tulane University, New Orleans, La. Clapp, Cornelia Maria, Ph.D., Professor of Zoology, Mount Holyoke College,

Sojith Hadley, Mass. Clark, Elbert, B.S., Instructor in Anatomj', University of Chicago, Chicago,

ni.

Clark, Eleanor Linton, A.]\I., Research Worker, Department of Anatomy,

University of Missouri, Columbia, Mo. Clark, Eliot R., A.B., M.D., Professor of Anatomy, University of Missouri,

Columbia, Mo. CoGHiLL, George E., Ph.D., Associate Professor of Anatomy, University of

Kansas Medical School, 338 Illinois Street, Lawrence, Kansas. Cohn, Alfred E., M.D., Associate in Medicine, Rockefeller Institute for Medical

Research, 315 Central Park West, N^ew York, N. Y. CoHOE, Benson A., A.B., :\I.B., Associate Professor of Therapeutics, University

of Pittsburgh, 705 North Highland Averiue, Pittsburgh, Pa. CoNANT, WiLLi.AM ^^Ierritt, M.D., Instructor in Anatomy in Harvard ^ledical

School, 4^6 Commonwealth Aven'ue, Boston, Mass.


148 AMERICAN ASSOCIATION OF ANATOMISTS

CoNKLiN, Edwin Grant, A.M., Ph.D., Sc.D., Professor of Biology, Princeton University, 139 Broadmead Avenue, Princeton, N. J.

Corner, George W., M.D., Assistant in Anatomy, Johns Hopkins University, Johns Hopkins Medical School, Baltimore, Md.

Corning, H. K., M.D., Professor of Anatomy, Bundesstr. 17, Basel, Switzerland.

Corson, Eugene Rollin, B.S., M.D., Surgeon, Lecturer on Anatomy, Savannah, Hospital Training School for Nurses, 10 Jones Street, West, Savannah, Ga.

CowDRY, Edmund V., Ph.D., Associate in Anatomy, Anatomical Laboratory, Johns Hopkins Medical School, Baltimore, Md.

Craig, Joseph David, A.M., M.D., Professor of Anatomy, Albany Medical College, 12 Ten Broeck Street, Albany, N. Y.

Crile, George W., M.D., Professor of Surgery, Western Reserve University, 1021 Prospect Avenue, Cleveland, 0.

CuLLEN, Thomas S., M.B., Associate Professor of Gynecology, Johns Hopkins University, 3 West Preston Street, Baltimore, Md.

Cunningham, Robert S., B.S., A.M., Johns Hopkins ^Medical School, 716 N. Broadway, Baltimore, Md.

Curtis, George M., A.B., A.M., Assistant Professor of Anatomy, Medical Department of the Vanderbilt University, 907 First Avenue, Nashville, Tenn.

Dahlgren, Ulric, M.S., Professor of Biology, Princeton University, 20^ Guyot Hall, Princeton, N. J.

Danforth, Charles Haskell, A.M., Ph.D., Instructor in Anatomy, Medical Department, Washington University, Medical School, St. Louis, Mo.

Darrach, William, A.M., M.D., Assistant Attending Surgeon, Presbyterian Hospital, Instructor in Clinical Surgerj-, Columbia University, 47 West 50th Street, New York, N. Y.

Davison, Alvin, M.A., Ph.D., Professor of Biology, Lafayette College, Easton, Pa.

Davis, David M., B.S., Johns Hopkins Medical ScJiool, Baltimore, Md.

Davis, Henry K., A.B., A.M., Instructor in Anatomy, Cornell University Medical College, Ithaca. N. Y.

Dawburn, Robert H. Mackay, I\I.D., Professor of Anatomy, New York Polyclinic Medical School and Hospital, 105 West 74th Street, New York, N. Y.

Dean, Bashford, Ph.D., Professor of Vertebrate Zoology, Colimibia University, Curator of Fishes and Reptiles, American Museum Natural History, Riverdale-on-Hudson, New York.

Dexter, Franklin, M.D., 247 Marlborough Street, Boston, Mass.

Dixon, A. Francis, M.B., Sc.D., University Professor of Anatomy, Trinity College, 73 Grosvenor Road, Dublin, Irela d.

DoDSON, John Milton, A.M., M.D., Dean and Professor of Medicine, Rush Medical College, University of Chicago, 5806 Blackston Avenue, Chicago, HI.

Donaldson, Henry Herbert, Ph.D., D.Sc, (Ex. Com. '09-'13), Professor of Neurology, The Wistar Institute of Anatomy and Biology, Woodland Avenue and 36th Street, Philadelphia, Pa.

Downey, Hal, M.A., Ph.D., Associate Professor of Histologj^ Department of Animal Biology, University of Minnesota, Minneapolis, Minn.

Dunn, Elizabeth Hopkins, A.M., M.D., Nelson Morris Laboratory for Medical Research, 4760 Lake Park Avenue, Chicago, III.


MEMBERS 149

EccLES, Robert G., :\I.D., Phar.D., 681 Tenth Street, Brooklyn, N. Y.

Edwards, Charles Lincoln, Ph.D., Director of Nature Study, Los Angeles City Schools, 1033 West 39ih Place, Los Angeles, Calif.

Eggerth, Arnold Henry, Assistant in Histologj-, University of Michigan, Ann ■ Harbor, Michigan.

Elliot, Gilbert ]SI., A.M., ^LD., Demonstrator of Anatomy, ^Medical School of Maine, 1S2 Maine Street, Brunswick, Me.

Emmel, Victor E., M.S., Ph.D., Associate Professor of Anatomy, Washington University Medical School, St. Louis, Mo.

EssiCK, Charles Rhein, B.A., M.D., Instructor in Anatomy, Johns Hopkins University, 1807 North Caroline Street, Baltimore, Md.

Evans, Herbert McLean, B.S., M.D., Associate Professor of Anatomy, Research Associate in Embryology, Carnegie Institution, Johns Hopkins Medical School, Baltimore, Md.

EvATT, Evelyn John, B.S., M.B., Professor of Anatomy, Royal College of Surgeons, Dublin, Ireland.

Eycleshymer, Albert Chauncey, Ph.D., M.D., Professor of Anatomy, Medical Department, University of Illinois, Honore and Congress Streets, Chicago, III.

Ferris, Harry Burr, A.B., ^I.D., Hunt Professor of Anatomy and Head of the Department of Anatomy, Medical Department, Yale Universitj^, 395 St. Ronan Street, New Haven, Conn.

Fetterolf, George, A.B., IM.D., Sc.D., Assistant Professor of Anatomj', University of Pennsylvania, 330 South 16th Street, Philadelphia, Pa.

Fischelis, Philip, ]\I.D., Associate Professor of Histology and Embryology, ]\Iedico-Chirurgical College, 828 North 5th Street, Philadelphia, Pa.

Flint, Joseph Marshall, B.S., A.M., M.D. (Second Vice-Pres. '00-'04), Professor of Surgery, Yale University, 320 Temple Street, New Haven, Conn.

Frost, Gilman Dubois, A.M., M.D., Professor of Clinical Medicine, Dartmouth Medica' School, Hanover, N'. H. y ' Gage, Simon Henry, B.S. (Ex. Com. '06-'ll), Emeritus Professor of Histology and Embryology, Cornell University, Ithaca, N. Y.

Gage, Mrs. Susanna Phelps, B.Ph., 4 South Avenue, Ithaca, N. Y.

Gallaudet, Bern Budd, A.M., M.D., Assistant Professor of Anatomy, Columbia University, Consulting Surgeon Bellevue Hospital, 110 East 16th Street, New York, N. Y, -j^_Geddes, a. Campbell, INI.D., ^NI.B., Ch.B., F.R.S.E., Professor of Anatomy, McGill University, Montreal, Canada.

Gibson, J.a.mes A., M.D., Professor of Anatomy, Medical Department, University of Buffalo, 24 High Street, Buffalo, N. Y.

Gilman, Philip Kingsworth, B.A., M.D., Professor of Surgery, University of Philippines, Suite 417-427 Kneedler Bldg., Manila, P. I.

Goetsch, Emil, Ph.D., M.D., Associate in Surgery, Harvard Medical School, Resident Surgeon, Peter Brigham Hospital, Boston, Mass.

Greene, Charles W., Ph.D., Professor of Physiology and Pharmacology, University of Missouri, Coliwibia, Mo.

Greenman, Milton J., Ph.B., M.D., Sc.D., Director of the Wistar Institute of Anatomy and Biology, 36th Street and Woodland Avenue, Philadelphia, Pa.


X


X


150 AMERICAN ASSOCIATION OF ANATOMISTS

GuDERNATSCH, J. F., Ph.D., Instructor in Anatomy, Cornell University Medical College, New York City.

Guild, Stacy R., A.M., Instructor in Histology and Embryology, University of Michigan, 1511 Washtenaiv Avenue, Ann Arbor, Mich.

GuYER, Michael F., Ph.D., Professor of Zoology, University of Wisconsin, 1S8 Prospect Avenue, Madison, Wis.

Halsted, William Stewart, M.D., Professor of Surgerj-, Johns Hopkins University, 1201 Eutaw Place, Baltimore, Md.

Hamann, Carl A., M.D., (Ex. Com. '02-'04), Professor of Applied Anatomy and Clinical Surgery, Western Reserve University, ^6 Osborn Building, Cleveland, Ohio.

Hardesty, Irving, A.B., Ph.D., (Ex. Com. '10 and '12-'15), Professor of Anatomy, Tulane University of Louisiana, Statio?i 20, New Orleans, La.

Hare, Earl R., A.B., M.D., Instructor in Surgery, University of Minnesota, 62S Syndicate Building, Minneapolis, Minn.

Harrison, Ross Granville, Ph.D., M.D. (Pres. '12-'13), Bronson Professor ol Comparative Anatomy, Yale University, New Haven, Conn.

Harvey, Basil Coleman Hyatt, A.B., M.B., Associate Professor of Anatomy, University of Chicago, Department of Anatomy, University of Chicago, Chicago, III.

Harvey, Richard Warren, M.S., M.D., Assistant Professor of Anatomy, Anatomy Department, Universit}' of California, Berkeley, Calif.

Hatai, Shinkishi, Ph.D., Associate in Neurology, Wistar Institute of Anatomy and Biology, Philadelphia, Pa.

Hathaway, Joseph H., A.M., M.D., Professor of Anatomy, Anatomical Department, Detroit Medical College, Detroit, Mich.

Hazen, Charles Morse, A.M., M.D., Professor of Phj'siologj-, Medical Collrge of Virginia, Richmond, Bon Air. Va.

Heisler, John C, M.D., Professor of Anatomy, Medico-Chirurgical College, 3829 Walnut Street, Philadelphia, Pa.

Heldt, Thomas Johanes, A. B., A.M., 200 East Lanvale Street, Baltimore, Md.

Herrick, Charles JuDSON, Ph.D., (Ex. Com. 1913-) Professor of Neurology, University of Chicago, Laboratory of Anatomy , University of Chicago, Chicago, III.

Hertzler, Arthur E., M.D., F.A.C.S., Associate in Surgery, University of Kansas, IOO4 Rialto Building, Kansas City, Mo.

Herzog, Maxi.milian, M.D., Professor of Pathologj- and Bacteriology, La Gola University, 1358 Fulton Street, Chicago, III.

Heuer, George Julius, B.S., M.D., Resident-Surgeon, Johns Hopkins Hospital, and Instructor in Surgery, Johns Hopkins Hospital, Baltimore, Md.

Heuser, Chester H., A.M., Ph.D., Fellow in Anatomy, Wistar Institute of Anatomy, 36th Street and Woodland Avenue, Philadelphia, Pa.

Hewson, Addinell, A.m., M.D., Professor of Anatomy, Philadelphia Polyclinic for Graduates in Medicine, 2120 Spruce Street, Philadelphia, Pa.

Hill, Howard, M.D., 1010 Rialto Building, Kansas City, Mo.

Hilton, William A., Ph.D., Professor of Zoology, Pomona College, Claremont, Calif.

Hodge, C. F., Ph.D., Professor of Social Biology, University of Oregon, Eugene, Oregon.


i^ 1,^-TT


MEMBERS 151

HoEVE, HuBERTUS H. J., M.D., Meherrin Hospital, Meherrin, Virginia.

Hooker, Davenport, M.A., Ph.D., Assistant Professor of Anatomj', University of Pittsburgh Medical School, Grant Boulevard, Pittsburgh, Pa.

Hopkins, Grant Sherman, Sc.D., D.V.M., Professor of Veterinary Anatomy Cornell University, Ithaca, N. Y.

Hoskins, Elmer R., A.B., A.M., Instructor in Anatomy, University of Minnesota, Minneapolis , Minn.

Hrdli6ka, Ales, M.D., Curator of the Division of Physical Anthropology, United Stales National Museum, Washington, D. C.

HuBER, G. Carl, M.D. (Second Vice-Pres. 'OO-'Ol, Secretarj'-Treasurer '02-'13, Pres. '14-) Professor of Anatomy and Director of the Anatomical Laboratories, University of Michigan, 1330 Hill Street, Ann Arbor, Mich. tJNTiNGTON, George S., A.M., M.D., D.Sc, LL.D. (Ex. Com. '95t'97, '04-'07, Pres. '99-'03), Professor of Anatomj', Columbia University, 4^7 West 69th Street, New York, N. Y.

Ingalls, N. William, M.D., Associate Professor of Anatomj^ Medical College, Western Reserve University, Cleveland, Ohio.

Jackson, Clarence M., M.S., M.D., (Ex. Com. '10-'14), Professor and Head of the Department of Anatomy, University of Minnesota, Institute of Anatomy, Minneapolis, Minn.

Jenkins, George B., M.D., Professor of Anatomy, Department of Anatomy, University of Louisville, Louisville, Ky.

Johnson, Charles Eugene, Ph.D., Instructor in Comparative Anatomj-, Department of Animal Biologj^, University of Minnesota, Minneapolis, Minn.

Johnson, Franklin P., A.M., Ph.D., Associate Professor of Anatomy, University of Missouri, 408 South Ninth Street, Columbia, Mo.

Johnston, John B., Ph.D., Professor of Comparative Neurology, University of Minnesota, University of Minnesota, Minneapolis, Minn.

Jordan, Harvey Ernest, Ph.D., Professor of Histology and Embryology, University of Virginia, University, Va.

Kampmeier, Otto Frederick, A.B., Ph.D., Instructor in Embryology and Anatomy, University of Pittsburgh Medical School, Pittsburgh, Pa.

Kappers, Cornelius, Ubbo Ariens, Director of the Central Institute for Brain Research of Holland, Mauritskade 61, Amsterdam, Holland.

Keiller, William, L.R.C.P. and F.R.C.S.Ed. (Second Vice-Pres. '98-'99), Professor of Anatomy, Medical Department University of Texas, State Medical College, Galveston, Texas.

Kelly, Howard Atwood, A.B., M.D., LL.D., Professor of Gynecology, Johns Hopkins Universitj^ I4I8 Eutaw Place, Baltimore, Md.

Kerr, Abram T., B.S., M.D., (Ex. Com. '10-14), Professor of Anatomy, Cornell University Medical College, Ithaca, N'. Y.

Kingsbury, Benjamin F., Ph.D., M.D., Professor of Histology and Embryology, Cornell University, 802 University Avenue, Ithaca, N. Y.

Kingsley, John Sterling, Sc.D., Professor of Zoology, University of Illinois, Urbana, III.

King, Helen Dean, A.B., Ph.D., Assistant Professor of Embryology, Wistar Institute of Anatomy, 36th Street and Woodland Avenue, Philadelphia, Pa.


152 AMERICAN ASSOCIATION OF ANATOMISTS

g^_~ Knower, Henry McE., A. B., Ph.D., (Ex. Com. '11-15), Professor of Anatomy, Medical Department, University of Cincinnati, Station V, Cincinnati, Ohio.

KoFOiD, Charles Atwood, Ph.D., Professor of Zoology University of California, Assistant Director San Diego Marine Biological Station, 2616 Etna Street, Berkeley, Calif.

Kunkel, Beverly W.a.tjgh, Ph.B.. Ph D., Professor of Zoology, Beloit College, Beloit, Wisconsin.

KuNTZ, Albert, Ph.D., Department of Anatomy, University of St. Louis, 3911 Castleman Avenue, St. Louis, Mo.

KuTCHix, Harriet Lehmann, A.M., Assistant in Biology, University of Montana, 527 Ford Street, Missoula, Mont.

Kyes, Prestox, A.m., M.D., Assistant Professor of Experimental Pathology, Department of Pathology, University of Chicago, Chicago, III.

Lamb, Daxiel Smith, A.AL, M.D., LI>.D., (Secretary-Treasurer '90-'01,Vice-Pres. '02-'03) Pathologist Army Medical Museum, Professor of Anatomy, Howard University, Medical Department, 2114 18th Street N. W., Washington, D.C.

Lambert, Adrian V.S., A.B., M.D., Associate Professor of Surgery, Columbia University, 168 East 71st Street, New York, N. Y.

Laxdacre Francis Leroy, A.B., Professor of Anatomy, Ohio State University, 2026 Inka Ave., Columbus, Ohio.

Lane, Michael Andrew, B.S., 122 S. California Avenue, Chicago, III.

Lee, Thomas G., B.S., M.D. (Ex. Com. '08-'10, Vice Pres. '12-'13}, Professor of Comparative Anatomj^ University of Minnesota, Institute of Anatomy, University of Minnesota, Minneapolis, Minn.

Leidy, Joseph, Jr., A.M., M.D., 1319 Locust Street, Philadelphia, Pa.

Lewis, Dean D., M.D., Assistant Professor of Surgery, Rush Medical College, People's Gas Building, Chicago, III. j^— Lewis, Frederic T., A.M., M.D., (Ex. Com. '09-'13, Vice-Pres. '14-), Assistant Professor of Embryology, Harvard Medical School, Boston, Mass.

Lewis, Warren Harmon, B.S., M.D., (Ex.Com. '09-'ll, '14- ), Professor of Physiological Anatomy, Johns Hopkins University, Medical School, -Baltimore, Md.

Lillie, Frank Rathay, Ph.D., Professor of Embryology, Chairman of Depart^ ment of Zoology, University of Chicago; Director Marine Biological Labor atory, Woods Hole, Mass., University of Chicago, Chicago, III.

Lineback, Paul Eugene, A.B., M.D., Teaching Fellow in Histology and Embryology, Harvard Medical School, Boston, Mass.

LocY, William A., Ph.D., Sc.D., Professor of Zoology and Director of the Zoological Laboratory, Northwestern University, /7450?Tm^<onAfenwc,£^i'ans<on,/Zi.

Loeb, Hanau Wolf, A.M., M.D., Professor and Director of the Department of the Diseases of the Ear, Nose and Throat, St. Louis Universitj', 537 A^orth Grand Avenue, St. Louis, Mo.

Lord, Frederic P., A.B., M.D., Professor of Anatomy and Histology, Dartmouth Medical School, Hanover, N. H.

Lowrey, Lawson Gentry, A.M., Harvard Medical School, Boston, Mass. ^^ Macklin, C. C, M.B., Assistant in Anatomy, Johns Hopkins Medical School, Baltimore, Md.

McCarthy, John George, M.D., Formerly Assistant Professor of Anatomy, McGill University, 112 St. .Mark Street, Montreal, Canada.


MEMBERS 153

MoClure, Charles Freeman Williams, A.M., Sc.D. (Vice Pres. '10-' 11, Ex. Com. 'r2-'16). Professor of Comparative Anatomy, Princeton University Princeton, N. J.

McCormack, William Eli, AI.D., Instructor in Embryology and Histology, University of Louisville, Louisville, Ky.

McCoTTER, RoLLO E., M.D., Professor of Anatomy, Medical Department, University of Michigan, Ann Arbor, Michigan.

McFarland, Frank Mace, Ph.D., Professor of Histology, Leland Stanford Junior University. Stanford, Calif.

McGiLL, Caroline, A.M., Ph.D., M.D., Pathologist, Murray Hospital, Butte, Montana.

McKiBBEN, P.\XJL S., Ph.D., Professor of Anatomy, Department of Anatomy, Western University, London, Canada.

McMuRRicH, James Playfair, A.M., Ph.D., LL.D. (Ex. Com. '06-'07, Pres. '08-' 09), Professor of Anatomy, University of Toronto, 75 Forest Hill Road, Toronto, Canada.

McWhorter, John E., M.D., Worker under George Crocker Research Fund, College of Physicians and Surgeons, Columbia University, 205 West 107th Street, New York, N. Y.

Mall, Franklin P., A.M., M.D., LL.D., D.Sc. (Ex.Com.'00-'05, Pres. '06-'07), Professor of Anatomy, Johns Hopkins Medical School, Baltimore, Md.

Mangxjm, Charles S., A.B., M.D., Professor of Anatomy, University of North Carolina. Chapel Hill, N. C.

Malone, Edward Fall, A.B., I\LD., Assistant Professor of Anatomy, University of Cincinnati, Station V, Cincinnati, 0.

Mark, Edward Laurens, Ph.D., LL.D., Hersey Professor of Anatomy and Director of the Zoological Laboratory, Harvard University, 109 Irving Street, Cambridge, Mass.

Martin, Walton, Ph.B., M.D., Professor of Clinical Surgery, Columbia University, 25 West 50th Street, Neiu York, N. Y.

Matas, Rudolph, M.D., Professor of Surgery, Tulane University, 2255 St. Charles Avenue, N^ew Orleans, La.

Maximow, Alexander, ]\LD., Professor of Histology and Embryolog}- at the Imperial Military Academy of Medicine, Petrograd, Russia, Botkinskaja 2, Petrograd, Russia.

Mellus, Edward Lindon, M.D., 10 Sewall Avenue, Brookline, Mass.

Mercer, William F., Ph.D., Professor of Biology, Ohio University. 200 East State Street, Athens, Ohio.

Metheny, D. Gregg, M.D., Associate in Anatomy, Jefferson Medical College, 11th and Clinton Streets, Philadelphia, Pa.

Meyer, Adolf, M.D., LL.D., Professor of Psychiatry and Director of the Henry Phipps Psychiatric Clinic, Johns Hopkins Hospital, Baltimore, Md.

Meyer, Arthur W., S.B., M.D., (Ex. Com. '12-16), Professor of Human Anatomy, Leland Stanford Junior University, Stanford University, Calif.

Miller, Adam M., A.M., Professor of Anatomy, Long Island College Hospital, Henry and Amity Streets, Brooklyn, N. Y.

Miller, William Snow, M.D. (Vice-Pres. '08-09), Associate Professor of Anatomy, University of Wisconsin, 415 West Wilson Street, Madison, Wis.


154 AMERICAN ASSOCIATION OF ANATOMISTS

MiXTER, Samuel Jason, B.S., M.D., Visiting Surgeon Massachusetts General Hospital, 180 Marlboro Street, Boston, Mass.

MooDiE, Roy L., A.B., Ph.D., Assistant Professor of Anatomy, University of Illinois Medical Colhge, Chicago, III.

Moody, Robert Orten, B.S., M.D., Associate Professor of Anatomy, University of California, 2826 Garber Street, Berkeley, Calif.

Morgan, James Dudley, A.B., M.D., Physician, Garfield Hospital, 919 15th Street, McPherson Square, Washington, D. C.

Morrill, Charles V., Ph.D, Instructor in Anatomy, New York University and Bellevue Medical College, 338 East 26th Street, New York,N. Y.

MuLLER, Henry R., M.D., Assistant in Anatomy, Johns Hopkins Medical School, Baltimore, Md.

MuNSON, John P., Ph.D., Head of the Department of Biology, Washington State Normal School, 706 North Anderson Street, Ellensburg, Washington.

Murphey, Howard S., D.V.M., Professor of Anatomy and Histology, Ames, la. 519 Welch Avenue, Station A., Ames, la.

Myers, Burton D., A.M., M.D., Professor of Anatomy and Secretary of the Indiana University School of Medicine, Indiana University, Bloomington, Ind.

Myers, Jay A., A.B., Ph.D., Instructor in Anatomy, University of Minnesota, Minneapolis, Minn.

Nachtrieb, Henry Francis, B.S., Professor of Animal Biology and Head of the Department, Universitj' ot Minnesota, 905 East 6th Street, Minneapolis, Minn.

Neal, Herbert Vincent, Ph.D., Professor of Zoology, Tufts College, Tufts College, Mass.

Newman, Horatio Hackett, Ph.D., Associate Professor of Zoology, University of Chicago, Department of Zoology, University of Chicago, Chicago, III.

Noble, Harriet Isabel, 262 Putnam Avenue, Brooklyn, N. Y.

XoRRis, H. W., B.S., A.M., Professor of Zoology, Grinnell College , Grinnell, Iowa.

Papez, James Wenceslas, B.A., M.D., Professor of Anatomy, Atlanta Medical College, Atlanta, Ga.

Parker, George Howard, D.Sc, Professor of Zoology, Harvard University, 16 Berkeley Street, Cambridge, Mass.

Paton, Stewart, A.B., M.D., Lecturer in Biology, Princeton University, Princeton, N. J.

Patten, William, Ph.D.. Professor of Zoology, Dartmouth College, Hanover, N.H.

Paterson, A. Melville, M.D., F.R.C.S., Professor of Anatomy, University of Liverpool, Liverpool, England.

Patterson, John Thomas, Ph.D., Professor and Chairman of the School of Zoology, University of Texas, University Station, Austin, Texas.

Piersol, George A., M.D., Sc.D. (Vice-Pres. '93-'94, '98-'99, '06-'07, Pres. 'lO-'ll) Professor of Anatomy, University of Pennsylvania, 4'^24 Chester Avenue, Philadelphia, Pa.

Piersol, William Hunter, A.B., M.B., Associate Professor of Histology and Fmbryology. Biological Department University of Toronto, Toronto, Canada.

Pohlman, Augustus G., M.D., Professor of Anatomy, Medical Department, University of St. Louis, St. Louis, Mo.

Potter, Peter, M.S., M.D., Oculist and Aurist, Murray Hospital, Butte, Montana, 41 1-413 Hennessy Building, Butte, Montana.


MEMBERS 155

Prentiss, Charles W., A.M., Ph.D., Professor of INIicroscopic Anatomy, Northwestern University Medical School, 2421 Dearborn Street, Chicago, III.

Prentiss, H. J., ]\I.D., INI.E., Professor of Anatomy, University of Iowa, Iowa City, Iowa.

Pryor, Joseph William, M.D., Professor of Anatomj^ and Phj'siology, State College of Kentucky, 261 North Broadway, Lexington, Ky.

Radasch, Henry E., M.S., M.D., Assistant Professor of Histology and Embryology, Jefferson Medical College, Daniel Baugh Institute of Anatomy, 11th and Clinton Streets, Philadelphia, Pa.

Ranson, Stephen W., M.D., Ph.D., Professor of Anatomy, Northwestern University Medical School, 2^31 Dearborn Street, Chicago, III.

Reagan, Franklin P., A.B., Princeton University, Princeton, N. J.

Reed, Hugh Daniel, Ph.D., Assistant Professor of Zoology, Cornell University, 108 Brandon Place, Ithaca, N. Y.

Reese, Albert Moore, A.B., Ph.D., Professor of Zoology, PFesi Virginia University, Morgantown, W . Va.

Retzer, Robert, M.D., Assistant Professor of Anatomy, University of Chicago, Department of Anatomy, University of Chicago, Chicago, III.

Revell, Daniel Graisberry, A.B., M.B., Provincial Pathologist, Bacteriologist and Analyst of the Provincial Laboratory, 901 Eighth Street, N . W., Strathcona, Alberta, Canada.

Rhinehart, D.A., M.D., Professor of Anatomy, University of Arkansas, Old State House, Little Rock, Arkansas.

Rice, Edward Loranus, Ph.D., Professor of Zoology, Ohio Wesleyan University, Delaware, Ohio.

Robinson, Arthur, M.D., F.R.C.S. (Edinbui;gh) Professor of Anatomy, University of Edinburgh, The University, Edinburgh, Scotland.

Ruth, Edward S., M.D., Professor of Anatomy, Southern Methodist University Medical Department, 41^3 Bryan Street, Dallas, Texas.

Sabin, Florence R., B.S., M.D., (Second Vice-Pres. '08-09), Associate Professor of Anatomy, Johns Hopkins University, Medical Department, Baltimore, Md.

Sachs, Ernest, A.B., jNI.D., Associate in Surgery, \yashington University Medical School, St. Louis, Mo.

Sampson, John Albertson, A.B., M.D., Professor of Gynecology, Albany Medical College, 180 Washington Avenue, Albany, N. Y.

Santee, Harris E., Ph.D., M.D., Professor of Anatomy, Jenner Medical College, and Professor of Neural Anatomy, Chicago College of Medicine and Surgery, 2806 Warren Avenue, Chicago, III.

Scammon, Richard E., Ph.D., Associate Professor of Anatomy, Institute of Anatomy, University of Minnesota, Minneapolis', Minn.

Schaefer, Marie Charlotte, M.D., Associate Professor of Biology, Histology and Embryology, Medical Department, University of Texas, Galveston, Texas.

ScHAEFFER, Jacob Parsons, A.M., M.D., Ph.D., Professor of Anatomy, Jefferson Medical College, 11th and Clinton Streets, Philadelphia, Pa.

ScHOEMAKER, Daniel M., B.S., M.D., Professor of Anatomy, Medical Depart ment, St. Louis University, 1402 South Grand Avenue, St. Louis, Mo.

ScHULTE, Hermann vonW., A.B., M.D., (Ex. Com. '15-) Associate Professor of Anatomy, Columbia University, 206 West 86th Street, New York, N. Y.


156 AMERICAN ASSOCIATION OF ANATOMISTS

ScHMiTTER, Ferdinand, A.B., M.D., Captain Medical Corps, U. S. Army, Department Hospital, Manila, P. I.

Scott, Katherine Julia, A.B., Johns Hopkins Medical School, Baltimore, Md.

Seelig, Major G., A.B., M.D., Professor of Surgery, St. Louis University, Humboldt Building, 537 North Grand Avenue, St. Louis, Mo.

Selling, Lawrence, A.B., M.D., 789 Lovcjoy Street, Portland, Oregon.

Senior, Harold D., M.B., F.R.C.S., D.Sc, Professor of Anatomy, New York University, University and Bellevue Hospital Medical College, 338 East 26th Street, New York, N. Y.

Sheldon, Ralph Edward, A.M., M.S., Ph.D., Associate Professor of Anatomy, University of Pittsburgh Medical School, Grant Boulevard, Pittsburgh, Pa.

Shields, Randolph Tucker, A.B., M.D., Dean, University of Nanking Medical School, Nanking, China.

Shipley, Paul G., M.D., Assistant in Anatomy, John Hopkins University, Johns Hopkins Medical School, Baltimore, Md.

Shufeldt, R. W., M.D., Major Medical Corps, U. S. A. (Retired)., 3356 Eighteenth Street, N. W., Washington, D. C.

Silvester, Charles Frederick, Curator of the Zoological Museum and Assistant in Anatomy, Princeton University, 10 N'assaii Hall, Princeton, N. J.

Simpson, Sutherland, M.D., D.Sc, F.R.S.E. (Edin.), Professor of Physiology, Cornell University, Ithaca, N. Y.

Sisson, Septimus, B.S., V.S., Professor of Comparative Anatomy, Ohio State University, 31€ West 9th Avenue, Columbus, Ohio.

Sluder, Greenfield, M.D., ClinicalProfessorof Diseases of the Nose and Throat, Washington University Medical School, 3542 Washington Avenue, St. Louis, Mo.

Smith, Charles Dennison, A.M., M.D., Superintendent Maine General Hospital, Professor of Physiology, Medical School of Maine, Maine General Hospital, Portland, Me.

Smith, George Milton, A. B., M.D., Associate in Pathology, Washington University Medical School, St. Louis, Mo.

Smith, Grafton Elliot, M.A., M.D., F.R.S., Professor of Anatomj^, University of Manchester, 4- Willoiv Bank, Fallowfield, Manchester, England.

Smith, J. Holmes, M.D., Professor of Anatomy, University of Maryland, Green and Lombard Streets, Baltimore, Md.

Smith, Philip Edward, M.S., Department of Anatomy, University of California, Berkeley, Calif.

Snow, Perry G., A.B., Professor of Anatomy, School of Medicine, University of Utah, Salt Lake City, Utah.

Spitzka, Edward Anthony, M.D., 66 East 73d Street, Neiv York, N. Y.

Steensland, Halbert Severin, B.S., M.D., Professor of Pathology and Bacteriology, and Director of the Pathological Laboratory, College of Medicine, Syracuse University, 309 Orange Street, Syracuse, N. Y.

Stiles, Henry Wilson, M.D., Professor of Anatomy, College of Medicine, Syracuse University, 309 Orange Street, Syracuse, N. Y. .

Stockard, Charles Rupert, M.S., Ph.D., (Secretary-Treasurer '14- ) Professor of Anatomy, Cornell University Medical College, New York, N. Y.

Stotsenburg, James M., M.D., Associate in Anatomy, Wistar Institute of Anatomy and Biology, Philadelphia, Pa.


i


MEMBERS 157

Streeter, George L,, A.M., M.D., Research Associate in Embryology, Carnegie Institution, Johns Hopkins Medical School, Baltimore, Md.

Stromstex, Frank Albert, D.Sc, Assistant Professor of Animal Biology, University of Iowa, 943 Iowa Avenue, Iowa City, Iowa.

Stroxg, Oliver S., A.I\I., Ph.D., Instructor in Anatomy, Columbia University, 437 West 59th Street, New York, N. Y.

Stroxg. Recbex Mtrox, Ph.D., Professor of Anatomy, University of Mississippi, Oxford, Mississippi.

SuxDWALL, JoHX, Ph.D., Professor of Anatomy, University of Kansas, Lawrence, Kansas.

Stmixgtox, Johxson, M.D., F.R.S., Professor of Anatomy, Queens University, Belfast, Ireland.

Swift, Charles H., M.D., Ph.D., Associate in Anatomj^ Department of Anatomy, University of Chicago, Chicago, III.

Taussig, Frederick Joseph, A.B., ^I.D., Lecturer in Gynecology, Washington University Medical School, 4506 Maryland Avenue, St. Louis, Mo.

Taylor, Edward \V., A.IM., M.D., Instructor in Neurology, Harvard Medical School, 457 Marlboro Street, Boston, Mass.

Terry, Robert Jajies, A.B., M.D. (Ex. Com. '08-'12), Professor of Anatomy, Washington University Medical School, St. Louis, Mo.

Thompsox, Arthur, M.A., M.B., F.R.C.S., Professor of Anatomy, University of Oxford, Department of Human Anatomy, Museuin, Oxford, Englanjd.

Thorkelson, Jacob, M.D., Professor of Anatomy, College of Physicians and Surgeons, Baltimore, Md.

Thro, William C, A.M., M.D. , Assistant Professor of Clinical Pathology, Cornell University Medical College, 28th Street and 1st Avenue, New York, N. Y.

Thyng, Frederick Wilbur, Ph.D., Assistant Professor of Anatomy in the University and Bellevue Hospital Medical College, 26th Street and 1st Avenue, New York, N. Y.

TiLNEY, Frederick, A.B., M.D., Assistant Professor of Neurology, Columbia University, 161 Henry Street, Brooklyn, N. Y.

ToBiE, Walter E., M.D., Professor of Anatomy, ^Medical School of Maine, 3 Deering Street, Portland, Me.

Todd, Thomas Wixgate, M.B., Ch.B. (]Manc.), F.R.C.S. (Eng.) Professor of Anatomy, Medical Department, Wester7i Reserve University, Cleveland, 0.

Tracy, Hexry C, A.M., Ph.D., Professor of Anatomy, Marquette University School of Medicine, Fourth and Reservoir Street, Milwaukee, Wis.

Tuckermax, Frederick, ]\I.D., Ph.D., 16 College Street, Amherst, Mass.

TuppER, Paul YoER, M.D., Clinical Professor of Surgery, Washington University Medical School, Wall Building, St. Louis, Mo.

Waite, Frederick Clayton, A.M., Ph.D., Professor of Histology and Embryology, Western Reserve University, 1353 East 9th Street, Cleveland, Ohio.

Walker, George, M.D., Instructor in Surgery, Johns Hopkins University, corner Charles and Centre Streets, Baltimore, Md.

Wallix, IvanE., B.S., :M.A., Assistant in Anatomy, Cornell University ^Medical College, 28th Street and First Avenue, New York, N. Y.

Warrex, John, M.D., Assistant Professor of Anatomj, Harvard Medical School, Boston, Mass.


158 AMERICAN ASSOCIATION OF ANATOMISTS

y^-" Waterston, David, M. a., M.D., F.R. C.S.Ed., Professor of Anatomy, University of London, Kings College, Harlaw, Northwood, Middlesex, England.

Weed, Lewis Hill, A.M., M.D., Instructor in Anatomy, Johns Hopkins Medical School, Baltimore, Md.

Weidenreich Franz, M.D., a. o. Professor and Prosector of Anatomy, ^5 Vogesen Street, Strassburg, i. Els. Germany.

Weisse, Faneuil D., M.D. (Second Vice-Pres. '88-'89), Professor of Anatomy, New York College of Dentistry, 108 East 30th Street, New York, N. Y.

Werber, Ernest I., Ph.D., Department of Biology, Princeton University, Princeton, N. J.

West, Charles Ignatius, M.D., Associate Professor of Anatomy, Medical Department of Howard University, 924 M Street N. W., Washington, D. C.

West, P. A., B.A., Johns Hopkins Medical School, Baltimore, Md.

West, Randolph, A.M., Student, College of Physicians and Surgeons, Columbia University, 24 West 59th Street, New York, N. Y.

Weysse, Arthur Wissland, A.M., M.D., Ph.D., Professor of Biology and of Experimental Physiology, Boston University, 688 Boylston Street, Boston, Mass.

Whipple, Allen O., B.S., M.D., Instructor in Clinical Surgery, Columbia University, 981 Madison Avenue, New York, N. Y.

White, Harry Oscar, M.D., Professor of Anatomy, Histology and Embryolo^}', Medical Department, University of Southern California, Los Angeles, Calif.

Whitehead, Richard Henry, A.B.,M.D., LL.D., Professorof Anatomy, University of Virginia, University P.O., Va.

WiEMAN, Harry Lewis, Ph.D., Assistant Professor of Zoology University of Cincinnati, Cincinnati, Ohio.

Wilder, Harris Hawthorne, Ph.D., Professor of Zoology, Smith College, Plymouth Inn, Northampton, Mass.

Williams, Stephen Riggs, Ph.D., Professor of Zoology, Miami University, 300 East Church Street, Oxford, 0.

WiLLARD, William A., A.M., Ph.D., Professor of Histology and Embryology, University of Nebraska, College of Medicine, 42d Street and Dewey Avenue, Omaha, Nebraska.

Wilson, J. Gorden, M.A., M.B., CM. (Edin.), Professor of Otology, Northwestern University Medical School, 2437 Dearborn Street, Chicago, III. y ^ Wilson, James Thomas, M.B., F.R.S., Challis Professor of Anatomy, University of Sydney, Australia.

Wilson, Louis Blanchard, M.D., Director of Laboratories, Mayo Clinic, 830 West College Street, Rochester, Minn.

WiNSLow, Guy Monroe, Ph.D., Instructor in Histology, Tufts Medical College. 145 Woodland Road, Auburndale, Mass.

Witherspoon, Thomas Casey, M.D., 307 Granite Street, Butte, Montana.

Worcester, John Locke, M.D., Instructor in Anatomy, University of Michigan, 1214 Willard, Ann Arbor, Michigan.


'\


A COMPARATIVE STUDY OF THE SHOULDER

REGION OF THE NORMAL AND OF

A WINGLESS FOWL

w. B. kirkha:m and h. w. haggard

From the Osborn Zoological Laboratory , Yale University

ELEVEN FIGURES (THREE PLATES)

INTRODUCTION

Among a lot of Rhode Island Red chicks hatched in an incubator by Dr. Fred Sumner Smith, of Chester, Connecticut, appeared one male individual entirely destitute of wings. This was reared to maturity, and lived for nearly two years, forming the subject of an extensive breeding experiment by Prof. Wesley R. Coe. (The results of this experiment wiU be the subject of a separate paper.) After the death of this bird his body was preserved in alcohol, and later handed over to the writers for a study of the modifications of the muscular and skeletal structures which might be correlated with the congenital absence of wings.

The writers knew of no connected, detailed account, in the literature, of the anatomj- of Gallus domesticus, so, with the aid of the brief references available, a study of the normal musculature and skeleton has been carried out on normal fowls of the breed of the wingless rooster. This study has been limited to the shoulder and thoracic regions, as examination of the wingless specimen revealed no abnormalities elsewhere.

No special study of the nerves and blood vessels of the shoulder region was made, but as on the wingless rooster a number of large nerves and blood vessels were found coming from the body ca^ity and breaking up into small branches to enter the thick

159

THE ANATOMICAL RECORD, VOL. 9, NO. 2 FEBRUARY, 1915


160 W. B. KIRKHAM AND H. W. HAGGARD

fascia and skin which covered the area where the wings would normally have been, it may be safely assumed that these were the blood vessels and nerves normally destined to go to the wings, in the absence of which they terminated in the skin and underljang fascia. The normal innervation of the shoulder region of the hen has been described and the nerves figured by Ftirbringer ('88). The muscles have been described in the present paper in an order based on their nerve supply, a scheme used by Gadow ('91).

All the variations appearing on the wingless rooster and described below were symmetrical on the two sides of the body unless otherwise stated.

MUSCULATURE

Rhomboideus superficialis (figures 6 and 7: 10 and 11)

Normal. This muscle takes its origin from the rib-bearing cervical vertebrae and from the crests of all of the fused thoracic vertebrae except the most posterior one. It is a very broad muscle, but made up of short fibers, its insertion being along the dorso-lateral surface of the scapula, from the posterior extremity to a point almost directly above the scapular tubercle of the coracoid, and extending ventrally to the dorsal margin of the origin of the scapuli-humeralis posterior.

Wingless: The superficial rhomboid muscles of the wingless rooster were much thinner than the normal, and showed decided variations as to origin and insertion on both sides. On the right side this muscle had its origin limited to the median third of the fused thoracic vertebrae, and its insertion on the dorsal border of the scapula was limited in a similar way. The left rhomboideus superficialis had an origin extending from the crest of the most posterior cervical vertebra to the posterior extremity of the crest of the fused thoracic vertebrae, while its insertion extended from the anterior extremity of the scapula to within a quarter of an inch of the posterior extremity of that bone.


SHOULDER REGION OF A WINGLESS FOWL 161

Rhomhoideus profundus (figures 7 to 11)

Normal The deep rhomboid muscle arises immediately beneath the hne of origin of the superficial one, but the origin of the deeper muscle extends one vertebra further, both anteriorly and posteriorly. Its insertion is on the medial surface of the scapula from the posterior extremity of that bone to a point about opposite the anterior limit of the superficial rhomboid, and from the dorsaL margin ventrally for about the same distance as the superficial muscle.

Wingless. On the abnormal bird the chief variations in the rhomboideus profundus were the extension of its origin posteriorly to the anterior margin of the ilium, and a restriction of its insertion on the scapula to an anterior limit opposite the space between the first and second cervical ribs. These variations were bilateral.

Serraius profundus {figures 7 to 11)

Normal. The serratus profundus is a very narrow, thin muscle whose fibers arise from the tip of the first cervical rib, and thence pass in an antero-dorsal direction to insert on themedioventral border of the scapula. The posterior margin of this muscle is closely applied to the anterior margin of the serratus superficialis anterior.

Wingless. This muscle on the wingless rooster was normal as to position and relations, but was at least twice as broad and thick as on the normal bird.

Serratus superficialis anterior {figures 6 to 11)

Normal. The anterior superficial serratus muscle is a broad, thin band, arising from the lateral side of the ventral extremity of the second cervical rib, and inserting just posterior to the serratus profundus on the medio-ventral border of the scapula. The fibers run in an antero-dorsal direction.

Wingless. On the wingless rooster the origin of this muscle was more extensive than usual, and, on account of the second cervical rib of this bird having retained its embr3^onic sternal


162 W. B. KIRKHAM AND H. W. HAGGARD

segment, the origin was along the antero-lateral border of the vertebral segment of this rib. The upper hmit of origin was opposite the base of the uncinate process. The muscle itself possessed more than the usual number of fibers, rendering it much thicker than the normal, but without increasing its breadth. The insertion on the scapula was normal.

Serratus superficialis posterior {figures 8, 10 and 11)

Normal. The posterior superficial serratus muscle consists of two shps, one arising from the dorsal third of the posterolateral border of the second cervical rib, the other arising in approximately the same place on the first thoracic rib. Both slips are broad and thin. The fibers run in a postero-dorsal direction, those of the two slips becoming indistinguishable where they he side by side. The insertion of this muscle is along the median ventral border of the scapula from a point opposite the anterior margin of the second thoracic rib posteriorly to a point opposite the anterior margin of the third thoracic rib.

Wiyigless. The origin, insertion, and topographical relations of this muscle were normal, but the muscle fibers were so few in number that it was almost reduced to a fascia.

Sterno-coracoideus {figures 10 and 11)

Normal. This is a very short, broad muscle taking its origin from almost the entire lateral surface of the anterior lateral process of the sternum and inserting on the adjoining margin of the coracoid. It lies mediad of the membrane stretched between the coracoid and the anterior lateral process of the sternum, and some of its fibers inosculate with this.

Wingless. Same as normal.

Latissimus dor si {figures 2, 6,7, 9 to 11)

Normal. The latissimus dorsi arises (1) from the mid dorsal line, starting with the neural crest of the most posterior cerv'cal vertebra and extending posteriorly over the crest of the first thoracic vertebra; (2) this muscle also has a Une of origin from the anterior margin of the ilium. The fibers from the iliac origin


SHOULDER REGION OF A WINGLESS FOWL 163

run almost straight anteriorly over the surface of the superficial rhomboid muscle until they inosculate with those coming from the vertebral origin; the combined fibers then run in an anteroventral direction to their insertion on the ventral surface of the humerus, somewhat posterior to the pneumatic foramen and alongside of one origin of the triceps.

Wingless. The wingless rooster showed the two separate points of origin of the latissimus dorsi, but the fibers from the two places never united, both sets running in a general ventral direction to inosculate separately with the pectoralis muscles. Furthermore, both points of origin were unusually extensive.

Deltoid major (figures 2, 6 and 10)

Normal. The deltoid major takes its origin from the highest point of the humeral tubercle of the coracoid, and extends a very short distance, as a thick, round bundle of fibers to its ten-, dinous insertion on the superior tubercle of the humerus.

Wingless. The wingless specimen showed no trace of this muscle unless a fascial mass covering the point of union of the three members of the shoulder girdle should be considered as the rudiments of this and the following muscle.

Deltoid minor {figures 2, 6 and 10)

Normal. The deltoid minor arises from the posterior border of the furcular tubercle of the coracoid, and like the deltoid major it is a very short muscle, having its insertion on the lateral surface of the humerus under the superior cristas and embraced by the insertion of the pectoralis major.

Wingless. As mentioned above, in connection with the deltoid major, a thick fascial mass of doubtful significance may represent on this bird both the deltoid muscles.

Scapuli-humeralis anterior (figures 2, 6, 8 and 10)

Normal. This is a small, round muscle arising from the ventrolateral border of the scapula just anterior to the origins of the subscapularis externus and the scapuh-humerahs posterior. The fibers run almost at right angles to the surface of the scapula to


164 W. B. KIRKHAil AND H. W. HAGGARD

insert on the ventral surface of the humerus just distal to the pneumatic foramen.

Wingless. On the wingless rooster the scapuli-humeralis anterior was entirely absent on both sides.

Scapuli-hwneralis -posterior {figures 2, 6,7, 9 to 11)

Normal. The scapuli-humeralis posterior is a broad sheet of muscle arising from the ventral three-fourths of the lateral surface of the scapula, from the posterior extremity of that bone to a point opposite the anterior margin of the most posterior cervical vertebra without a rib. Its fibers run in an anteroventral direction, and when about in line with the anterior limit of origin they abruptly join a tendon which inserts on the lateral border of the pneumatic foramen between two origins of the triceps. The anterior border of this muscle is overlaid by the latissimus dorsi.

Wingless. On the abnormal rooster the origin of the scapulihumerahs posterior extended much nearer the dorsal margin of the scapula than on normal specimens. The fibers ran in the usual direction, but ended by fusing with those of the coracobrachiales and subcoraco-scapulares.

Suhcoraco-scapulares {figures 2, 6 to 10)

Normal. The subcoraco-scapulares are three muscles, external and internal subscapular and the subcoracoid, arising separately, but grouped together because all three possess a conmaon tendon of insertion. The subscapularis externus arises from the ventro-lateral margin of the scapula, ventral and shghtly posterior to the anterior limit of origin of the scapuh-humeralis anterior. The subscapularis internus arises (1) from the medial surface of the scapula from a posterior limit corresponding to the origin of the externus on the lateral surface, anteriorly to the coracoid; (2) from the medial border of the coracoid for a distance of three-quarters of an inch from the ventral margin of the scapula; (3) a few fibers arise from the membrane separating this muscle from the coraco-brachialis anterior. The fibers of the subscapularis externus run ventrally, those of the subscapularis


SHOULDEE REGION OF A WINGLESS FOWL ' 165

internus converge to join the tendon common to the three subcoraco-scapular muscles.

The subcoracoideus arises (1) from the ventral third of the medial border of the coracoid; (2) from the medial surface of the furculo-coracoid membrane, which separates it from the coracobrachialis anterior; and (3) from the posterior surface of the anterior median process of the sternum together with the margins of the body of that bone.

The common tendon of these three muscles passes upward across the lateral surface of the scapula to insert on the humerous proximal to the pneumatic foramen, and between the humeral origin of the biceps and the insertion of the coraco-brachialis posterior.

Wingless. The subcoraoo-scapulares were represented on the wingless rooster by the subcoracoid and the internal subscapular, the external subscapular being absent on both sides. The origins of the two muscles present differed from the normal in being unusually extensive, the subcoracoideus arising from the whole posterior border of the coracoid, and the origin of the subscapularis internus extending along the medio-ventral margin of the scapula from the anterior extremity of that bone to the normal posterior limit of its origin. Fibers from both these muscles inosculated with fibers of the coraco-brachiales, and there was also a common tendon, not shown on our diagrams, which inserted on the humeral tubercle of the coracoid.

Pecioralis major (figures 2, 6, 7, 10, 11)

Normal. This muscle takes its origin (1) from the ventral quarter of the keel of the sternum throughout its entire length; (2) from the ventral part of the lateral surface of the membrane connecting the furcula and the sternum; (3) from the entire lateral surface of the furcula with the exceptions of a very short distance at its dorsal extremity and of the postero-dorsal angle of its enlarged ventral extremity; (4) from that part of the furculo-coracoid membrane adjoining its origin on the furcula; (5) from the external and internal posterior lateral processes of the sternum and from the membrane joining them to each other,


166 • W. B. KIRKHAM AND H. W. HAGGARD

to the keel, and to the bod}' of that bone; (6) some fibers of the pectorahs major arise from the fascia covering the dorsal border of the pect oralis minor.

The insertion of the pectorahs major is on the upper end of the humerus, under the superior crista.

Wingless. On the wingless rooster the origin of the pectorahs major was considerably reduced, the reduction being in different regions on the two sides of the body. On the right side the origin of this muscle failed to reach the posterior tip of the keel of the sternum while anteriorly it crossed the membrane from the sternum to the furcula, ran up the latter bone for only a short distance beyond its enlarged ventral extremity, and that, except for the membrane stretched between the posterior lateral processes of the sternum is the whole extent of its origin on that side. The left side of the wingless bird showed a normal origin from the keel of the sternum, and from the membrane between that bone and the furcula; on the furcula the origin extended dorsally further than usual but was everywhere limited to the anterior margin of the bone. The only other point of origin of the pectorahs major on the left side was from the dorsal angle of the posterior lateral process of the sternum.

The origins of the pectorahs major muscles of the wingless bird were, however, nowhere near as unusual as were the insertions. On the right side the muscle was saddle-shaped, its fibers inosculating wdth both the posterior and the anterior portions of the latissimus dorsi. The left side showed a more complex anomalj^, the shp of the pectorahs major arising from the external posterior lateral process of the sternum inosculating with the posterior portion of the latissimus dorsi, while the main part of the pectorahs major inosculated with a slip from the anterior portion of the latissimus dorsi, the two parts of pectorahs major appearing to be entirely separate from each other.

On both sides of the body the fibers of the pectorahs major and of the pectorahs minor inosculated anteriorly, and sent dorsally a common tendon which bifurcated just before it inserted on the dorso-lateral border of the scapula, anterior to the origin of the scapuh-humerahs posterior.


SHOULDER REGION OF A WINGLESS FOWL 167

Pectoralis minor (figures 2, 6 to 11)

Normal. The pectoralis minor arises (1) from the posterodorsal angle of the ventral extremity of the furcula, and from the lateral surface of the membrane stretched between that angle, the ventral end of the coracoid, the body and keel of the sternum; (2) from the ventral border of the body and the dorsal three-quarters of the keel of the sternum; (3) from the ventral margin of the membrane between the keel and the internal posterior lateral process of the sternum. The fibers of this muscle converge toward its midline, and its tendon of insertion passes with that of the coraco-brachialis anterior through the foramen triosseum — between the anterior extremities of the furcula, coracoid, and scapula — to attach to the upper end of the humerus at the base of the dorsal surface of the superior crista.

Wingless. On the wingless rooster the pectoralis minor, like the major, showed an origin over a smaller area than the normal, the reduction being more marked on the right side, where no fibers arose from the sternum, the origin being limited to the ventral extremity of the furcula and the membrane stretched between that bone and the sternum. On the left side the origin of the pectoralis minor was practically confined to the ventral half of its normal limits, with the further abnormality of a dorsal extension along the posterior border of the furcula to the extremity of that bone. Inosculations with the pectoralis major were present on both sides, and on both sides of the body there was a small tendinous insertion on the scapula near the scapular tubercle of the coracoid. The posterior portion of the left pectoralis minor inosculated with a slip from the latissimus dorsi.

Coraco-brachialis anterior (figures 2, 6, 8 to 11)

Normal. This muscle arises (1) from the lateral surface of the anterior median process of the sternum, (2) from the ventral haK of the medial border of the coracoid, (3) from the lateral surface of the furculo-coracoid membrane bordering the coracoid. The muscle narrows at the dorsal end and its tendon accompanies that of the pectoralis minor through the foramen trios


168 W. B. KIRKHAM AND H. W. HAGGARD

seum; it inserts on the anterior dorsal margin of the superior crista of the humerus.

Wingless. On the wingless rooster the usual place of origin of the coraco-brachialis anterior was covered with a heavy fascia, possibly representing this muscle, which ran posteriorly to inosculate with the coraco-brachiahs posterior.

Coraco-brachialis posterior {figures 2, 6, 8 to 11)

Normal. The coraco-brachialis posterior arises (1) from the fascia of the pectorahs minor at a point on the dorsal border of that muscle near the sterno-coracoid articulation; (2) from the lateral surface of the coracoid with a ventral limit at the line of articulation of that bone with the sternum and a dorsal limit just ventral to the capsule of the humeral joint; (3) by a narrow slip from the body of the sternum starting anteriorly from the line of articulation of the coracoid and terminating posteriorly at the base of the lateral processes of the sternum.

This muscle runs abruptly into a tendon in the axillary space, and thereafter it joins by slips with the tendon of the subcoracoscapulares, the two tendons finally separating and that of the coraco-brachialis posterior passing posterior to that of the subcoraco-scapulares and inserting on the anterior end of the humerus proximal to the pneumatic foramen, and embraced by the tendon of insertion of the subcoraco-scapulares.

Wingless. The coraco-brachialis posterior, and possibly some of the anterior as well, was represented on the wingless rooster by a large mass of muscle fibers which arose over almost the entire lateral surface of the coracoid, and passed in a posterodorsal direction to inosculate with fibers of the scapuli-humeralis posterior.

Biceps hrachii {figures 2, 6 and 10)

Normal. This muscle arises by two heads, one a long tendon from the furcular tuberosity of the coracoid, the other a short tendon from the proximal end of the humerus along a lateral line starting distal to the caput, a little ventral to the dorsal margin of the bone, and extending around to the ventral surface,


SHOULDER REGION OF A WINGLESS FOWL 169

anterior to the pneumatic foramen, to where the tendon of the subcoraco-scapulares inserts. The head of the biceps brachii which has its origin on the coracoid, passes first over the deltoid minor, then over the base of the broad Hgament uniting the coracoid and humerus, to finally join the head arising from the humerus. The insertion of this muscle is on the radius and ulna. Wingless. Absent.

Triceps cuhiti s. anconeus (figures 2 and 10)

Normal. The triceps muscle arises by three heads of which the two tendinous ones, attached to the scapula along its ventrolateral border just caudad of the capsule of the humeral joint, are sometimes (Beddard '98) described as a separate muscle, the anconeus longus. These two tendons, which are oval in section, unite at once, but do not join the third head until near their common insertion on the olecranon process of the ulna and on the capsule of the neighboring joint. The third head of the triceps arises fleshily from a limited area on the humerus just proximal to the pnemnatic foramen, and from the greater part of the ventral surface of that bone, exclusive of the articular portions.

Wingless. This muscle was absent from the wingless rooster, but attached to both scapulas in the position of its posterior tendinous origin from that bone were tendons connected with the pectoraUs muscles.

SKELETON

The skeleton of the wingless rooster (figs. 4 and 5) differs in its entirety from any of our normal specimens (fig. 3) in being more heavily built; the individual bones are broader and thicker than usual. One notices also that the sternum is more nearly parallel to the vertebral column than in the normal bird of this species, a condition apparently correlated with the more perpendicular position of the coracoid. Aside from these peculiarities the abnormalities of the wingless skeleton are limited to the thoracic region and will be taken up individually.


170 W. B. KIRKHAM AND H. W. HAGGARD

The vertebrae present no abnormalities.

The ribs show shghtly different anomalies on the two sides of the body, the cervicals being the ones affected. On the left side the first cervical rib is unusual in possessing an uncinate process, while the second cervical rib on this side has an incomplete sternal segment. The first cervical rib on the right side likewise has an uncinate process, and the second shows a condition further removed from the normal than its mate on the left side, possessing a complete segment uniting it to the anterior lateral process of the sternum.

The most posterior thoracic rib on the left side appears at some time to have had its vertebral and sternal segments separated so that they slid past each other, and their ends formed a new ligamentous connection between the ventro-median extremity of the vertebral segment and the dorso-lateral extremitj^ of the sternal segment.

The sternum of the abnormal bird is quite aberrant in form, showing a very gradual, instead of an abrupt, transition from the vertical to the horizontal plane at the dorsal margin of the keel, being unusually broad just anterior to its caudad extremity, and having a thick and very short anterior median process. The anterior lateral processes of this sternum are also unusual in their perpendicularity. The dextral curvature of the anterior end of the keel is probably due to many falls the rooster had while this bone was still somewhat cartilaginous.

The shoulder girdles of the wingless bird are both normal to the extent of each possessing the usual three members, in their normal positions. The abnormalities are in the proportions of the separate bones, and in their articular relations or absence of them. The two sides require separate attention. On the left side the scapula is essentially normal except for a much reduced humeral process, the coracoid is shorter than usual and has its ventral extremity faced more laterally than the normal, while the furcular tubercle of the coracoid is absolutely lacking and the humeral tubercle is rudimentary. The left half of the furcula is normal except for the absence of an articular enlargement at its dorsal extremity. A movable joint exists on the


SHOULDER REGION OF A WINGLESS FOWL 171

left side between the scapula and the coraeoid. The right shoulder girdle is decidedly more aberrant than the left, the scapula fails to narrow at its anterior extremity, faces more laterally than usual, bears no trace of a humeral process, and is completely fused with the coraeoid along the entire dorsal margin of the latter bone. The right coraeoid resembles the left in general form and the absence of a furcular tubercle, but differs from its mate in having no humeral tubercle and only a very rudimentary scapular tubercle. The right half of the furcula is like the left except for a decided median convexity, perhaps, like the asymmetry of the sternum, due to falls in early life.

The foramen triosseum, bounded by the antero-dorsal extremities of the scapula, coraeoid, and furcula, is absent on the right side and decidedly reduced in caliber on the left side of the wingless skeleton. On both sides of the wingless bird the angle between the scapula and the coraeoid is almost twice the normal, while the angle between the coraeoid and the furcula has been correspondingly reduced, carrying the ventral extremity of the furcula almost against the anterior margin of the sternum.

Absolutely no trace of wing bones, nor indication of a humeral joint capsule, is present on either side of the skeleton of the wingless rooster.

CONCLUSIONS

It now remains to consider the cause and the significance of the already described abnormalities of this wingless rooster.

Two unpublished instances of wingless hens are known to us. Concerning one of these wingless hens we possess no details; the other was an incubator-hatched bird which was killed when only a few weeks old and lost to science.

It is well known to those who use incubators extensively that whenever, through some error of the regulating mechanism, the temperature rises a few degrees above the optimum, abnormalities result which in the majority of cases prevent the embryos from developing to the hatching stage. In view of this, and also of the evidence set forth below, we believe our wingless


172 W. B. KIRKHAM AND H. W. HAGGARD

rooster to have been produced by unusual temperature conditions in his environment, probabh^ at the end of the first week of incubation.

The muscular anomahes fall into two groups: (1) Muscles which were present on the wingless bird but which differ from the normal in origin, insertion, or number of fibers; (2) muscles which were absent. A complete list of the muscles having unusual origins would include almost all of those present on this bird, but without more extensive knowledge of the normal limits of variation it is impossible to tell just how far abnormal these origins are, and furthermore the causes of such abnormalities must in most instances be far too complex for us to analyze them. The pectoralis muscles, however, are so evidently outside the normal limits of variation that attention should be called to them, and the partial explanation may in this case be hazarded that the reductions in origins are due to disuse, there being no wings present for them to move. The same is true of size of muscles, as of origins.

The abnormal insertions of muscles of the wingless rooster are of great interest and importance, and they can be collectively described as an inosculation between the fibers of the muscles arising along the dorsal side of the body, with normal insertions on the humerus, and the fibers of muscles, likewise with normal insertions on the humerus, but with origins on the ventral side of the body, the specific unions being between muscles of the same plane. This condition exactly coincides with what might be expected to occur in case the wings failed to develop while the rest of the body grew normally, for in the embrj'o the wing buds starting to grow out from the body wall carrj^ with them the tissue destined to form their musculature.

The absent muscles would normally all have had their origins in the vicinity of the antero-dorsal angle of the shoulder girdle, where very evidently the focus of disturbance was located, and their insertions on the humerus, which is absent. What trie immediate cause was of their failure to develop or of their subsequent atrophy, there is no evidence to show, but in the case of the deltoids and the biceps their place of origin is absent,


SHOULDER REGION OF A WINGLESS FOWL 173

while the triceps origin may be represented by an anomalous tendon from the pectoralis minor.

The entire skeleton of the wingless rooster is heavier than any of our normal specimens of the same breed. Miss Lindsay ('85) states that in the chick, early in the sixth day of incubation, both cervical ribs are attached to the sternum at their ventral extremities while the scapula and coracoid are fused into a continuous cartilaginous plate. She further states that on the seventh day of incubation the cervical ribs have lost their connection with the sternum. The wingless rooster of the present paper has therefore on his right side the persistent embryonic condition of the sixth day of incubation as regards the second cervical rib and the relation between the coracoid and scapula. On his left side the sternal segment of the second cervical rib started normally to atrophy but never completed the process, while the coraco-scapular plate developed a normal joint. The fact of these abnormalities being normal for the six day embryo is our reason for believing that the disturbance which produced these abnormalities must have occurred at about that time. Why no traces of any wing bones are present it is impossible to say, but the complete absence of any capsule for a humeral joint goes to prove that they never started to develop.

In a word, all the evidence derived from a study of this wingless rooster, including the failure of extensive breeding experiments to produce any wingless offspring., indicates that his abnormahties were all instances of arrested development.

No extensive bibliography of the literature on avian anatomy accompanies this paper as such lists can be found in the works of either Gadow ('91) or Furbringer ('88).

The drawings used to illustrate this paper were, with the exception of those of the humerus, built up on photographs of skeletons; the parts desired being outlined in ink on the photographs, the latter then bleached with hj^o and red prussiate of potash, and after they were dry the details put on in ink.

July. 1914


174 W. B. KIRKHAM AND H. W. HAGGARD

LITERATURE CITED

Beddard, F. E. 1898 The structure and classification of birds. London. FuRBRiN'GER, M. 1888 L'ntersuchungen zur Morphologic und Systematik der

Vogel zugleich ein Beitrag zur Anatomie der Stiitz- und Bewegungs organe. Bijdragent. d. Dierkunde K. Zool. Genootschap. Amsterdam.

15« Afl. Gadow, H. 1891 Vogel. Bronn's Klassen und Ordnungen des Thier-Reichs.

Leipzig. Lindsay, B. 1885 On the avian sternum. Proc. Zool. Soc, London.


Fig. 1 Photograph of the wingless rooster when about one year old.

Fig. 2 Normal left humerus showing topography of the bone and points of origin and insertion of muscles belonging to the shoulder region. Four views, from left to right, lateral, ventral, medial, and dorsal. B., biceps brachii; c, caput; Cb.a., coraco-brachialis anterior; Cb.p., coraco-brachialis posterior; c.i., inferior crista; c.s., superior crista; D.vij., deltoid major; D.mn., deltoid minor; f.p., pneumatic foramen; L.d., latissimus dorsi; P.mj., pectoralis major; P.mn., pectoralis minor; Sh.a., scapuli-humeralis anterior; Sh.p., scapuli-humeralis posterior ; S.s., subcoraco-scapulares; T"., triceps cubiti; t.i., inferior tubercle; t.s., superior tubercle.


SHOULDER REGION OF A WINGLESS FOWL


175



Drrj


THE ANATOMICAL RECORD, VOL. 9, NO. 2


176


W, B. KIRKHAM AND H. W. HAGGARD



Fig. 3 Thoracic region of normal skeleton viewed from left side, a.l.p., a.m. p., b., anterior lateral and median processes, and body of sternum; cap., capsule of humeral joint; e.p.l.p., i.p.l.p.,k., external and internal posterior lateral processes, and keel of sternum; p.f., p-h., furcular and humeral processes of scapula; t.f., t.h., i.s., furcular, humeral, and scapular tubercles of coracoid, /. cer., II. cer., first and second cervical ribs.

Fig. 4 Thoracic region of wingless skeleton, viewed from left side, a.l.p., b., e.p.l.p., i.p.l.p., k., anterior lateral process, body, external posterior lateral process, internal posterior lateral process, and keel of sternum; p.f., furcular process of scapula; i.h., i.s., humeral and scapular tubercles of coracoid; I. cer., II. cer., first and second cervical ribs.

Fig. 5 Thoracic region of wingless skeleton, viewed from right side, a.l.p., b., e.p.l.p., i.p.l.p., k., anterior lateral process, body, external posterior lateral process, internal posterior lateral process, and keel of sternum; p.f., furcular process of scapula; i.s., scapular tubercle of coracoid; I. cer., II. cer., first and second cervical ribs.


SHOULDER REGION OF A WINGLESS FOWL


177





PLATE 1


SHOULDER REGION OF A WINGLESS FOWL

W". B. KIRKHAM AND H. W. HAGGARD


Scai>uli-hiinicralis anterior


Coraio-bratkialis anlerii>r \ \ \

Deltoid 111 ijor ^\ ^^ \

1-Ps\\\


Deltoid 111 Subcoracn-scapuU


Coraco-brachi.-ilis pi


Latissimus dorsi

/ / Rhoniboideus superficial!;



Latissimus dorsi Scapuli-humeralis posterior


Serralus superJicialis anterior


Rhoniboideus profundi Rhoniboideus superficial


Scrralus* supcrficialis

Serratus profundu:

Subcoracu-scapul, Pecteralu


- Rhoniboideus supcrficialis

- Rhoniboideus profundus

- Scapuli-hunieralis posterior

/ I.atissinius dorsi


- Hectoralis major


Fecturalis niaior


EXPLANATION OF FIGURES

6 Diagram of superficial muscles of shoulder region; normal rooster. Inserfons in italics.

7 Same as above; wingless rooster.

178


SHOULDER REGION OF A WINGLESS FOWL

W. B. KIRKHAM AND H. W. HAGGARD

Subscapulans cxternus


PLATE 2


Scapiih-hunieralis antcn Pecl0ralis


Subcoracn-scapularcs —



Khoniboideus profundus


Serratus superticialis posterior


berratus superlicialis anterior Serratus profundus


Coraco-brachialis posterior


Scrraius supcrficialis ant

Serratus profundu


Subcoraco-scapul;

Cnracn-hrachialis Pecteralis


Rhomboideus profundu


'^^ir'=-3 — Scaputi-humeralis posterior



- Pectoralis minor


EXPLANATION OF FIGURES

8 Diagram of deep muscles of shoulder region; normal rooster. Insertions in italics.

9 Same as above; wingless rooster.

179


PLATE 3


SHOULDER REGION OF A WINGLESS FOWL

W. B. KIBKHAM AXD H. W. HAGGARD


Rhomboi/ieus superficiaJis Lalissimus dorsi

\ /

Scapuli-bumeralis posterior \ / Rhomboideus superticialis


Subscapularis externus \ \


Scapuli-bumeralis anterior

Triceps<. X^ \

l)cll..id major ^ --:^x Dclt..id minor ^\ ^^^ \ V N

I'.iceps


Coraco-bracbialis posterior — Coraco-bracbialis anterior


anterior \ ^ \ / / /

\ \ \ / / /


/ Rhomboideus prufundu


Pectoralis major


Rhomboideus pnifundti*; Rkontboidfus sttperficialis Peeloraiis (;

Peclorah


Coraco-brnchiaUs



Latissimus dorsi


J Scrratus superficialis posterior

Serratus profundus Scrralus superficialis anterior


Sierno-coracoidrus


Pectoralis major


Pectoralis mino


lalissimus dorsi

Scaputi-humcralts posterior


Serratus superticinhs posterior

bcrraius superhcialis anterior Serratus profundus

- Pectoralis major Stc^no-coracoideu^


Pectoralis major — '


Pectoralis minor


KXPLANATION OF FIGURES

10 Diagram of origins and insertions of suptM-ficial and deep muscles of shoulder region; normal rooster. Insertions in italics.

11 Same as above; wingless rooster.

180


REPORT OF THE ANOMALIES IN A SUBJECT WITH A SUPERNUMERARY LUMBAR VERTEBRA

H. RYERSOX DECKER

From the Anatomical Laboratories, School of Medicine, University of Pittsburgh

SIX FIGURES

The specimen here reported was obtained in the dissecting room of the School of Medicine, L^niversity of Pittsburgh. The body was that of an adult white male.

In the vertebral column there are thirty-three vertebrae arranged as follows: seven cervical, twelve thoracic, six lumbar, four sacral and four coccygeal. In the cervical region there are no anomalies. In the thoracic region there is a right scoliosis with lordotic tendenc}^ corresponding to the bodies of the fourth to seventh vertebrae and the spines of the fourth to sixth vertebrae. The ribs on the right side are so bent as to narrow and deepen the costo-vertebral groove. The twelve ribs are in normal position but the lower ribs, especially the twelfth pair, are longer than usual, measurimg 18 cm. and reaching bilaterally to within 4 cm. of the iliac crest.

There are six lumbar vertebrae. The first vertebra carries a lumbar rib bilaterally^ This is short, 2.5 cm. long b}^ 1.2 cm. wide, and articulates by a facet on the upper half of the lateral aspect of the body of the vertebra, as well as b}^ a facet on the transverse process. It resembles in everj' way except for its articulations the transverse process or costal element of the other lumbar vertebrae. The vertebra itseK resembles morphologically a lumbar rather than a thoracic vertebra. It has the quadrate horizontal spine, the larger body, the well-defined mammillary process. Of the other lumbar vertebrae, the sixth only is anomalous. It presents a spine rather narrow and clubbed at the end, which is deflected 0.7 cm. to the left of the median line.

181


182


H. RYERSON DECKER



Superior Articular Process v'Dacrum

Inferior Articular Right Lamina


tocess



Articular Surface of Kight 5pine


Fig. 1 Diagram of ^'Ith lumbar vertebra from behind, showing cleft in spine at a.

Fig. 2 Drawing of detachable portion of neural arch of Vlth lumbar vertebra from in front.

Fig. 3 Drawing of detachable portion ot neural arch of the Vlth lumbar vertebra, lateral aspect. Articular surface in pedicle shown at h.

The spine itself is split into two unequal portions with an articular surface between. The left portion is shorter, 1.2 cm. long, more or less pointed, and is attached to a lamina 1.5 cm. broad, and with the lamina is directed backward and outward so as to be slightly concave laterally. The right portion embraces most


SUPERNUMERARY LUMBAR VERTEBRA 183

of the spine, is club-shaped, and is attached to a lamina 1.6 cm. broad, which is directed ahnost horizontally outward (fig. 1). Another defect in the neural arch occurs in the right pedicle just behind and below the superior articular process, where there is a narrow irregular articulation, 2.3 cm. by 0.6 cm. long, looking upward and slightly forward. The separation of the pedicle is not complete, however, for below this joint, between it and the inferior articular process there is definite bony continuity. In other respects the vertebra is normal (figs. 2-4).

The sacrum presents only four vertebrae, and the coccyx four. The first coccygeal vertebra is ankylosed to the last sacral. The anomalies of this vertebral column then, summarized, are the presence of an extra lumbar vertebra, the absence of one sacral segment, the addition of a lumbar rib, a thoracic scoUosis, and an ununited neural arch in the sixth vertebra.

The intervertebral foramina correspond to the number of segments in each region. Thus there are six in the lumbar region and four in the sacral region. Through the foramen between the sacrum and the sixth lumbar vertebra, the spinal branch of the iliolumbar artery passes in, as it does normally, between the fifth vertebra and sacrum, while an extra nerve which may be designated as the sixth lumbar nerve, passes out to join the fifth lumbar and a communication from the fourth lumbar and first sacral to form the sacral plexus (figs. 5-6). Through the foramen between the fifth and sixth vertebra passes a spinal branch of the fifth lumbar artery, which in turn is of large size and given off in normal fashion from the middle sacral artery. Through the first four foramina lumbar branches of the abdominal aorta enter (fig. 5). There are no muscular or ligamentous anomalies.

Special mention is made of the arterial and nervous arrangement because in the usual description of anomalous vertebral columns found in the literature no record is made of the disposition of the soft parts.

From this description it will be noted that the specimen presents both numerical and morphological variations. Numerical variations in the experience of all investigators are most frequent


184


H. RYERSON DECKER


Articular Surface of Left 5pine Spinous Proce55 V^"^ Lumbar Vertebra

Superior Articular Process 5acrum Articular Surface in Pedicle upenorArticular Process



n^iiit2ii:cmlj " M'^ Sacral 5pine


Fig. 4 Drawing of Vlth lumbar vertebra with detachable portion of neural arch removed.


in the coccygeal region, since here a certain number of original embryonal segments fail to persist. In the adult there may be as few as three, the others having been lost or fused. Steinbach


SUPERNUMERARY LUMBAR VERTEBRA


185


5pine.l branch V Lumbar Artery ,;

spinal branch of Iliolumbar lliolumbdr tlYpo(ja5tric Inf. Pudendal External Iliac


II Lumber A lULumbarA

N Lumbar A

VLumbarA



Inf. Lpiqa5tric / Obtup Sup. Vesical/ 5up7Glu Inf. (

Lateral 5acral

Middle 5acrai

Fig. 5 Diagram of arterial distribution in region of Vlth lumbar vertebra.

('89) believes that five are normal for the male and four for the female, while Bardeen ('04) thinks that normally not more than four sacral vertebrae persist. \^ariations are less frequent in the


186


H. RYERSON DECKER


Ilio-tiYpogastnc llio-lnguina!



Lateral Cutaneous


femora!


Genito-femoral


Obt u rator

Lumbo-Sacral Cord Vl'^ Lumbar

P'5eLcral

5acral Plexus


3.L.rtAT50N


Fig. 6 Diagram of lumbosacral plexus iii region of Mth lumbar vertebra.


sacral region, and the frequency diminishes as we ascend the vertebral column, so that in the cervical region numerical variation is rare.


SUPERNUMERARY LUMBAR VERTEBRA 187

In the presacral region there are normally twenty-four vertebrae, numerical variations here arranging themselves into two groups; first, where the total number of segments is either increased or diminished without compensation from another region; secondly, where the total number of presacral vertebrae is twentyfour but increase or diminution in one region occurs at the expense of an adjacent region, as in the specimen here described, where a sacral deficiency is compensated for in the lumbar region. Variation of this type seems to be concomitant with the development and attachment of the costal element. Thus in the lumbosacral region the last lumbar vertebra may be sacralized b}- fusion of its costal element in the lateral mass, or the first sacral vertebra may be set free and lumbalized because of lack of fusion of its costal element.

Numerical variations have been studied by a number of investigators, notably Bianchi, Steinbach, Paterson, Ancel and Sencert, Topinard, Dwight, Rosenberg and Bardeen. Bardeen ('04) after a study of reports of 1059 specimens including 75 of his own, found that numerical variations occur in about 16 per cent of vertebral columns of which 7.3 per cent have compensated variations and 8.7 per cent uncompensated, equally divided between an increase and decrease of segments.

Morphological ^'ariations are comparatively infrequent, although there are no actual figures. Anomalies of form may exist in any part of a vertebra and may be unilateral or bilateral. The common types are defects in the neural arch, defects in the body, deviation in the normal alignment of parts, and synostoses. Variations in the size of spinous processes, laminae, articular processes, bodies, from hypertrophy to dwarfing are not uncommon. When morphological defects occur they are usually in the Imnbar region.

Defects in the neural arch may occur at any place, but commonly are seen in the pedicle between the superior and inferior articular processes, so that a segment consisting of spinous process and laminae may be lifted away when the soft parts are divided. They may be, as in the specimen here described, asym


188 H. Rl'ERSOX DECKER

metrical and incomplete. Complete absence of part of the neural arch as occurs in spina bifida is not uncommon. Anomalies of this tj'pe are easily explained by the failure of centers of ossification to develop fully and unite.

^^Tien one comes to account for numerical variations, explanations are not so easy to give, leading to the development of a number of theories which are well discussed by Bardeen ('04) and by Testut ('11). It is not within the scope of this report to discuss these further than to state that numerical variation can be reasonabh^ explained on the simple basis of errors in segmentation.

From a clinical standpoint it would seem that numerical variation is not an important factor. There is no ground for beUeving that one vertebra more or less regionally or otherwise is of disadvantage to an individual. Morphological anomalies, on the other hand, may easily be the cause of or be associated with definite disturbance in body function. Defects in the neural arch or defects in normal proportions of a vertebra may tend to render that vertebra more unstable, its articulations more insecure, and to permit abnormal motion between the bodies or adjacent articular processes. When such a vertebra is subjected to acute or to long-continued force, muscular strains, joint sprains, spinal curvature, and even dislocation may happen. ^Nluch backache may be due to vertebral defect. If the last lumbar vertebra be the one affected, instability may be given to the lumbo-sacral articulation, and a true projection forward of the promontory' of the sacrum may occur to such an extent as to interfere with normal parturition. Lack of fusion in the neural arches in spina bifida is of course a distinct clinical entity, as is often the presence of a cervical rib. Just what was the exact clinical aspect of the case here reported, is not on record.

I desire to acknowledge manj- suggestions received from Professor Sheldon in connection with the preparation of this article.


SUPERNUMERARY LUMBAR VERTEBRA 189

LITERATURE CITED

Ancel, p., et Senxert, L. 1901 Variations numeriques de la colonne vertebrale. Comptes rendus de I'Assoc. des Anatomistes, Lyon, pp. 158-165, figs. 1-2.

1902 a Les variations des segments vertebro-costaux chez rhomme. Bibliographia Anatomique, T. 10, pp. 214-239, figs. 1-7.

1902 b De quelques variations dans le nombre des vertebres chez rhomme. Journal de'l Anatomie et de la Physiologie, T. 38, pp. 217258, pi. 6-7.

Bardeex, Charles Pi. 1904 Xumerical vertebral variation in the human adult and embryo. Anat. Anz., Bd. 25, pp. 497-519.

1905 Studies of the development of the human skeleton. Am. Jour. Anat., vol. 4, no. 3, pp. 265-302.

BiANXHi, S. 1895 Sulla trequenza della anomalie numeriche vertebrali nello scheletro dei normali e degli alienati. Atti della R. Accademia dei Fisiocritici di Siena, vol. 7, pp. 21-33.

DwiGHT, T. 1906 Xumerical variation in the human spine, with a statement concerning priority. Anat. Anz., Bd. 28, pp. 33-40, 96-102.

Harrison, R. G. 1907 Experiments in transplanting limbs, and their bearing upon the problems of the development of nerves. Jour. Exp. Zool., vol. 4, pp. 239-281.

Leboucq. H. 1898 Recherches sur les variations anatomiques de la premiere cote chez Thomme. Archives de Biologie, T. 15, pp. 125-181, figs. 1-13, pi. l-«.

Patersox, a. ]\I. 1893 The human sacrum. Scientific Transactions of the Royal Dublin Society, vol. 5, pp. 123-204, pi. 16-21.

Rosexberg, E. 1876 Ueber die Entwicklung der Wirbersaule und das Centrale carpi des IVIenschen. Morph. Jahrb., Bd. 1, pp. 83-197, pi. 3-5.

1899 Ueber eine primitive Form der Wirbelsiiule des ^lenschen. MorphJahrb., Bd. 27, pp. 1-118, figs. 1-3, pi. 1-5.

Steinbach. 1889 Die Zalil den Caudahvirbel beim Menschen. Dissertation. Berlin.

Testut, L. 1911 Traite d'anatomie humaine, T. 1.

TopixARD, P. 1877 Des anomalies de nombre de la colonne vertebrale chez rhomme. Rev. d'Anthropologie, T. 6, pp. 577-649.


INCREASE IN PRICE OF JOURNALS

In order to extend and improve the journals published by The Wistar Institute, a Finance Committee, consisting of editors representing each journal, was appointed on December 30th, 1913, to consider the methods of accomplishing this object. The sudden outbreak of European misfortunes interfered seriously with the plans of this committee. It was finally decided, at a meeting held December 28th, 1914, in St. Louis, ]VIo., that for the present an increase in the price of these periodicals would not be unfavorably received, and that this increase would meet the needs of the journals until some more favorable provision could be made.

This increase brings the price of these journals up to an amount more nearly equal to the cost of similar European publications and is in no sense an excessive charge.

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THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY

36th Street and Woodland Avenue

Philadelphia, Pa.


On The Anlage Of The Bulbo-Urethral (Cowper's) and Major Tstibular (Bartholin's) Glands In The Human Embryo

Arnold H. Eggerth

Department of Anatomy, University of Michigan

FOUR FIGURES

The fii-st observations on the development of Bartholin's glands were published in 1840 by Tiedemann, who saw them in embrj'os of five, six and seven months. Huguier fomid the glands in an embryo of fom' and a half months. Hoffman determined that the anlage of Cowper's glands first appeared in the tenth to eleventh week, on both sides of the urogenital opening, near the anlage of the penis. Toldt recorded that both Cowper's and Bartholin's glands originated as outpouchings of the urogenital smus. Debierre saw Cowper's glands m a seven-months' fetus, and declared its anlage to be an outpocketing of the epithelium of the urethra. Beigel observed Bartholin's glands in a six-months' fetus, and Swiecicki m one of 99 mm. \an Ackeren states that he fomid Bartholin's glands in an embryo at the end of the fourth month, and records that he observed the gland duct as entering the lowest portion of the urogenital sinus. He further states that the blind end of each duct bore five epithelial twigs, separated from each other by connective tissue. Cadiat indicated the anlage of Cowper's glands in his figure of a 3.5 cm. embryo; the validity of his interpretation, however, is questioned by v. ]Muller. Toumeaux fomid in a 4.4 cm. embiyo the anlagen of Bartholin's glands in the form of epithelial buds having a length of 120 m The observations of ^'italis IMiiller deserve fuller consideration. An embryo of 27 mm. length did not show any trace of Bartholin's glands. The next eml^ryo in his series was one of 6.5 cm. length, though one of 8 cm. length showed an earlier stage of the gland anlage. In the latter embrjo. the two epithelial buds were respectively 133 n and 166 m in length, and without lumen. A male embrj^o of 6.75 cm. showed buds of 300 AC and 100 m, with a lumen in the longer bud. In a female embryo of 6.5 cm. length, he observed the left bud as having a length of 400 m and presenting two end branches, and the right bud as having a length of 750 fx with three end branches, both buds showing lumina. From these and other embryos, ]\Iiiller concluded that the first appearance of these glands is irregular as to time, and may take place in embryos of from 4 to 8 cm. in length. This author states, m substance, that the anlagen of Cowper's and Bartholin's glands arise as solid buds from thickenings ot the epithelium of the urogenital sinus. The solid anlagen later acquire a lumen, the ends extendmg as solid sprouts, the beginnmgs of division. Between the distal buds there is found a cellular mesenchyme. He further notes that m cross-sections of the urogenital sinus, this has the form ol a five-raj^ed star, the gland anlagen always arising from the two lower or ventral rays; in younger embryos growing laterally, in embryos of 10 to 11 cm., latero-dorsally. Miiller also studied ox embrj'os of 6 cm. length. In these he observed that the urogenital canal presents in transverse section the form of a cross with side arms rmining to a point. On the crest of these side arms, as seen in cross-section, he fomid the anlagen of Cowper's glands as two solid buds of 100 n to 150 ju in length.

Nagel observed the anlagen of Cowper's glands in a 4 cm. embryo, these appearing as solid tube-like epithehal buds on the sides ol the urogenital sinus, somewhat above its external openmg. The epithelium of the gland l)uds he found to be of a high cubic variety. He found end branches in the gland anlagen of embryos of 5 to 6 cm., rump length. In older embryos, the hollowed-out ducts of the gland anlagen were lined by a low cubic epithelium, as in the canalis urogenitalis ; while the branches had a high, almost cylindrical epithelium, as in the early stages of the anlagen.

Robert Mayer, in his accomit ot the development of the glands of the vagina and the vulva, gives consideration to the Bartholin's glands as observed in embryos of five months and older. He notes that in the vestibule of the female embryo, longitudinal folds are formed at an early stage; in embrv'os up to about five months old, these folds appear, in cross-sections of the vestibule, arranged in the form of a star having five principal rays on each side. As descril^ed by him, the first pair of rays rmis in front from the urethral opening parallel to the clitoris. The second pair of rays passes on both sides of the papilla urethralis, passing diagonally backward from what has been termed the 'sulcus paraurethrahs.' This pair of folds, which early bears relatively large glandlike recesses, remains backward in growth, and is poorly developed in the newborn, though still recognizable. The third pair of folds or rays — which as seen in cross-section of the urogenital sinus, forms the middle of the star — is characterized by the ducts of Bartholin's glands. The fourth pair, situated just behmd the third pair and running parallel to the ducts of Bartholhi's glands, have a direction which is obliquely backward, and support, in the newborn, glandular anlagen which are similar to those of Bartholm's glands, except that shorter tubules are found. The fifth pair of folds is situated in the fossa navicularis, beside the midline, having a direction which is upward rather than backward. ]\Iayer points out that it is along these five rays or folds that the glands of the vulva first develop, and it is here that they form in the greatest numbers.

Keibel's observations on Echidna embryos have influenced the more recent investigators who have considered the anlage of Cowper's gland ia Homo. Keibel found in his echidna embryo 45 a, length 7.7 mm. a thickening of the ectodermal epithelium to the right and left of the midline vhich, to use his own words, "may perhaps be ascribed to the anlage of Cowper's gland." This region is stated to be at the cranial end of the just forming ectodermal cloaca. In his Echidna embr>'o 46, the Cowper's glatid anlage is present as an elongated solid bud arising from the ectoderm at the base of the penis; that is, from the craniolateral wall of the ectodermal cloaca (see Keibel's text figures 53 a and 53 b, and plate figures 17, 19 and 20). The upper end of the gland anlage is invested by a muscle complex that is continuous with the muscle of the skin.

Van der Broek established a similar origin for Cowper's glands in the embryos of Marsupia. In a Halmaturus embrj'o of 17.5 mm., he observed what he took to be the anlage of Cowper's glands, arismg from the ectoderm of the ectodaum (Keibel's ectodermal cloaca) on both sides of the urethral plate (Phallusleiste). In later stages of the embryos of Halmaturus and other Marsupia, he fomid Cowper's glands as solid epithelial buds, arising from the urogenital smus at the boundarj^ between the ectoderm and the entoderm.

Lichtenburg, in a comprehensive investigation on the development and structure of the urogenital canal in man, in the course of which he made free use of reconstruction methods, accepts without verification the account given by Keibel and \an der Broek of the ectodermal origm of Cowper's glands as observed in the Monotremata and Marsupia, and makes their findings applicable to man. In a 48 mm. human embrj'o, the youngest stage described b}- him, Lichtenburg finds the anlagen of Cowper's glands "at the typical place on the dorsal wall of the urogenital sinus." It appeared to him, to quote further, "as if the tubules were not naked, but that a kind of compressed embryonic connective tissue formed a capsule aromid them." In a 65 mm. embrj^o, the gland buds were found to be mibranched, though both buds possessed a lumen; small side buds indicated future branching. Lichtenburg's figure (p. 143) shows the gland buds lying side-by-side near the mid-line and dorsal to the urogenital sinus. In an embry^o of 68 mm. length, terminal branching of the gland buds was evident, while one of 70 mm. length showed an accessory Cowper's gland.

Felix, in his account of the anlage and development ot the urogenital organs as given in Keibel and Mall's "Human Embryology," makes the following observations concerning Cowper's glands: "They arise as paired soUd epithelial buds from the pars peMna of the urogenital sinus" . . . "and are therefore of entodermal origin. The solid epithelial buds grow upward almost parallel to the urogenital sinus, and lie from the beginning m the compact mesenchyme which is the anlage of the corpus cavemosum urethrae. The glands grow through this mantle, and only when they have reached the looser mesenchynie between the rectum and the sinus are they able to enlarge." Felix observed the anlagen of Bartholin's glands in an embr^'o of 36 mm. ;the first evidence of branching in the gland-buds of BarthoUn's glands were observed in an embrv'o of 80 mm. length.

Broman states that Bartholin's glands are first evident in female embryos of the third month, 4 to 8 cm. long, as paired outgrowths from the epithelium of the urogenital sinus, basing his statement on the observations of Mtalis Aluller. Cowper's glands arise as buds from the entodermal urogenital sinus epithelium, in 4 to 5 cm. embryos. His figure 397 reproduces a model of the urogenital sinus and Cowper's glands of a male embryo of 6 cm. head-breech length.

This brief review of the Hterature may serve to show that while the embryologj^ of Cowper's and Bartholin's glands has received consideration by numerous investigators, there is as yet no unanmiity as to the period when their anlagen in the human embryo may first be recognized, nor has the region of their anlagen been definitely determined, and, with the exception of the figure of Broman, there exist no comprehensive figures showing their relation to the urogenital sinus, mesonephric ducts, and IVIlillerian ducts. At the suggestion of Dr. Huber, models of the epithelial portions of the genital tubercle, urogenital sinus to base of bladder, ureters, mesonephric and ^Miillerian ducts, and rectum of human embr3^os, both male and female, at the critical period of their development, were undertaken. The models thus obtained, while in part duplicating certain of the Keibel models, seem worthy of reproduction, in that the anlagen of Cowper's and Bartholin's glands are portrayed in their relation to other structures. The question of the ectodermal or entodermal origin of these glands is not considered, as a solution of this question is not to be obtained from embryos of the age of those used in this investigation. For this, much younger stages showing early cloacal development would be necessar}^ The problem confines itself to a study of the anlage of Cowper's and Bartholin's glands in their relation to the urogenital sinus and associated structures, as shown in a series of reconstructions of critical stages.

The human embryos from Dr. Huber's collection (table 1) wore placed at my disposal, the measurements referring to crownbreech length, as obtained in fixed material (formalin fixation). With the exception of Embryo 48, in which there is evidence of maceration, the embryos are all well preserved. The series are double stained in hematoxylin and congo red. Reconstructions were made from the first four of the embryos listed; the other three were studied without being modelled. The drawings for the reconstructions were made with the aid of an Edinger projection apparatus, at a magnification of 100 diameters. In all cases, the epithelium alone was reconstructed. These models, which form the basis of the study, are figured as seen from the left side. The figures were made by photographing the m.odels and using the negative for lantern shde projection, accurate outfines being thus obtained. By placing the drawing paper at the right distance from the lantern, it was possible to give a definite magnification to the figures. ^ly own account consists mainly of a description of the models made.

TABLE 1

Xo. 47 32 mm. female sagittal 15 n sections

No. 15 30 mm. male sagittal 10 ix sections

Xo. 18 45 mm. female sagittal 10 n sections

X"o. 23 60 mm. female sagittal 10 m sections

X'o. 39 39 mm. male sagittal 10 m sections

X'o. 49 47 mm. female sagittal 15 m sections

Xo. 48 48 mm. female sagittal 20 n sections

The model made from Embryo 47 is shown in figure 1. This embryo was secured from the service of Professor Peterson, from a case of hysterectomy for large fibroma; it was fixed while still warm, and is in an excellent state of preservation. In the model are reproduced the lower part of the much distended bladder, the mesonephric and ^liillerian ducts and ureters. These structures present the typical, normal arrangement, with as yet no degeneration of the mesonephric ducts. Externally, the phallus shows, between its distal and middle thirds, a shallow coronal groove, the sulcus coronarius glandis. A small depression marks the anal pit, and a similar one the ostium urogenitalis, a shallow groove connecting the two depressions. The anal membrane is still unbroken.

Each side of the wall of the urogenital sinus presents three epithehal ridges or folds. These may be designated as the upper.


ABBREVIATIONS


bl., bladder

b.nr.gl., bulbo-urethral glands (Cowper's glands)

l.f.nr.si., lateral folds of the urogenital sinus

m.rs.gl., major vestibular glands (Bartholin's glands)

iii.n.d., mesonephric duct


M.d., Miillerian ducts

utero-vaginal canal pa.u.gl., paraurethral glands (Skene) ret., rectum

s.cor., sulcus coronarius s.ny.l., sulcus nympho-labialis u., ureter ur.pl.. urethral plate



Fig. 1 ^Model of epithelial portion of urogenital system of human Embryo 47 (Huber collection); female, 32 mm. crown-breech length. X 20.


middle, and lower lateral folds of the urogenital sinus. These folds begin in a region which is 0.7 mm. distal or caudal to the entrance of the mesonephric ducts into the urogenital smus, and spread out radially. Of these folds, the upper lateral folds are the most prominent. When the model is viewed from above, it may be seen that they enclose a relatively deep fossa before blending in the sagittal plane to form the uppermost portion of the urethral plate. The middle lateral folds, shorter than the upper ones, run nearly parallel to them, and are separated from the upper folds by relatively deep, narrow grooves. In their proximal portion, each middle fold presents an elevation of about 75 m; distally or caudally, each middle fold slopes downward, becoming broader and lower, and is ultimately lost in the urethral plate. The lower lateral folds taken together form a thickened ridge along the bottom of the urogenital sinus, blending distally with the surface epithelium. They are the smallest of the three folds, both in length and elevation. That portion of the urethral plate found in the angle between the middle and the lower folds is relatively thin. Of the three sets of lateral folds observed in this embryo, only in the middle ones can a lumen or extension of the cavity of the urogenital sinus be at all clearly traced, and this as a narrow slit having a depth of about 20 to 30 yu.

On the left side of the model, as shown in figure 1, the middle lateral fold presents, near its cephalic end, a small projecting bud of epithelium, which passed through only one of the sections, having a thickness of 15 ix. The relative position of this epithelial bud is shown in this figure at m.vs.gl. Looking at the model from below, it may be observed that about 0.3 mm. from the cephalic end of the middle lateral fold, there is evident an abrupt rise or shoulder, and that the epithelial bud above referred to, caps this shoulder. From the older stages modelled, it is evident that this epithelial bud may be regarded as the anlage of Bartholin's gland. A similar bud is as yet lacking on the other, the right side of the urogenital sinus, though three lateral folds, similar in extent and arrangement to those figured for the left side may be seen in the reconstruction. The cells of the Barthohn's gland anlage of the left side, like those of the lateral folds and the wall of the urogenital sinus, may be characterized as of the cuboidal variety and stratified. The short epithelial bud is surrounded by a membrana propria, the surrounding mesenchymal cells having in the immediate vicinity a concentric arrangement.

The model made from Embryo 15 is shown from the left side in figure 2. This is a male embryo having a crown-breech length of 30 mm., and shows a shghtly older stage of development than the female embryo, the model of which is shown in figure 1.


The anal membrane is perforated, and the anal pit is a distinct fossa. The perineum has a length of only 0.15 mm. The cephalic ends of the Mtillerian ducts present evidence of beginning degeneration.

The three lateral folds of the urogenital sinus present essentially the same relative positions as those described in connection with the model shown in figure 1. By reason of the thickening


Pig. 2 Model of epithelial i)ortion of urogenital system of human Embryo 15 CHuber collection^ ; male, 30 mm. crown-breech length. X 20.


of the epithelial plate in the region between the middle and lower lateral folds, the lower folds are less conspicuous than in the preceding model. The middle fold is also somewhat shorter than in Embryo 47 (fig. 1). The anlage of Cowper's gland, present on both sides of the urogenital sinus, is observed in essentially the same relative position as given for the anlage of Bartholin's glands, namely, in the middle fold, capping an abrupt shoulder seen on this fold near its cephalic end, about 1 mm. below the entrance of the mesonephric ducts into the urogenital sinus. The bud of the left side is shown in figure 2 at h.ur.gl. The gland anlagen are in the form of solid epithelial buds, composed of cells of a cuboidal form; the left bud having a length of 50 n, the right bud a length of 60 m- Both buds project laterally into a dense mesenchyme with a direction which is perpendicular to the long axis of the middle lateral folds. The gland anlagen are surrounded by a membrana propria, the surrounding mesenchymal cells having a concentric arrangement.

The shape of the sinus lumen for the region of the lateral folds differs from that described for Embryo 47. In Embryo 15 (fig. 2) the pars phallica sinus urogenitaUs (Felix) has been extended by central desquamation of the cells of the urethral plate, the sinus lumen having invaded the upper lateral folds and that portion of the urethral plate found between the middle and the lower folds.

Embryo 39, male, crown-breech length 39 mm., was studied with reference to the urogenital sinus region, but not modelled. The lateral folds of the urogenital sinus were determined, the lower lateral folds being, however, quite inconspicuous. The anlagen of Cowper's glands were found near the cephalic ends of the middle lateral folds, as soUd epithelial buds with as yet no peripheral branching. The bud on the right side passed through five 10 At sections; that on the left, through nine 10 /i sections.

Embryo 18, from which the model shown in figure 3 was made, is a female embryo having a crown-breech length of 45 mm. In this embryo the mesonephric ducts present marked evidences of degeneration. When compared with Embryo 47, the general advance in the development of the urogenital structures may be noted. The phallus (clitoris) and the perineum are relatively shorter. A well marked sulcus coronarius glandis is present; a shallow groove, the urethral groove, extends to it from the ostium urogenitalis. Laterad, the sulcus nympho-labialis separates the phallus from the genital swelling. The ostium urogenitahs has increased in size, both in length and in width. The pars phallica sinus urogenitalis has developed to such an extent that it now forms the widest part of the urogenital smus caudal to the junction of the Miillerian duct with the urogenital sinus.

The model made from this embryo is shown from the left side in figure 3. The three lateral folds of the urogenital sinus are evident, and present some points of difference when compared with the three lateral folds as modelled from male Embryo 15.



Fig. 3 Model of epitlielial portion of urogenital system of human Embryo 18 (Huber collection); female, 45 mm. crown-breech length. X lo.


Only the upper lateral folds have not materially altered their form and relations. As previously stated, when viewed from above, these enclose a deep fossa at their cephalic end, blending caudally in the sagittal plane to form the ridge-like crest for the urethral plate. The middle lateral folds have developed so as to be relatively long, being now continuous caudally with the lateral expansion of the sinus wall in the region of the ostium uro


AXLAGE OF COWPER's AND BARTHOLIN'S GLANDS 201

genitalis. The most distinctive change, however, is noticed in the lower lateral folds. These, though still the least conspicuous of the three sets of folds, have increased in length and elevation. The sinus lumen of this region presents a distinct difference from that found in Embryo 15. The lumen has invaded the upper and middle lateral folds, but the plate between the middle and lower folds is still solid, while in the region of the lower folds, there is a narrow lumen, blind at its cephalic end, but opening independently into the urogenital sinus.

The epithelial buds which form the anlagen of BarthoUn's glands have the same relative positions as in younger stages (m.vs.gl.). Measured on the model, these buds are situated 1.2 mm. caudal to the point of junction of the Aliillerian duct with the urogenital sinus, and spring from the cephalic portion of the middle lateral fold. The bud on the left side has a length of 120 jjL, and presents a short, sohd side bud at its distal end. In the middle third of its length, a loosening of the central cells suggests the beginning of a lumen. The bud on the right side has a length of 150 fx, presenting an expanded knob-like end, probably the anlage of side branches. A narrow lumen is present, just proximal to this expanded end; this lumen is surrounded by a layer of quite regular cells of a compressed cuboidal shape. In this embryo, both gland buds extend obliquely laterad and dorsaUy in the general direction of the middle lateral fold.

Embryo 48 is a female embrj'o of 48 mm. crown-breech length, and was not modelled. It presents the same general arrangement of lateral folds as described for Embryo 18. The lower lateral folds are distinct, and possess a narrow lumen which no longer ends bUndly at its cephahc end, but here communicates with the lumen of the m-ogenital sinus. On the right side, the gland anlage passes through seven sections of 20 n thickness; on the left side, through three such sections. However, the real difference in length of the two gland anlagen is not so great as this would seem to indicate, as the sections are not cut parallel to the mid-plane, and the left gland anlage is consequently cut very obUquely. The gland buds are still solid, with no evidence of branching.


202 ARNOLD H. EGGERTH

Embrj^o 49 is a female embrj^o of 47 nun., crown-breech length, and was not modelled. The lateral urogenital sinus folds, as also the gland anlagen for Bartholin's glands, present the same general relations as in Embryos 48 and 18. The gland bud on the right side passes through eight sections having a thickness of 15 M- The bud on the left side was very obliquely cut and loosened from the surrounding mesenchyme, so that its length was not determined.

Embryo 23, a female embryo having a crown-breech length of 60 mm., represents the oldest stage modelled. This model, as seen from the left side, is shown in figure 4. The model shows the downward (caudal) projection of the clitoris anlage, characteristic of this stage. When compared with the three preceding embryos, it is seen that the clitoris has become relatively, though not absolutely, smaller. A well-defined sulcus coronarius glandis is present, as also a deep sulcus nympho-labiahs, bounding the base of the clitoris laterad. The urogenital sinus opens externally by two ostia ; the larger one near the sulcus coronarius, the smaller one at the base of the clitoris. Externally, the two ostia are united by a deep groove. A continuation of this groove leads toward the anus, disappearing at about the middle of the perineum. The mesonephric ducts have degenerated to such an extent that they are incomplete on both sides.

The utero-vaginal canal fAIiillerian tubes) is well developed, though its lumen does not appear to have joined that of the urogenital sinus. At the place of its fusion with the urogenital sinus, there may be observed, in the model, projections of the sinus epithelium, regarded as the anlagen of the paraurethral glands of Skene; three are to be observed on the right side, two on the left.

On each side, all of the three lateral folds have extended cephalad so as to reach the region of the utero-vaginal canal. In this embryo, the folds are complicated by the appearance of secondary folds. The upper lateral folds present each a secondciry fold extending caudad to meet the middle lateral fold. The middle folds also present secondary folds, beginning just below


ANLAGE OF COWPER's AND BARTHOLIN'S GLANDS 203

the anlagen of Bartholin's glands, and extending caudad. It seems possible to relate this model with the account given by R. Mayer, quoted in preceding pages of this communication. This observer has described five lateral folds or rays. Of the tliree



Fig. 4 Model of epithelial portion of urogenital system of human Embryo 2.3 (Huber collection) ; female, 60 mm. crown-breech length. X 15.

primary lateral folds here described, the upper, with a secondary fold imperfectly developed, seems to correspond with Mayer's first and second rays; the middle lateral fold as here designated, with its secondary fold, forms the third and fourth rays of flayer's account; the lower fold corresponds with his fifth ray.


204 ARNOLD H. EGGERTH

In Embryo 23, the gland buds forming the anlage of Bartholin's glands are shown in figure 4 at m.vs.gl. They arise from the middle lateral fold, 1.2 mm. from the caudal end of the uterovaginal canal, extending from this fold obliquely laterad and dorsad. The gland bud on the left side has a length of 200 fx; on the right side, of 240 n. Both gland buds show a knob-like end, with a slight constriction proximal to the terminal enlargement. The end of the left gland bud shows partial division into four branches, so that the cross section of this portion resembles a shamrock leaf; there is as yet, no mesenchyme separating the anlagen of the branches. The neck or stalk of this gland bud presents an interrupted lumen. Each of the branch anlagen shows a compact arrangement of the cells at the periphery, with loosely arranged central cells, preluding a lumen. The gland bud on the right side is similar to that on the left, except that only three branches are indicated, and one of these is completely surrounded by mesenchyme. Both gland anlagen are surrounded by dense mesenchyme, the beginning of a capsule. In the region of the gland anlagen, the sinus lumen has invaded the secondary fold found between the middle and lower lateral folds. The independent lumen of the lower fold was not to be observed in this embryo.

The figures of the models seem to portray the relations and extent of the lateral folds of the urogenital sinus so clearly, as also the anlagen of Bartholin's and Cowper's glands, that extended description was deemed unnecessary. The following summary- and conclusions seem warranted.

SUMMARY AXD CONCLUSIONS

1. Human embryos, both male and female, of the ages studied in this investigation, 3 to 6 cm. crown-breech length, present three pairs of lateral folds on the wall of the urogenital sinus. In the younger stages, these folds extend from the ostium urogenitalis to a point about halfway to the place of entrance of the mesonephric ducts into the urogenital sinus. In the older stages, they extend more cephalad; in the 6 cm. female embryo reconstructed, to the caudal end of the utero-vaginal canal.


ANLAGE OF COWPER's AXD BARTHOLIN'S GLANDS


205


2. These three folds first appear as solid epithelial ridges, symmetrically arranged on the two sides of the urethral plate. Keibel's models would indicate that thej^ do not appear until the embryo has reached a length of more than 28 mm.

3. The upper lateral folds are at first the more prominent; later the middle lateral folds are relatively larger. The lower lateral folds remain inconspicuous.

4. A male embryo of 5 to 6 cm. length was not available, but the figures of Lichtenburg, A'an der Broek, and other investigators would indicate that in the male, these folds become obliterated. The model figm-ed by Broman (fig. 397) of a 6 cm. male embryo, does not show clearlj^ whether lateral folds are present or not.

5. The anlagen of Bartholin's and Cowper's glands may be first recognized in embryos having a crown-breech length of 3 cm., as solid epithelial buds arising from the middle lateral fold near its cephalic end; in the younger stages extending laterad, in shghtly older stages extending obhquely laterad and dorsad.

6. When the embryo has reached a crown-breech length of about 4.5 cm., the distal end of the gland bud presents a knoblike end with a narrower proximal portion in which a lumen is preluded. After attaining a crown-breech length of 5 to 6 cm., evidence of distal branching of the gland anlage may be observed.

7. The development of the glands on the two sides is not symmetrical, neither as to time of anlage, nor as to extent of development. This table 2 may serve to show.


TABLE 2


CATALOGUE NO.


CBOWN-BBEECH

LENGTH IN I

MM. I


LENGTH OF

GLAND AND

ANLAGEN,

LEFT SIDE,


LENGTH OF GLAND AND

ANLAGEN, RIGHT SIDE,




iJ> n


i« n


47


32



15


15


30


60


50


17


39


50


90


18


45


150


120


48


48


140


60


49


47


120


?


23


60


240


200


206 ARNOLD H. EGGERTH

In conclusion, I desire to express my sincere thanks and appreciation to Professor Huber, who, in addition to suggesting the problem, has given me material aid at every step in the making of the reconstructions and in their interpretation.

BIBLIOGRAPHY

Van Ackeren, F. 1889 Beitriige zur Entwickelungsgeschichte der weiblichen

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beim Menschen. Verb. d. Phys.-Med. GeselL zu Wiirzburg. Xeue

folge., Bd. 17. Van der Broek, A. J. P. 1908 Zur Entwickehing des Urogenitalkanales bei

Beutlern. Verb. d. Anat. GeselL, p. 104. Broman, J. 1911 Xormale und Abnormale Entwickehing des Alenschen Berg mann. Wiesbaden. Cadiat, L. O. 1884 Du developpement du canal de I'urethre et des organes

genitaux de I'embryon. Jour, de I'Anat. et de la Phys. Debierre, C. 1883 Developpement de la vessie, de la prostate, et du canal de

I'urethre. These; Paris; Doin; quoted from v. jNIliller. Felix, W. 1910 Development of the urogenital organs. Keibel and 'Sla.W,

Human Embryology, vol. 2. Hoffman, G. 1877 Lehrbuch der Anatomic des ]\Ienschen. Erlangen. Bd. 1

part 2, p. 695. HroiuER. 1847 Memoire sur les appareils secreteurs des organes genitaux

externes chez la femme et chez les animaux. .\nnales des sciences nat urelles. Third series, Zoology, vol. 13, p. 239. Quoted from v. Miiller. Keibel, F. 1904 Zur Entwickelung des Urogenitalai>parates von Echidna acu leata var. typica. In Semon, Zool. Forschungsreisen in Australia, vol.

3, Monotremen und Marsupialer. LicHTENBURG, A. 1906 Beitrage zur Histologic, Alikroskopische Anatomic, und

Entwickelungsgeschichte des Urogenitalkanals des Mannes und seiner

Driisen. Anat. Hette, Bd. 31. Mayer, R. 1901 tJber Driisen der Vagina und Vulva bei Foten und Xeugebor enen. Zeitsch. f. Geburt. u. Gyn., Bd. 46. MuLLER, V. 1892 Ueber die Entwickelungsgeschichte und feinere .\natomie der

Bartholini'schen und Cowper'schen Driisen des ^Menschen. Arch. f.

mikr. Anat., Bd. 39. Nagel, W. 1892 Ueber die Entwickelung der Urethra und des Dammes beim

Menschen. Arch. f. mikr. Anat., Bd. 40. SwiEciCKi, H. V. Zur Entwickelung der Bartholini'schen Driise. In: L. Gerlach,

Beitrage zur Morphologic und Morphogenie, Bd. 1, pp. 99-103. Quoted

from.v. Miiller. TiedEjMann, F. 1840 Von den Duvernej^'schen, Bartholini'schen, oder Cowper'schen Driisen des Wcibes. Heidelbg., Leipzig. Quoted from v. Miiller. ToLDT, C. 1877 Lehrbuch der Gewebelehre. Stuttgart, p. 466. TouRNEACx, F. 1889 Sur le developpement et revolution du tubercule g^>nital

chez le foetus humain. Jour, do I'Anat. et de la Phys.

Volumetric determinations of the parts of the brain in a human fetus 156 mm. long (crown-rump)

F. C. DOCKERAY

Department of Psychology, University of Kansas

In the present communication there is reported a study of the volume of the main divisions of the brain as they are found in a fetus about four months old. The work was undertaken as a step in the history of the growth of the individual parts of the brain under the premise that a knowledge of their volume priority would indicate in a general way the functional prioritj^ of these parts. By means of the wax-plate reconstruction method it is possible to make an accurate enlarged model of the brain that can be separated into its chief component parts. Since such a model is made of wax of a uniform composition the relation by volume and by weight of the different parts can be determined both as to each other and as to the brain as a whole. This same method was used in determining the volume of the different parts of the opossum brain, by Professor Streeter and by Mr. H. A. Tash, who reported their results at the meeting of the American Association of Anatomists at Ithaca.^

The brain measured was taken from a male fetus measuring 156 mm. crown-rump, and 201 mm. total, length. The head measurements w^ere: Bitemporal, 48 mm.; occipito-frontal, 58 mm. These measurements were made on the fresh specimen. Its weight was 296 grams. The specimen was preserved in 10 per cent formalin, the skull having been opened to facilitate the penetration of the fixative. Subsequent^ the brain was removed, embedded in celloidin and prepared in serial sections 50 /jl thick,

1 streeter, G. L., 1911, Volumetric analysis of the brain of the opossum. Proc. Amer. Assoc. Anat.; Anat. Rec, vol. 5, p. 91.


every other section saved and stained with ahmi-cochineal. From this series a model was made enlarged five diameters after the well known Born method. Serial drawings were made with a projection apparatus on papers which were then incorporated in wax plates of such a thickness that the enlargement in all planes was the same ( X 5) . The drawings were then cut out from the plates and filed. This gave a model of the whole brain with the ventricles removed. The plates were then gone through a second time and the various parts cut awa}^ from each other so that their individual weights and volum.es could be separately determined. It was found that this could be done with considerable accuracy, and having the stained sections as a guide, it would have been possible to have carried the subdivisions further. But, having in mind both younger and older stages, it was decided that the adopted subdivision would prove most practical in the end. The results are given in table 1. In the first column of the table is given the weight in grams of the whole model and of its parts. In the second column is given the percentage of the total weight formed by each part, which would hold true for


TABLE


1


MODEL WGT.


PEH CENT OF


MODEL VOL.


ACTUAL


IN GMS.


TOTAL WGT.


INCC.


VOLUME


72.135


4.973


80.565


0.644


32.325


2.228


36.500


0.292


39.810


2.744


44.065


0.352


20.900


1.441


23.659


0.189


69.761


4.809


78.970


0.631


1287.673


88.776


1457.658


11.661


110.610


7.625


125.210


1.001


73.150


5.043


82.805


0.662


33 . 161


2.286


37.538


0.300


4.299


' 0.296


4.867


0.039


33.865


2.334


38.341


0.306


26.075


1.797


29.522


0.236


5.815


0.401


6.583


0.052


1.975


0.136


2.236


0.017


1143.198


78.815


1294.100


10.345


1450.468


100.000


1641 .929


i 13.135


Rhombencephalon

PvIeduUa and pons

Cerebellum

Mesencephalon

Diencephalon (inc. epiphysis)

Telencephalon

Basal ganglia

Caudate nucleus (inc. parolf. body and amygdaloid nuchuis)

Putamcn

Globus pallidus

Archipallium

Fornix and hippocampus

Paraterminal body

Olfactory bulbs

Neopallium

Total brain

the actual brain just as for the model. In the third column is given the volume in cubic centimeters of the whole model and of its different parts. Instead of determining the volume of each part separately it was found more practical to determine the specific gravity of the wax plates and then calculate the volumes from the weights given in the first column. In the last column is given the volume of the brain itself and of its parts. This was obtained by dividing the volume of the model by the amount of the enlargement, i.e., the cube of five diameters. It is to be remembered that this is the volume of the brain after it has been embedded and prepared in serial sections. The volume of the fresh brain could be obtained only by calculating the amount of shrinkage the specimen experienced in this process.

The subdivisions that were used follow as far as possible the embryological subdivisions adopted by His. Their boundaries could in most cases be determined by the cell structure of the sections. In some cases it was necessary to depend on the surface configuration of the model. The landmarks utilized in carrying out this subdivision are herewith detailed :

Rhombeiicephalon. This was separated from the spinal cord as nearly as possible at a point post cephalic to the first cervical nerve. The cephalic boundary was determined by a plane just skirting the inferior colliculus and passing out ventrally just in front of the pons. Laterally this plane passes just in front of the brachium connecting the cerebellum and pons.

Cerebellum. This is plainly demarcated by its surface outUne, while the pons is determined more by its internal structure, the main characteristic being the densely massed nuclei. The cerebellum at this time consists of a well fissured vermis and the two lateral lobes which are fissured dorsally but are still smooth, ventrally. In removing it the floccular margin was included and also the brachium pontis on each side to the point at which it meets the pons. The removal of the cerebellum leaves the medulla and pons, whose weight and volume are given together.

Mesencephalon. The caudal Umit of the mesencephalon is the same as the plane marking the cephalic border of the rhombencephalon, which has already been given. Its cephalic limit is a wedge-shaped plane that projects in between the masses of the diencephalon. At the median Hne its boundary is marked dorsally by the posterior commissure and ventrally by a point post caudal to the mammilary bodies. From this median line the plane of division on each side extends backward so as to include the red nucleus with the midbrain and comes to the surface at a groove marking the antero-lateral margin of the superior colliculus. Owing to the advanced development of the colliculi and the retarded development of the peduncular portion, the mesencephalon is V-shaped as regards its ventral aspect, as well as its cephalic boundary.

Diencephalon. Its separation from, the mesencephalon we have ah'eady indicated. From the telencephalon it is separated bilaterally by the internal capsule, and a sharp line of demarcation on the surface is afforded by the stria terminalis. Ventral!}^ where this is not present the line of division is continued along the anterior margin of the optic tract. By this manner of subdivision there is comprised in this portion the optic tract and thalamus including the habenular nuclei and epiphysis and also the whole hypothalamus with the exception of the hypophysis, which had been removed.

Telencephalon. This includes all the remainder of the brain. It was subdivided into three main divisions as follows:

Ba.2al ganglia. At the end of the fourth month these structures are clearly defined and bear a relation that closely appro?qimates the adult. The putamen and globus pallidus are easily recognized in transverse sections. As for the lamina of capsule fibers that surround them, the incisions were made half-way, so that part of the fibers would go with the globus pallidus and part with the caudate nucleus. The caudate nucleus throughout its greater extent is likewise clearly defined. At its head and tail ends, however, it is complicated by fusing with the parolfactory body and amygdaloid nucleus respectiveh'. On this account these latter were included with it.

Archipallium. This includes, in the first place, the olfactory bulbs, which were removed at a transverse line at the point where they become free from the brain wail. This corresponds to both the bulb and stalk of the adult. The paraterminal body includes the gray substance where the olfactory bulb is attached and the region of the future septum pallucidum and the pillar of the fornix, which could not be easily separated from it. The remainder of the archipallium is made up of the body of the fornix and its fimbricated extension into the hippocampus. The hippocampus is easily recognized by its histological structure and by the way it bulges into the lateral ventricle. With it was included the dentate fascia and the uncinate bod3\ The corpus callosum was included with the neopallium.

Neopallium. This includes the remainder of the telencephalon and represents what we know in the adult as the convoluted cortex, together with the subjacent white matter and includes the corpus callosum, as we have just pointed out.

In conclusion I wish to acknowledge the courtesy of Professor Streeter, who kindly put the resources of the Anatomical Laboratory of the University of Michigan at my disposal for the purpose of this investigation, and gave me many helpful suggestions as the work progressed.


BOOKS RECEIVED

The receipt of publications that may be sent to any of the five biological journals published by The Wistar Institute will be acknowledged under this heading. Short reviews of books that are of special interest to a large number of biologists will be published in this journal from time to time.

A LABORATORY :\IAXUAL AND TEXT-BOOK OF EAIBRYOLOGY. By Charles W. Prentiss, A.M., Ph.D., Professor of Microscopic Anatomj' in the Northwestern University Medical School, Chicago. Octavo, 400 pages, 368 illustrations, many of them in colors. Philadelphia and London : W. B. Saunders Company, 1915.

Preface. This book represents an attempt to combine brief descriptions of the vertebrate embrj-os which are studied in the laboratory with an account of human embrj'ology adapted especially to the medical student. Prof. Charles Sedgwick ]\Iinot, in his laboratory textbook of embryology, has called attention to the value of dissections in studying mammalian embryos and asserts that "dissection should be more extensively practised than is at present usual in embryological work. . . ." The writer has for several years experimented with methods of dissecting pig embryos, and his results form a part of this book. The value of pig embryos for laboratory study was first emphasized bj' Professor Minot, and the development of my dissecting methods was made possible through the reconstructions of his former students. Dr. F. T. Lewis and Dr. F. W. Thyng.

The chapters on human organogenesis were partly based on Keibel and flail's Human Embryology. We wish to acknowledge the courtesy of the publishers of KoUmann's Handatlas, ^Marshall's Embryology, Lewis-Stohr's Histology and McMurrich's Development of the Human Body, by whom permission was granted us to use cuts and figures from these texts. We are also indebted to Prof. J. C. Heisler for permission to use cuts from his Embryology, and to Dr. J. B. De Lee for several figures taken from his Principles and Practice of Obstetrics. The original figures of chick, pig and human embryos are from preparations in the collection of the anatomical laboratory of the Northwestern University Medical School. My thanks are due to Dr. H. C. Tracy for the loan of valuable human nlaterial, and also to Mr. K. L. Vehe for several reconstructions and drawings.

C. W. Prentiss.

Northwestern University Medical School, Chicago, 111., January, 1915.


ox THE AA^IGHT OF THE ALBINO RAT AT BIRTH AND THE FACTORS THAT INFLUENCE IT

HELEN DEAN KING

The Wistar Institute of Anatomy and Biology

In the course of an extensive series of breeding experiments with the albino rat a large amount of data has been collected regarding the body weight of these animals at different stages of their growth. The records dealing with the weight at birth are given in the present paper: those of postnatal growth will be published later.

Two sets of observations on the body weight of very young albino rats have already been recorded. In a paper published by Donaldson in 1906 the average weight of 40 young male albino rats is given as 5.4 gi'ams, and that of 17 females is stated to be 5.2 grams. The more extensive records of Jackson ('13) give the average weight of 107 young male albino rats as 5.1 grams, and that of 109 females as 4.8 grams.

The body weights, as given above, are those of animals that were 'newborn' when weighed. The term 'newborn,' as Jackson states, covers the period in the life of the animal from the time of bu'th up to one day. As a rule, young rats begin suckling ver}^ soon after their birth, and not infrequently part of a Utter will have suckled before the rest have been born. The weight of 'newborn' animals, therefore, is probably not the same as the birth weight in many cases. To obtain the birth weight it is necessary that the animals be weighed before they have suckled, since the amount of food consumed during the first few hours of postnatal life very appreciably increases the body weight. One can tell very easily whether or not the young rats have suckled, as the skin of the young animals is quite


213


THE AXATOMICAL RECORD, VOL. 9, XO. 3 MARCH, 1915


214 HELEN DEAN KING

transparent and if milk is present in the stomach or in the intestines it can be seen very clearly through the body wall.

In the com^se of this investigation 113 litters of rats were obtained at or soon after birth and weighed before any of the individuals had taken food. The same course of procedure was followed in making the records for each of the litters. The young rats were first separated according to sex by the method devised by Jackson ('12). Animals of the same sex were then weighed together to a tenth of a gram and the average weight for each individual computed; if, however, there was a very marked difference in the size of the individuals of the same sex the rats were weighed separately and the weight of each recorded. In addition to recording the number of young, the sex distribution and average body weight of the members of each Utter, the exact age of the mother at the time the litter was born was noted, also her body weight after the birth of the litter and her general physical condition.

The complete series of records comprise data from five different strains of rats that are being bred in The Wistar Institute animal colony at the present time:

1. Stock albinos: Members of the general colony that supposedly represent the normal albino type as it exists at the present time.

2. Inbred albino rats: Animals, originally taken from the general stock colon}^, that have been closely inbred for many generations.

3. Extracted albinos : A strain of rats descended from albinos cast by F, hybrids of the albino and the wild Norway rat (Mus norvegicus) .

4. Piebald rats: A strain derived from Fj hybrids of the albino and Norway rat.

5. Extracted grays: A strain also derived from the Fi hybrids of the albino and the Norway rat.

Table 1 gives a general summary of the birth records arranged according to the strain of rats from which the litters were obtained. The data in this table show that, regardless of strain, the


WEIGHT OF ALBINO RAT AT BIRTH 215

weight of the albino rat at birth is considerably less than that of newborn animals as given by Donaldson and by Jackson. As a rule the male rat at birth is somewhat heavier than the female, as is the case in many other mammals including man.

TABLE 1


Showing the birth weight data for various strains of rats




.STR.UX OP R.\.TS


is

a a


- r.

7i


■I.


<

fa


TOTAL WEIGHT OF MALES IN GRAMS

TOTAL WEIGHT OF FEMALES IN GRAMS


AVERAGE WEIGHT , OF MALES IN GRAMS


^g5 < * 5

W o o

<


Stock albinos

Inbred albinos

Extracted albinos


12 73

8 19

1

113


95 644

43

147

9


47

311

21

80

4


48

333

22

67

5


215.6 216.1 1409.51410.8

' 88.2 88.2

386.1 324.3

22.9 27.7


4.59 4.53 4.20

4.82 5.72


4.50 4.23 4.00


Piebalds

Extracted gravs


4.84 5.54




Total


938


463


475


'




On comparing the data for the various strains of rats it is found that stock albinos, both males and females, weigh slightly more at birth than do the inbred rats. The differences between them are not sufficiently great to have much significance, especially as the number of stock litters that was weighed was relatively small. Extracted albinos weigh considerably less at birth than either the stock or inbred rats. This fact is not surprising considering that these animals grow much less rapidly than stock or inbred albinos and that many of them, particularly the females, fail to attain the average adult size of stock animals. Piebald rats, both males and females, have a birth weight that is greater than that of any of the albino strains.

The average weight of the piebald females, as given in table 1, is shghtly greater than that of the males. This is probably a chance variation, since in 12 of the 19 Utters that were weighed the average weight of the males exceeded that of the females. From the single litter of extracted gray rats weighed at birth


216 HELEN DEAN KING

one can obtain but little idea of the birth weight for the strain, yet the records are significant in that they show an average weight for both sexes that is close to the mean betw^een the birth weight of the wild Norway rat, which is about 6.4 grams for both sexes according to Miller ('11) and that of the albino rat.

In any litter of rats, as a rule, individuals of the same sex are practically of the same size and body weight at birth. Occasionally, however, very marked exceptions to this rule are found. In one of the litters of inbred rats the difference in the weights of the various individuals was so unusually great as to call for more than a passing notice.

The litter in question contained eleven individuals, four males and seven females. One of the males, which was the largest rat yet obtained at birth, weighed 7.5 grams; the other three males were nearly uniform in size, weighing 4.9 grams, 5.0 grams and 5.1 grams, respectively. The females in this litter also showed considerable variation in body weight. The largest of the seven females weighed 4.6 grams, the smallest weighed 2.9 grams. The latter is not the smallest birth weight for the rat that has been obtained, however, as in one case in which the mother of the litter was in the last stages of pneumonia when the litter was born, two of the three males in the litter weighed 2.6 grams each; the third male weighed 2.9 grams which was also the weight of the one female in the litter. Female rats do not seem to show as great a variation in body weight at birth as do the males. The largest female yet obtained weighed 5.9 grams at birth; the smallest weighed 2.7 grams.

It seems most probable that such marked variations in the size of the different members of a litter at birth as are shown above must ])e due to a difference in the age of the embryos at the time that parturition occurs, not to causes acting late in gestation. Evidence already presented (King '13) indicates that, under certain conditions, ovulation in the rat may extend over three or four days, possibly longer. Ova liberated at various intervals for several days would probably all be fertilized, as the period of heat in the rat exists for about one week (Miller '11). The body growth of the embryos is very rapid during the latter part


WEIGHT OF ALBINO RAT AT BIRTH 217

of gestation, and embryos that developed from the ova first set free might be expected to have a greater body weight than the embryos that developed from ova hberated late in the period of ovulation, since they would have a longer time in which to grow. Rats born at one period of parturition, however, must be very nearly the same age, as the smaller individuals show no evidence of immaturity other than in their smaller size. If there is considerable difference in the age of the embryos developing simultaneously in the uterus the more mature ones are born first, and the remaining ones are born from one to several days later when they have reached the proper stage of development (King '13).

The variations in body weight found among rats at birth are seemingly greater than those in 'newborn' animals. The largest male in Donaldson's series weighed 6.5 grams, the smallest weighed 4.3 grams: corresponding figures for the females give 6.2 grams as the heaviest weight and 4.2 grams as the lighest weight. In Jackson's series the weights of the males range from 3.4 grams to 6.6 grams and those of the females from 3.5 grams to 6.3 grams.

There is a possible explanation for the narrow range of variation in the weights of 'newborn' rats besides the obvious one that the series of animals weighed was too small to contain the extreme variates in body weight. Individuals that are very small at birth may increase in body weight and in size more rapidly during the first few hours of postnatal life than the members of the litter that have a heavier birth weight. This would tend to equalize the size of the individuals and so give all of them approximately the same chances of obtaining food. The early growth changes in the rat have not been studied sufficiently as yet to give evidence on this point.

In analyzing the data collected in connection with the birth weights with a view of ascertaining, if possible, some of the factors that help to determine the weight of the rat at birth, it has been considered advisable to make use only of the records for the 85 htters of stock and of inbred albino rats. The average weight of the young in the piebald and in the extracted gray litters is so much greater than that of the albinos that the effects


218 HELEN DEAN KING

of these records on the general averages, when taken in small groups, would be altogether disproportional to the number of individuals in^'olved. The birth weights for the extracted albinos, on the other hand, fall so far below those for the other albinos that they seem properly to belong in a class by themselves. It does not seem worth while to analyze the data for these strains otherwise than in the manner shown in table 1. The records are as complete as for the stock and inbred albinos, however, and are filed at The Wistar Institute.

THE EFFECTS OF THE AGE OF THE IMOTHER OX THE WEIGHT OF HER YOUNG AT BIRTH

Slonaker ('12) states that the age of the mother affects not only the number of young rats in a litter but also their weight at birth, young mothers being less prohfic than older ones. He makes no mention, however, of the extent of the data on which this conclusion is based.

Under the conditions existing in The Wistar Institute animal colony the female albino rat usually has her first litter when she is about three months old, and she is capable of bearing young until she is about fifteen months old. In order to study the effects of the age of the mother on the weight of her young at birth the reproductive period in the life of the albino female has been arbitrarily divided into the four following periods:

1. From 90 to 120 days: This is the age when young females are growing very rapidly and the time when the great majority of them cast their first litters.

2. From 120 to 180 days: During this time the female reaches the end of the rapidly growing period and becomes fully mature.

3. From 180 to 300 days: The female is at the height of her reproductive powers during this period and has attained full growth.

4. From 300 to 450 days: In this period there is a dying out of the reproductive power and little, if any, growth.

Table 2 shows the data for the 85 litters of stock and of inbred albino rats arranged in four groups according to the age of the


WEIGHT OF ALBINO RAT AT BIRTH


219


mother at the time that the Utter was born. The data, as arranged in this table, do not show the gradual increase in the body weights of the young from the first to the fourth group that one would expect to find if the age of the mother is the dominant factor in determining the bu'th weight of her young. If, however, we compare the average birth weight of the rats in Utters cast by females during the first reproductive period with that of the individuals belonging to litters born when the reproductive power of the mother is waning, it is found that the average body weights in the first group are considerably less than those in the last group. The difference between them, amounting to 0.3


TABLE 2


Showing the birth weight data for 85 litters of stock and inbred albino rats arranged according to the age of the mothers at the time that litters icere cast



gram in the case of the males and 0.2 gram in the case of the females is sufficiently great, I think, to warrant the conclusion that the weight of a litter at birth depends, to a certain extent, on the age of the mother. During the first reproductive period young females are growing very rapidly both in body size and in bodj^ length and presumably, therefore, the growth processes consume a considerable part of all available energy. Litters cast by females at this time contain, as a rule, few individuals and these are of relatively small size. In older females growth has practicaU}^ stopped and more energy can be used for the production of larger Utters containing individuals that have a heavier weight at birth.


220 HELEN DEAN KING

THE INFLUENCE OF THE BODY WEIGHT OF THE MOTHER ON THE BIRTH WEIGHT OF HER YOUNG

Under normal conditions body weight and age are closely correlated in the rat, as Donaldson's investigations have shown. Body weight, however, being easily affected by changes in environment or in nutrition is, to a certain extent, independert of the age factor and indicates very clearly the physical condition of an animal. Rats that are heavy for their length and age are usually in excellent health; those that are light in weight are generally ill, as certain diseases — for instance, 'pneumonia' — may be shown by a rapid drop in the weight of the animal before any other symptoms of illness are manifested. The body weight of a female, as indicating her general physical condition irrespective of age, may possibly, therefore, be a factor that would tend to influence the birth weight of her young.

As age is the factor that so largely determines body weight in the rat, it has seemed advisable to group the records for the body weights of the females according to age. To do this it is necessary to know the body weights that are normal for various ages. Table 3, compiled from an extensive series of unpublished data collected in the course of my breeding experiments, gives the normal weight of stock and of inbred albino females that correspond with the age groups used as the basis of analysis in the previous section. Inbred albino females are shghtly heavier

TABLE 3

Showing the body weight of stock and of inbred albino rats normal for different age

groups


AGE OP FEMALES IN BATS


NOEMAL WEIGHT OF STOCK ALBINO FEMALES


NORMAL WEIGHT OP INBRED ALBINO FEMALES


90 to 120 days 120 to 180 days 180 to 300 days 300 to 450 days


148 to 173 grams 173 to 195 grams 195 to 219 grams 219 + grams


156 to 175 grams 175 to 199 grams 199 to 221 grams 221 + grams


for a given age than are stock albino females, as is shown in table 3. Since the great majority of the birth weights recorded are of litters belonging to the inbred strain, the body weights


WEIGHT OF ALBINO RAT AT BIRTH


221


of the inbred females have been used as the basis for the grouping of the data in the present instance.

Table 4 gives the various birth weight records arranged according to the body weight of the mothers at the time that parturition occurred. If the body weight of all the females had been normal for the age at which their litters were cast, table 4 would be practically a duplicate of table 2, where the data are arranged according to the age of the mothers. A comparison of the two tables shows, however, a very different distribution


TABLE 4


Showing the birth weight data for stock and inbred albino rats arranged according to the body weight of the mothers at the time that the litters were cast



^


^




fc m


fe z


H Z


^ !5




Q




O S


O "


K "


K S



^3


g




K a


Eh


o


S n


BODY WEIGHT OF FEMALE


O





a "


a H » >3


^:i




K

w to n m 2 « 



m

i-i


<




^ o o






S


b.


H


H


■4


-<


To 175 grams


27


209


98


111


423.8


440.7


4.46


3.86


175 to 200 grams


23

25


222 233


108 111


114 122


491.3 508.7


506.8 524.7


4.55 4.58


4 47


200 to 220 grams


4.30


220 + grams


10


75


41



201.7


158.0


4.91


4.64


of litters in the corresponding groups. The first group in each table happens to contain the same number of litters, but in table 4 this group comprises 9 litters from females that were over 120 days of age when parturition occurred. These females had fallen below the normal weight for their age and were, presumably, not in especially good physical condition. The second group in table 4 contains 6 litters from females younger than 120 days, and 4 litters from females that had passed 180 days of age when the litters were cast. In this group, therefore, 10 of the 23 litters belonged to females that did not have a normal body weight. Eighteen of the 25 litters belonging to the third group of table 4 were cast by females younger than -180 days of age and two of them by females older than 300 days. In the last group only thi-ee of the 10 litters came from females that had a body weight normal for the age of which the litters were cast.


222 HELEN DEAN KING

According to the records as given in table 4, the a\'erage weight of young rats at birth increases directly as the body weights of the mothers increase. ^\Tien the body weights of the females are below 175 grams the average weight of the young males in the litters is 4.46 grams. This average rises to 4.91 grams for the males in the litters cast by females weighing 220 grams or more. Records for the female young do not show quite such uniformity as in the case of the males, since the weights of the individuals belonging to the third group are less than those of the individuals in the second group. The weight of the females in the fourth group, however, is greater by 0.78 grams than that of the females belonging to the first group. This difference is considerably greater than that shown by the males in the two groups.

That these results depend to a considerable extent on the age of the mothers of the litters there can be little doubt, since body weight is closely associated with age and in the noi'mal animals the range of variation is not very great.

If, however, we disregard the age factor and take the body weights of the mothers as indicative of the physical fitness of the animals, it is evident that the heavier females, being in excellent condition, tend to produce young that are larger at birth than the young cast by females that are relatively light in weight and probably, therefore, not in very good condition.

From this analysis of the data it follows that it is not the body weight of the female in itself, but the factors on which the weight largely depend, i.e., age and physical condition, that have a pronounced influence on the birth weight of the young,

THE INFLUENCE OF THE LITTER SIZE ON THE WEIGHT OF THE

YOUNG AT BIRTH

The size of a litter of albino rats depends, seemingly, on a number of different factors, one of which is undoubtedly the age of the mother. Very young females and those that have passed their prime have smaller litters, as a rule, than females at the height of their reproductive powers. The physical condition of the mother is also a factor that apparently affects the litter size,


WEIGHT OF ALBINO RAT AT BIRTH 223

as females in poor condition rarely have a large litter, and if the number of young exceeds the average for the species several of them are usually stillborn. Litter size therefore is another factor so inseparably linked with the age and physical condition of the mother that its influence on the birth weight of the young must be considered in connection with the other factors involved. Unpublished data for over 1000 litters of stock albino rats show that the average litter contains seven j^oung. The size of the litter varies greatly in different cases, the range being from one to thirteen.

TABLE 5

Showing the birth weight data, for stock and inbred albino rats, arranged according to the size of the litter. G, litters cast by females in good physical condition; P, litters cast by females in poor condition


SIZE OF LITTER


&<


m 1


OS



<



S '


X





a


z


■$■


to !




J



< < 1


S^


H


1


B* -• ir -I ac

K « , a S aw

^ < ID \ ~„*' -ST.


o or less


[4(0) 18 ' 9 9 45.1 39.6 o.0l\ I 4.40l

\5(P) 24 10 14 37.3 50.8 3.73/3.62;


6 to 8 30 217 111 106 512,6 464.7 4.61 4.38

9 or more 46 480 228 252 1030.01075.7 4.51 4.26


In order to analyze the birth records on the basis of litter size, the litters have been arbitrarily divided into three groups: small htters, containing five or less young; medium sized Utters, containing six to eight individuals; large litters with nine or more young.

The arrangement of the data according to the above classification is shown in table 5. The data, as shown in this table, seem directly opposed to the generally accepted view that animals belonging to small litters weigh more at birth than those belonging to large litters, since the average weight of both males and females is considerably less for the small litters than for the very large ones. The record cards show, however, that five of the nine small htters were cast by females that were in poor physical condition. In these five litters the average weight


224 HELEN DEAN KING

of the males was 3.73 grams and that of the females was 3.62 grams; in the fom' htters from females apparently in good condition the average weight of the males was 5.01 grams and that of the females was 4.40 grams. Only seven of the 85 htters weighed were cast by females in poor condition, and five of them, as shown above, belong in the small litter group. The other two were litters of medium size, and if their records were omitted from table 5 the average bkth weight of both males and females in this group would be raised shghtly.

It seems justifiable, therefore, to disregard the data for the fi\-e small htters cast by females in ill he'alth and to take the records for the four litters cast by females in good condition as representing the bhth weights for the small litter group. If this be done, the data in table 5 show that the average weight of the 3^oung in small litters greath^ exceeds that for the individuals in large htters: individuals in medium sized litters weigh close to the mean between the weights of the animals in the small and in the large litters. This rule holds true for animals of both sexes, and seems to indicate that the birth weight of young rats depends to a considerable extent on the size of the litter, irrespective of the other factors that may be involved.

Additional evidence that the size of the litter influences the birth weight of the young is furnished by the records for the largest Utter of albino rats as yet obtained. This litter, which belonged to the inbred strain, contained 17 individuals, 10 males and 7 females. The young rats in this litter were several hours old when first examined and they had all suckled, so that it was not possible to obtain their birth weights. The average weight of the 17 individuals at the time they were found was 2.7 grams. At birth, therefore, these rats probably weighed not more than 2.5 grams each. The smallest bu'th weight for the rat that has as yet been taken is 2.6 grams. In this litter, therefore, the very small size of the individuals was undoubtedly due- to the exceptional size of the litter, as the mother of the litter was large for her age and seemingh' in the best of condition when the litter was born.


WEIGHT OF ALBINO RAT AT BIRTH 225

In a study of the weight of guinea-pig Minot ('91) found that the size of the pigs at birth depends to a considerable degree on the number of young in a litter; the larger the htter the smaller the pigs at birth. According to ^Nlinot, the litter size influences the birth weight by changing the length of the gestation period.

When the htter is large the gestation period is shortened and therefore the young pigs do not have as long a time in which to grow as is the case when the litter is small and consequenth^ the gestation period longer. The birth weight of guinea-pigs, therefore, does not depend, according to ^Nlinot, on "the ratio of food supply and demand" but on the length of gestation.

In the rat, as in the guinea-pig, the length of the gestation period varies considerably in different cases. Normally it is from 21 to 23 days,, but in lactating females it may be extended to 34 days (King '13). As far as I am aware, no attempt has been made as yet to ascertain the relation between the number of young in a litter and the duration of gestation in the rat. When a lactating female becomes pregnant the number of young in the second htter is certainly a factor of considerable importance in determining the length of the gestation period, for gestation is prolonged from one to thirteen days if the number of young carried is very large. How the birth weight of the yomig is affected by this prolongation of the gestation period remains, to be determined. Growth is so rapid during the latter part of gestation that the extension of the period for even one day might be expected to materially increase the size of the embryos unless other factors tend to check growth at a certain stage of development.

THE RELATIOX OF THE LITTER SERIES TO THE WEIGHT OF THE

YOUNG AT BIRTH

To arrange the records for the birth weights according to the position of the Utters in the litter series would seem to be merely another way of testing the effect of the age of the mother on the weight of her young at birth, since it is impossible to eliminate the factor of age in carrjdng out such a plan. Female rats show very great individual differences, however, in regard to the


226


HELEN DEAN KING


time when their htters are produced. Seme rats begin breeding before they are three months old; others do not have their first litter until they are four or six months old. Certain females will cast a litter every month for several succeeding months; others never have a litter oftener than every two months and not infrequenth' tlii^ee or four months will intervene between htters even when the females are apparentlj^ in excellent condition.

The plan of the breeding experiments at present under way requires that every breeding female shall have four htters. Some females have the required number of litters by the time they are six months old ; others not until they are a year or more old. While, therefore, the range of variation in the age of the mothers is comparatively shght for the first and for the second pregnancies, it may be extended over several months before the third and the fourth litters are produced.

The litter series must always be, in a sense, an age series, yet the individual variations in the frequency of the litter production are sufficiently great, I think, to make it worth while to study the birth weight records from the point of view of the number of the pregnancy.

Table 6 shows the records for birth weights arranged according to the litter series. An analysis of the litters from several hundred females has shown that the first of a rat's four litters


TABLE 6


Showing the birth weight data for stock and inbred albino rats arranged according to the position of the litters in the litter series



,


a ?:





b. m


6- Z


H Z


f z



^


B

^




o a


O « 


X "


s



e





^ ■<



o




c



i^





a


n



LITTER SERIES

a a


S ° « 


2


Hi

w

<


w




VERAOE OF MA ORAM3


VERAGE OF FEM GRAMS




■<


z


s .



f


H


<


<


1


i

' 22


8.5


187


91


96


400.0


390.2


4.39


4.06,


2


21


S.9


188


82


106


370.8 452.7


4.52


4.27


3


25


0.4


236


125


111


576.6, 492.5


4.61


4.43


4


17


7 5


128


60


68


278.61 296.5


4.64


4.36


WEIGHT OF ALBINO RAT AT BIRTH 227

is usually the smallest, the second and the third the largest, and the fourth a little larger than the first. This rule, however, does not happen to apply in the case of the litter series shown in table 6. Not only is the average number of young in the first group considerably above that which is normal for the species, but it greatly exceeds that for the fourth group; the second and third groups are fairly normal in size. Litter size is, in all probability, a factor that in the present instance does not materially affect the birth weights of the young rats, since the average size of the litters varies but little for the four groups.

Table 6 shows that the birth weights of the males increase with the ascending scale of the litter series; for the females there is a slight irregularity in the figures for the third and fourth groups, but the average weight of the young females in the fourth group is 0.3 grams greater than that in the first group. A comparison of these birth weights with those given in table 2, where the age of the mother formed the basis of the classification of the data, shows that the figures for corresponding groups are much the same, the deviation in no case being greater than 0.07 grams. No other tables given show such close agreement, and, therefore, it appears that the position of a litter in the litter series influences the birth weight of the young chiefly because it so closely involves the factor of age.

THE EFFECTS OF THE PHYSICAL CONDITION OF THE MOTHER ON THE WEIGHT OF HER YOUNG AT BIRTH

One accustomed to the care and handling of rats can quickly tell from the general appearance and weight of an animal whether or not it is in good physical condition. A hunched back, labored breathing, dark red eyes and a relatively light weight indicate internal disorders from which the rat rarely, if ever, recovers. On the other hand, a heavy weight for body size and pronounced vigor in action shows that the animal is in excellent health.

Seven of the 85 females whose litters were weighed were noted as in exceptionally good condition when theu' litters were born, and seven others showed unmistakable signs of ill health. Records for the weights of the litters from these 14 females are given in


228


HELEN DEAN KING


table 7. In the litters from females that were in excellent condition when their litters were born the average birth weight of the 3oung for both sexes is much greater than the normal, and it exceeds the average weights of the young in the litters cast by females that were in ill health by over 1.1 grams, as is shown in table 7. This result indicates that the physical condition of the mother, irrespective of her age, is a very important factor in determining the weight of her young at birth, probably through its action on the nutritive conditions to which the embryos are subjected.

TABLE 7

Shoiving the birth xveiglit data for 14 litters of stock and of inbred albino rats arranged according to the physical conditions of the mothers at the time that the litters ivere cast.



^


3




! §S


S2


£S


£2



ij







tt


o „







' £ « 


5 ="


3n


H »


COXDITIO.V OF MOTHER


o


6.




2 "




i*^



K « ti



to

S

5

m


^ to

< <



w O O




z


z


S


f=,


EH


H


•<;


^


Excellent


7


66


37


29


183.2


136.6


4.95


4.71


Poor


7


39


14


25


53.4


89.5


3.81


3.58


Another way of studying the same problem is to compare the physical condition of the mothers of the litters in which the individuals were unusually heav}^ at birth with the condition of the females that cast litters having a very light weight. Data for such a comparison are given in table 8, w^here the body weights of the mothers of the litters are taken as indicative of the physical condition of the animals. There was a total of 13 litters in which the average weight of the young of both sexes was 5 grams or over at birth. The records show that in ten cases the mothers of the litters weigh considerably more than the amount normal for their age; each of the remaining females had a body weight that corresponded exactly with her age. All 13 litters, therefore, were cast by females that were in very good physical condition as far as one could judge from the general appearance and weight of the animals.


WEIGHT OP ALBINO RAT AT BIRTH 229


TABLE 8


Shoicirig the body weights of the mothers of those litters in which the birth weights of the young were above or below the normal weight


AVERAGE WEIGHT OF YOUNG IN GRAMS


NUMBER OP LITTERS BODY WEIGHT OF MOTHERS


5


or


more


/ I


10 3


above normal normal


■4


or


less


•• {


9 9


below normal normal


No definite conclusions can be drawn from the records of the 18 Htters in which the young had a birth weight of 4 grams or less since the;, results are, in many cases, complicated by the factor of litter size. In 9 cases the body weight of the mother of the litter was below the weight normal for the age indicated; in the remaining cases the weights of the females were normal for their age, but all of the litters were very large (containing from 9 to 14 young) so Utter size was doubtless a factor that had lowered the weight of the young to a certain extent. As far as the evidence from this set of records goes it seems to indicate that, in some cases at least, the small size of rats at birth is due to the poor physical condition of the mother which prevents the proper nourishment of the young and so inhibits their growth.

SUMMARY

1. Data for 113 litters show that the body weight of the young at birth differs considerably in various strains of rats. Stock and inbred albino rats weigh about the same at birth; the average weight of the males being 4.54 grams and that of the females 4.27 grams in the 85 litters that were weighed. Extracted albinos have a very low birth weight; while piebalds and extracted grays weigh much more at birth than do any of the albino strains (table 1).

2. The male rat at birth usually weighs about 0.2 grams more than does the female.

3. There is a wide range of variation in the birth weights of albino rats. The weights for the males range from 2.6 grams

THE ANATOMICAL RECORD, VOL. 9, NO. 3


230 HELEN DEAN KING

to 7.5 grams; those for the females vary between 2.7 grams and 5.9 grams.

4. In any Utter, as a rule, individuals of the same sex are practically of the same size and body weight. Alarked exceptions to this rule are probabh' due to a slight difference in the age of the embryos at the time that parturition occurs.

5. The body weight of rats at birth depends upon a number of different factors that are more or less closely related:

(a) The age of* the mother. Individuals in litters cast by older females weigh more at birth, as a rule, than do the individuals in litters belonging to very young females (table 2).

(b) The physical condition of the mother. Rats in good physical condition bear young with a birth weight considerably above that of the young cast by females in poor condition (tables 7, 8).

(c) The body weight of the mother. The body weight of a female influences the birth weight of her young chiefly because it depends on the two more important factors of age and physical condition. Rats that have a Ver\' heavy body weight are older and in better physical condition than rats with a light body weight, and their litters comprise individuals with a corresponding greater weight at birth (table 4).

(d) The size of the litter. Individuals in small litters weigh more at birth than do individuals in large litters (table 5).

(e) The position of the litter in the litter series. The birth weight of young rats increases directly with the ascending scale of the Utter series. But, as the litter series is always an age series, it is probable that the number of the pregnancy affects the birth weight onh' because it involves the factor of age (table 6).

(f) The length of the gestation period. The evidence regarding the influence of this factor is slight as yet. It is very probable that the prolongation of the gestation period for even one day materially increases the weight of the young at birth.


WEIGHT OF ALBINO RAT AT BIRTH 231

LITERATURE CITED

DoxALDSON, H. H. 1906 A comparison of the white rat with man in respect to the growth of the entire body. Boas Anniversary Volume, New York.

J.\CKSox, C. M. 1912 On the recognition of sex through external characters in the young rat. Biol. Bull., vol. 23.

1913 Postnatal growth and variability of the body and of the various organs in the albino rat. Amer. Jour. Anat., vol. 15.

KixG, Helex Deax 1913 Some anomalies in the gestation of the albino rat

(Mus norvegicus albinus). Biol. Bull., vol. 24. Miller, Newtox 1911 Reproduction in the brown rat (JNIus norvegicus). Amer. Natur., vol. 45.

MixoT, C. S. 1891 Senescence and rejuvenation. I. On the weight of guineapigs. Journ. Phys., vol. 12.

Sloxaker, J. R. 1912 a The normal activitj^ of the albino rat from birth to natural death, its rate of growth and the duration of life. Jour. Animal Behavior, vol. 2.

1912 b The effects of a strictly vegetable diet on the spontaneous activity, the rate of growth, and the longevity of the albino rat. Leland Stanford Junior Univ. Pub.


OBSERVATIONS ON THE ORIGIN OF THE MAST LEUCOCYTES OF THE ADULT RABBIT

PRELIMINARY NOTE

A. R. RINGOEX

From the Histological Laboratory of the Department of Animal Biology, University of Minnesota, Minneapolis

The investigations of Maximow have shown that in mammals the connective tissue mast cells are very different from the mast cells of the blood. _ Maximow and Weidenreich believe that the only feature which the two types of cells have in common is the presence of basophilic granules in the cytoplasm, which stain metachromaticallj^ with basic aniline dyes. The two types of cells, however, represent independent lines of leucocyte differentiation and development, with their own peculiar nuclei and granules.

Maximow ('06) found histogenous mast cells in all the mammals he investigated, even in the rabbit where most investigators have failed. He calls attention to the fact, that where there are relatively few histogenous mast cells, the deficiency is made up by increased numbers of haematogenous mast cells, and vice versa. That such a close compensatory relationship exists between the two tj^Des of cells is shown very well in the adult rabbit, there being comparatively few histogenous mast cells, but numerous mast leucocytes.

Within the past few years the origin of the haematogenous mast leucocyte has been the subject of considerable haematological investigation. The earlier mvestigators, including Ehrlich, assumed that mast leucocytes were represented in the bonemarrow by certain characteristic myelocytes and evolved like the other granular cells. Weidenreich, however, has recently shown that this is not the case with the human mast leucocyte. He believes that human mast leucocytes are formed from de 233


234 A- '^- RINGOEN

generating lymphocytes within the circulation. He derives the mast granules from the fragmenting nucleus and not from the protoplasm of the degenerating cell. Various other investigators in working on the mast leucocytes of the rabbit have come to similar conclusions with reference to the origin of these cells within the blood stream.

In 1909 Proscher concluded from his observations that the mast leucocytes of the blood of the rabbit are merely lymphoid cells of various types whose 'spongioplasm' has undergone a special form of mucoid degeneration, which results in the formation of granules which are closely related to mucin. Mast leucocytes of the rabbit are, therefore, not true granulocytes and are not derived from myelocytes of the bone-marrow.^

Pappenheim's students Benacchio ('11), .Kardos ('11), and St. Szecsi ('12) came to similar conclusions with reference to the mast leucocytes of the guinea-pig and the rabbit. . They could find no mast myelocytes in the marrow of either of these animals; they therefore concluded that the mast leucocytes are not true granulocytes. They beheve that the mast leucocytes of the guinea-pig are merely eosinophil leucocytes whose granules have remained in an unripe basophilic condition. They claim that they can find all the intermediate stages between these so-called mast leucocytes and the ripe eosinophil leucocytes whose granules have an acid staining reaction. Benacchio concluded that all of the myelocytes with basophilic granules in the marrow of the guinea-pig and rabbit were either unripe eosinophiles or special cells. In other words, he believed that all of the granulocytes with basophilic granules were destined to differentiate either mto eosinophiles or into special cells, and that mast cells are not present in the marrow of these animals. ^

1 Pappenheirn came to similar conclusions. His views, however, are based largely upon the work of Proscher.

2 Pappenheirn and St. Szecsi also believe that mast leucocytes are not represented in the marrow of the rabbit. "Die sog. Blutmastleukozyten stai-men natiirlich aus dem Knochenmark, aber z. T. sind sie keine eigentlichen Mastzellen, sondern nur unreifkornige sonstige Granulocyten, deren Granula andere chromophile Reaktion hat, z. T., soweit sie eigentlichen Blutmastzellcn sind. bilden sie sich aus Lymphoid-zellen wohl erst im Blut selbst oder untcr pathologischcr Einwirkung (Myelosc)."


ORIGIN OF MAST LEUCOCYTES 235

In a recent paper Maximow ('13) has shown that mast myelocytes are present in the bone-marrow of man, and that they are actually seen undergoing mitosis. Maximow, therefore, believes that the granules of haematogenous mast ceils cannot be products of the degenerating nucleus or spongioplasm. He could never find any evidence for the degenerative processes described by Weidenreich and Pappenheim. Maximow was able to trace the differentiation of the granules and the evolution of the cells from the tji^ical myelocytes and beUeves, therefore, that the haematogenous mast cells are true granular leucocytes which are equivalent to the other types of granulocytes of the blood and marrow. Maximow is also the chief exponent of the theory that the mast leucocyte of the rabbit is a true granular cell, which is in all respects equivalent to the human mast cell. He found nothing that would lead him to conclude with Benacchio, Kardos, and others that the mast leucocyte is not differentiated in the bone-marrow.

Maximow's observations on the origin of the mast leucocytes are of the greatest importance, but his observations should be confirmed by further studies, since he maintains that the mast leucocytes do not arise in the circulating blood from altered lymphocj^tes, but are differentiated in the marrow from certain specific, characteristic, basophilic granulocytes. Downey's* recent studies ('13) on the mast leucocytes of the guinea-pig have resulted in the complete corroboration of Maximow's findings. He finds that the granules of mast leucocytes can always be distinguished from those of eosinophil and special myelocytes, even though they are subject to shght changes in size and shape. My observations on the mast leucocytes of the rabbit, which were carried on under the direction of Professor Downej^ and to whom I wish to extend my most sincere thanks, are also a further confirmation of Alaximow's results.

It is a well known fact that the early myelocyte stages of eosinophiles and special cells have a primitive or 'prodromale' granulation which is decidedly basophilic when first differentiated.

3 A preliminary report was published in the Proceedings of the American Association of Anatomists, The Anatomical Record, 1914, vol. 8, no. 2.


236 ' A. R. RINGOEN

According to Pappenheim ('12) this primitive granulation is supposed to have nothing to do with the final eosinophilic or special granulation which is developed later. Pappenheim believes that this primitive granulation is basophilic, but that it disappears when the specific granulation develops later. The latter is also basophilic when it first forms. According to Maximow ('13) the prunitive granulation is azurophilic. Downey has shown that in the guinea-pig histogenous mast cells are derived from a type of cell similar to the clasmatocyte with a prunitive granulation. MTiether the primitive granulation disappears or becomes the final mast cell granulation is not known.

Maximow and Pappenheim have called attention to the very decided basophilic quota of j^oung eosmophil and special granules in the eosinophiles and special cells of the rabbit. Bone-marrow of the' rabbit, prepared according to Pappenheim's^ method, show the preponderance of basophilic granules in eosinophil and special myelocytes very well. The granules are seen to ^^ary in size, but are generally rounded or sUghtly irregular and show no definite arrangement withiu the cell body. All of the granules when first formed have a strong affinit}^ for basic aniline dyes, in which respect they resemble the basophilic granules of mast cells. Other cells, however, whose general character is siaiilar to these contain a few granules which are intermediate in staining reaction, having an affinity for both the acid and basic component of the staining mixtm^e which gives these granules a mixed tone. Cells can also be found in which the number of basophilic granules is greatly reduced with a corresponding increase in the number of the intermediate granules. This change of staming reaction in the basophilic granule suggests that the early myelocyte with basophilic granules is being differentiated into a cell in which the granules are acidophilic, and shows that granules of this type are not true mast granules.

Benacchio has made similar observations; however, he goes further and concludes that the myelocytes with basophilic granules, similar to those described above, are the only type of

Folia Haem, Archiv., Bd. 13.


ORIGIN OF MAST LEUCOCYTES 237

basophilic myelocyte present in the marrow of the rabbit; in other words, that all of the myelocytes with basophilic granules are destined to differentiate into eosinophiles and special cells.

Kardos, in workmg with sections of bone-marrow fixed in 100 per cent alcohol and Helly's mixtm-e, found neither mast cells, nor cells of any kind which contained basophilic granules. Paraffin sections and smears were studied in the present investigation, but with decidedly different results from those obtained by Kardos. In sections (material fixed in 100 per cent alcohol and stained in alcoholic thionin) basophilic myelocytes are just as numerous as they are in the bone-marrow smears prepared according to Pappenheim's method. The alcoholic material shows practically the same conditions as are seen in the bone-marrow smears. Sections stained in May-Giemsa show many cells which contain basophilic granules only, while others contain both basophilic and eosinophihc granules, and in still other cells all the granules are decidedly acidophilic. Furthermore, and in direct opposition to the findings of Benacchio and Kardos, it is possible to demonstrate in these same preparations and in smears also, a second type of basophihc myelocyte in the marrow of the adult rabbit. This is the mast myelocyte or the precursor of the mast leucocyte. Scattered throughout the section one sees numerous cells which contain a variable number of granules; the granules have a remarkable avidity for basic aniline dyes. These granules are metachromatic as well as basophilic, in fact, the metachromasia of the granules is so pronounced that they can neither be over-looked nor interpreted as the ordinary basophilic granule of the eosinophil and special myelocyte. The size and shape of the metachi'omatic granule, and the configuration of the nucleus are very suggestive of the mast leucocyte of the blood. On closer investigation and observation their identity is at once apparent.

In the marrow of the adult rabbit, in addition to the fully differentiated mast leucocytes with a more or less poljinorphous nucleus, all intermediate stages between them and their myelocytes can be followed out. In the early myelocyte stages the nucleus is round, but later it becomes polymorphous. A dis


238 A, R. MNGOEN

tinctive feature of the mast myelocyte, as pointed out by iVIaximow, is its very thick nuclear membrane. The writer can also add in further support of Maximow's statement, that eosinophil and special myelocytes usually occur in groups, while mast leucocytes and mast myelocytes appear more or less scattered throughout the section.

Mast mj^elocytes are well preserved in bone-marrow smears fixed in lucidol-acetone and stained in either alcoholic thionin or May-Giemsa. For fixation the solution devised by St. Szecsi^ is used. Smears of fresh bone-marrow were made by rolling a small piece of marrow over a chemically clean cover-slip. Without allowing the smears to dry in the least they were immediateh' placed into a covered dish containing the lucidol-acetone fixative. At the expiration of fifteen minutes the smears were removed from the lucidol-acetone mixture, transferred without drying to another covered dish containing a mixture of acetone and xylol, thi'ee parts of the former to two parts of the latter. St. Szecsi states that the object of using this mixture is to dissolve the lucidol crystals, and clear the preparations, ten minutes are sufficient to complete the process. Finally the smears are placed in methyl alcohol, from one-half to one minute. Bonemarrow smears, provided that the smear is not too thick, are well fixed after being subjected to the action of the lucidol-acetone.

In view of the fact that several modern haematologists have denied the presence of mast leucocytes in the bone-marrow of the rabbit, the lucidol-acetone preparations are of particular value and interest. After seeing a single preparation there can be no doubt as to the presence of mast myelocytes and mast leucocytes in the marrow of this animal. A single preparation usually shows great numbers of mast cells. In a single field I have often counted as manj^ as six fully differentiated mast leucocytes.

The mast myelocyte is such a distinctive type of cell that it is easily distinguished from eosinophil and special myelocytes. In lucidol-acetone preparations stained with May-Giemsa the granules of mast leucocytes stain an intense bluish black, while the

^ His method of procedure appeared in the Deiitschen Medizinischen Wochenschrift, no. 33, 1913.


ORIGIN OF MAST LEUCOCYTES 239

basophilic granules of eosinophiles and special cells are of a reddish black tinge. The sharp contrast in the staining reactions of the mast myelocyte as compared with the eosinophil and special myelocyte is so pronounced and so characteristic that every mast cell is easil}^ separated from the eosinophil or special myelocyte.

Of the various methods tried none gave sharper pictures for the demonstration of mast cells than did the lucidol-acetone fixation. The basophilic granules of the mast leucocyte are very well preserved. In some instances the cell body is so filled with the basophilic, metachromatic granules that the outline of the nucleus is extremely difficult to follow.*^ In cases, however, where the exact outline can be seen, I find that the nucleus is typically polymorphous and shows no similiarity to a lymphocyte nucleus, neither does it possess lymphocyte characters nor show signs of degeneration. My preparations showed nothing to support Proscher's theory that the mast leucocyte is derived from a h^mphocyte and that the nucleus remains practicalhidentical with the lymphocyte nucleus. In all probability Proscher based his theory on the early, basophilic, mononuclear myelocj^tes of eosinophiles and special cells. At any rate, the technique which he used was such that the granules of mast leucocytes would not be preserved.

The lucidol-acetone preparations show further that the basophilic granules of mast leucocytes vary in form, size, and in number as previously stated. In the rabbit the granules are fine, usually rounded or slightly irregular. As far as the mast leucocyte of the rabbit is concerned there is no evidence to show that the nucleus is concerned in the elaboration of the granules, as is claimed by Weidenreich for the mast leucocyte of man. Proscher also claims that the nucleus takes no active part in the elaboration of granules.

Maximow's method of fixing bone-marrow in 100 per cent alcohol followed by staining in alcoholic thionin or May-Griinwald was also tried. These preparations also show that the

^ A more detailed description of these cells, with figures, will appear in the final publication (Folia Haematologica). »


240 A. R. RINGOEN

mast leucocytes are present in the marrow and that the staining reactions are very characteristic. It is not the object of the -WTiter to re-describe Maximow's results with this method.

In previous work on the mast leucocytes of the rabbit, Maximow has called particular attention to the fact that the granules of these cells are extremely soluble in water, and has cautioned against using watery fixatives and watery stains. The writer found that after fixation in Helly's mixture no mast granules could be detected with any of the various stains used. This would indicate that the mast granules are soluble in water. However, after alcohol and lucidol-acetone fixation, the granules are able to resist the short exposure to water to which they are subjected while being stained in the Giemsa solution. In the material fixed in Helly's mixture, however, the granules are exposed to the action of water for a long period of time which is sufficient to dissolve them. It is obvious that only those methods of technique which preserve the granules will be of real value in determining the origin of mast leucocytes, since the cells are difficult to recognize after their granules have been dissolved out. Little heed has been given to Maximow's repeated warning as to the solubility of the granules in water, and in all probability this accounts for the fact that Benacchio and others have failed to find mast leucocytes in the marrow of the rabbit.

SIBEVIARY

The bone-marrow of the rabbit contains true mast myelocytes with basophilic granules in addition to the myelocytes of eosinophiles and special leucocytes whose granules are also basophilic. With ordinary methods all of the myelocytes with basophilic granules seem to belong to the latter two types of leucocytes, but after fixation in alcohol, or better in lucidolacetone, the granules of the true mast leucocytes are also preserved. Their distinctive characters are such that they can always be distinguished from the basophilic granules of the eosinophil and special myelocytes.


ORIGIN OF ]VL\ST LEUCOCYTES 241

The general life history of the mast leucocyte runs parallel to that of the other granular leucocytes of the bone-marrow. Their granules are differentiated gradually out of the basophihc cytoplasm of mononuclear cells. The granules are strongly basophilic from the moment of their first appearance and remain so throughout the life-history of the cell. As the number of granules increase the nucleus gradually changes shape, becoming distinctly polymorphous in the fully differentiated cell.

Fully differentiated mononuclear mast leucocytes are never found in the blood or marrow of the adult rabbit. These cells, therefore, do not show the relationships to lymphocytes of the circulation described by Prdscher and others, and they are never differentiated from the lymphocytes of the circulating blood in the normal animal.

When the proper methods of fixation have been used the mast leucocytes of the rabbit show no evidence whatever of degenerative changes. Then' granules are, therefore, not products of a mucoid degeneration of the spongioplasm of lymphocj'tes (Proscher, Pappenheim and others), but are formed by the progressive differentiation of the cytoplasm of mononuclear cells of the bone-marrow.

The haematogenous mast cells of the rabbit form a distinct and independent line of granulocytes which is in no way related to the eosinophil or special leucocytes excepting through the non-granular parent-cell of the bone-marrow.

LITERATURE CITED

Benacchio, G. 1911 Gibt es bei Meerschweinchen und Kaninchen Mastmyelocyten und stammen die basophilgekornten Blutmastzellen aus dem Knochemnark? Folia Haem., Archiv, Bd. 12. Downey, H. 1913 The development of the histogenous mast cells of adult guinea-pig and cat, and the structure of the histogenous mast cells of man. Folia Haem., Archiv, Bd. 12.

1914 Heteroplastic development of eosinophil leucocytes and haematogenous mast cells in bone marrow of guinea-pig. Anat. Rec, vol. 8, no. 2.

1914 The origin and development of eosinophil leucocytes and of haematogenous mast cells in the bone marrow of the adult guinea-pig. To be published shortly in the Folia Haem.


242 A. R. RINGOEN

Kardos, E. 1911 Uber die Entstehimg der Blutmastzellen aus dem Knochen mark. Folia Haem., Archiv Bd. 11, part 1. AIaximow, a. 1906 Uber die Zellformen des lockern Bindegewebes. Archiv,

f. mikr. Anat., Bd. 67.

1907 Experimentelle Untersuchungen zur postfotalen Histogenese

des myeloiden Gewebes. Beitr. z. path. Anat. und allg. Pathol., Bd. 41.

1910 Die embryonale Histogenese des Knochenmarks der Saugetiere.

Archiv f. mikr. Anat., Bd. 76.

1913 Untersuchungen liber Blut und Bindegewebe. Vi Uber Blutmastzellen. Archiv f. mikr. Anat., Bd. 83, Abt. 1. Pappexheim, a. 1899 Vergleichende Untersuchungen iiber die elementare

Zusammensetzung des roten Knochenmarks eineger Saugetiere. Virch.

Archiv, Bd. 157.

1904 Zusatz zu der Mitteilung von Proscher uber experimenteller

Leucocytosen. Folia Haem., Bd. 7.

1912 Zur Blutzellfarbung im Klinischen Bluttrockenpraparat und

zur histologischen Schnittpraparatfarbung der hamatopoetischen

Gewebe nach meinen Methoden. Folia Haem., Archiv, Bd. 13, 1.

Tail. Pappenheim, a. und St. Szecsi 1912 Hamoz3'tologische Beobachtung bei

experimenteller Saponinvergiftung der Kaninchen. Folia Haem., Bd.

13. Proscher, Fr. 1909 Experimentelle basophile Leukocytose beim Kaninchen.

Folia Haem., Bd. 7. St. Szecsi 1913 Lucidol, ein neues Fixiermittel. Deutsche Medizinische

Wochenschrift, no. 33. Weidenreich, F. 1908 Zur Kenntnis der Zellen mit basophilen Granulationen

im Blut und Bindegewebe. Folia Haem., Bd. 5.

1910 D.'e INIorphologie der Blutzellen und Ihre Beziehung zu Einander. Anat. Rec, vol. 4.

1911 Die Leucocyten und verwandte Zellformen. Weisbaden, J. F. Bergmann.


A NOTE ON THE COURSE AND DISTRIBUTION OF THE NERVUS TERMINALIS IN MAN

ROLLO E. .AIcCOTTER

From the Deparlment of Anatomy oj the University of Michigan

TWO FIGURES

Johnston ('13) was the first observer to determine the presence of the nervus terminahs in man. He first reported its occurrence in human embryos and later ('14) described the nerve for the adult. Brookover ('14), working independently, also observed the presence of this nerve in adult man. Apparently the material used by these authors permitted only of the examination of a portion of the intracranial course of this nerve. It is the purpose of the present paper to report observations on the intracranial course and nasal distribution of the nervus terminahs in man.

The observations about to be reported are based on gross dissections of prepared specimens of the heads of several human fetuses varying in age from ten weeks to the newborn. Two adult heads were examined. The ner\'Tis terminalis was identified in all the specimens. Drawings were made from the two most favorable dissections. Figures 1 and 2 represent such drawings. The former represents the medial sagittal dissection of the head of a six-months human fetus, the latter a similar dissection of a ten-weeks human fetus. For purposes of dissection the specimens were prepared as described by the writer ('12) in a previous communication.

The intracranial portion of the nervus terminalis, as shown in figure 1, appears on the surface of the brain in the region of the olfactory trigone and courses anteriorly over the medial surface of the olfactory tract and bulb and on to the lateral surface of the crista galli, to pass thi'ough foramina in the cribri 243


244 ROLLO E. McCOTTER

form plate well forward. In its course over the medial surface of the olfactory tract it will be seen that the nerve forms a compact bundle of nerve fibers. On the medial surface of the olfactory bulb, however, it breaks up into a close plexus of fibers intimately associated with the fila olfactoria. It forms


Fig. 1 Medial section of the head of a six-months human fetus with the nasal septum removed, showing the origin, course and distribution of the nervus terminalis. Cor. Col., corpus callosum; A.C., anterior commissure; N.T., nervus terminalis; O.B., olfactory bulb; O.N., olfactory nerves; V.N.N. , vomero-nasal nerves; V.N.O., vomero-nasal organ; Hy., hypophysis.

a loose plexus on the lateral surface of the crista galli imbedded in the layers of the dura mater. In this position the separated filaments of the nervus terminalis lie some distance dorsal to the cribriform plate of the ethmoid bone instead of lying directly on its upper surface as do the fila olfactoria. In the specimens examined the height to which the nerve attains on the lateral surface of the crista galli or the amount of arching upw^ard of


NERVUS TERMINALIS IN MAN


245


the filaments of the nervus terminahs in this region, depends apparently upon the degree of development of the crista galli. The distribution of the nervus terminalis to the nasal septal mucosa is similar to that described by Huber and Guild ('13) for the rabbit. Within the cranium filaments of the nervus terminalis join the olfactory and the vomero-nasal nerves and



Fig. 2 Medial section of the head of a 4.5 cm. human embr3^o, with the nasal septum removed to show the origin, course and distribution of the nervus terminalis. C.H., cerebral hemisphere; L.T., lamina terminalis; N.T., nervus terminalis; P.C., posterior commissure; O.B., olfactory bulb; S.P., soft palate; V.3, third ventricle; V.N.O., vomero-nasal organ.

apparently pass to the septal mucosa with them. The majority of the fibers, however, form a single strand and pass through the cribriform plate anterior to the exit of the vomeronasal nerves. Upon reaching the nasal cavity the nervus terminalis takes a path anterior to that of the vomero-nasal nerves, lying just posterior to the antero-superior border of the nasal septum. In figure 1 it is represented as breaking up into three main filaments which can be traced downward nearly to the level of the vomero-nasal organ. In the first part of its nasal course it is joined by a small filament from the mechal nasal branch of the anterior ethmoid ner\'e.


THE ANATOMICAL RECORD, VOL. 9, XO. .3


246 ROLLO E. McCOTTER

In figure 2 the long axis of the olfactory tract and bulb occupies a plane approaching the perpendicular instead of the horizontal, as is shown in figure 1. The nervus terminalis appears on the surface of the brain in relatively the same position as in figure 1 and passes directly downward to the cribriform area where it lies in close proximity to the vomero-nasal nerves. After sending a few strands to accompany the vomero-nasal nerves the larger portion of the nervus terminalis passes through the cribriform area and is distributed to the septal mucosa anterior to the path of the vomero-nasal nerves.

In conclusion it may be stated that on account of the relation of the nervus terminalis to the crista galli, where the latter is sufficiently developed to cause a stretching out, as it were, of the overlying dura mater with its contained nerve, the continuity is here usually lost in gross dissections and the fibers associated with the vomero-nasal and olfactor}' nerves alone remain to determine its distribution to the septal mucosa.

The distribution of the nervus terminalis in man as in the rabbit is mainly to the mucosa of the nasal septum anterior to the path of the vomero-nasal nerves. Their ultimate terminations could not be determined.

LITERATURE CITED

Brookover, Charles 1914 The nervus terminalis in adult man. .Jour.

Comp. Neur., vol. 24, p. 131. HuBER, G. Carl, and Guild, S. R. 191.3 Observations on the peripheral

distribution of the nervus terminalis in mammals. Anat. Rec, vol.

7, p. 253. Johnston, J. B. 1913 The nervous terminalis in reptiles and mammals.

Jour. Comp. Neur., vol. 23, p. 97.

1914 The nervus terminalis in man anrl mammals. Anat. Rec,

vol. 8, p. 185. McCoTTER, R. E. 1912 The connection of the vomero-nasal nerves with the

accessory olfactory bull) in the opossum and other mammals. Anat.

Rec, vol. C, p. 29'i.


ox WEBER'S :^1ETH0D OF RECONSTRUCTION AND ITS APPLICATION TO CURVED SURFACES

RICHARD E. Sa^IMON

Institute of Anatomij, University of Minnesota

FIVE FIGURES

In embiyological work it is sometimes a matter of importance to determine with accuracy areas of epithelial thickening which are not demonstrated satisfactorily by the ordinary methods of graphic or plastic reconstruction. Placodal thickenings of the skin ectoderm, thickened zones in the neural tube, and the thickened areas found in the early archenteron are examples of structures which are not well demonstrated by these customary methods. A method of reconstruction which brings out graphically the extent and comparative thickness of such areas was de\ised some years ago by A. Weber /and was used by him with much success in the study of the very early development of the great glands of the digestive tract. Weber first published an account of his method in 1902,' and again a shorter summary in connection with the final report on his work in the following year.- Apparently the method has not been employed elsewhere. I have found it of such interest in the study of the earlier stages of the pancreas and li^'er that it has seemed desirable to present it here with some modifications which may be found useful, particularly in its application to curved surfaces.

AVeber's method is based upon that of graphic reconstruction' from transverse sections. An outline (from either lateral or dorsal view, as desired) of the organ to be reconstructed is plotted

^ Une methode de reconstruction graphique d'opaisseurs et quelques-unes de ses applications a I'embryologie. Bibliog. Anat., T. 11.

- L'origine des glandes annexes de T intestine moyen chez les vertebres. Arch. d'Anat. Micr., T. 10.

■2A7


248 RICHARD E. SCAMMOX

out on transverse section lines in the customary manner. Instead, however, of completing the reconstruction by indicating the contour of the surface thus outlined (as is commonly done), the thickness of the wall which forms that surface is measiu'ed in the transverse sections, and the variations in this thickness are plotted out upon the reconstruction. The reconstruction will then bear a nmiiber of lines which mark the boundaries between areas of epithelium of different thicknesses. To finish the reconstruction, the areas thus outlined are filled in with different shades of a single color, the darker shades being used for the thicker areas of the epithelial wall. The finished reconstruction then will exhibit the outline of the structure and the variation in the thickness of the part of its wall which is shown in this particular view. It will give no conception of the surface modeling of this wall aside from what can be determined from the outline alone.

The picture obtained is much the same as would be secured were it possible to remove the wall of the structure, render it translucent and, magnifying it greatly, hold it before a bright light. The thicker portions of the wall would then appear to the observer as darker areas, as they do in the reconstruction.

Figure 1 is a graphic reconstruction of the left side of the archenteron of an embrj'o of Torpedo ocellata, 4.0 mm. in length (Xo. 765 of the Harvard Embryological Collection). The portion of the gut l.ying on either side of the anterior intestinal portal and included between the lines A and B has been reconstructed by Weber's method and is shown in fgure 4. The latter figure shows by means of its coloring a broad band of thickened epithelium extending dorso-^'ent rally across the gut at the level of the anterior intestinal portal. The lower and thickest part of this band represents the anlage of the gall bladder and liver, while the upper part includes the future pancreatic region. A thickened spur extends backward from this zone, and marks off the line along which the intestine will eventually separate from the yolk-stalk ventral to it.

The method of prepaiiition of such reconstructicms can best be explained in detail by following an example of the process.


ON WEBER S METHOD OF RECONSTRUCTION


249


For this purpose I will use the reconstruction shown in figure 4 which has just been described.

In preparing this reconstruction, drawings were made of each section of the portion of the gut involved, although fairly satisfactory results can be secured with drawings of every other section. These drawings should be made at a high magnification, preferably over 300 diameters. As the sections are drawn, the}' show of course the curvatures of the contour of the archenteron wall. It is desirable to eliminate these curvatures in the reconstruction and to present the gut wall as an approxi


Fig. 1 A graphic reconstruction (lateral view) of a portion of the archenteron of an embryo of Torpedo ocellata 4.0 mm. long (H.E.C. 765). X 30. The outline of the embryo is represented in broken line. The archenteron is drawn in solid line. The jiortion of the archenteron lying between the dotted vertical lines A and B is shown in a Weber's reconstruction, at higher magnification, in figure i. • ■


mately flat plane. If this is not done, areas which project sharph' from the general plane of the archenteron will be represented in the reconstruction as much narrower than they actually are in the specimen or, if small, may be lost entirely. To eliminate these curvatures, it is necessary to divide the outer margin of each section into a number of short cords or segments, each of which will be comparatively straight, and to lay off segments of an efiual length on the transverse section lines of the reconstruction. This can be done with a pair of small screw compasses. For work at a magnification of 300 diameters and over,


250 RICHARD E. SCAMMOX

segments of 1 cm. are small enough to eliminate most of the error from curvature. Figure 2 is of a section (No. 104) of the reconstruction under discussion. The short lines on the inner side of its margin represent the boundaries of these centimeter segments.

The thickness of the epithelium forming the gut wall is now to be measured in each drawing. For this purpose a unit of measurement must first be determined. Working with drawings made at a magnification of 300, it has been found that the 1.5 mm. is the smallest unit practicable for such a scale. By using this unit one is able to measure ^'ariations of less than 5 micra in the thickness of the gut wall, and errors of projection and ch"awing would probably render more refined measurements of little value. A scale of 1.5 mm. units is laid out upon a stiff card, or better, a piece of transparent celluloid. This scale or gauge is then passed over each section, care being taken to keep its graduated margin at right angles to the axis of each segment of the drawing and its zero point at the inner margin of the epithelium. This process is begun at the dorsal median line on each section and is carried laterally or ventrally from that point. At the first place where the thickness of the epithelium is found to correspond to a graduation point on the scale, a fine line is drawn out to the side of the section and the thickness noted at its end. The scale is carried along the section imtil a point is reached where the thickness of the epithelium corresponds with the next graduation (either above or below the former one) on the scale. Again a line is drawn out from the section at this point and the thickness noted. This process is continued until the entire side of the section has been gauged and marked off into segments in which the variation in thickness is not over 1.5 mm. on the drawing or 5 micra in the corresponding section. An example of a section thus gauged is shown in figure 2. As shown by the gauge lines, the epithelium immediately below the dorsal median Une is between 30 and 25 micra f6.5 mm. at X 300) in thickness. The thickness falls to 25 micra at the point indicated. This is followed by a broad zone which is less than 25, but over 20 micra thick. Ventral to this zone, the epithelium increases to


ox WEBER S METHOD OF RECONSTRUCTION


251


a thickness of between 35 and 40 micra, and then again decreases to less than 10 micra as it approaches the blastoderm. The arrows seen in the figure point towards the thinner edge of the segment and are used to avoid _confusion in mapping out the gauge lines on the reconstruction at a later time. It is impor


%H


Fig. 2 Drawing of a transverse section of the archenteron of a Torpedo embryo 4.0 mm. long (H.E.C. 765) showing the method of measuring sections for reconstruction by Weber's method. The short lines extending into the section mark the centimeter segments used in eliminating lateral curvature from the section. The longer lines extending out to the right from the section are the gauge lines. The figures at the end of the gauge lines indicate in micra the thickness of the epithelium at the points touched by them.

tant that in gauging the section drawing the scale be held at right angles to the long axis of that particular part of the wall which is being measured rather than at a similar angle to either the inner or outer surface of the epithelial strip. This holds particularly when gauging the thickness of an epithelial band which


252 RICHARD E. SCAMMON

is rapidh' changing in caliber, or when gauging a portion of a band which forms a sharp curve. Failure to observe this precaution causes noticeable error both in the gauge readings and in the position of the gauge points on the drawing. There will often be encountered considerable portions of the wall, the thickness of which corresponds exactly to the gauge unit or a multiple of it. My rule, made arbitrarily, has been to mark as the gauge point the first Ti.e., most dorsal) level at which such a zone is encountered.

A reconstruction outline is now made on section-lined paper in the usual manner, except that only the dorsal margin of the gut is mapped out. Using this margin line as a base, the transverse section lines are divided into centimeter segments corresponding to those made on the margins of the drawings of the sections. In practice it is convenient to mark the point separating each block of 5 cm. segments in a different color to aid in plotting. The ventral margin of the gut and the gauge points, which have been determined on the cross section drawings, are now plotted on the transverse lines of the reconstruction in the usual manner, except that instead of measuring the distance of each point from the dorsal margin of the section and transferring this measurement to the corres])onding section line as is customary, one measures the distance of the point from the nearest centimeter mark in each case. The ventral outline of the reconstruction and the gauge lines indicating the thickness of the epithelium are established by connecting all the points of the same order as is done in an ordinary graphic reconstruction. The reconstruction will now have the form seen in figure 3. There the base and transverse reconstruction lines are lightly drawn and the centimeter segment points are indicated as small dots on the latter. The outline of the reconstruction is indicated in heavy line. The ventral margin posterior to the anterior intestinal portal has been cut away arbitrarily in a straight line. The gaug(^ lines indicating the thickness of the epithelial wall of the organ are represented in heavy broken line. The vertical figures placed at the termination of the gauge lines indicate their values in micra.


ON WEBER S METHOD OF RECONSTRUCTION 253

90 s lOO


110


120


130



30 20 10


Fig. 3 Reconstruction plat of a Weber's reconstruction (lateral view) of the portion of the archenteron bounded by the lines A and B in figure 1. The light vertical lines represent the transverse sections. The outline of the reconstruct on is represented in heavy solid lines. The gauge lines bounding areas of epithelium of different thicknesses are represented in heavy broken lines. The dots on the transverse lines represent the boundaries of the centimeter segments described in the text and shown in figure 2. The vertical figures at the margins of the reconstruction give the value of the gauge lines in micra. The figure is reduced to one-half the size of the original reconstruction, which was made at a magnification of 350.

There remains but to color in the areas which are marked off by the gauge Imes. Weber did this with water-color and secured excellent results, as his figures show, but a much simpler and quite as satisfactory a method is to use papers of different shades of gray for the different areas. Such papers should be as near 'pure' mixtures of black and white as it is possible to secure. The only kind which I have found satisfactory is the 'Herring' series which has been prepared for color work in psychological


254 RICHARD E, SCAMMOX

laboratories. The shades numbered 3, 4, 7, 10, 16, 20, 30, 42 and 46 make a satisfactory series of marked but fairl}- equal gradations.

To build up the final colored reconstruction gray papers are selected, equal in number to the areas mapped off on the reconstruction by the gauge lines. The entire outline of the reconstruction is now traced upon the lightest colored paper. This area is cut out and pasted firmly upon a piece of compo or plaster board. Upon the paper of the next darker shade there is traced an outline similar to the preceding except that the space representing the thinnest area is cut away. This second sheet is pasted upon the first one so that the similar angles and sides correspond. In this way the area of thinnest epithelium is represented by the lighter colored paper and all thicker areas by the darker one. This process is continued, all thinner areas being cut aw^ay from each new outline until the darkest and final shade of paper will have the shape and will represent the area of the thickest epithelium only. This method of building up the papers of different colors in strata will l)e found much easier than to cut out each separately and then attempt to fit them together in a mosaic. Figure 4 is a half-tone made directly from such a colored reconstruction and based upon the plotting illustrated in figure 3.

The example just described is of a lateral view reconstruction. Reconstructions may be made by Weber's method to show dorsal or ventral views of epithelial structures as well. For this purpose the transverse sections of the structure are drawn and measured in the same manner as that described. A reconstruction i:)lat is then laid out as follows. A vertical line is drawn in the middle of the sheet to represent the dorsal median line of the structure and transverse section lines are di'awn on either side at the proper distance apart and at right angles to the median vertical one. The centimeter points, which on lateral view reconstructions must be measured off on each transverse section line, can be located on the plat in this case by simply ruling vertical lines parallel to and at centimeter intervals from the median one. The gauge i)oints and lines mai'king the boundaries


ox WEBER S METHOD OF RECONSTRUCTION


255



Fig. 4 A finished \yeber's reconstruction (lateral view) made from the plat represented in figure 3 and including that part of the archenteron lying between the lines A and B in figure 1. The thicknesses of the epithelium in several parts of the reconstruction are represented bj^ the various shades of grav. Starting with the lightest, these several shades represent the following epithelial thicknesses; (1) below IOjjl; (2) 10 to 15^; (3) 15 to 20^; (4) 20 to 2om; (5) 25 to 30^; (6) 30 to 35m; (7) 35 to 40m ; (8) above 40m. This figure is reduced to tlueo-fifths the size of the original reconstruction.


between areas of different epithelial thickness are mapped out as in the lateral-view reconstruction. Should the reconstruction be of a tubular structure, the ^'entral median line must be determined in each cross section drawing. In reconstructing, the tube is then represented as split along its ventral median line and flattened out lateralh^; i.e., the lateral margins of the reconstruction represent in fact the ventral median line of the original tube. Figm-e 5 is an example of such a reconstruction plat made from the same object employed for the lateral view reconstruction already described. The method of representation and lettering are the same as used for figure 3.


256 RICHARD E. SCAMMON

Several of the possible uses and advantages of this method of reconstruction have been mentioned. It remains to speak of a few disadvantages and sources of error. In the first place the outlines of the reconstructions, aside from the one used as a base line, are not strictly such as would be secured by the ordinary graphic or plastic methods. In eliminating the lateral curvatures from the transverse sections, the dimensions of the figure are increased dorso-ventrally or laterallj^, as the case may be, without a similar increase antero-posteriorly. Weber made no attempt to eliminate the curvature seen in cross sections, regarding it in fact as of some value in indicating contour. I have already pointed out the disadvantage in reconstructing without making this correction, which I think should be done even at the expense of some accuracy of outline, which can easily be determined by the other reconstruction methods.

While the error introduced by this method is small when dealing with structures having surfaces approximating those of cones or cjdinders, it is considerable when applied to spherical surfaces. Spherical surfaces do not admit of being spread out into planes as do those of cones and c^dinders. Cartographers, who have much this same problem in representing large areas of the globe, have developed a number of methods of projection to meet, in part, this difficulty. These are, however, too complex for our work and are all based upon representations of the perfect sj^here. For the purpose at hand surfaces which approximate spherical ones can best be treated by first compensating for the vertical curvature by the method of segmenting the outline of the section already described; and, second, by allowing for longitudinal or horizontal curvature by increasing the distance separating the cross section lines on the reconstruction plat. T\w latter can be done by determining the actual length of the outline of the structure to be reconstructed and dividing this distance by the number of sections which the structure contains. Multiplying the figure thus secured by the magnification at which the reconstruction outlines are drawn gives one the distance which should separate the section lines on the reconstruction plat. This j)ractice differs from that of ordinary reconstruction in


ON WEBER S METHOD OF RECONSTRUCTION


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258 RICHARD E. SCAMMOX

that the longitudinal axis of the structure is used in the customary method instead of the actual length of the outline as in this case. Reconstructions made with these corrections will show approximately the area and shape of any gi\-en outline upon a curved surface, although neither will be strictly accurate. As a rule such correction will be unnecessary unless one is dealing with surfaces which curve very abruptly. INIeasurements of the thickness of epithelial plates which curve longitudinally or horizontally will always be a little exaggerated because such plates are cut somewhat obliquely by transverse sections. There seems to be no practical way of eliminating this error.

Finally, the reconstruction will represent the variations in thickness of the epithelium as occurring in definite steps and not as gradual transitions as in nature. Alost of this artificial distinction can be ehminated by using the smallest unit of measurement practicable and thus increasing the number of shades present in the reconstruction while decreasing the degi'ee of their difference. Great reduction of figures in their reproduction also aids in securing the effect of gradual transition.


ox THE STRUCTURE OF THE ERYTHROCYTE

CHARLES D. CUPP

From the Depnrlmeni of Anatomy, Tulane University of Louisiana

FOUR FIGURES

This paper was undertaken with the hope of contributing something as to the structure of the so-called stroma of erythroc3'tes and as to the presence and character of a capsule or cell-membrane belonging to them.

The fact that the mammalian red blood corpuscle upon losing its nucleus becomes biconcave, its peripheral ring remaining thicker than its central region from which the nucleus has been lost, has always suggested the existence of a supporting framework. Were the corpuscle merely a hemoglobin-carrying sac borne in the blood stream, the natural tendency would be for it to assume a spherical form, the pressure on all sides being equal. The mammalian erythrocyte after being carried through capillaries smaller than its diameter, and after being drawn around angular cur\'es of capillaries, which may stretch and modify its form considerably, always resumes its original form when returned to larger capillaries. This not only suggests a supporting frame-work for its content but also that this framework is plastic or even possesses certain elasticity.

The question of a membrane about the corpuscle is most disputed in the discussions. The most frequently advanced theory against the existence of such is that the corpuscle possesses no membrane at all but is merely co^'ered by a film of lecithin or other lipoid substance acquired from its environment, and Xorris (Physiology and pathology of blood '82) even suggests evidence that fluid droplets enclosed by lipoids (myelin) tend to assume flattened shapes, while when enclosed by films of ordinary fats they are invariably spherical. The very probable presence of a film of some lipoid or fat surrounding the entire corpuscle is

259


260 CHARLES D. CUPP

seldom disputed and is accepted here. This is indicated by and explains the phenomena of forming into rouleaux and is supported by other arguments as well. But the presence of such a film need not disprove the existence of a membrane or capsule as a structure belonging to the corpuscle itself and which may be covered without b}^ a film of lipoid substance. Fluid droplets enclosed in lipoid or fat films when shaken will become divided into smaller droplets and droplets of greatly var^'ing size, whereas the erythrocytes of normal blood are strikingly uniform in size and while shaking them may break up or burst many of them, fragments resulting do not assume the form of the original corpuscle. Further, it seems very improbable that a film of lipoids alone would result in the folded and crumpled appearances shown by the so-called 'crenated corpuscles' resulting from extraction of a portion of the content. On the contrary, it would seem that such a film, still in the blood plasma, would merely thicken instead of becoming folded. Also, crenated corpuscles have lost the biconcave form, do not have the flattened shape suggested by Xorris for fluid droplets surrounded by a film of lecithin. Crenation is suggested here as indicating the presence of a membrane intrinsic to the corpuscle which has become folded due to partial extraction of the original content by exosmosis, the crenated corpuscle becoming approximately spherical, due to a disturbance or destruction of its original internal structure by the process. The chemical compound, hemoglobin, so far as is known, has no anatomical structure. It is a complex organic compound in solution capable of various degrees of dilution. The loss of the biconcave form in crenation and the assumption of the spherical form in swelling from the action of distilled water, for example, suggest the destruction of a framework in wliich the hemoglobin was supported and })y wliich the biconcave form of the nonnucleated corpuscle was maintained.

The original cell, the typical cell, possesses a framework of spongioplasmic filaments, a cytoplasmic and karyoi)lasmic reticulum, in the meshes of which are the more fluid portions (hyaloplasm) and the various forms of granules comprising the structure and content of the cell. In the functional differentiation


STRUCTURE OF THE ERYTHROCYTE 261

of certain cells a marked increase in the evidence of a cytoplasmic reticulum is well known. The neuro-fibrillae of the nerve cell, for example, consist of anastomosing filaments more abundant and more evident than in the germinal or neuroblast stage of this element. Certain functioning gland cells show a reticulum in their cytoplasm. Hardest}' COo) and Nemiloff ('10) have shown that the emulsion comprising the medullary sheath of the nerve fiber has its component globules suspended and supi:)orted by a delicate reticulum, Hardesty showing this reticulum to be continuous into the membrane or neurilemma without and into a thinner bounding membrane (axolemma) about the axone of the ner\'e fiber, and that this framework and these two membranes, and not the fat of the sheath, maintain the shape of the sheath. He considered the membranes of the sheath as condensations of the internal framework. It is very probable that the corpuscle of adipose tissue, the fat cell, possesses an internal framework continuous with its capsule, both maintaining its general shape. Schafer (vol. 2, part 1, Quain's Anatomy, 11th edition, '12) cites the fact that an erythrocyte, that of the newt for example, may be cut into two without resulting exudation of its content. Like the medullary sheath, the muscle fiber, the nerve cell or the fat corpuscle, the erythrocyte is an example of an especially differentiated arrangement for the performance of a special function.

The findings in the literature dealing with the structure of the red blood corpuscles seem to vary according to the methods of preparation used by the various authors and according to the different interpretations of the results obtained by them. Of the very voluminous literature, many of the papers consulted indicate a lack of familiarity with histology in general and an incompleteness of investigation to an extent that they seem of no value here. Howe\'er, some authors give definite statements as to what they deem the structure of the erj'throcyte and a number have considered the subject thoroughh'.

Renant in his Histology ('89-'93) says red blood corpuscles possess no true cell-membrane, but merely a peripheral condensation of the cytoplasm such as that formed about a cell when

THE AXATOMICAL RECORD, VOL. '.), XO. 3


262 CHARLES D. CUPP

exposed to air. Von Ebner (in Kolliker's Handbook, '02) states that a membrane must be assumed on the surface of the erythrocyte, a membrane insoluble in water and which allows osmosis, but which cannot be called a membrane in the ordinary sense and may be similar to the exoplasm of other cells. Lohner ('07) believes that a true histological membrane, similar to a cell membrane, is improbable. His method of preparation of the corpuscles for study consisted in crushing mammalian corpuscles on the slide. He also tried drying them in indifferent substances. He describes them as jelly-like and elastic in character with a thinner, more compact peripheral layer and a broader less compact inner region, similar to the exoplasm and endoplasm of Protozoa. If the outer compact layer is referred to as exoplasm, he thinks the superficial part of this may be termed a physical membrane or plasma-film. Dehler ('95) studied the red corpuscles of the chick, fixing them in sublimate solution and staining with ironhematoxylin. He described the convex cells as possessing a sharp border or rind of .25 to .5 yu in thickness. Heidenhain ('96), working with the red blood corpuscles of Proteus, using the same method as Dehler, found the same appearances. Nicholas ('96), likewise using the same procedure, found the sharp border manifest on the erythrocytes of the chick, salamander, triton and viper.

Meves f'04 and '06) studied amphibian red blood corpuscles (frog and salamander). After condemning the technique used by Weidenreich and showing the results obtained by the latter were artifacts, he describes a very complicated procedure used by himself. In general this consisted of dried smears on the slide subjected to warmth for 30 minutes, then subjected to Flemming's fluid (weak formula) plus 1 per cent sodium chloride, washed in running water, stained with safranin, hematoxylin and safranin and Gentian orange, decolorized with neutral alcohol, and cleared and differentiated in clove oil. He describes the corpuscles as showing circumferential fibrils, which were disposed either in an arrangement parallel to the surface or in the foi'iu of a continuous skein, and radial fibrils running, some from the periphery toward the center of the corpuscle and some crossing each other, form


STRUCTURE OF THE ERYTHROCYTE 263

ing a net. In some cases the net-work arose only in part from the peripheral arrangement. He refers to the circumferential fibrils as a membrane which is continuous with the fibrils of the network within, and he interprets the fibrils as resulting from linear arrangements of mitochondria, granules having fused to form them. He thinks the arrangement of the fibrils is similar to that described by Heidenhain for Krause's membrane in muscle fibers, the fibrils continuing into the membrane (sarco-lemma) in a regular system. Shafer ('05) suggests that Meves' circumferential or peripheral fibrils merely represent a part of the reticulum of the corpuscle.

Ruzicka ('03 and '00 j worked with frog, guinea-pig and human blood. He stained with a dilute solution of methylen blue both without and after the action of 1 per cent pyrogallic acid, which latter he thought dissolved hemoglobin. The drop of blood was mounted in normal salt solution and the methylen blue solution (0.5 gram to 1000 cc. of water) added at the edge of the coverglass. When used, the pyrogallic acid was applied followed by the methylen blue solution. Blood from the three sources gave the same results. All showed a fine meshed reticulum with occasional knobs at the junction of its filaments. He did not think an actual membrane is present but that the corpuscle is bounded by the reticulum. The knobs at the junction of the fibrils of the reticulum being found smaller and fewer after the action of pyrogallic acid, he assumed them to represent hemoglobin. He denied the possibility that the reticulum represented a coagulation product, thinking the meshes too fine and uniform and not arranged as coagulum filaments.

In the mammalian erythrocytes, Ruzicka also observed the previously described large granules dispersed in the center of the corpuscle, the so-called "nucleus of the mammalian corpuscle." Quoting Lowit ('87) as claiming a character for these granules in the rabbit similar to nuclear chromatin, he claims they are only present in case of incompletely dissolved hemoglobin and are thus analagous to the larger of the knobs described at the junctions of the filaments of the reticulum and therefore are not of chromatin nature.


264


CHARLES D. CUPP


Brvce ('04) studied tlie erythrocytes of the larvae of Lepidosiren paradoxa. He fixed the tissues with the blood vessels containing the erythrocytes in dtu and used sections of 10 m- He Zd 'ublimate-acetic as a fixing fluid. This was tned in th.s laboratory but was found unsuited for the study of adult erythrocytes in that it precipitates hemoglobin. Bryce's dlustrataons show that at least in the erythrocytes of these larvae, not having acquired sufficient hemoglobin to color them there is a reticular structure in the cytoplasm connecting with a membrane at the periphery, and he describes a meshwork or reticulum in them which was radially arranged from the nucleus to the periphery the meshes of which in section were 3 to 4 m m size. At the nocial points or junctions of the filaments forming the nieshe. he found "strongly refractile granules of considerable size and he states that in some of the corpuscles the filaments near the nuc eus appear as arranged in parallel threads, extending from the .mcleus'a short distance toward the periphery He doe. no pa judgment on the nature of the membrane observed, but states that he was dealing with very young corpuscles.

\L\TEKI.\I. AND MKTHODS

\s is known the Amphiumae carry the largest red blood coipu^e of anv\-ertebrate as yet examined. One of the spec.es th^ animai, the Amphiuma means (the ■blind eel (being easi Iv obtainable in the ditches of New Orleans, a study o he sti~ of its corpuscle was suggested by Professor Hardesty. .. easure ments of its corpuscles in the fresh gave, measured "" 'h ^a^'^ .,n average of 72.9 m in length by 44..5 m m width. \\ ith the "me chnique as f^rally employed for those of the Amphiuma erythrocytes from the alligator, frog, snake, guinea-pig an.l human were also prepared and studied in coinparison.

Obviously, a study of the internal structure ot the e > lu" cytes of Amphiuma and those of other animals, or the study of membranes probably existing, could not be a«-omplished in a,^ detail except with very thin stained sections ;->";.«' framework existed and if a membrane p,.ssesscd v-'"'"; * Ji to observe such, it was equally obvious that the hemoglobm ..u


STRUCTURE OF THE ERYTHROCYTE 265

ried must be wholly, or at least partially remoA'ed from the specimens. Therefore any accomplishment of the purpose in mind depended largelj' upon the technique employed.

The greatest difficulty was encountered in finding a fixing fluid suitable for the purpose. A fluid was desired in which hemoglobin is dissolved rather than precipitated. Hemoglobin not removed or precipitated within the corpuscle of course obscures whate\'er other cytoplasmic structure it may possess. Further, a fixing fluid was necessary whose osmotic action results in neither appreciable shrinkage nor swelhng of the corpuscles, and one the diffusion currents resulting from whose action does not break up the structural content.

Osmic acid, bichloride of mercury, chromic acid and its potassium salts precipitate hemoglobin, and fluids in which an}- of these act of themselves were found impossible for the results desired. It is doubtful whether, according to Ruzicka ('03), pyrogallic acid is a solvent of hemoglobin. It was deemed necessary here to fix, embed and section the corpuscles, which he did not do, and no suitable fixing fluid containing pyrogallic acid has been devised. Hemoglobin is dissolved in alcohol, distilled water, acetic acid and formic acid, and formalin does not precipitate it. The action of alcohol alone distorts the corpuscle and produces shrinkage and rupture, and acetic acid, formic acid and formalin not only produce swelling but in themselves are very poor fixing agents for the structure of cells. Van Gehuchten's (Carnoy's) fluid, containing absolute alcohol, acetic acid and chloroform, was tried and found to rend the fresh corpuscles into small fragments.

Bryce obtained his results after the action of sublimate-acetic, but he was dealing with corpuscles of larvae which probably contained considerably less hemoglobin than the corpuscles of the adults whose study was here desired. After trying a number of fluids containing corrosive sublimate and acetic acid, it was decided that the action of the sublimate in all precipitated the hemoglobin. Suggestive but incomplete results w^ere obtained with corpuscles fixed in a mixture containing 5 cc. saturated aqueous solution of bichloride of mercury, 2 cc. glacial acetic acid, cc. 40 per cent formaldehyde, and 88 cc. 95 per cent alco


266 CHARLES D. CUPP

hol. Preparations of nucleated corpuscles after this fluid showed a cytoplasm more or less transparent in places and a distinct membrane bounding the periphery. In the clearer places in the c3"toplasm a fairly well marked reticulum could be discerned. In preparations of mammalian (non-nucleated) corpuscles such were much less indicated.

Of all the fixing fluids tried, the most satisfactory results were obtained after using a well ripened mixture containing the following parts :

Aqueous 3 per cent potassium bichromate 100 cc.

Commercial (40 per cent) formaldehyde 4 cc.

■ Glacial acetic acid 5 cc.

When first made, this fluid has the color of the bichromate solution, but if allowed to stand or if warmed it becomes a dark greenish brown, due chiefly to the oxidation of the bichromate in the resultant reactions. Our best results were, or maybe happened to be, obtained with a mixture which had been standing several weeks. The formation of formic acid is one of the results of the ripening process.

In using this fluid fand all those tried) a fairly large shell-vial was filled about half full of the fluid and, gently shaking it, the blood was dripped, drop by drop, directly from the animal into the fluid. Even by agitating the mixture while adding the blood, some coagulated clumps cannot be avoided. The corpuscles in these clumps were found not so good for study as those floating free in the fixing fluid. All finally settle upon the bottom of the vial and the fluid may be removed with a pipette or decanted. The fluid was allowed to act for twelve hours. Changing it once or twice was thought to result in better extraction of the hemoglobin.

This fluid does not require a preliminary washing of the material in water. Small paper boxes were made from ordinary tliin letter j)aper, labels written on the sides in pencil, and the accumulated corpuscles transferred to the boxes by i:)i])ette. The boxes nearly full of fixing fluid and corpuscles were then placed in a stender dish containing 30 per cent alcohol to a depth of about


STRUCTURE OF THE ERYTHROCYTE 267

half the depth of the boxes. In 5 to 10 minutes the corpuscles settle to the bottom of the box and some of the fixing fluid may be pipetted awa}'. Gradual dehydration is accomplished by the transfusion of the alcohol through the paper walls of the boxes. If several boxes are carried in a small stender dish, the 30 per cent alcohol should be changed during the hour. Then the 30 per cent alcohol in the stender dish was replaced with 40 per cent alcohol and so on with grades of alcohol progressively increasing by 10 per cent in strength up to 90 per cent, which was replaced with 95 per cent alcohol and this in turn by absolute. To insure complete transfusion of the different grades and the action of each upon the corpuscles, the paper boxes should remain in each alcohol at least one hour with the stender dish covered.

From the absolute alcohol, the boxes were transferred to equal parts absolute alcohol and xylol for about 30 minutes and then placed in pure xjdol to complete clearing. The boxes were next placed in a dish of melted paraffin in the thermostat for two hours. Owing to the xylol present, it was found necessary to change the paraffin or transfer the boxes to another dish of paraffin during the first hour. When first in melted paraffin, the corpuscles float about and show a tendency to adhere to the sides of the box, and to avoid much of this in the final the boxes should be gently shaken a few times during the first half-hour.

The specimens were embedded, paper box and all. The corpuscles w^ere settled in a layer at the bottom of the box, so, when the paper was pulled off, a paraffin block was obtained with them accumulated in one side.

For the sections, the ordinary Alinot rotarj' microtome was used, set at 1 ii. The large corpuscles especially were found to have settled for the most part on the flat, or with their widths parallel to the bottom of the boxes. To obtain sections cut in this plane, the paraffin block had to be arranged with its bottom surface parallel with the edge of the knife. The paraffin ribbon was of course much jmcked and crumi)led and, of course, few if any of the sections could have been of 1 ii in thickness, but setting the microtome at 1 ^ was thought to give thinnest sections


268 CHARLES D. CUPP

possible. The sections were straightened and fixed on the shde by the usual water-method, without using albumen fixative. After drying, the paraffin was removed with xylol, the slides transferred to absolute alcohol and then passed through the gradually descending grades of alcohol, 3 to 10 minutes in each, down to water.

Of the staining methods tried, including gentian violet with safranin, the best results were given b}- alizarin and toluidin blue. To distilled water was added enough of a saturated solution of the sulphalizarinate of soda in 70 per cent alcohol to make the water a straw yellow, and in this the sections were immersed for about 12 hours. The sections were then rinsed in distilled water and some slides were placed in a 0.5 per cent aqueous solution of toluidin blue to stain nuclear structures. Other slides, in order to study the region occu])ied by the nucleus in greater detail, were not stained with the toluidin blue at all. The stained sections were then rinsed with distilled water and dehydrated by passing through the gradually increasing strengths of alcohol, 3 to 5 minutes in each, up to absolute, cleared with xylol and mounted.

The action of the fixing fluid and the technique of embedding, etc., when carefully applied, seemed to have produced little change in the shape and size of the corpuscles of the Amphiuma, frog, alligator and snake. Measurements of the sections of those of the Amphiuma, judged truly sagittal by the shape and the position and size of the nuclei, gave an average of 69 m loi^g ^^.Y 38.6 }x wide as compared with the average 72.9 m long and 44.5 /i wide given b}' the fi-esh corpuscles. For the blood of all four of the animals mentioned, sections showing the evenly oval contours characteristic of the fresh corpuscles were frequent on the slides and no disturbances of interior arrangement seemed evident in these. P'ragments of corpuscles and fragments of sections of them were abundant, but most all such, from their form, were evidently })r()du('ed by crushing and breaking by the knife in cutting and by the crumpling of the paraffin ribbon. Fragments of .sections were often more favoi'able for the study desired than sections of whole corpuscles. In the sections containing the


STRUCTURE OF THE ERYTHROCYTE 269

inainmalian corpuscles ( giiinea-pio; and human), there showed much more evidence of distortion hoth as to contour and internal arrangement.

OBSERVATIONS

The nuclei of the nucleated corpuscles could be best observed as to their position, size, form, and arrangement of chromatin in corpuscles stained whole, after fixation, without embedding. The nuclei in the corpuscles of the Amphiuma and alligator especially appear to consist of a tangled coil of one or more coarse rods of chromatin supported in non-chromatin substances. The coiled and tangled chromatin rods in Amphiuma are very much larger than those in the alligator and, in Amphiuma especially, the peripheral loops of the rods produce a scalloped and lobulated contour of the nuclei quite evident in whole specimens. In the thin sections of stained nuclei, the chromatin rod or rods appear cut into short segments, as shown in figures 1 and 3. A delicate membrane about the nucleus was e\'ident in all the nucleated corpuscles examined, but could be seen only in the thin sections and best in those in which the nucleus was not stained ffigs. 2 and 3, B).

A membrane about the entire red corpuscle, after the technicjue here emplo^^ed, was distincth' present in the blood of all the animals used. In proportion to the size of the corpuscle, it appeared relatively thicker and more condensed as possessed by the mammalian corpuscles (fig. 4, human). In the thin sections of corpuscles of Am}:»hiuma. this membrane, actually thicker than that of smaller corpuscles, could be resolved under oil immersion ol> jective into an apparently parallel arrangement of very delicate threads. With the fragments of corpuscles, broken and torn by the knife in sectioning and frequently found in the preparations, the nature of the membrane could be better observed than with intact sections. Torn and broken membranes often appeared slightly frayed in the tearing and close study led to the conviction that in Amphiuma, at least, the membrane consists not of a condensation of concentrically arranged parallel threads, and certainlv not of concentric lamellae, Init instead, of a very deli


270


CHARLES D. CUPP


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Fig. 1 Drawings from very thin paraffin sections of erythrocytes of Ani])hiuma means, fixed in the bichromate-formalin-acetic acid mixture and stained with sodium sulphalizarinate and toluidin bhic, showing the capsule, reticulum, perinuclear membrane and the coiled rods of nuclear chromatin in stained section. A, corpuscle sectioned on the flat; B, corpuscle sectioned in profile.

Fig. 2 Erythrocyte of Amphiuma sectioned on the flat and slightly tangentially . Same technique as in figure 1 except that the toluidin blue was omitted. Given to show the full shape of the fixed corpuscle and, especially, the perinuclear membrane and reticulum within the nucleus.


STRUCTURE OF THE ERYTHROCYTE


271



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P'ig. 3 From sections of en^throcytes of the alligator (Alligator mississippiensis). Prepared w-ith same technique as figure 1 and drawn in same scale as figures 1 and 2 and to represent the same structures. A, section with nucleus stained by toluidin blue; B, piece of section from preparation in which tohiidin blue was omitted.

Fig. 4 From sections of human erythrocytes prepared with same technique as figure 1, except that toluidin blue was not applied to the sections used for the drawing. Drawn in somewhat larger scale than figures 1 to 3. A, two sections of erythrocytes considered as representing more nearly the normal condition of the reticulum, capsule and central knots, with hemoglobin for the most part removed. B, erythrocytes with knots more distributed. C, D and E, varying degrees of rupture of the reticulum, presumably produced by diffusion currents set up by the reagents.


979


CHARLES D. CUPP


cate reticulum so condensed or compressed that its meshes are much elongated and thus produce the impression of a parallel arrangement (fig. 1, A). Aleves, describing red blood corpuscles of frog and salamander as "showing circumferential fibrils arranged either parallel to the surface or in a continuous skein, must have obtained the same appearances.

A very distinct reticulimi is evident in the cytoplasmic areas of the sections and the threads of its meshes are continuous into the membrane. The meshes of this internal (cytoplasmic) reticulum, or stroma of the corpuscle, appear larger in the corpuscles of Amphiuma than in those of the alligator ffig. 3), frog and snake. Corpuscles of the frog and snake, not figured here, gave appearances practically identical with those given by the alligator. In the more transparent sections, those supposedly more free from hemoglobin, the fibrils of the reticulum, though very delicate and varying somewhat in size, appeared distinctly threadlike, and the meshes made by them were angular in form. That the threads of the peripheral meshes grade directly into the peI'ipheral membrane, which itself appears as a condensed reticulum, supports the conclusion that the meml^rane is nothing more than a peripheral condensation of the internal reticulum and that the membrane could better be called a 'capsule' of the corpuscle. In one of his papers, Meves referred to it as a 'feltwork membrane.' This, and likewise the statement of Ruzicka that the corpuscle j)()ssesses no actual membrane })ut is bounded by the limits of a fine-meshed reticulum, seem warranted.

In preparations of corpuscles, of Amphiuma especially, in which the hemoglobin was obviously not so completely removed, the component threads of the internal reticulum (stroma) appeared coarser and ga\'e the impression of being rod-like in form, and the meshes of the reticulum appeared o\al instead of angular. The oval form of the mesh was due in part to larger knobs or accumulations of substance at the points of junction ('nodal points') of the threads in forming the meshes. Ruzicka described these knobs in liis preparations of frog and mammalian blood as round in form and concluded they represented undissolved hemoglobin. Their larger size in certain preparations here and the


STRUCTURE OF THE ERYTHROCYTE 273

apparent!}^ larger size of the threads of the reticukim accompanying them is interpreted as cUie to imremoved hemoglobin adhering to or precipitated upon the reticulum throughout, for such preparations were always less transparent and coarser in appearance and the membrane or capsule of the corpuscle appeared dark and homogeneous as compared with those from which the hemoglobin was considered more completel}' removed.

All the figures here given are attempts to represent corpuscles considered as having been rendered most free from hemoglobin. The knobs, or junctions of the filaments making the reticulum, appear quite small in these, usually about as large as would be possible were two or more plastic filaments to cross each other in contact and fuse giving an increased amount of substance at their junctions, a knob, or knot of the mesh of the net. In the most clear of the preparations, occasional larger knobs occurred at the junctions of the threads. Several such are shown in figure 2. These larger knobs were usually angular or stellate with their points extending upon the threads joining in them and are interpreted as representing small masses of unremoved hemoglobin adhering upon junction points of a greater than usual number of threads.

In the corpuscles of the Ami^hiuma, alligator and frog, the threads which join or grade into the capsule at the periphery of the reticulum appear for the most part to join with the capsule at right angles and thus present here a somewhat radial arrangement. The meshes formed by these threads in joining the capsule average somewhat larger in size than elsewhere in the cytoplasm of the nucleated corpuscles. The greater amount of light admitted by these larger meshes compared with the greater density of the capsule gave the impression of a narrow, clear zone about the corpuscle just under the capsule. This was especially true with the corpuscles of Amphiuma (figs. 1 and 2) in which the meshes are larger throughout than in the other nucleated corpuscles examined. Aleves obser^'ed this radial arrangement of the peripheral filaments of the reticulum in the corpuscles of the frog and salamander, and thought them in regular system similar to the relation of Krause's membranes in the muscle fiber.


274 CHARLEvS D. CUPP

Bryce likewise observed it in the corpuscles of lepidosiren larvae, but he considered it a part of a general radial or parallel arrangement of the filaments extending throughout fiom the nucleus to the periphery of the corpuscle. Our preparations do not show these peripheral filaments to join the capsule in a definitely regular system but at various angles and to form meshes of varying size and shape; nor do the threads of the reticulum extend from the nucleus to the capsule in definitely radial, and certainly not in parallel, arrangements. Only in the thinnest region of the cytoplasm, in the middle of the corpuscle on the flat where the nucleus is nearest the capsule, can threads be traced directly from the nucleus to the capsule ffig. 1, B, section in profile). Here the peripheral zone comprises practically the entu'e cytoplasm. As Schafer f'05) suggests, these peripheral threads are only a part of the general reticulum of the corpuscle. Continuous into and stretched from the capsule or membrane, they happen to appear more sparse and regular than the threads of the remainder of the reticulum.

For the larva of Lepidosiren paradoxa, Bryce described in each end of j^rofile views of the corpuscles a small area free of reticulum but occupied by a number of fine dots, and he interpreted these dots as transverse sections of cu'cumferential filaments running m the plane of the flat dimension. Our preparations showed no differences in this respect betw^een sections cut on the flat and profile sections Tfig. 1).

As noted above, the chromatin in the nuclei of the corpuscles of the Amphiuma and alligator appears collected into definite coiled rods instead of being scattered in granules of varying size throughout the nucleus. Preparations in which the nuclei are stained differentially do not show a sharp, dark-staining membrane bounding the confines of the nucleus as is found in certain other tissue cells where such is probably due to chromatin material being invoh'ed in or adhering upon the nuclear membrane. On the contraiy. ilic miclear membrane appears here to be another but thinner condensation of the reticulum or general framework, being comparable in origin and structure with the capsule, or membrane, about the corpuscle. The threads of the cyto


STRUCTURE OF THE ERYTHROCYTE 275

plasmic reticulum grade directly into it and it stains in the same way as the threads of the reticulum. It could best be studied in preparations to which a nuclear stain had not been applied (fig. 2 and fig. 3, B). Figure 2 represents a slightly tangential section of a corpuscle of Amphiuma on the flat. In such corpuscles, with nuclei not differentially stained, it could be noted that the threads of the reticulum grade directly into the nuclear membrane, that the meshes become suddenly smaller or more dense to produce it and that the membrane carries the same stain-reaction as the reticulum. In other words, it is here suggested that the nuclear membrane is but a peri-nuclear condensation of the general framework of the corpuscle. Sections of corpuscles in profile (fig. 1, B) show the threads to serv^e as continuations between the capsule and the nuclear membrane.

Furthermore, our preparations suggest that the general reticulum, or framework, is continuous into and throughout the nucleus, contributing to the support of its structures. Figures 1, A, and 2 and 3, B, are attempts to show this suggestion. In such corj)uscles, the very thin sections showed the dehcate filaments extending from the nuclear membrane and forming a reticulum throughout the nucleus. The meshes of this intranuclear framework seemed somewhat larger than the average of those in the cj^toplasm, and especially large when containing a segment of the coiled chromatin rod. The threads stained just as those of the cytoplasm and the membranes. Knobs at the junction points of the threads could not be observed as so definite nor so large as in the cytoplasm, probably due to some extent to the necessarily more obscured nuclear area. The suggestion that the cytoplasmic reticulum is continuous and identical with the nuclear reticulum is somewhat supported by the frequently presented view that the spongioplasmic reticulum of the general cell structure is identical to (stains the same) and is continuous with the karyoplasmic reticulum, or nuclear linin.

The chemical composition of either or both of the reticula, including the membranes, may be that of a nucleo-proteid or lecithin or cholestrin, but in our preparations it occurs in the form of a network in whose meshes is supported the remaining cell load,


276 CHARLES D. CUPP

including the hemoglobin and the nuclear structures. Schafer states that substances dissolving lecithin or cholestrin will produce an increase in the permeabiUty of the membrane. Bryce thinks that the peripheral capsule ("peripheral ring or band," he calls it) is due to a condensation or massing of the meshes of the reticulum, and he suggests that the filaments of the reticulum are not necessarily fixed fibers but that they may be of colloidal nature. Taking all into consideration, he thinks the reticulum is not an artefact but an actual protoplasmic framework. Citing Blitchli's "Foam theory" of the structure of protoplasm, and noting that the meshes of the reticulum are larger than the limits given for the protoplasmic alveoli of this theory, and much larger than the meshes described for the cytoplasm of leucocytes, Bryce thinks that if the protoplasm of the erythrocyte may at one time have been alveolar in structure, the reticulum could be later derived from a vacuolated condition in which the hyaloplasm of the cell is greatly reduced and the alveolar arrangement lost by the breaking through of the walls of the alveoli. Ruzicka thinks the observed reticulum is not artefact but an actual structure, that its meshes and the knobs at the junctions of the threads are not coagulation products, for the meshes are too fine and uniform and the threads are not arranged as are coagulum filaments; that the hemoglobin is carried dispersed in the meshes of the net to the periphery of the corpuscle, that the net is the vegetative part of the corpuscle and the hemoglobin the functional part.

Whatever the chemical character, our preparations seem to support the conclusion that the structures observed are not artefact, that the corpuscle is pervaded by a true reticulum, a network of threads joining each other throughout and extending m all the planes of space. That the thrc^ads of the reticulum observed serve as a supporting framework of the coriniscle and possess a certain amount of elasticity is suggested by several observations on the living red blood corpuscle: (1) the manmialian corpuscle, after losing its nucleus, remains thinner in its center from which the nucleus was lost; (2) a living corpuscle may be cut in halves and neither half suffer exudation of its content; (3) corpuscles in the circulation may l)e elongated and their usual


STUrCTlTRE OF THE ERYTHROCYTE 277

shape considerably distorted in passing- through the smallest capillaries but always resume theu- shape upon reaching the larger vessels; and (4), in this laboratory, by tapping under the microscope the cover-glass upon fresh mounts of corpuscles of the Amphiuma, the nuclei could be made to shift considerably from their normal position, moving back and forth with the tapping, sometimes being slightly' spread by the pressure, but, the pressure removed, they would resume their normal position and size in the center of the corpuscle floating in the plasma.

With human corpuscles, the technique here employed was not altogether as successful as with the nucleated forms. The stained sections showed more distorted contours and internally ruptured corpuscles than those of Amphiuma, alligator and frog blood prepared in the same way. In the latter preparations, evidences of rupture produced by the reagents used were somewhat rare. Figure 4 is given to represent appearances found in the preparations of human corpuscles. Blood from the guinea-pig gave the same appearances. The two corpuscles farthest in the left (fig. 4, A) represent the form most common in the preparations and, showing less distortion in contour, were the form considered as most nearly representing the normal. The remaining four corpuscles were selected as an attempt to illustrate, progressively, appearances of injurious effects produced by the reagents.

It may be noted that the capsule, the sharp peripheral border of the corpuscle frequently mentioned in the literature, is here relatively thicker and more densely staining than that of the Amphiuma. This may be due in part to a less complete extraction of the hemoglobin considered evident in the interior. The threads of the reticulum, while grading into the capsule and continuous with each other throughout the corpuscle, do not present so nearly uniform size as in the other forms studied. Filaments much thicker than others appear to radiate from the central region, while attached to these are numerous smaller threads joining throughout and completing a general reticulum. At the junction of the larger filaments with the capsule there usually appears a visible knob, or hillock of attachment. One gets the impression in close study that the smaller, probably the

THE ANATOMICAL RECORD, VOL. 9, NO. 3


278 CHARLES D. CUPP

normal, meshes are themselves crossed by still finer threads, while a larger mesh may appear perfectly clear. Fme knobs show at the junction or nodal points of the threads, varymg in size with the size of the threads.

In the corpuscles considered more nearly normal (fig. 4, A), the frequently described large knobs dispersed in the central region of the corpuscle comprised the most promment feature m our sections. These appeared approximately spherical m shape and uniform in size and the number observed varied from 1/ to 6 a variation due no doubt in part to the planes m which the corpuscles were sectioned. In sections in which the knobs were less darklv stained, one could get the impression, under highest magnification, that these knobs themselves are fibrillar, that they are knots or condensations of very fine threads. If they carry anv nuclear material (they have been called the nucleus of the mammalian ervthrocyte), our sections suggested it very doubtfully that anv stain reaction of a chromatin character isretamed in them Vniline nuclear dves. such as gentian ^■iolet, and even hematoxvlin mav be retained in them longer than in the threads of the reticulum, but the color will wash out. and the fact that it is retained in them more deeply at times is considered due (1) to their greater compactness of mass holding more of the dye than the smaller and looser structure, but indifferently nevertheless and (2) to unremoved hemoglobin being entangled within them Thev were alwavs darker than the filaments, but this is to be expected, due to their greater density obscuring the light Occasionallv the knobs or knots appeared more scattered throughout the corpuscle and then to vary more in size, as shown

in B of figure 4. i i i • i

The larger filaments, those usually described and wJiicli appear more or less radially arranged, are here considered as artefact ('orpuscles manifestlv ruptured internally by the action of the reagents (fig. 4, E) show large, clear, vacuole-like meshes and these are always bounded by the thick filaments. It is suggested that these large clear meshes represent areas of the reticulum ruptured bv diffusion currents of the fixing agent or alcohols in preparation, and that the broken threads of these


STRUCTURE OF THE ERYTHROCYTE 279

areas have been washed together or condensed to form the thicker filaments. Often the latter give the impression that they themselves are composed of finer threads. Thej^ occur more or less radially between the centrally placed knots and the capsule probably because these knots are the firmest fixation points.

As to the knobs or knots ('nuclei'; of the central region, we beg to suggest the possibility that they may represent remains of an originally existing membrane about the nucleus and of a reticulum within the nucleus of the erytlu'oblast, or nucleated stage of the mammalian corpuscle, similar to those found in the nucleated corpuscles of the Amphiuma and alligator; that the knots represent the remains of these resulting from or after the disturbance of the central reticulum at the time the nucleus disintegrated or was extruded, and that their densit}' may be added to by hemoglobin retained in them.

The membrane or capsule of the erythrocyte, derived as a peripheral condensation or massing of the reticulum, must be the most resistant part, the structure last to rupture under stress. It is permeable, as is well known, allowing a readj^ diffusion through it. The fact that the mammalian erythrocyte assumes a spherical form before bursting, when swollen and distended by excessive endosmosis in the action of distilled water or weak acetic acid, for example, may be explained as due to its less resistant internal framework being first torn asunder and destroyed by the diffusion currents and the stress. The erythrocyte then becomes a mere turgid sac, the capsule itself rupturing at continued pressure. Both the capsule and framework are dissolved by alkalies.

The red blood corpuscle is a tissue element extremely differentiated in structure for the performance of an extremely specialized function. In the mammal it is more differentiated than in the lower vertebrates, being one of the two bodies possessed that, containing no nucleus, can no longer be called a cell. From the above studies it is concluded (1) that it normally possesses a framework in the form of a fine threaded, somewhat elastic reticulum in the meshes of which its hemoglobin is supported so intimately that its content partakes of the physical characters of


230 CHARLES D. CUPP

gelatin- (2) that in the nucleated forms, this same reticulum is continuous into the nucleus, supporting its structures; (3) that it possesses a peripheral mpni])rane or capsule into which the threads of the reticulum grade and which is deri^-ed from and consists of a peripheral condensation or massing of the reticulum; (4) that there is a similar but thinner perinuclear condensation of the reticulum l^ounding the confines of the nucleus and forming a nuclear membrane of the nucleated forms, and (5) that the central knots, or nucleus of the mammalian corpuscle," are masses of the material of the nuclear membrane and reticulum originally existing in the central part and result from or after the distm-bance of the interior produced by the dismtegration or

extrusion of the nucleus. . ^ ^^ a

Finally is due an expression of appreciation of the kindness of Professor Hardesty at whose suggestion and with whose guidance and collaboration this study was made.

BIBLIOGRAPHY

Bryce, T. H. 1903-1905 Trans. Royal Soc. Edinburgh.

Dehler, a. 1895 Archiv fiir mik. Anat., Bd. 46.

FoA 1889 Ziegler's Beitrage, Bd. 5.

Hardesty, I. 1905 km. Jour. Anat., vol. 4 Heidenhaix, M. 1912 Quoted from Schafer m Quam's Anatomy, ^ol. _, pait 1.

Lohxer, L. 1907 Archiv fiir mik. Anat., Bd. 71.

LowiT, M. 1S87 Sitzungsbr. d. K. Akad. d. ^\ len, lid. 9o.

Meves, 1"k. 1904 Anat. Anz., Bd. 24.

1906 Anat. Anz., Bd. 28 Nemiloff, a. 1910 Archiv fiir mik. Anat., Bd. 76. Nicholas 1896 Bibliographia Anatomique. RuzicKA, V. 1903 Anat. Anz., Bd. 23.

•1906 Archiv fiir mik. Anat., Bd. 67. Schafer, E. A. 1905 Anat. Anz., Bd. 26.


x%


ox the provisional arraxgeaiext of the e:\ibryoxic lymphatic system

AN ARRANGEMENT BY MEANS OF A^TilCH A CENTRIPETAL LYMPH FLOW TOWARD THE VENOUS CIRCULATION IS CONTROLLED ANT) REGULATED IN AN ORDERLY AND UNIFORM MANNER, FROM THE TIME LYMPH BEGINS TO COLLECT IN THE INTERCELLULAR SPACES, UNTIL IT IS FORWARDED TO THE VENOUS CIRCULATION

CHARLES F. W. IMcCLURE

From the Department of Comparative Anatomy, Princeton University

SIX FIGURES

One of the most interesting problems of the lymphatic system is the determination of the manner in which the continuous centripetal lymph flow is established in the embryo, in relation to the developing lymphatic vessels by which it is subsequently conveyed to the venous circulation.

It is well known that the anlagen of the lymphatic system do not normally make their appearance in the embryo until after the haemal vessels have been established. As soon, however, as the haemal vessels begin to function, lymph begins to collect in the intercellular spaces of the embryo and, as we know, is subsequently collected by a set of newly-formed vessels, the lymphatics, which convex" it to the venous circulation.

Those who maintain that the lymphatics sprout centrifugally and continuoush" from the veins, would necessarily hold that the lymph in the intercellular spaces patienth' awaits the arrival of closed and hollow outgrowths from the veins, the lymphatics, before it can be received into any portion of the lymphatic system. Such continuous outgrowths from the veins would necessarily take place in a centrifugal direction which is opposed to that of the centripetal flow of lymph they would receive.

It has always proved a difficult matter for some of us to reconcile the view that the dii^ection of the growth of the vessels

281

THE ANATOMICAL RECORD, VOL. 9, NO. 4 APRIL, 1915


2g2 CHARLES F. W. McCLURE

in which the flow takes place should be opi)osed to that of the flow One might expect a continuous centripetal lymph flow toward the venous circulation to be estabUshed m a gradual manner in the embryo, and to be regulated from the tune b^nph first made its appearance in the intercellular spaces, until it was continued on to the venous circulation. In fact, one might expect to find some provisional condition of the embryonic lymphatic svstem which should exactly accord with the maintenance and regulation of such a centripetal flow. Such a provisional condition of the embryomc lymphatic system I believe^ 1 ham been able to demonstrate in a positive manner in the living

embryo of the trout. , , • .i •, i

One of the most salient features noticeable m the development of the lymphatic system of the trout, as well as m that ot mammals, is that the main lymphatic channels are formed through a oradual concrescence of independent and discontinuous anlaoen or lymph vesicles. These independent lymph vesicles mike then- appearance in the embryo in a progressive manner along the lines subsequently followed by continuous lymphatic vessels and. in certain districts of the mammalian embryo, they utilize the static fine vacated by degeneratmg veins so that certain Ivmphatic ^'essels of the body subsequently follow the course of abandoned veins. These independent lymph vesicle'^ of the embryo first become concrescent to form continuous channels contiguous to the points at which the lymphatics establish tvpical communications with the veins. AA ith these points of Ivmphatico-venous entry, the vesicles continue to become concrescent in a progressive manner, so that the outlying or peripheral lymph vesicles are the last to establish a communication with the vein^.

The view which calls for the development ol th(« mam lymphatic channels through a confluence of independent and discontinuous anlagen was advanced by Hunthigton and Mc( lure


h chauiu'ly


. Huntington HH.l M.Clure. The development „f the mam lymph of the cat 'n their relations to the venous syste.u. Anat Eee.. ol. 07

llcad before the An.eriean Assoeia.ion of An,....nnsts a, the -neetn,, hehl .n New York in Decemlx-r. 1906.


PJMKRYONIC LYMPHATIC SYSTEM 283

in 1906. Since a recognition of this fact is a necessary corollary to the main i jsue invoh'ed in the present paper, we will first consider what constitute the main lymphatic channels in the embryo of the trout and show how, in their development, they follow this ]5lan.

Figure 1 represents a ventral view of a reconstruction of the main hiiiphatics, veins, and arteries found in the regions of the head and pharynx of a rainbow trout embryo, on the twentysecond day after fertilization. This embryo was developed at a temperature of about 10. o"" C. and its Ijanphatic system is represented, for the most part, by a continuous system of vessels which drain into the veins at typical points. The typical points of lymphatico-venous communication in the regions of the head and pharynx occur in the cardino-Cuvierian district (9): with the precardinal (jugular) vem near the caudal end of the otocyst (IS) ; and with the precardinal, near a point where the latter leaves the cranial cavity (2). The first and last mentioned points of communication appear invariably' to be retained in the adult.

The principal or main lymphatic vessels found in the regions of the head and pharynx of a twenty-two day rainbow trout embryo are as follows:

1. The Huhocuhir lymph sacs (saccus lymphaiicus subocidaris,

1 in figure l)

The subocular hmiph sacs of the trout embryo consist of two relatively huge sacs or vesicles, each of which lies ventro-medial to the 63^6. They are more or less triangular in form, with their apices directed forward. In the twenty-two day trout under consideration, they extend between the hyoidean artery (Id) and the olfactory invagination (21). as shown in hgure 2. At its postero-lateral angle, each subocular lymph sac (1) communicates directh' with the lateral pharyngeal lymphatic (3 in fig. 1) and it is solely through the latter vessel that the subocular lymph sac drains into the veins.


284


CHARLES F. W. M( CLURE



Fig. 1 Reconstruction of tiie main lymphatics, arteries and veins found in the regions of the head and pharj^nx of a twenty-two-day rainbow trout embryo; ventral view. P. K. C. series 648. Reconstructed after the method of Horn at a magnification of 200 diameters.


EMBRYONIC LYMPHATIC SYSTEM


285


REFEREXCE NUMBERS


1, Subocular lymph sac 11,

2, Medial pharyngeal communication 12,

3, Lateral pharyngeal lymphatic L\

4, Medial pharyngeal lymphatic 14,

5, Precardinal (jugular) lymphatic 15,

6, Precardinal (jugular) vein 16,

7, Communication between the pre- 17,

cardinal lymphatic and the lat- 18,

eral pharyngeal lymphatic 19,

8, Caudal end of otocyst 20,

9, Cardino-Cuvierian conununication 21, 10, Lymphatic of the lateral line of the 22,

trunk


Postcardinal vein Duct of Cuvier Otic communication Dorsal aorta Hyoidean artery First efferent aortic arch iSecond efferent aortic arch Third efferent aortic arch Fourth efferent aortic arch Caudal end of eye Olfactory invagination Carotid artery



Fig. 2 Sagittal section taken through the head and pharynx of a twentytwo-day rainbow trout embryo, showing the relations of the subocular lymph sac to the eye, the hyoidean artery and the olfactory invagination; /, subocular lymph sac; 1-', hyoidean artery; 21, olfactory invagination. P. E. C. series 816.


286 CHARLES F. W. McCLURE

2. The lateral pharyngeal lymphatic (truncus lymphaticus pharyngeus lateralis, 3 in figure l)

This vessel occupies a superficial position in the lateral wall of the pharjTix and forms, on each side of the body, the dhect anterior continuation of the lymphatic of the lateral line of the trunk (truncus lymphaticus longitudinalis lateralis, 10 in fig. 1). The lymphatic of the lateral line of the trunk is completely de\'eloped in the twent3^-two day rainbow trout and can be followed can dad to the region of the caudal Ijaiiph heart. The lateral pharyngeal Ijanphatic drains the subocular lymph sac and, at a shghtly later stage of development, also the dorsal region of the head and pharynx, the operculum and the lower jaw. It communicates with the veins in the cardino-Cuvierian district (9) in common with the lymphatic of the lateral line of the trunk (W).

S. The medial pharyngeal lymphatic {truncus lymphaticus pharyngeus medialis, 4 in figure 1)

This vessel occupies a more central position and is more deeph" situated than the lateral pharyngeal lymphatic. It follows an oblique course, in a postero-anterior direction, from about the middle of the lateral pharyngeal lymphatic with which it subsequently comnumicates, to open into the precardinal vein just caudal to the ]:)oint where this vein emei'ges from the cranial cavity (2 in fig. 1).

j!f. The precardinal or jugular lymphatics {truncus lymphaticus precardinalis vel jugularis, 5 in figure 1)

These vessels tlevelop along I lie hue of the ])i-ecardhial vehis. The}' are not completely established on the twenty-second day in the form of continuous channels and are represented by r.flch vessels only near the caudal end of the ]:)harynx, where they communicate with the lateral ])haryngeal lymphatic (7 in fig. 1).

All of the continuous lym))hati(' channels described above, as occui'iing on the t wentv-second d.-iv in the cmbi-vo of the I'liin


EMBRYONIC LY:\rPHATIC SYSTEM 287

bow trout, can be readily injected from the veins, through any one of the typical points of communication which are estal)Ushed between the lymphatics and the veins. By injecting into the subocular lymph sacs it is also possible to fill the continuous lymphatic A'essels with inject a. as well as the veins. At this particular stage of development, in the absence of lymphatico-venous valves, blood may flow freely into the lymphatics from the veins, at the tj^pical points at which the hmiphatics communicate with the \'eins. In rainbow trout embrj'os slightly older than twenty-two days, and in which lymphatico-venous valves have been formed, the application of chloretone apparently vitiates the normal function of these valves. Blood may then also flow freely from the \'eins into the lymphatics and fill up completely all of the continuous lymphatic channels, including the subocular lymph sacs. If such embryos are remo\'ed to water in which no chloretone is present, the blood will flow back from the lymphatics into the \'eins.

The age of the rainbow, steelhead or brook ti-out embryo in which a continuous system of lymphatic channels, as shown in figm'e 1, is met with for the first time, naturally varies wdth the temperature of the water in which development takes place. Much variation is also met with in the rate at which the lymphatic system of the trout develops in different embryos of the same age, as well as upon opposite sides of the same embryo. When developed at a temperature of about 10. o° ('.. a continuous lymphatic system, as shown in figure 1, is usually found in rainbow and steelhead trout embryos on the twentj-second day after fertilization, which is six or seven days after its earliest anlagen can first be observed in sections.

In all stages of development, prior to the establishment of such a continuous system of h^mphatics as shown in figure 1, a condition is invariably met with in the embryo in which the IjTQphatic system is represented by a progressively appearmg series of discontinuous anlagen, that present varying degrees of concrescence with one another to form continuous lymphatic vessels which communicate with the veins, only at the typical points at which the h^mphatics establish communications with the


288


CHARLES F. W. McCLURE



Fig. 3 Reconstruction of the Ij'mphatics, arteries and veins found in the regions of the head and pharynx of a twentj'-day rainbow trout embryo; ventral view. P. E. C. series 668. Reconstructed after the method of Born at a magnification of 200 diameters; reconstruction of an injected embryo. For reference to numbers see under figure 1.

veins. Two siioh stages of dev^elopment are herewith presented ill illustration of this fact.

Figures 3 and 4 represent, respectively, reconstructions of the lymphatics, veins, and arteries found in the regions of the head and pharynx of a rainbow trout embryo on the twentieth and


EMBRYONIC LYMPHATIC SYSTEM


289



Fig. 4 Reconstruction of the lymphatics, arteries and veins found in the regions of the head and pharynx of a twenty-one-day rainbow trout embryo; ventral view. P. E. C. series 646. Reconstructed after the method of Born at a magnification of 200 diameters; reconstruction of an injected embryo. For reference to numbers see under figure 1.

twenty-first days after fertilization. These embryos were developed at a temperature of about 10.5°C. When compared with the conditions found in the embryo on the twenty-second day (fig. 1), it is seen that the subocular lymph sacs (1 in figs. 3 and 4) are entirely independent of the veins and of other independent h'mph vesicles, and that a series of discontinuous


290 CHARLES F. W. McCLURE

and independent lymph vesicles lie exacth' in the Ime subsequenth' followed by continuous lymphatic channels on the twenty-second day (fig. 1). It is also seen that these tymph vesicles present vaiying degrees of concrescence beginning at the points at which the lymphatics establish typical communications with the veins. It may also be observed that none of these independent lymph vesicles communicate with the veins except those which lie contiguous to the points at which the lymphatics establish typical communications with the veins.

For the purpose of the present paper reconstructions of the twenty and twentj-one day trout are sufficient to illustrate the general principle of development followed b}* the main lymphatic channels.

The main question in\'olved in the j^resent issue is, however, what functional significance does the presence in the embryo of such an mdependent and discontinuous series of lymph \'esicles miply? A study of one of these lymph vesicles, the subocular lymph sacs, as observed and experimented upon in the living trout embryo gives, I believe, a positive answer to this question.

When rainbow and steelhead trout embryos are de\'elo]ied at a temperature of about lO.o^C, the de^'elopment of the anlagen of the subocular lymph sacs is initiated on about the sixteenth day after fertilization. These anlagen first appear as small clear vesicles which lie in the mesenchyme in an area between the hyoidean artery and the eye and just dorsal to the maxillary ridge. These small vesicles finalh' become confluent to form a larger \esicle which gradually increases in size. Injection experiments \\\)(m the living trout embryo, controlled by sections, have shown that the anlagen of the subocular lymph sacs never establish a communication with the veins in the neighborhood of the sacs. They have also shown that the subocular lymph sacs cannot be injected from the veins at any stage of their development, until after the independent and discontinuous anlagen of the lateral ]:)haryngeal have become concrescent with one another to form a continuous vessel and until a comnumication has been established between this vessel and the subocular


EAIBKYONIC LYMPHATIC SYSTEM 291

Ij'inph sac (compare figures 3 and 4 with figure 1). In other words, at no stage of development has it been possible to inject the subocular lym])h sac of the trout embr^^o except by way of the lateral pharyngeal h'mphatic, which signifies that the subocular lymph sac of the trout embryo is entirely independent of the veins and of other Mnphatics, until this communication has been made.



Fig. .3 Photograph of the ventral aspect of the head of a twenty-day rainbow trout embryo on which an attempt was made to inject the lymphatics and the veins by injecting into the subocular lvmi)h sacs. Spalteholz prejiaration. 1, subocular lymph sacs.

Injection experhnents have also proved that the subocular lymph sacs of the trout embryo do not grow caudad and that they are invariably bounded posteriorly by the hyoidean artery; (compare 15, hyoidean artery, with 1, subocular lymph sac, in figures 2, 3 and 4) . Figure 5 is a photograph of a Spalteholz preparation of a twenty-day rainbow trout embryo on which an attempt was made to inject the lymphatics and the veins by injecting into the subocular lymph sacs (1 in fig. 5). The figure shows the position occupied by the subocular lymph sacs


292


CHARLES F. W. McCLURE


ill the living embryo and, since the sacs alone filled with the injecta, is illustrative of an experiment which proves that the subocular lymjih sacs have not grown caudad, nor do they communicate with the lateral pharyngeal lymphatic, nor with the veins at the stage of development presented bj^ this twenty-day trout.



Fig. 6 Transverse section taken through the subocular lymph sacs of a twenty-one-day rainbow trout embryo in which, as independent structures; the sacs have reached the maximum stage of their development. P. 1^. C. series 646. Injected embryo. /, subocular lymph sac; 6, precardinal (jugular) vein; 20, eye; 22, carotid artery.


The subocular lymph sacs of the trout embryo are non-pulsatile in charactei- and are Hned by an endothelium around which no muscular coat is formed. J)uring the stage of their independence they become gradually distended with lym]ih which must necessarily enter them in a centripetal direction from the


EMBRYONIC LYMPHATIC SYSTEM 293

intercellular spaces of the head. As this lymph gradually mcreases in amount the subocular sacs of the trout can be easily observed in the living eml^ryo, and are especially prominent in the rainbow trout between the nineteenth and twentyfirst days. B}' the time the subocular h'mph sacs have attained their maximmii size as independent structures, on the twentyfirst day (figs. 4 and 6), a considerable pressure must be exerted by their lymph upon their walls, which would account for the distended appearance presented by the sacs (1) at this stage (fig. 6). As soon, however, as the subocular haiiph sacs establish tlieir communication with the lateral pharyngeal lymphatic, so that their h'mph can flow continuously and centripetalh' to the veins, this pressure against their walls is immediately released, and the sacs then appear less prominenth' in the li\-ing embryo, due to a partial collapse of their walls.

It is thus seen that, during the period of its independence, the subocular lymph sac of the trout embryo serves as a local and independent reservoir for the reception of lymph which enters it in a centripetal direction from the intercellular spaces; that it retains this lymph only temporarily, until the sac establishes a communication with the lateral pharyiigeal lymphatic, through which a continuous centripetal lymph flow may then pass from the intercellular spaces to the venous circulation.

The subocular lymph sacs of the trout embryo therefore furnish us with a striking example of the fact that, not only do independent and discontinuous anlagen of the lymphatic system actually exist, but, that they can also be observed and be experimented upon in the living embryo.

The functional role played by the subocular lymph sacs of the trout embryo, during the stage of their independence, as well as after they have estabUshed a communication with the venous circulation, undoubtedly gives us the clue to the function assumed by the independent lymph vesicles of the embryo in general. It also explains the manner in which a continuous centripetal lymph flow is estabUshed in the embryo, between the intercellular spaces and the venous circulation, in relation to the developing hmiphatic vessels.


294 CHARLES F. W. McCLURE

On the basis of the functio?ial rule played by the subocular lymph sacs — and this can be actually demo7istrated in the living trout embryo^-dt is highly probable that the independent lymph vesicles, of the embryo in general, also serve as local reservoirs for the temporary retention of lymph which enters them in a centripetal direction from the iiitercellular spaces; that these lymph vesicles become progressively concrescent with one another to form continuous channels, through which the lymph collected and temporarily retained by them is then forwarded to the venous circulation. In this manner the centripetal flow of lymph which continuously enters these independent lymph vesicles from the outlying intercellular spaces, is continued on to the venous circulation.

It may be mentioned here, incidentally, that the functional role plaj^ed b}' the subocular lymph sacs of the trout embryo during the stage of their independence, is also evidence of the fact that the lymphatics of fishes function solely in the capacity of lymphatics at the time of their inception, and that they are therefore not transformed \'eins.

In case the independent lymph vesicles of the embryo should fail to become concrescent with one another and with the veins, at the typical points of lymphatico-venous entry, an oedematous condition of the body would undoubtedly arise, aiid the ontogenetic condition, in which only independent and discontinuous anlagen are present, might then be retained in the adult. That such might actuall}- be the case seems to be borne out by the conditions observed in an oedematous human foetus alreadj^ desci'ibed by Smith and Birmingham.'- These investigators ha\'e described a case in which that peculiar and rare condition known as oedematous foetus was found to depend upon the complete absence of the thoracic duct, lymphatic glands and lymphatic trunks in general, and in which the lymph was stored in what they described as "greatly distended tissue spaces" which neither communicated with one another, nor with the veins.

- Smith iintl IJirmingham. Absent tlioracic duct ciiusiuy: ocdeina of n foetus. .]our. Anat. aiirl Physiol., vol. 23.


EMBRYONIC LYMPHATIC SYSTEM 295

Only two possible conclusions can be drawn regarding the significance of the complete absence of continuous lymphatic trunks and of the presence only of independent and discontinuous lymph-containing tissue spaces in this human foetus: Either there has been a complete failure on the part of the h^raphatic system even to initiate its development, so that these 'tissue spaces' are in no sense related to the true lymphatic system, or, the presence of these spaces signifies a condition in which the normal development of the Ij-mphatic system has been arrested at an early ontogenetic stage.

Huntington and the writer'* have repeatedly described and figured the presence of independent lymph vesicles or lymph spaces in the mammalian embryo, and Huntington has recently made a more extensive and detailed study of these structures, as theA' occur in the subclavian and primitive ulnar regions of the cat. Although one is not given the opportunity of studying these independent lymph vesicles in the living embr3^o of the mammal, as is the case in the trout, it would now seem quite a waste of time to parley further over the question of their presence in the mammalian embryo, or, that it is through the concrescence of such independent vesicles that the main lymphatic channels of mammals are formed.

The oedematous human foetus described by Smith and Birmingham appears to present us with the most striking evidence, not only of the fact that the presence of independent lymph vesicles may actualh^ be demonstrated, in certain circumstances, as functional structures in mammals, but, also, that the functional role played by them is similar to that plaj'ed b}' the subocular h'mph sacs of the trout during their independent stage. It is

•' Huntington and ]\IcC"lure. The anatomj- and development of the juguhir Iraiph sacs in the domestic cat (Felis domestica). Amer. Jour. Anat.. vol. 10, 1910. fig. 66.

' Huntington. The develoiunent of the mammalian jugular lymi)li .sac. of the tributary primitive ulnar lymphatic and the thoracic ducts from the viewpoint of recent investigations of lymphatic ontogeny, together with a consideration of the genetic relations ot lymphatic and haemal vascular channels in the embryos of amniotes. Amer. Jour. Anat., vol. 16, 1914. Also, The development of the IjTnphatic drainage of the anterior limb in embryos of the cat. Proc. Amer. .\ss. .\nat.. Anat. Rec, vol. 9, 1915.


296 CHARLES F. AY. McCLURE

highly probable, therefore, that the conditions found in this human foetus indicate that the development of the lymphatic system had been arrested at a normal ontogenetic stage; that its oedematous condition was due to the circumstance that the independent and discontinuous anlagen of the lymphatic system had failed to become concrescent with one another and with the veins, in order to establish a continuous system of channels, through which a continuous centripetal lymph flow could pass from the outlying tissue spaces to the venous circulation.


THE PYRA]\IIDAL TRACT IX THE GUINEA-PIG (CAVIA APEREA)

IDA L. REVELEY

Fro))i the Pinjsiological LohDralnnj, Mtdlcdl College, Cornell University,

Ithaca, X. Y.

TEX FKUTfES

IXTRODUCTIOX

The pyramidal tract (fasciculus cortico-spinalis) in rodents, so far as it has been examined in this order, is crossed and runs in the dorsal column of the spinal cord, but there are exceptions to this rule. In the family Leporidae, including- the rabbits and hares, it lies in the lateral columns, and in the ( 'anadian porcupine there is a dorsal column, a lateral column and a ventral column tract (Simpson '14). In view of the fact, therefore, that such wide variation exists between closely related species, it is desirable that as man^^ as possible of these be examined.

In the guinea-pig, the animal with which this paper deals, Spitzka ('86), Bechterew ('90) and Wallenberg ('03) have found that the pyramidal tract decussates into the posterior column.

Ranson ('13) states that in the albino rat the tract consists of a mixture of meduUated and non-meduUated fibers, and b}' the use of the pyridine-silver method of Cajal (modified), the non-medullated fibers are stained, so that the course of the tract can be followed by this means.

According to Linowiecki ("14), who worked in Ranson's laboratory, also with the pyridine-silver method, the same obtains in the guinea-pig. In this annual the tract lies in the posterior column, but it does not forrh such a compact uniform area when stained by this method as is found in the rat, indicating, ajoparentl}', that the proportion of medullated to nonmedullated fibers is greater in the guinea-pig.

297

THE ANATOMICAL RECORD, VOL. 9, XO. 4


298 IDA L. REVELEY

The pyridine-silver method may be regarded as the complement "^of the Marchi method since the latter stains only medullated fibers in the process of degeneration.

PRESENT INVESTIGATION

The object of the present research was to trace the fibers of the pyramidal tract in the guinea-pig from their origin in the cerebral motor cortex to their termination in the lower levels of the brain and spmal cord. The method of secondary degeneration was employed, with Marchi staining.

Eight anhnals (adults) in all were used. The cerebrum was exposed on the left side, under ether anesthesia, and the motor cortex removed. At the end of periods varying from twelve to sixteen days after the operation they were killed by ether or coal gas, when the brain and spinal cord were removed and placed in 3 per cent potassimii bichromate. After three weeks in this fluid, with frequent changing, the tissue was cut into slices 3 to 4 mm. thick and placed in ^larchi's fluid (3 per cent potassimn bichromate, 4 parts, 1 per cent osmic acid, 1 part). At the end of eighteen days the pieces were removed, washed in running tap water for twelve hours, and taken through the alcohol-xvlene-paraffin series into paraffin in which they were imbedded and cut. Sections from all levels of the bram and from most of the segments of the spinal cord were mounted and examined.

COURSE OF PYR.-OIIDAL TRACT FOLLOWED BY SECONDARY DEGENERATION

The course of the pyramidal tract through the midbrain, pons and upper part of medulla oblongata is similar to that found in the higher mammals such as the cat, dog, monkey and man, and is so well known that no detailed description need be given. In the midbrain it occupies the middle three-fifths of the crusta, more or less, and is continued downwards as the pontine bundles, which unite at the lower border of the pons to form the anterior pvramid of the medulla. Above the level of


PYRAMIDAL TRACT IN THE GUINEA-PIG


299


the general decussation, in the lower part of the medulla oblongata, there is no evidence of any crossing of fibers; all the degeneration appears to be confined to the side of the lesion.

Sections through the lower or closed half of the medulla oblongata, about 1 mm. below (caudal to) the calamus scriptorius, show the beginning of the pyramidal decussation. The



Fig. 1 Transverse section, medulla oblongata through upper extremity of pyramidal decussation. X 10.

Fig. 2 Transverse section, medulla oblongata through middle of pyramidal decussation. X 10.


pyramid, in transverse section, is triangular in outline at this level, and from the dorso-mesial angle a few fibers can be seen passing backwards along the median raphe. They cross the raphe close to the central gray matter and curving outwards, in front of the hypoglossal nucleus, turn backwards ip the gray substance. One or two small bundles reach the posterior column but most disappear in the gray matter (fig. 1).


300


.• »t , lower level, al^out the .nickUe of the decus In sections at a lo«ei le^e , ^^^ ,„ore or less

sation, the fibers cross in great ™>^b«^^ j^ ; ^^^,,,,^ intei ,,ell defined bundles ff^^ Crt tund side. After

lacing with -"-P-;^;"|^r U^rroutwards and then curve crossing the raphe the Abes 'i ^^^^ ^j ^,^^„^

backwards and inwards *'°"Sb the 8ia transversely,

passing into the funiculus '^'^^^^^l^ik- 2). Along the Ly form a distinct and ^°™Pf^\*7„'u bundles are seen dorsal margin of the gray matter a ^e.^ sm

on the mesial side of f?Xt:aTf generated fibers runs At this level a smg e small stianc| « g ^^^^^

backwards through the f^-^^-^^^Zv bend outwards; to the central canal, and *""^^Vit Caches the dorsal

^— Tis^trf:Lrwir:^^^^^^^

r:Us"r:entoii^^infour c^^^^^^^ ^,^. 3, At the junction of the medulla ^Mth tlie i ^^^^^

practically all the fibers have er - ^ « ^ he ^^.^^^

L 1,1 the ^^--^vraHetached .Zues extend from its m outline, but a le^^ -m^ matter, as de mesial angle along ^^^^^^^'^^Zll^-'^ ^^--Ale, seen near scribed in the last section, ihc "o" , ^^^^ ^,o,,_

the middle of the "at'on, is a^^^^^^^ ^ ^^^ „„ ,,, ing seems to l^e complete, no ae„e decussa same side. Between the upper ^^^^ ^,, Regeneration many fibers seem to ha^ e "^^^^^^^^ ^^^ , „„,.«  tion m the anterior pyramid '^«^".^' ' ,^„,„ ^.-aet. These extensive area than in the crossed do sal oUn ^^^_^^^ ._^ have presumably terminated m the g.aj matte, this region. , „,.„„,ed pvramidal tract I, the first c«-v.ca -g™-* . * , ' Xmn of Burdach of reaches its largest size. /* "^" "\ ' „„,terior horn and «ray the opposite side, in -"*-';"* ^.^i™ line, its ventro commissure. It - — *^^ ™to and meeting its fellow mesial angle extendmg t«the middle ^^ ^^^ ^^^^,^ ^^^,^

of the homolateral side (fig. 4). All ^ .,,„l„„ in tlie

decussated and there is no evidence of ,un cU^o


PYRAMIDAL TRACT IX THE GUIXEA-PIG


Wl


crossed lateral or direct ventral columns as is the case in the Canadian ])orcupine.

Sections through the second cervical segment (fig. 5) show a considerable change in the area occupied b}' the fibers of the tract. It is crescent-shaped; the dorsal border is concave; the mesial border lies against the ])osterior medium septum, oc


Fig.


5 6

3 Transverse section, medulla oblongata through lower (caudal)


extremity of pyramidal decussation. X 10.

Fig. 4 Transverse section, first cervical segment of spinal cord. Fig. 5 Transverse section, second cervical segment. X 10. Fig. 6 Transverse section, fifth cervical segment. X 10.


X 10.


cupying about one-fourth of the distance between the posterior gray commissure and the free margin of the section. The degeneration is less dense than in the first cervical segment indicating a distinct diminution in the number of fibers.

In the third, fourth and fifth cervical segments (fig. 6) the general appearance of the tract changes little, but there is a progressive faUing off in the number of fibers which it contains.


302


IDA L. REVELEY


The degeneration seems to be densest near the gr^y/^^^*^^' the fibers becoming more and more scattered towards the dorsal

border of the area. .

Between the fifth cervical and first thoracic segments (hg. 7) a still further dhninution in the nmnber of fibers is evident. In the latter segment the tract, considerably reduced m size, occupies an oval area which is no longer in contact with the posterior median septum except at its ventro-mesial extremity.




Fie 7 Transverse section, first thoracic segment. X 10.

Fig 8 Transverse section, eighth thoracic segment. X 10.

Fig q Transverse section, first lumbar segment. X 10.

Fig. 10 Transverse section, fourth lumbar segment. X 10.

In the eighth thoracic segment the area of degeneration is still more restricted (fig. 8). It has now withdrawn from the middle line and lies in the recess formed by the narrowing of the neck of the posterior horn. Tracing it caudalwards it is found to occupy the same relative position in the succeeding segments, becoming more and more reduced m size ^ntil the fourth lumbar segment is reached, where it is represented by a very small number of scattered fibers lying against the neck of the posterior horn (figs. 9-10). Beyond this level it cannot be followed.


PYRAMIDAL TRACT IX THE GUINEA-PIG 303

It is interesting to compare the above results, obtained b}^ the ]\Iarchi method, where the medullated fibers alone are stained, with those of Linowiecki, in the same animal (guinea-pig), who used the pyridine-silver method which brings out the nonmedullated fibers. According to his description: "In the seventh cervical segment the pjTamidal tract is located in the ventral

part of the posterior funiculus The fibers of the

tract are more densely grouped ventrally and lateralh' near the grey substance and this gives the cross section of the two tracts somewhat the form of the letter V." (Compare with figures 6 and 7.)

At the level of the eighth thoracic segment, by the p,vridinesilver method, the tracts are crescentic in outline and much diminished in size; they are still further reduced at the twelfth thoracic segment where they consist of two compact groups of axons which have become separated at the posterior median septum. Proceeding caudalwards they become less distinct and at the level of the second lumbar segment the groups tend to move posteriorly and to separate from each other. From here on they narrow markedly and fade in color until at the level of the fifth lumbar segment they consist of two narrow strips, one on each side of the posterior median septum, which are hardly visible.

It will thus be seen that the descriptions of the position and outline of the pyramidal tract, as brought out by the two methods, are in close agreement. This would indicate that the mixture of medullated and non-medullated fibers, of which the tract appears to be made up, is more or less uniform throughout its entire course in the spinal cord.

In the fifth lumbar segment, according to Linowiecki, the tracts consist of two narrow strips on each side of the posterior medium septum,"^ but he does not say whether they are in contact at the septum or separated from each other. At the level of the fourth lumbar segment almost the same words might

1 Taken as it stands, this sentence would seem to indicate that the tract is represented by tico narrow strips on each side. What the author does mean, probably, is that there are two narrow strips, one on each side.


OQ^ IDA L. REVELEY

be used to describe the tract, as brought out by the degeneration method, if it be added that the narrow- strip hes close to the S aspect of the gray n.atter forming the neck of the posterior

horn (fig. lOj.

SUMMARY

The course of the pyramidal tract in the guinea-pig, from the beginning of the decussation in the medulla oblongata caudalwaids, as brought out by the method of secondary degeneration with ^larchi staining, is as follows: , c .^

The decussation begins al,out 1 mm. below the evel of he calamus scriptorius and ends near the junction of he medulla ^"h the spinal cord. All the fibers cross, between these limits, "nd most pass on into the funiculus cuneatus where they turn 'coudahvards into the spinal cord but many end in the gray matlei of the bulb in this region. As this dorsal column tract is followed downwards, from segment to segment of the cord

t outline changes considerably (see figures) and here is a progressive diminution in the number of fibers which it con ains but this loss of fibers is most marked in the upper cervical and

'X'tr c—be traced farther than the fomth lunibar segment, where it is represented by a very few degeneiated fibers Iving close to the gray matter of the posterior horn.

Iccording to Eanson the pyramidal tract consists of a mixture of meduUated and non-medullated fibers, the former o which, while un<lergoing degeneration may be ^t^ined by the Marchi method, the latter bj' the pyndine-silver method. Ihe d sc tioi of the spinal portion of the tract in the guinea-pig J^n bv Linowiecki, who used the pyridine-silver method fstaclose agreement with what I have found by the degenera ion ,ethoc°- thi' would appear to point to the fact that the mixture ofihe two varieties of fibers, within the tract, is fairly uniform throughout its course.


PYRAMIDAL TRACT IX THE GUINEA-PIG 305

BIBLIOGRAPHY

Bechterew, W. 1S90 I'eber die verschiedenen Lagen imd Diniensionen der Pyramidenbahnen beim ]\Ienschen und den Tieren iind fiber das \'orkommen von Fasern in denselben, welche sich durch eine friihere Entwickelung anszeichnen. Xeurol. Centrabl., p. 738.

LixowiECKi, A. J. 1914 The comparative anatomy of the pyramidal tract. Jour. Com]j. Xeur., vol. 2-4, p. 509.

Raxsox. S. W. 1913 The fasciculus cerebro-s])inalis in the albino rat. Amer. Jour. Anat., vol. 14. p. 411.

SiMPSox. S. 1914 The motor areas and pyramid tract in the Canadian porcupine (Erethizon dorsatus, Linn.) Quart. Jour. Exper. Phj'siol., vol. 8, p. 79.

Spit/ka, E. C. 1886 The comparative anatomy of the pyramid tract. Jour. Comp. ;Med., vol. 7. ]>. 1.

Wallexbekg, C. a. 1903 Cited by Cokistein. Zur vergleichenden Anatomie der Pyramidenl)ahn. Anat. Anz., Bd. 24, p. 454.


A STUDY OF THE AFFERENT FIBERS OF THE BODY

WALL AXD OF THE HIXD LEGS TO THE CERE BELLU:\I OF THE DOG BY THE AIETHOD

OF DEGENERATION

GILBERT HORR.VX From the Anatomical Laboratory of the Johns Hopkins Medical School

SEVEX FIGURES

This work was begun under the stimulus of the work of Bolk, who based an hypothesis of a localization of a series of coordinating centers in the cerebellum upon studies in comparative anatomy. Bolk has simplified the nomenclature of the parts of the cerebellum and, using his terms, sums up the localization in the cerebellum as follows:

The lobus anterior cerebelli contains the coordinating centers for the groups of muscles of the head, nameh' those of the ej^es and tongue, the muscles of mastication and muscles of expression beside those of the larynx and pharjaix; the IoIduIus simplex contains the coordinating centers for the neck musculature; the upper part of the lobulus medianus posterior contains the unpaired coordinating centers for the right and left extremities; the lobuli ansiformes and paramedian! contain the paired centers for the two extremities, while the rest of the cerebellum has the coordinating centers for the' trunk musculature ('07, p. 170).

In general, Bolk thinks that the coordmating centers for symmetrical muscles which act together are in the vermis, while the centers for those which act independently are in the hemispheres.

This hypothesis has been borne out by the experunental work of Rynberk ('04) from Luciani's laboratory, for example, by obtaining special movements of the neck muscles after a unilateral exthpation of the lobulus simplex. These results suggest further work on the end station of the fibers of the different regions of the body by the inethod of degeneration, though

307


308 GILBERT HOKRAX

it is of course clear that the tracing of the afferent fibers of each region to their end station does not unravel the nature of a coordinating center in the cerebellum. The results of tracing the fibers of the different regions of the cord to the cerebellum indicate that the fibers of each of the regions of the body sends fibers to almost the entire vermis.

The most recent and the most extensive work on determining the distribution of spinal fibers in the cerebellum is that of Sir Mctor Horsley in 1909. In this article he gives a complete analysis of the literature of the work on the fasciculis spinocerebellares ^'entralis and dorsalis. As far as the point of the distril)ution of the fibers to the cerebellum is concerned, the main results are as follows: In 1890 Auerbach stated that the fasciculus dorsalis (Flechsig) ended in the dorsal — that is to say, in the cephalic — part of the superior vermis, and the fasciculus ventralis (Gower's) in the ventral part. In 1892 Mott reversed this statement by showing that the fasciculus dorsalis ends in the vermis, caudal to the end station of the fasciculus ventralis, which enters the cerebellum farther cerebralwards by way of the brachium conjuncti^^um or superior cerebellar peduncle. This point is well shown in the well-known diagram of his figure 1, page 219.

Collier and Buzzard in 1903, in an anaWsis of human material, confirmed Mott's view of the relative position of the end station of the dorsal and ventral cerebellar tracts; that is, that the fasciculus spino-cerebellaris dorsalis ends in the inferior vermis, though they find that some of the fibers end in the nucleus dentatus and in the nuclei of the roof. The fasciculus spino-cerebellaris ventralis they trace b}^ way of the superior cerebellar peduncle to the superior vermis but in small part also to the lateral hemispheres.

Sir A'ictor Horsley divided the coi-d in a general way into four regions: the first, from the fii'st to the fourth cer\'ical segment, representing movements of the head and neck ; the second, from the fifth cervical to the first thoracic segment, representing movements of the arm; the third, from the second thoracic to the secfuid lumbar, representing movements of the body: and the


AFFEREXT FIBERS OF THE DOG 309

fourth, from the third kinibar to the second sacral, representing movements of the leg. He made the lesion cover the fibers representing a given region, by destroying the cells of origin for the tract rather than the fiber tract itself. Indeed, his purpose was to determine which cells of the cer\-ical and lumbar regions of the cord are homologous with the nucleus dorsalis. The lesion for the first or upper cer\-ical region was in the gray matter of the cord, taking in the cells in the homologous position to the nucleus dorsalis and the cells of the middle region of the gray matter. Within the cerebellum the fibers passed to all the vermis except the most anterior part of the lobus anterior, namely, the lingula, and the most posterior part of the lobulus medianus posterior, namely, the uvula and the nodulus. Thus the end station for the afferent fibers of the neck is not limited to the lobulus simplex but includes almost the entire anterior lobe and most of the median posterior lobe as well.

The fibers of the second region, representing fibers from the arm, he found to pass forward mainh' on the same side but in part on the opposite side. M'ithin the cord they run both in the dorsal and in the ventral cerebellar tracts, ^^'ithin the cerebellum they end in the lobulus centralis, the ventral half of the culmen and the ventral half of the pyramidalis; or in Bolk's termmology, in the lobus anterior, in all the lobulus simplex and in most of the lobulus medianus posterior. Horsley did not study the fibers of the third of the iDody regions, but the fibers from the leg region he found ended in exactly the same parts of the cerebellum as those of the arm region.

Thus from the literature it is clear that the spino-cerebellar fibers end in the vermis; that the fasciculus spino-cerebellaris ventralis fGow^er's tract) ends in the more cerebral part of the vermis, while those of the fasciculus spino-cerebellaris dorsalis end in the more caudal part of the ^'ermis. The fibers representing the four regions of the body — namely, the neck, the arms, the body and the legs — pass through both cerebellar tracts and are distributed to all parts of the vermis except the most anterior and the most posterior folia. These results are confirmed in the experiments herein reported.


310 GILBERT HORRAX

As far as the symptoms of lesions of the cerebellar tracts are concerned, our results also agree with those of Horsley, who found that there was no loss of efferent (purposeful) movement in the muscles involved ; that all the motor effects were transitory and probably due to interference with the anterior cornus, and that there was ataxia and clumsiness of mo\'ement. These results are practically the same as those of Bing.

TECHNIQUE AND METHOD OF INVESTIGATION

Three dogs, each about the size of an ordinary fox terrier, were used for the purpose of our study, and in all cases the technique of operation and preparation of material was identical. In Dog 1, experiments with regard to various sensations were carried out during the period between the operation and the killing of the anunal for histological study. As these experiments were not of a sufficiently satisfactory nature, they were omitted in Dogs 2 and 3, but are recorded in connection with Dog 1 for the sake of completeness. The artificial lesion in the cords of the dogs was made as follows : An incision was made in the median line of the back, extending between the scapulae down toward the lower dorsal region, for a distance of about 10 cm. Very little hemorrhage took place and this was quickly stopped. Laminectomy of the 4th, 5th and 6th dorsal vertebrae was performed and the cord in its dura exposed. An aneurism needle was placed under the cord very genth' and the cord in its dura was lifted slightly and rotated a little toward the left. A \'ery superficial slit was then made with a narrow scalpel, through the dura and into the substance of the cord at right angles to its long axis, and on the right side of the animal, in an effort to cut the fasciculus spino-cerebellaris dorsalis (Flechsig) and possibly the fasciculus spino-cerebellaris ventralis (Gowers) ; the cord was then slipped back. There was no hemorrhage in any case during the cutting of the cord.

The wound was closed in tighth^ by sutures of silk through the muscles, fascia, subcutaneous tissue and skin. All the dogs made prompt recoveries, but in Dog 2 the skin layer of the


AFFERENT FIBERS OF THE DOG 311

wound was opened by the dog's scratching on his cage. The skin separated, but the wound was kept swabbed out with iodine so that the lower layers did not open and were not involved in the superficial infection. The dog improved steadily and granulations formed rapidh' over the wound.

The operations were performed by Dr. Goetsch, of the Johns Hopkins Hospital, on Dog 1; by Dr. Hunnicutt, of the Johns Hopkins Hospital, on Dogs 2 and 3, under strict aseptic precautions, the total time of anesthesia being from an hour and a quarter to two hours; ether was used as an anesthetic.

The dogs were kept alive for periods of ten days to three and one-half weeks, during which time observations were made on them in order to ascertain the nature of the sj'mptoms caused by the lesion. The wounds of the operations healed perfectly within a few days. The symptoms observed were recorded each day, and in brief were as follows:

Dog 1. April 26, 1910, the da}' after the operation, 9.00 a.m. No apparent disability except in use of hind legs; dog sits at rear of cage, with left leg extended and raised at an angle of 35° to -15°; right hind leg somewhat flexed and lying on floor. ^Yhen called and coaxed by snapping the fingers, the dog responds by wagging tail, and by slight effort s at movement, but does not actually change position. Head, fore legs and fore feet, are moved in a perfectly coordinated and intelligent waj'.

April 27, 1910, 9.30 a.m. Dog still sits in about the same position as on previous day, but the left hind leg, instead of being raised, is more nearly or quite touching the floor. When called, the dog crawls to the door of the cage, locomotion being accomplished mainly by the use of the fore legs, the animal remaining in the sitting posture throughout. The hind legs are both more or less flexed, and during locomotion perfectly definite, although almost ineftectual, movements are made by them; the toes of the left hind leg are occasionally flexed. Movements of all parts of body except hind legs seem perfectly normal.

April 28, 1910. When taken out of cage to-day, the dog moves along with its hip against the wall for support, the hind legs not working nmch better than the day before. Once it sat down and scratched with the right hind leg, just posterior to the right fore leg.

April 29. 1910. When taken out on the grass, the dog took several steps in a normal manner on all four legs, but finalty the hind legs weakened, spread apart, and collapsed, throwing the rear half of the dog's body first to one side and then to the other. The dog was seen to scratch again in the same manner as j^esterday, only the


312


GILBERT HORRAX


left hind leg was used. Hot and cold water was applied to all four less bv means of dipping the latter into a beaker of water (during these tests the dog was bhndfolded). Following are the results:

Temperature of 3° to O^J. Causes no effect on any of feet.

Temperature of 20^ to 37°, 47°, 57° Causes no effect on any of feet.

Temperature of 67° Causes both hind legs to be withdrawn from the water 20 seconds after time of immersion; both front legs were withdrawn 2 to 3 seconds aftei- immersion; pinching toes with forceps causes prompt withdrawal of all four legs.

\pril 30, 1910. This morning the dog shook the fore part of the body, also got up on all four legs and stood for some time.


Temper Temper


ature of 37° ature of -47°


Temper Temper


•ature of 58°


Temperature of 65°


Gives no effect on any of feet.

Xo effect on hind legs; right front leg was withdrawn when the tips of toes came in contact with the water; left fore leg not tried.

Xo effect on hind legs; right fore leg was withdrawn on being touched to the water; no effect on left fore leg.

All legs withdrawn from 6 to 12 seconds after time of immersion, fore legs a litt'e t-ooner than hind legs; toes of hind legs were shaken in the water before withdrawal.

Same as 58°.

Tail withdrawn 6 seconds after immersion m water of 56° temperature.


^Iav 2 1910. Dog showed marked improvement in walking more normally.' Hind legs used most of the time, but with an unsteady, swaying motion from side to side.


Xo effect on hind feet: front feet were withdrawn upon contact with water. Xote: ^^ hen the fore feet were held in the water, no signs of discomfort were apparent.

Same as at 37°.

Same as at 37°, except that discomtort was evidenced when fore feet were held in the water.

Left hind foot withdrawn in 5 seconds; right hind foot withdrawn in 15 seconds; fore Teet l)oth withdrawn ui)on contact.

May 3 1910. Improved general condition was noted to-day, with better use of hind legs, although the drunken, swaymg gait was still marked.


Temperature of 37'


Temperature of 43' Temperatui'c of 53'

Temperature of 57'


AFFERENT FIBERS OF THE DOG 313

Temperature of 28° No effect on hind feet; fore feet withdrawn upon

contact with the water. Temperature of 35° Hind feet withdrawn after 15 seconds; fore feet

withdrawn upon contact. Temperature of 47° Right hind foot withdrawn upon contact; left

hind foot not withdrawn at all; both fore feet

withdrawn upon contact; no effect on tail.

May 4, 1910. Temperature observations.

Temperature of 28° Hind feet at first withdrawn upon contact, but subsequently allowed to remain in water; fore feet withdrawn upon contact and not subsequently allowed to remain.

Temperature of 37° No effect on hind feet; fore feet withdrawn upon contact, but allowed to remain upon subsequent immersion.

Temperature of 47° All feet withdrawn almost immediately ; when beaker containing no water was touched to the hind feet there was no withdrawal nor other noticeable effect; same beaker to fore foot caused withdrawal of latter; right fore foot was not withdrawn.

\Iay 7, 1910. Temperature of 42°, Xo effect on hind feet; fore feet withdrawn upon

contact. Temperature of 45°, 47° Same as 42°. Temperature of 55° Hind feet withdrawn after 9 seconds; fore feet

withdrawn upon contact.

May 10, 1910. Again a marked improvement in the use of the hind legs was noted. Dog was very lively, running and jumping around, but there was still lack of coordination in the hind legs.

May 11, 1910. Dog was livelier than on previous day; ran about and sprang upon the observer in puppy-like fashion, playing around with very little departure from normal movements. However, the same uncertain gait of the hind legs was noticed when the dog would stop jumping and either walked or ran slowly away.

May 13, 1910. Knee jerks of hind legs present and equal on both sides.

May 14, 1910. Dog killed; brain and cord removed.

Dog 2. December 7, 1912. Operation, 10 a.m.

December 7, 1912. Dog conscious and sitting up at 2.30 p.m.

December 8, 1912. Sitting up; can move back legs.

December 9, 1912. Makes attempt at locomotion with hind legs.

December 10, 1912. Can stand up on all fours.

THE ANATOMICAL RECORD, VOL. 9. XO. 4


3][4 GILBERT HORRAX

December 11, 1912. Walks a little, with a typical extreme ataxic gairibaik feet sometimes interfering with each other) and often falls to one side or the other.

December 13. 1912. In getting into his box thei^e seems to be more uncertainty of his right than of his left hind leg; dog walks more todqv same aait but some improvements. . , i i

%ex"nLl-14,1912. 4 p.m. walks f^--\ffjr'^^^nAZ' follows one around the room, comes when ca led etc. His hnd legs however, are very ataxic. th<. right bemg noticeably more so than the

^^ecember 15, 1912. Walks alx.ut: shows umch improvement in

December l(i. 1912. Cait much improved: ataxia in right hind leg

^%eSer 17-20. 1912. Gait steadily improving; also marked gain

"' December 20, 1912. Dog killed; l)rain and cord removed.

Doqfl. December 14, 1912. Operation. 10.30 a.m. ,.,.,,,,„.

December 14 1912. 4 p.m. ; dog gets up on all fours and ^^ alks about the room his hind legs being very ataxic, but his recovery m general behio qSckei alui his ability to walk coining much sooner than was the

'%e«>mW?%2."Dog walks about the room: ataxia <.f right

^'"D(^nber Ki. 1912. Walks about : ataxia of right hind leg perfectly

'^'December 17-20, 1912. Improvement rapid and more complete than in Dogs 1 and 2; runs and jumps about the room.

January 8, 1913. By this time no ataxia can be noticed, dog > Rait and' actions are apparently normal in every way.

.January 10. 1913. Dog killed; brain and cord removed.

At periods, varying from 10 days to :U weeks from the date^ of operation, as noted above, the dogs were anesthetized with chloroform. The right femoral vein was opened, after which a cannula was inserted into the left common carotid artery and thr.mgh the latter a liter and a half of 10 per cent formalm solution was injected into the animals.

\fter waiting half an hour in order that as much hardening as possible might lake place, the brain and cord were remoAec carefully. The cord was cut inK. three approxnnately eciua lengths' and put at once into a vessel contaimng a 10 per cen solution of formalin. The material was left in this solution un .1 various parts of it were wanted for study. Th(> f-rst blocks


AFFERENT FIBERS OF THE DOG 315

were cut out of the cord three days after it had been put into the formalin and the other blocks were taken subsequenth^ for study througliout the following year; all the blocks were from 5 to 10 mm. thick. The part containing the medulla and pons, with the cerebellum, was cut into four blocks which w^ere numbered as is shown in figure 1. As will be seen, the first and second blocks contain, in Bolk's nomenclature, the lobulus medianus posterior of the cerebellum; the third block contains the lobulus simplex and the caudal part of the lobus anterior; the first block contains the rest of the lobus anterior. The blocks were all treated in the same manner; they were stained en hlocke by a modified Marchi method; they were placed for from o tf) 7 days in the following solution:

Osmic acid 1 part

XalOs 3 parts

Distilled water 300 parts

The blocks were embedded in celloidin and all the sections showed an excellent staining of the degenerated myelene.

EVIDEXC'ES OF DEGENERATIOX IX THE SECTIONS

The study of the sections of the first dog showed ab()\'e the lesion degenerated fibers scattered throughout the section on both sides. In the upper cervical region, as shown in figure 2, there is a very abundant, scattered, bi-lateral degeneration of fibers, covering tlie entire ai'ea of the fasciculus spino-cerebellaris dorsalis and ventralis. It is difficult to understand wh,v there is so extensi\'e a degeneration on the left side, inasmuch as the cord was cut only on the right; l)ut as has been seen, the symptoms in\'olved both sides and there is an almost symmetrical degeneration.

Sections through the first block containing the cerebellum, as shown in figure 3, have a concentration of the degenerated fibers in the corpus restiforme and along the lateral margins of the medulla, with a second concentration in the tractus spinocerebellaris ventralis, especially of the right side. In the cerebellum the degeneration is confined to a liand across the vermis


316


GILBERT HORRAX


in its ventral third. This degeneration does not appear until the cephahc end of the first block is approached

\s one follows the sections farther cerebralward m the second block, as seen in figures 4 and 5, there is the same concentration of degenerated fibers in the corpus restiforme and along the rioht margin, while the fibers on the left side are less nunierous but have the same general pattern. Withm the cerebe lum the degenerated fibers are found throughout the second block, that is, the lobulus medianus posterior. For the most part, the degeneration is confined to the vermis but in figure o can be seen a few fibers in the edge of the hemispheres.

From here on the course of the filbers of the fasciculus spmocerebeUaris dorsalis can be followed easily in their position m the mferior cerebellar peduncle. In the third block, as seen in figure 6, the fibers of the corpus restiforme can be seen m the foUa of the vermis of the lobulus simplex. The cephalic Innit of the ending of the fasciculus spino-cerebeUaris dorsahs withm the cerebellum is reached m the caudal half of the thhd block, as shown in figure 6. Above this level, namely, m the^ lobus anterior, only the fibers of the fasciculus spmo-cerebellans dorsalis are to be found (fig. 7). , , ^^i f .i

It will tluis be seen that we have traced those fibers of the fasciculus spino-cerebellaris dorsahs (Flechsig), which represent the legs and possibly the lower body waU, from their situaion in the cord, up through the corpus restiforme of the medulla into the vermis cerebelli, in the caudal half of which they were distributed. In the most caudal part of the verinis their distribution is confined to one or two lammae, but farther cerebralward the distribution is very diffuse throughout all the

laminae. , , , , , ii

V part of the sensory fibers from the legs and lower body ^ all pass to the cerebellum through the fasciculus spino-cerebellaris ventralis (Gowers). These fibers occupy the antero-laiera margin of the cord, being more scattered than those of the dorsal tract of Flechsig. The ventral position of the tract is plain in figures 4, 5 and 6 for the region of the medulla. In the pons the


AFFERENT FIBERS OF THP: DOG 317

ventral fibers shift to their more dorsal position in the lateral margin of the brachium eonjunctivum, as seen in figure 7. Throughout the cephalic half of the third block and a part of the fourth block — that is, in the lobus anterior — the fibers of the fasciculus spino-cerebellaris ventrahs are distributed throughout the folia of the vermis, as seen in figure 7.

It has thus been made clear that the fibers from the legs and lower body wall pass to the vermis of the cerebellum and are distributed throughout the ^'ermis, with the exception of the most anterior and the most posterior folia. A part of these fibers pass through the dorsal cerebellar tract and the inferior cerebellar peduncle to the caudal half of the vermis, while the fibers of the ventral tract pass through the superior cerebellar peduncle to the cephalic half of the vermis.

In the second dog the lesion was in the sixth segment and sections at the level of the operation showed that the entire dorsal cerebellar tract, and a part, if not all, of the ventral tract, were cut. Both above and below the lesion, degenerated fibers were very numerous all through the ventral half of the white columns and along the dorso-lateral margins. There were a few scattered degenerated fibers in the fasciculi gracilis and cuneatus. Above the lesion the degeneration was nearh' identical with that found in the first dog. The degeneration of the cerebellar tracts was again double, though the lesion was confined to one side. There were fewer degenerated fibers on the un-operated side than in the first dog. In the distribution of the degenerated fibers in the cerebellum there was a little farther extension of the fibers into the lateral hemispheres. In the third dog the results were practicalh' the same as in the other two. There was the same bilateral degeneration, less extensive on the un-operated side; the distribution of the fibers in the cerebellmii also showed a slightly greater extension into the lateral hemispheres than is shown in the figures from the first dog.


31^ GILBERT HORRAX

c()^'CLUSIOXS

1 The onlv symptoms caused by a lesion of the spmo-cerebellar tracts ill the dog are those referable to a loss of muscle sense and tone The symptoms were bilateral in all three experiments and there was almost complete recovery in three weeks

9 These symptoms, in a lesion of the tracts at the level o the sixth thoracic spinal nerve root, are confined to the hmd legs and possibly the lower portions of the trunk.

3 The fasciculus spino-cerebellaris dorsalis, so far as its distribution in the cerebellar cortex is concerned, is confined to the caudal half of the vermis, and to the medial portion oi the

lateral hemispheres. , „ • ^ i 4 The distribution of fasciculus spino-cerebellaris ventraiis in the cerebellar cortex is confined to the cephalic half ol the

vermis. „ . ^. ,

5. There is no definite cerebellar center for association regarding the hind legs.

6. The cerebellar tracts are represented fiy crossed, as well

as by direct, fibers in the dog.

.My verv earnest thanks are due to Dr. Florence R. Sabin, whose cooperation and help alone have made this paper possible- and I also wish to express my thanks and appreciation to Drs ' Emit Goetsch, Jacobson, and Hunnicutt, of the Johns Hopkins Hospital, for theh invaluable help in operating on the dogs used.

LITERATI-RE CITED

\rFKH\<-.. L. ISOO Zur Anaiounv .ler Vorderscitenstrangreste. An-l,. f. path \nat. and Phys. imd f. klm. Medicin., Bd. 121.

li.xr Hmhkht lUdC. Experimentelles zur Physiologic der Tractus spmo(•c.iol,cUares. Arch. f. Anat. u. Phys. Abth. , • , ,

li,„K 1) mr, 1907 Das Corebclhun der Saiigetierc. Erne vergleichend ' ■ anatomischo Untersuchung. Erstor und Zwoiter Toil. Potrus ( amper., Bd. 3. Dritter Toil., Bd. 4.

Bruce \ X.niax 1910 The tract of Cowers. Quart. Journ. Exp. 1 hys. Nol-i.

CoLLTKR AND Buz.AUD 1903 The degenerations resulting from lesions of posterior nerve roots and from transverse lesions of th<' spinal .-ord m man. A study of twenty cases. Brain, vol. 2G.


AFFERENT FIBERS OF THE DOG 319

LuxA 190(3 Localizzazioni cerehcUaii : Contributo sperimentale anatomofisio logieo. Ricorche fatto iicl Lah. di Anatomia della R. Univ. di Roma,

torn. 13.

1908 Einige Beobachtungen iibtn- die Lokalisationen des Kleinhirns.

Anat. Anz., Bd. 32. .MacXalty and Horsley 1909 On the cervical spino-bulbar and spino-cerc bellar tracts and on the question of topographical representation in

the cerebellum. Brain, vol. 32. ^loTT, F. A. 1892 Ascending degenerations resulting from lesions of the spinal

cord in monkeys. Brain, vol. 15.

1895 Experimental enquiry u])on the afferent tracts of the central

nervous system of the monkey. Brain, vol. 18. Pellizzi, G. B. 1895 Sur les dcgcncrescences secondaries, dans le systeme

nerveux central, a la suite de lesions de la moelle et de la section de

racines spinales. Contribution a I'anatomie et a la physiologic des

voies cerebelleuses. Archives Ital. de Biologie, torn. 24. Vax Gehuchtex, a. 1904 Le corps restiforme et les connexions bulbo-ccrc' belleuses. Le Xevraxe. tom. 6. Vax Ryxberk, Ct. 1904 Tentativi di localizzazioni funzionali nel cervelletlo.

Archivio di Fisiologia, tom. 1.

1908 Das Lokalisationsproblem in Kleinhini. Ergeb. d. Phys.,

Bd. 7.


320


GILBERT HORRAX


PLATE 1 EXPLAXATIOX OF FIGURE

1


Dorsal view of the medulla and the cerebellum of a dog, to show the blo;ks i^to .iich the cerebellum was cut. The well marked groove be ..^^^^^ the lobus anterior and the lobulus simplex falls m the third block The first and second btocks contain the lobulus medianus posterior; the thud block mXdes lobulus simplex and a part of the lobus anterior, while the fourth block

Tir>liirlp<? the rest of the lobus anterior. rE^;: IpUX a^^^ L I^er^ed ,..r. «Uea .. f,ee hand. TKe H,M

Selellar s ventralis in the medulla. In the cerebellum ,t shows degenerated fibet In one folium of the n.iddle .egion of the lobulus -'-^^J-f ° „^,^, 4 Section through the medulla and cerebellum of Dog 1. taken t"'""?" the caudal part of the second block. X 8. It shows the separation o the fibers of the' corpus re.,tifornre from those of the fasciculus sptno-cerebellarrs

"f tctSnThrough the medulla and cerebellunr of Dog 1, taken through the ceohalk end of the second block. X 8. It shows degenerated fibers of the Lft ?ltuTu"pino-cerebeUaris dorsalis, entering the lobulus med.anns posterior

°' rSectfonthrough the medulla and cerebellum of Dog 1, taken through the Cauda end of the third block. X 8. The section is so near the hne shown on figure 1 that the section of the pons is incomplete ; it show s the .obulus simple v 7 Section through the pons and cerebellum of Dog 1, taken througn the cephaTc end of the third block. X 8. It is above the level at which the o pns'restiforme enters the cerebellum and shows the f-"™'-f^--f„7,t lari^s vcntralis in the edge of the brachmm eonjunctivum and the fibers of same tract in the lobus anterior of the vermis.


AFFEHEXT FIBERS OF THE DOG

GILBERT HORRAX


PLATE 1


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SOME NEW re(;eptacles for cmda^^ers and

GROSS PREPARATIONS

RALPH EDWARD SHELDON

From the Anatomical Laboratories, the School of Medicine, C'nlrerslty of Pittsburgh

EIGHT FHiURES

RECEPTACLES FOR CADAVERS

lustituticjii.s whicli do not possess cold storage facilities usually keep cadavers in tanks of various kinds. These may be of metal (galvanized iron), wood with a metal lining (lead, zinc or coppei'). or of concrete. The fluids used ai'e such, however, that the galvanized tank rusts through in a comparatively shoi't time, since in most cases it cannot be protected by paint, on account of the solvent power of the alcohol and carbolic acid used. The stock is usually thm, necessitating the use of angle irons or planks in order to prevent bulging. Also on account of this weakness, if the tank contains material, it may not 1)6 moved without injury to the bottom. The lined tanks, which must be soldered at the corners, likewise eventually leak, the solution then making its wa}' into the spaces between the lining metal and the wooden supjiort. The lining is I'arely smooth, considerable dirt accumulating, therefore, in cracks and uneven places. On account of these factors, the tank becomes foul and undesirable in a well-kept laboratory. Concrete tanks properly built and lined with cement are satisfactory, excepting that they cannot be moved and that they take up a large amount of space.

After some experience with various types of receptacles, the tank described below was designed for the Anatomical Laboratories at Pittsl)uigh. It has now been in use for more than a year and has given perfect satisfaction. Essentially it consists of a box built of two-inch cypress with half-inch bolts running in the wood, horizontally through the bottom and vertically in the sides and ends. The individual pieces of wood are fitted together as shown in figure 1. By this method of construction a solid and exceedingly strong box is obtained. If any leakage occurs through excessive drying, it is necessary only to tigliten the nuts on the bolts. The case is further strengthened by two angle irons (d, figs. 2 and 4) running lengthwise along the bottom at the corners. Through these pass the horizontal bolts (a. figs. 2. 3 and 4), also the vei'tical bolts (c, fig. 3). The ends of


324 RALPH EDWARD SHELDON

all other bolts pass through bars of iron one-half mch by two inches; e, figure 2, for the horizontal bolts, b, figure 2; /, g and h, figures 2 and 3, for the vertical bolts c. These strengthen the case and prevent heads and nuts from being drawn into the wood through its swelling or the tightening of the nuts. Two strips of oak one inch by six inches {i, figs. 2 and 3) are placed lengthwise under the tank in order to permit the floor underneath to be cleaned. These are removable so that they may be eventually replaced. It will be noted that the}" do not come in contact at any point with the wood forming the floor of the tank, thus preventing its rotting. The top is hinged and consists of one-inch cypress, properly battened. A gate valve for emptying the tank is desirable. Hot oil should be applied to the raw wood unless it is to be painted.

While this tank is moderately hea-vy, it can be easily moved when emptj", or even when partially' full, as it is not injured by the use of levers. Even when full of solution there is no bulging of the sides. Since all parts are tightty fitted, it may be used for the storage of cadavers in alcohol fumes. In fact, such a tank has been thus used here for nearh' a 3'ear, the material keepmg perfectly. Such a receptacle, six feet, six inches long by two feet, ten inches wide and two feet, eight niches high, inside measurements, will hold fifteen cadavers of average size. It is practically indestructible and should last indefinitely. The first cost is sixty dollars.

RECEPTACLES FOR GROSS PREPARATIONS

Large gross preparations, particular!}^ dissections, are ordinarily kept in tanks smiilar in structure to those mentioned for the storage of cadavers, although often smaller in size. Such tanks are subject to the same disadvantages as when used for cadavers. In addition, they are usualh' unsightly in appearance and therefore undesirable in laboratories and museums. Glass jars of sufficient size for large human preparations are very expensive and easily broken; earthen crocks are likewise very fragile. It is not feasible, moreover, to use either of these for large preparations, such as longitudinal sections. The receptacles described below are designed to serve as museum cases for large specimens and as storage receptacles for material wliich it is desired to have constant!}'" available for students or members of the instructing staff'.

These cases are constructed on essentially the same plan as the cadaver tanks. Lighter material, however, may be used in their construction, since the cul^ic contents is considerably less. The cy]3ress used is somewhat thinner, the bolts are three-eighths inch instead of one-half inch, while the angle irons and iron bars are omitted entirely, washers being used instead. The tank proper (j, fig. 6) is placed on a removable base (/.-, fig. 6) in order to make it of the proper height for use. The top, which is largely of glass, is sloped foiwai'd in oi'der to give a good view of the contents when the case


for Cad5ver5



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NEW RECEPTACLES FOR CADAVERS 327

is used for niuseuiu preparations. The groove (/, fig. 7) runs entirely around the case: into it projects one arm of an angle iron (m). When the groove is filled with cotton the case is made practically air-tight so that there is almost no evaporation where it is desired to keep material in alcohol fumes. The catches used are Corbin tool box locks number 1217 in, fig. 5). By the use of catches of this t3'pe, it is possible always to draw the co\-er tight and hkewise lock the case if desired.

At Pittsl)urgh. we have placed cases of this type in tlie dissectingroom, where we have found them very useful for longitudinal sections of cadavers and for large gross dissections kept as museum pi-eparations. One case is used for the best dissections made each year b}the class, which are thus available the succeeding 3^ear as demonstration preparations. Cases of this type, two feet two and a half inches wide, eight feet long, one foot high in front, one foot, six niches in the rear, inside measurements, with a base, maj- be secured finished for forty-two dollars each.

Acknowledgments should be made to Mr. E. B. Lee. architect. Pittsburgh, for the prelhninary sketches. It should also be stated that the idea of using ])olts in the manner indicated above was first suggested to me b}' some small wooden cases which I saw some years ago in the Anatomical Laboratories at the L'niversity of Pennsylvania.


INCREASE IN PRICE OF JOURNALS

In order to extend and improve the journals published by The Wistar Institute, a Finance Committee, consisting of editors representing each journal, was appointed on December 30th, 1913, to consider the methods of accomphshing this object. The sudden outbreak of European misfortunes interfered seriously with the plans of this committee. It was finally decided, at a meeting held December 28th, 1914, in St. Louis, Mo., that for the present an increase in the price of these periodicals would not be unfavorably received, and that this increase would meet the needs of the journals until some more favorable provision could

be made.

This increase brings the price of these journals up to an amount more nearly equal to the cost of similar European publications and is in no sense an excessive charge.

The journals affected are as follows:

THE AMERICAN JOURNAL OF ANATOIVIY, beginning with Vol. 18, price per volume, $7.50; foreign, §8.00.

THE ANATOMICAL RECORD, beginning with \^oL 9, price per volume, $5.00; foreign, $5.50.

THE JOURNAL OF COMPARATIVE NEUROLOGY, beginning with Vol. 25, price per volume, $7.50; foreign, $8.00.

THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY

36th Street and Woodland Avenue Philadelphia, Pa.


VASCULARIZATION PHEXO^IEXA IN FRAGMENTS OF

EIMBRYONIC BODIES CO^IPLETELY ISOLATED

FROM YOLK-SAC BLASTODERM

FRAXKLIX PEARCE REAGAX

Department of Compnrallvc Anatomt/, Princeton Vnirersity

TEX FIGURES

Recent experimental work points to the possibility of a final solution of the j^roblem of the origin of intra-embrj-onic vascular endothelium. Methods of procedure affording results to which there can be no doubt of interpretation are especially desirable.

So far there ha\'e been developed two methods by which yolksac ^\ngioblast' may be kept out of communication with intraembryonic vessels: mechanical separation of the vessels of these two regions, and exposure of the de\eloping embryo to anesthetics. The former method was employed to the extent of partial separation by Graper,^ Hahn,- and Miller and McWhorter.^ These observers have obtained endothelium on both sides of chick embryos in which one side was severed from extraembryonic blastoderm. The second method has been perfected by Stockard^ who has, in cases of arrested development, been able to secure intra-embryonic endothelium ({uite independent of that in the yolk-sac.

The intra-embr^'onic vessels in the experiments of Miller and ]\IcWhorter were in part non-continuous and somewhat diminutive in size; this is ])erha])s due to the fact that heart-pressure is necessary for the normal growth of endothelium even after the latter has been established. The work of these two ob 1 Griiper, L., Archiv fiir Kntw. niecli.. Hd. 24. 1907. -Hahn, H., Archiv liir Knlw. mcch., lid. 27, 1909.

^ISIiller, A. ^\.. and .McWliorter, .J. K.. Anat. Roc, vol. 8, p. 91, 19U. ^ Stockard. (\ R., Proc. Am. Atssn. Anatomists, Anal. Rec, vol. 9, no. 1, 191.5.

^29 THE .VX.VTO>nCAI. HECOHI), \ Ol.. !l, Nil. 4.


330


FRANKLIN PEARCE REAGAN


servers was submitted as proof of the local origin of mtra-embryonic endothelium; previous toand following its publication, this work was objected to quite vigorously on the following grounds: the incision may not have l^een made sufficiently early or sufficiently close to the embryonic body; vessels may have grown into the injured side from the unoperated side or from either end. To the latter objection Miller has replied that this unusual growth would require a permeation of such sohd structures as notochord and neural tube. A later examination o Miller's material by Bremer, as well as ^filler's own careful reconstructions, failed to reveal such ingrowths.

While the work of Miller and ^IcWhorter seems m itselt to be quite conclusive, a confirmation of their results by more rigorous methods of experimentation may not be superfiuous. A most feasible method of procedure seems to be that o complete separation of an embryonic body, or a portion thereof, from the extra-embryonic blastoderm prior to a possible invasion by the so-called yolk-sac 'Angioblast.' If in such a meroplast there should develop legitimate vascular cavities possessed of good endotheUum it is confessedly futile to argue further for the necessity of ^\ngioblastic' origin of intra-embryonic en dothelium. . , u • i.- ^

The following experiments meet, I believe, the objections urged against the work of Miller andMcWhorter, supplementmg at the same time the work of Stockard. . - ,•

About forty chick embryos corresponding to stages 4, o, b and 7 of Kiebel's Normentafel (Zweites Heft) constitute so far the material studied. The operations consist in varying degrees of separation of the projecting head from the remainder of the embrvonic bodv and the blastoderm.

On; experiment which I shall designate as Type I consisted in the following incisions (fig. 1): longitudinal incisions lateral to, but close to the projecting head on each side, extending trom points slightly posterior to the anterior intestinal portal to the opaque area anteriorly; a transverse incision through the embryonic body just posterior to the anterior intestinal portal, l^ollowing this the blastoderm was entirely removed except the


VASCULARIZATION PHENOMENA


331


k


E-l


Fig 1 Diagram to illustrate the blastodermal incisions in experiments of lypes I and 11. Broken lines represent the incisions in Type T. Dotted line - to //indicates the transverse incision in Type II -n uhich incision ^ to F is omitted.

Ft^- 2 Lateral view of the head-fragment of Tvpe I pushed back to be severed trom tne proamnion at point where a broken line intersects.

Fig. .3 Section through the anterior portion of the forebrain of a head-meropiast, showing unusual head-coelo:n. Total incubation thirty-two hours. Operation at the time of the first intersomitic groove ( X 160). Experiment, Tvpe i. no. 19; b, aniage of ventral aorta; c, coelom; d, pharvnx; e, forebrain.


332 FRANKLIN PEARCE REAGAN

small strip of proamnion which suspended the head-fragment from the opaque area anteriorly. (In this way it was possible to section later the blastoderm and determine the status of vascular development in the extra-embryonic area and Jo hww certainly that the embryo had not yet been vascularized). Ihe head-fragment was then pulled backward and turned so that the proamnion could be snipped off close to the head-tissue proper (fig 2) leaving a free meroplast which would sink to the bottom of the sub-germinal cavity. The egg was then sealed and inculmted further. -n «•

\lthough manv other methods were utilized, it will suthce for the present work to describe one more experiment— Type II Longitudinal and transverse incisions were made as m Type I, except that the transverse incision extends entirely across the l3lastoderm. The blastoderm was removed to be sectioned while the head-fragment was left connected anteriorly with the opaque area bv the small strip of proamnion. Thus the headfold rested on a double membrane of ectoderm and entoderm which was also excised laterally but not anteriorly from the

opaciue area.

Complete separation of the posterior region proved to be quite unsatisfactorv owing to the circumstance that the reliet of normal surface tension induces abnormal conditions m the embrvonic body. In the projecting head-region surface tension evidentlv does not enter so extensively into the mechanics ot development. Furthermore a relatively small anKumt of m.iury in the head region serves to isolate C()m])lotely an embryonic fragnienl in which development proceeds in a surprisingly

normal manner.

In order to preclude the possihiHty of clrawmg conclusions tr„ni tissue which had already been 'invaded- by 'Angioblast the remainder of the blastoderm which had been ivmoved at the time of operation was sectioned. The region oi the embryonic bodv which would have first been vascularized was contained in ihe axial ])ortion of such blastoderms. Beiore each incision the instruments w.mv sterilized. These precautions together with that of complete isolation should render the


VASCl LAKIZATION PHENOMENA


333


procedure sufficiently rigorous to satisfy all reasonable demands of experimental jiroof.

The tissue was fixed in a picro-acetic mixture; sections were stained in a modification of :\Iann's methyl blue-eosin stain -^



I'lR. 4 Section through the forebraiu of a head-meroplast, sliowiiif. earlv stages in the formation of vasofactive cells. Total incubation, twentv-nine hours: Operation previous to the formation of the first intersomitic groove (X ■-'00). Experiment, Type I. no. 24; a. prevascular mosenchvme; r. coelom : d, pharynx; e, forehrain.

which i)roved especially \-aluable in the differentiation of endothelium.

' lieagan, V. P., Anat. Rec, vol. 8, no. 7, 1914.


334


FRANKLIN PEARCE REAGAN


When the head-fragments as above described had been incubated for a total period of from thirty to forty-eight hours and then sectioned, thev were found to possess blood vessels in varying degrees of development. In general it may be said that regardless of the amount of incubation beyond a total period of thirtythree hours, differentiation never proceeded beyond the normal stages of differentiation at that age. After forty-eight hours some signs of degeneration made their appearance. It seems that the embryonic meroplast possesses an inherent capacity for differentiation which tides it over to the time when heartpulsations would normally provide a means of tissue respiration. ^^'hile differentiation proceeds always at the same rate and to the same extent, growth varies greatly. Meroplasts equally differentiated may vary greatly in size.

Practicallv the onlv unusual condition met with in these headfragments i; the presence of a head coelom (fig. 3), the origin, fate and significance of which will be considered later.

Between the base of the coelomic pouch and the pharyngeal entoderm rounded or cuboidal cells become proliferated. Tbeir point of origin is in most instances between the base of the coelomic pouch and the pharyngeal entoderm (figs. 4, 5 and 7), where it is difF.cult to determine which of these two epitheha is ot primarv importance in such cell proliferation. C^ells of this sort are midoubtedlv proliferated to a certain extent by the pharyngeal wall and also by mesothelium. In neither of these latter cases do the cells originate by foldings and constrictions of cell aggregates, but singly or in a linear proliferation This same region is found, in somewhat later stages (fig. 4) to be occupied bv irregular stellate cells resembling mesenchyme cells. Their processes fuse forming a parenchyma-like complex which merges dorsallv into the true interstitial mesenchyme

Simultaneously with the accumulation of a plasma-hke fluid which may be detected in this parenchyma by sections of its coagulum, the loose structure becomes transf.M-med into a longitudinal tubeof endothelium (figs. 6 and?) . The tubes thus formed, though far anterior to the heart-region, may simulate heart-formation in a remarkable manner. The coelomic ].ouches may meet to


VASCULARIZATIOX PHENOMENA


335


possess a continuous ca\-ity, a condition approached in figure 6. Since the phar3^ix in this region is already tubular it does not become constricted in this process, the endothelial tubes meeting ventral to it. There is no reason to believe (though such an inference is possible) that the endothehal tubes thus formed are new or abnormal formations: they occupy the position of normal ventral aortae.



Fig. 5 Section through the forebrain oi a head-meroplast showing a loose parenchyma in a position occupied by the isolated vasofactive cells of figure 4. Total incubation thirty hours. Operation at the time of the first intersomitic groove (X 150). Experiment, Type I, no. 18; a, prevascular mesenchyme; c, coelom; d, pharynx; r, forebrain.

The conditions so far described are found in embryonic fragments of T}TDe I which were incubated not more than a total period of thkty-three hours. It will be well to consider some of the conditions found in a meroplast of Type II incubated for



tl—


7 ^>

Fio- ,i S..r.iun ll,n.U^h -1,.. lorrLran. ..1 a l.oa.l-nu-n.plast sl.nuin^ anlaRcn Of thrven.ral a-Hao as disn-eto ves.ols. The longitudinal m<.,s>on "" th. n, > side of th,- iH.a.l was n>lativoly c-los. to the neural fold Ihe cu edges he

nharynKoal<-n,„.lennhave l.een pulled apart, the ventral tissues having suung I tlUrt. Total uu-uha.ion thirty-.wn hours. ..perat.on at *»- t-e " »,c seeond intersount ,<■ groove (X 210). lX,.eruuent . I vpe 1. no. .,1, h. ^.nt,al aorta; c, eoelom; <L i)haryii\; r, forehram. .

Fig. 7 Section through the lorebrain of a head-n,eroplas, «»---"^/-;; Wolined ventral aorta. The right longitudinal ineisu.n was elose ^^^^l^l^] fold. .None of the exeised head has regenerated: the rnesenohynie s very com pact near the cut surface the- cells of which aresomewhatepahehal. 1 "t.d m^^a tion thirty-three hours. Operation at the tin.e of the u-st '"<— ^Z^^;;; (X 170). Type I, no. 17; /,. ventral aorta; c, eoelo.n ; ./. pharynx. <. loiebra.n.

33()


VASCULAKIZATIOX PHENOMENA


337


a total period of forty-eight hours (figs. 8, 9 and 10). No attempt will be made at present to set forth the processes which inter\-ene l^etween the stages of thirty-two and fortv-eight hours.

The ]:)roanmion (fig. 8), a region normally devoid of mesoderm, contains a rounded jiouch which is continuous anteriorly with the extra-embryonic coelom. The cut edges of the ectodermal and entodermal layers of the proamnion have fused forming a blind sac around the enclosed coelomic pouch; likewise the cut



Fig. S .Section throiigli the t'orebrain of a hcad-merophist .showing a proainn'otic sac containing a pouch of coelomic mesothelitna. On the ventral side of the sac is a peculiar proliferation of entodermal cells very constanth' ap])euring in experiments of this type, generally more symmeti'ically situated. Total incubation, forty-eight hours. Operation v\ the time of the second intersomitic groove (;< 55). E.xperiment, Type IT, no. 3 r, coelom; e. forebrain; C, ectoderm; f/, entoderm ; J, extra-embryonic vessels.

edges of the once continuous blastoderm have fused. On the ventral surface of the proamniotic sac will be noticed an entodermal thickening, in appearance not unlike an in\'erted nem-al groove. This structm'e is quite constant in experiments of this type. I would interpret it as a cell-complex representing potentially the floor of the fore-gut in case of normal infolding. The transverse incision in this experiment was made some distance behind the site of the anterior intestinal portal, so that there projected behind the posterior extent of the proamniotic


338


FRANKLIN PEARCE REAGAN


sac a portion of the embryonic bod}' bounded dorsally bj' ectoderm and ventrally by entoderm (fig. 9). The cut edges produced by the longitudinal incision have fused, the point of fusion being indicated by the apex of the projection on the left side in figure 9. In this figure we have a photograph of a 'projecting' head; the section passes through the anterior part of the midbrain region, presenting a rather puzzling condition in that it is entirely devoid of fore-gut. Two large dorsal aortae are present; the larger one is located on the side containing the greater amount of mesenchyme; correlated also with the fact that the



Fig. 9 Photograph of a section through the midbrain of the same meroplast as in figure S. show'ng we!! developed dorsal aortae and the absence of a tubular pharynx in a tubular head. Fusion of entoderm and ectoderm at points indicated by X (X 120). /, ectoderm; g, entoderm; /(, dorsal aorta; i, midbrain.

incision on this side was made at a greater distance from the median line. Both aortae are bounded by distinct and unmistakable endothelium. In the aortic cavities blood plasma has coagulated. No coelomic pouches are present in this section. Pleart-formation has not taken place in this particular experimental casei

The phenomena under consideration are not to be regarded as regenerative changes. The head does not regenerate the yolk-sac, neither does the yolk-sac regenerate the head. In figures 6 and 7 it will even be seen that portions of the head itself were not regenerated. There is a genesis of the first order in


VASCULARIZATION PHENOMENA


339


case of the. development of endothelium. While it is not always possible to be sure of the extent to which experimental conditions portray a truly normal process, the results here presented, together with those produced by Stockard seem to afford positive evidence in favor of the local origin of blood vessels.

It is of interest to note the statement of Bremer (Am. Jour. Anat., vol. 16, no. 4, p. 463) that mesothelial anlagen "might arise under abnormal conditions in positions where they are normally absent." The isolated cells proliferated from this



Fig. 10 Photograph of one of tlie hrst avaihxble sections of the bhistoderm behind the incision G to H of Experiment Type II, no. 3, showing the freedom of the pellucid area from endothelium (X 160).

imusual mesothelium are, according to my observation, not comparable to the gross infoldings of cell-aggregates described by Bremer, though they seem to be vasofactive in nature. To designate certain of these proliferated cells as mesothelium would be as uncalled for as to designate others of undoubted entodermal origin as pharynx. While I do not question the ability of mesothehum to proliferate pre-vascular mesoderm (indistinguishable from mesenchyme), I do wish to question the justice with which Bremer would accredit mesothelial tissue with the production of the entire vascular tissue. An assignable reason for conferring this distinction on mesothelium might be the desire to maintain for endothelium a monogenetic origin — the first requisite to the specificit}' of a tissue.

The fact that endothelium exists in the sauropsidan yolk


340 FRANKLIN PEARCE REAGAN

sac prior to the establishment of a coelom cannot be satisfactorily explained by a hypothetical ■"premesothelial stage of mesoderm" (Bremer, loc. cit., p. 4(53). It has been shown that 'Angioblast/ so far from l^eing a daughter-tissue of premesothelial mesoderm, is really a parent-tissue of the latter; in isolated blood islands Riickert*^ has shown that cell groups proliferated from this early vascular tissue cleave to form slit-like cavities which unite later with other similarly formed cavities to contribute to the extra-eml)ryonic coelom. Of logical necessity it follows that mesothelium and 'Angiol)last" (in the sense of His) must have come from a common cell-complex.

Should we ever be so fortunate as to find the ultimate font and source of all vascular tissue there would be no objection to its designation as 'Angioblast,' so long as we bear in mind the original implications of the Angioblast Theory: the essentials of this theory have ])een outlined by Minot (Human Embryology, Keibel and Mall, vol. 2, pp. 498-99) as follows:

Comparative embryology teaches that the first bloodvessels appear on the 3'olk-sac collectively and at one time. They form a unit anlage which wo call angioblast according to the suggestion of His. * * * The angioblast probably maintains its complete independence throughout life. In other words it is prol^ablc that the endothelium of the l>lood vessels (and of lymph vessels) and the blood cells at every age are direct descendants of the piimitive angioblast.

The fact that allantoic vessels may ai)pear j)rl<)r to those in the yolk-sac in early human development (Bremer, ibid.) is probably an expression of the tendency towards that sequence of local origin which is correlatf^d with the functioning of the part \'asculai"ized. A diffei'ent se(iiience is found in animals whei'e the allaiitois functions relatively later.

When it is stated that endothelium differentiates fi'oin an 'indifferent' mesenchyme the specificity or non-specificity of the immediate source of the pr(>-\'as(*ular mesenchyme is not

Ivi'ickcrt, .1., I'!tit\\ ickcliiufi dci' cxI r;i-('inl)r_\<)ii:il(ii ( id'asse dcr \'<ificl. IlaiidhiK-li der N'erfil. ii. exj). Entw-lehrc. IM. I. l". 1. I'.KKi. ("cbor die Ahstaimimiin dcr hIuth:ihig(Mi (IcfiissmiluKon Jx-ini Huliii. uiid iihcr dir iMit.stchuiig des Handsinus bcMrn llidiii uhd l>ci Toipfdo Sit zinitislxM-. dcr lia.w Akad. Wiss.. ino.i.


VASCrLARIZATIOX PHEXOMEXA 341

brought into question; the statement merely means that in their earUest stages such cells are morphologically indistinguishable from other mesenchyme cells which may or may not be capable of like de^'elopment. Whether each vasofactive cell behaves as it does in accordance with a definite teleology is at present entirely beside the question.

Like considerations apply to the study of 'indifferent' capillary plexuses, some of the meshes of which ]3ersist while others degenerate. That one should observe this process from time to time, and from the mere fact that the process takes place, be able to determine the extent to which the changes are due to heredity or mechanical influence is to be accepted with some caution; cell organization is excluded with great difficulty. In a regenerating jugular vein Clark' believes he has a case in which heredity plays no part. It may be stated that authorities on regeneration do not usually exclude considerations of heredity from the conclusions at which they arrive. Certain it is that the development of the vascular system furnishes an unproductive field for the solution of the problems of preformation and epigenesis.

In conclusion it is well to consider the following recently established facts which should share in defining our morphological interpretations. The yolk-sac is not necessarily the site of formation of the earliest blood vessels. Intra-embryonic vessels de\-elop in .situ when communication of extra-embryonic vessels with intra-embryonic tissues is prevented \)y chemical or mechanical means.


•Clark E. R.. Proc. Am. Assn. Anatomists, Anat. Ket-.. \ol. !i. no. 1. litl.T.


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THE IDEXTIFICATIOX OF TISSUES IN ARTIFICIAL

CULTURES

E. D. CONGDON

From the Medical Department of Leland Stanford Junior University, Calif oryiia

TEN FIGURES

In spite of the numerous studies upon tissue culture the usefulness of the method is still limited greatly by uncertainty in classification of many cell tj^pes most vigorous in their growth and of commonest occurrence. The nerve cell, the thyroid parenchyma, kidney tubules, ectoderm and a few other tissues are easily identified. But the ever varying linear, reticular and epitheloid growths are of undetermined origin. Although they are the predominating form in cultures they have only been referred provisionally to the group of embrj^onic sustentative tissues.

The structure of the growths is of only secondary importance in determining their classification. While it has by no means been established that tissues take on a more embryonic character in the plasma it is true that with few exceptions they assmne the form of cell strings, reticula or membranes. Thus even the tubules of embryonic kidney are described by Lewis and Lewis ('12 b) as growing out in the form of a loose mesh. Much can be accomplished in the wa^^ of classification by comparing the growths from various organs and drawing inferences based on their tissue composition. In this way the probability has already been established that many of the common growths are derived either from supporting tissues or endothelium. Yet the character of the growths is too variable and too little under control to arrive at a final classification b}' indirect methods. They must be traced directly to their source in the parent tissue. For this purpose sectioned cultures are necessary. Little direct

343

THE ANATOMICAL RECORD, VOL. 9, KO. 5


344 E. D. CONGDON

evidence of this character has been obtained because up to the present time whole preparations have been used to the almost complete exclusion of sectioned cultures.

In the present study sectioned and whole preparations were used to supplement one another in identifying the growths. Cultures were made from chick ventricle of ages rangmg from four to eighteen days. Lunb buds of from four- to seven-day embryos were used. A much smaller nmiiber of series were made from liver and intestme. The comparison of the growths from the younger and older organs disclosed certain differences dependent upon the histogenetic stage of the organs. These are considered briefly.

The cultures were made in plasma according to the procedure of Carrel and Burrows ('11). The description of this method has been given too frequently to require repetition m detail. The plasma was taken from young chickens varying m age from two weeks to four months. Most vigorous growths took place in clots from a mixture of two parts of plasma to one of distilled

w^flter

The preparation of cultures for sectioning presents considerable difficulty due to the marked tendency to shrink shown by the plasma clot and the very watery cells of the growths. Experience shows that care in adapting the technique of fixation and imbedding to the peculiarities of this material is especially

worth while. . ,

A brief description of the various types of heart ventricle growth will be given before considering the evidences as to their classification. The cultures from embryos of more than five days' incubation are divisible into a number of regions, four ot which have a concentric arrangement determined by the rounded surface of contact between plasma and tissue. These are not well-defined in preparations of four- and five-day tissue because of the flowing and distortion consequent on the fluidity o the early embryonic tissue. Figure 1 shows them diagrammaticaliy in a section of a culture cut parallel to the cover-slip. The central zone a is made up of tissue that remains for the larger part inactive. There is no evidence for the migration of any ot


IDENTIFICATION" OF CULTURES


345


its cells outward although it is not possible to prove that some few do not leave the region. The boundary of the inactive zone does not become well-defined until degeneration has begun and the tissue external to it has become modified by the migration outward of its cells. Degeneration is often found in eighteento thirtj'-six-hour cultures to be confined to a central area much smaller than finally occupied by the inactive zone. Evidently death takes place first at the center of the tissue because of its remoteness from the plasma. The limits of the dead region then extend gradually toward the surface of the tissue. The inactive zone shows pyknosis and chromatolysis of the nuclei



Fig. 1. Diagrammatic section of ventricle culture; a, inactive zone of implanted tissue; h, active zone of implanted tissue; c, region of reticular growth; d, cover-slip sheet; e, covering layer.


of heart-muscle cells. In two-week-old ventricle there is a clumping of the cytoplasm into large masses staining with basic as well as acid dyes. Epicardial and peritoneal endothelium have greater vitality than the heart-muscle. This also may be said for the endothelium of sinusoids except where the breaking down of the erythrocytes brings injury to the contiguous wall. Surrounding the central zone except upon the cover-slip side, is a peripheral active region from which cell migration into the plasma takes place (fig. lb). It is never many cells thick and does not necessarily include all of the living tissue if the period of incubation of the culture has been short. In cultures of pulsating heart segments the cells contained in the active zone are put on the stretch at every systole. Fixation often causes the heart tissue to contract and thus preserve them in the condition of extension. Cell debris is usually present at the line of contact between tissue and plasma as a result of cutting the tissue from the parent mass.


346 E. D. CONGDON

Aside from a very fine, often degenerate reticulum, the remaining growths lying free in the plasma can best be described under two types, one fine and the other coarse. Neither of these give evidence of being separated by cell walls when stained with iron hematoxylin and erythrosin after Zenker or osmic acid fixations. There are all intermediate forms but many of the cultures are predominated by the one or the other type. Of the two kinds the finer ismuch more abundant. The nuclei in both varieties contain the one or two chromatic masses usually to be found in embryonic chick tissue, A measurement of the nuclei shows no constant difference in diameter from growths of heart-muscle, endothelium or reticular tissue. The cytoplasm of all cells in the plasma is watery and coagulates into a loose foam structure not resembling heart-muscle substance.

The finer mesh crosses the field at all angles. It differs from the coarse reticulum primarily in the much greater independence of its cells. It is made up of two intergrading cell forms of which one is elongated, slender and cylindrical while the other is polyhedral and usually triangular or quadrilateral in optical section. The ends of the first t^^pe and the angles of the other are drawn out into longer or shorter filaments. The cylinders may not be more than a micron in diameter although they are many micra in length. Their nuclei are forced to take on a rod shape by the limited diameter of the cells. The contact of the cells is at all times slight and often made only by the most delicate of filaments. The free ends at the periphery of the mesh send out fine pseudopodial processes. The two-cell forms intermingle freely in the reticulum.

The coarse mesh in all but the four-day cultures consists of bands 2 to 6 m in width. They tend to flatten in the plane parallel to the cover-slip although they connect with each other at all levels. The growth has flowing outlines and forms loops which are characteristic in appearance and include spaces of more constant dimensions than found between the elements of the fine mesh. Nuclei are occasionally found side by side in the broader bands. The diameter of the narrower bands are no greater than usual for the fine mesh. In the nodes of the


IDEXTIFICATIOX OF CULTURES 347

coarser growth several nuclei occur all of which are in a plane parallel to the cover-slip. The triangular intersections of the strands 2 ^x in diameter contain only one nucleus.

A sparse reticular growth of very fine texture often occurs in cultures of ventricle which have been injured in handling. By the use of dog plasma as a culture medium a sunilar growth is obtained. Both elongated and polyhedral cells are present in the fine mesh. The former are frequently drawn out into filaments not more than half a micron in diameter. The polyhedral cells also may be extended into such long threads at their angles that the central portion is much reduced in volume. The filaments are often tortuous and enlarged at successive points to give a bead-like appearance. The more normal part of this growth stains faintly. In other regions there is pyknosis and chromatolysis of the nuclei. The peculiarities of the growth are plainly an expression of decreased vitality and in many cases of actual cell death. In some instances it is the action of plasma from alien species that causes the injury. When the plasma is not responsible the growth comes from the tissues injured in cutting and handling. In this case toxic substances from the degenerating cells probabl}^ not only act upon the growth before it reaches the plasma but do harm by diffusing into the culture medium. Lambert ('12) describes a similar sparse and delicate growth from cultures of chick heart in rat plasma.

The cover-slip growth (fig. 1 d) is of almost as constant occurrence in vigorous cultures as the reticulum. It is so frequently in plain continuity with the latter that no doubt of the identity of the two is possible. Sections of many cultures made perpendicularly to the cover-slip show the reticulum grading into the cover-slip membrane and frequently stained whole mounts enable one to trace the mesh into the sheet growth. The continuity' occurs most frequently close to the tissue where the growth is most crowded. It is often possible to make out a progressive flattening of the bands of the reticulum as they approach the cover-slip. Close to the tissue the cover-slip growth may be many cells in thickness. Tracing outward,


348 E. D. CONGDON

however, it soon flattens out into a single laj^er. The elements are often much flattened, especially at the border of the sheet and the nuclei may attain an area in this plane ten times as great as its usual cross section. The membrane growths agree with the reticular formation in the apparent absence of cell walls. While they have every appearance of a syncytial structure a final decision is impossible because a silver nitrate test for intercellular cement substance was not made. Aside from any differences as to cellular independence that may exist in various growths depending upon the greater or less development of cell walls it is certain that membranes show marked diff'erences in this respect depending upon the extent of the spaces between the cells. The cover-slip growth associated with the finest mesh is made up of cells separated from each other by wide intervals of plasma and seldom intercommunicating by more than a few slender threads: The finer normal reticulum when flattened upon the cover-slip shows a frequent union by broad bands but intercellular conamunication may also be only by slender processes (fig. 6). In the membrane growth from the coarse reticulum broad attachments and multinuclear sheets occur.

The difference between the cover-slip growths corresponding to the coarse and fine mesh is especially noticeable at the border of the sheet. The former sends out cell bands which either project radially or form loops. The border of the membrane associated with the other mesh has a more finely broken border although its cells may also be connected with one another by their slender processes to form loops (fig. 6).

The third region of growth (fig. 1 e) of ventricle cultures is in the plasma next to the surface of the tissue. Burrows ('11) mentions its occurrence in earl}^ embryonic chick preparations but few others have referred to it. It is not confined to the earher embyronic growths but is well developed from two weeks old ventricle. It has doubtless failed to attract atcention because it can not be seen so well in whole preparations as in sections. It consists of flattened cells which are often piled upon one another to a great depth. Tangential sections from the surface of the implanted tissue opposite to the cover-slip


IDENTIFICATION OF CULTURES 349

often show them to be as thin and sheet-hke as at the border of cover-shp membranes. They are often elongated and rounded in cross section on the sides of the cultures. These dissimilarities of form are the result of the varying conditions of pressure in different regions of the culture brought about by the shrinkage of the plasma clot. The cells are in contact by slender filaments or less commonly by wide bands. Although frequentlj^ closely packed together a thin layer of plasma always separates them on most of then- peripheries from neighboring cells. The transition of the layer into the reticulum and coverslip sheet is usually gradual. As the reticulum is traced toward the tissue and into the covering sheet it is evident that even near to the tissue where the cells are the most flattened and in closest proximity they still form a compressed reticulum. Cell associations similar in make-up to the covering layer are often formed in relation to the free surface of the plasma or around droplets of serum contained within the clots.

The cultures from four-day ventricle give rise to an extremely heavy reticulum with bands often exceeding 15 m in width (fig. 5). Their massiveness will be appreciated when it is recalled that the coarse mesh of older heart cultm-es are at the most 6 m across. The appearance of the growth is also similar to the coarse mesh with its oval spaces. Thick masses apparently made up of the same tissues as the coarse mesh flatten out upon the cover-slip to form a sheet one cell in thickness at the periphery. Sometimes a finger-like form occurs in partial contact with the cover-slip and intermediate between membrane and reticulum. The great fluidity of both reticular and membrane growi^h is shown by their flowing outlines and lack of cell independence. A finer reticulum is also common in the four-day cultures which has nothing to distinguish it from the coarse form of the older tissue. The five-day cultures are intermediate in character between the growth from four-day and older heart. Figure 4 is from one of the finest reticular growths seen at this stage.

Before considering the evidence regarding the sources of the ventricle growth the tissues which compose it may be enumer


350 E. D. CONGDON

ated. They include heart-muscle, nerve, endothelium and supporting tissue. Heart-muscle is, of course, the most abundant of these since it comprises the bulk of the myocardium. Nerve tissue is represented by a few neuroblasts. Endothelia include the endo- and peri-cardial layers and in the ventricle of the older embryos the walls of the sinusoids as well. The myocardium is separated on its inner and its outer surfaces from the endothelial covering by reticular layers. These consist of a mesh of formed substance upon whose strands are stretched cells which during embryonic development are becoming progressively more independent of their support. In the region of the atrial canal the sub-endocardial reticulum is continued into thickenings called endocardial cushions whose appearance is not unlike embryonic mesenchyme. EndotheUum and reticulum approach the heart-muscle in abundance and like it are met on every cut surface.

In considering evidence for the growth of heart-muscle the cultures from six- to eighteen-day ventricle require consideration separate from that of four- and five-day tissue. Material from the former source gives no direct evidence for the participation of heart-muscle in the culture. Many hundreds of sections were searched for myofibrillae without success. Direct evidence for heart-muscle growth was obtained however in the sections of a culture from five-day heart which happened to include not only ventricle tissue but a portion of the atrial canal. The contents of the walls of the atrial canal was seen to be flowing out into a heavy band such as made up the coarser loop-like reticulum of the four-day ventricle cultures. The wall at this point is so thin and the process growing out from it relatively so large that the conclusion is unavoidable that the whole cell-mass was moving out into the growth. At six days muscle and reticulum make up about equal parts of the wall of the canal. At five days the tissue is in large part a primitive myocardial layer. Since there is every reason for supposing that the heart-muscle cells differentiate in situ the evidence is therefore very good that primitive heart-muscle cells take part in the growth. The appearance


IDENTIFICATION OF CULTURES 351

of the coarse growths in unsectioDed four-day cultures seems to justify their classification as primitive myocardium. Their strands broaden out in such a way at the base as to appear as a projection from the whole ventricle mass rather than from small portions of its surface. If primitive heart-muscle cells grow from five-day heart, it is, of course, probable that they are more frequently represented in growths of fom-day ventricle. On the other hand, since the verj^ hea\'y reticulum is rare in fiveday cultures and entkely absent in growths of older tissue they probabl}' do not grow from embryos more than five or six days old. These conclusions are in agreement with Burrows' ('11) observation of sparse growths of heart-muscle in a small part of his cultures of two-and-a-half -day chick heart.

A growth of nerve cells was not found in any ventricle culture. The neuraxones are so characteristic in appearance that they could hardh^ have escaped detection had they been present. Their failure to appear m the growth is doubtless to be explained by the smallness of their number and the consequent imhkelihood of their coming into contact with the plasma, for the responsiveness of neuroblasts to cultivation has been amply demonstrated by Harrison ('07), Burrows ('11), Lewis and Lewis ('12) and Ingebrigtsen ('13).

The abundant growths of the older embryonic ventricle and finer reticulum of the four-day organ which are not made up of heart-muscle tissue must evidently take their origin either from the endothelium of pericardium, endocardium or sinusoids if not from the reticulum. Few of the various studies of chick ventricle growths which have appeared are especially concerned with questions of identification. Lambert ('12) describes the mesh as of connective tissue origin and Burrows ('11) as mesenchyme. Lewis and Lewis ('12 b) think that it may be mesenchymal but consider the matter of its classification unsettled. In various growths of chick organs certain of these authors have suggested that flat polygonal cells may be of endothelial origin but have not traced their connection with the tissue. It is difficult to follow the growth either to endothelium or to reticulum. There


352 E. D. CONGDON

is confusion in the histological picture because of the cell debris which results from cutting the tissue. The collapse of the ventricular ca\dty and distortion of the tissue, especially in the younger ventricles, prevents contact with the plasma on surfaces sufficiently large to allow a proof of their continuity with the growth.

Cultures in which the pericardium and its reticulum are next to the plasma are better adapted for this purpose than sections through the endocardium covering the trabeculae of the spongy ventricle. Relatively large masses of pericardimn may come in contact with the plasma while the endocardium is always intimately mingled with muscle. Figure 2 is from a photograph of a sectioned culture in which the active zone is made up of reticulum. The denser tissue internal to it is heart-muscle. Although the preparation was not killed until degenerative processes were well under way there is no difficulty in making out these tissues. The contrast between the two is seen much more clearly through the microscope than in the photograph because the muscle stains very intensely. A growth of fine mesh is plainly seen coming off from the reticulum. Xo traces of the pericardial endothehum which at first separated the reticulum from the plasma can be made out.

Figure 3 is from a photograph of a sectioned growth of the endocardial cushion of a thirteen-day heart. There has been no cutting with a knife. The free endocardial surface is in contact with the plasma. Because of the absence of the usual dead tissue resulting from cutting, strands from individual cells can be traced directly into the parent tissue. There is no room for doubt that the growth comes from the endocardial cushion. Just as the cushion is distinguishable from the reticulum by the presence of only one type of cell, so the elements of its growth are of a single form. They resemble the polyhedral cells of the fine reticulum.

There was no ventricle growth in which a connection could be traced with endothelium. The difficulties in the way of finding a region favorable for this purpose are too great to warrant concluding that endothelium does not take part. Indeed,


IDENTIFICATION OF CULTURES 353

there is considerable reason to think that it does grow into the plasma. In the two cultures which have just been described the tissues concerned which are separated by endothelium from the plasma could not have grown into it had not the covering sheets ceased to bar their way. Inasmuch as no remnants of dead endothelial cells are to be seen, they have in all probability migrated into the plasma. Of the two types of ventricle reticulum the coarser has the greater similarity to endothelium. The finer mesh has alread}^ been shown to have its origin in part at least from sub-pericardial reticulum. It must not be forgotten in this connection that since the very fine degenerate mesh grades into the normal fine mesh and this again into the coarser variety, the claim is possible that since the first transition is due to differences of the plasma the change from the fine to the coarse type has a like explanation. Such an interpretation is not in agreement, however, with the conditions found in the heart or other cultures. The so-called normal fine mesh and the coarse variety are vigorous and abundant in growth. Their cells give every indication by structure and staining reactions of being healthy tissue. The very fine growth without question stands apart from these as a type modified by its struggle with an unfavorable environment. If the coarse mesh comes from endothelium and the fine mesh from reticulum the inter-mixture of the two may well result from their close association in the ventricle itself.

Lewis and Lewis describe two types of cover-slip membrane for chick ventricle cultures. One of these which they find to be syncytial is said to develop from nearly all embryonic chick organs. They think that it arises from mesenchyme or connective tissue. Their figures correspond closely with the cover-slip membranes associated with the fine mesh. They also occasionally get from heart a non-syncytial membrane with pigment deposits around the nuclei. This variety was not encountered in my preparations.


354 E. D. CONGDON

LIMB-BUDS

It is of special interest to study limb-bud and ventricle cultures together because the growth of pre-muscle cells can be compared with primitive heart-muscle. The degree of similarity of the mesenchymal growths from limb-bud and of ventricle reticulum also has significance in view of the uncertainty as to whether reticulum makes its origin from endothelium or directly from mesenchyme.

The five-day-old embrj^onic limb-bud consists of ectoderm and closely-packed mesenchyme in which the axial scleretogenous tissue is just beginning to differentiate as an especially dense region. In the surrounding zone the pre-muscle cells can be distinguished by their elongation parallel to the axis of the bud. The vascular system is represented by sinusoids. Nerve fibers have not yet extended into the bud. The ectoderm consists of a layer two cells in thickness. At seven days a difference can be made out in the form and staining qualities of the sub-dermal and the scleretogenous tissues. The pre-muscle cells are markedly elongated. Sinusoids now form an extensive system and nerve fibers have migrated in.

The difference in appearance of the cells of scleretogenous pre-muscle and ectodermal regions combined with their separation into independent zones render the limb-bud favorable material for tracing the growth to its parent tissue. The manner of growth of the limb tissue differed greatly from heart, due to the influence of ectoderm and mesenchyme. The former tissue invariably retains its continuity as a sheet and when it grows vigorously can limit the distribution of other tissues to the region internal to it. The mesenchyme often flows out en masse taking with it sinusoids and pre-muscle cells (fig. 8).

The ectoderm can easily be traced from tissue to growth either in sections or whole preparations. Its presence in the plasma is clearly in part due to a creeping of the edge of the sheet out into the plasma. The portion retaining its contact is often stretched into a thin sheet. In the plasma the ectoderm may form masses several cells in thickness. Single cells or


IDENTIFICATION OF CULTURES 355

small groups occasionally project from the border of the sheet but there is always a considerable cellular contact.

The various mesodermal elements of the seven-day limb-bud are already sufficiently differentiated to give rise to a number of distinct growths.

Scleretogenous tissue can be identified in the plasma of many cultures close to regions of its contact with the plasma. Sometimes there is a migration of an entire region of the scleretogenous axis out into the plasma but the cells show no power of orientation and soon die. In most cultures the scleretogenous tissue is internal to mesenchyme and ectoderm and for this reason unable to reach the plasma quickly. Making due allowance for this handicap in position the vitality of the tissue from the seven-day embryo still appears to be of a low order.

The pre-muscle cells can be easily traced out into the plasma in many stained whole mounts because of their spindle form in the organ and their still greater elongation in the plasma (fig. 8). They form long strings which seldom branch. They are often long enough to reach the confines of the plasma drop and be deflected parallel to its surface. When in contact with the cover-slip the growth still maintains its elongated form thus differing from any other membrane growth (fig. 9). It is of interest that both primitive heart and skeletal muscle retain sufficient plasticity to appear in the plasma.

Another mesenchymal limb-bud growth is made up of large masses of cells formed, as in the case of the scleretogenous tissue, by the loosening up of the intercellular bonds of entire regions and a flowing out upon the cover slip (fig. 8). The cells are piled upon one another without a definite arrangement and at the outer border of the mass lie scattered upon the coverslip in a much more irregular manner than in the membrane growths of heart reticulum. In figure 8 the growth is plainly seen to be intermingled with spindle shaped pre-muscle cells. This identifies it as the little differentiated mesenchyme surrounding the scleretogenous and the pre-muscle cells. From among mesenchymal cells of cut surface a reticulum often ex


356 E. D. CONGDON

tends into the plasma which is apparently also mesenchymal in origin. The membrane associated with it is sunilar to the usual cover-slip sheet described with the fine mesh of the ventricle. The view that it is mesenchymal is strengthened by the fact that similar although somewhat more flowmg and embryonic growths occupy the chief place in cultures from five-day embryos. If the reticulum as well as the more massive growth is from mesenchyme there is need of an explanation for the development of two such different types from the same tissue. A possible clue is to be found in the fact that the reticulum only occurs in connection with the free cut surfaces while mesenchymal cellmasses are associated with the cultures in which a scant plasma drop has flattened out the border of the implanted tissue by its shrinkage. Together with the flattening of these cultures there is always an extension of the ectodermal sheet out toward the periphery of the drop thus greatly Imiiting the plasma accessible to the mesenchyme and remaining tissues.

If it be correct to regard the reticular growth of the limbbud as of mesenchymal origin, then heart reticulum and mesenchyme are closely similar in their growths and as far as this evidence goes are closely related. If, on the contrary, it should be shown later that mesenchyme gives rise only to the massive growth the arguments from tissue cultures would be in support of the origin of reticulum from endothelium.

LIVER AND INTESTINES

A few series of cultures from five- and eight-day intestine as well as from five- and ten-day liver were prepared as a basis for comparison of the growths.

A fine reticulum can be clearly traced in many sections to the mesenchyme of the intestine. Growths which arise from surfaces of the intestine with portions of the peritoneum intact often contain trabeculae of greater diameter than found where the growth is plainly of mesenchymal origin. It is not possible to trace the broader bands definitely to the peritoneum because the mesenchyme is always found to be taking part in the growth where the continuity of the peritoneum is lost. It is very prob


IDENTIFICATION OF CULTURES 357

able, however, that they arise from the peritoneum just as similar growths from heart ventricle also "probably are of endothelial origin. Whole mounts of the intestine sometimes show a flattening down of a part of the organ, accompanied by the flowing out of the mesenchjmie of the region upon the cover-slip just as seen in lunb cultures. It is usually possible in these preparations to trace the peritoneum out as an unbroken sheet into the plasma. Lewis and Lewis ('12 b) describe and figure this type of growtii and look upon it as peritoneal. The reticular growth which has just been described as present in sectioned cultures does not occur where there is such a flattening but is confined to free surfaces of the tissue.

Liver cells do not take part in growths from the ten-day organ. A coarse and a fine mesh occur with about equal frequency. Figure 7 shows the cover-slip growth associated with the fine mesh. The coarse form appears in many sections to come from the peritoneum. Elsewhere there is no proof of a deeper origin. Figure 10 showing the fine mesh growth is from a ten-day embryo and is fixed after twenty-four hours of incubation. No peritoneum is present in the culture. The growth can not come from connective tissue septa except possibly at a few restricted regions. In ten-day chick livers a reticulum is already present, as can be ascertained in part of the implanted tissue where degenerating liver cells have dropped out of a section. Endothelium is also present in large amounts in the form of sinusoids. The occurrence of mesenchyme in the embryonic liver has not been proven. It is therefore not possible to determine the source of the growth from the interior of the organ.

SUMMARY

Reticulu7n. The common reticulum with its corresponding membrane-growth is traceable to sub-pericardial reticulum in six-day ventricle.

Endothelium. There is indirect evidence for a coarse reticular growth from the peritoneum of liver (five- and ten-day) and intestine (five- and ten-day) and from the endocardium and


358 E. D, CONGDON

pericardium of ventricle (five- to fourteen-day). An unbroken sheet is found to arise from intestinal peritoneum under certain conditions (six-day).

Mesenchyme. Sectioned cultures of intestine (six-day) gave rise to a fine mesh similar to that of ventricle reticulum. Mesenchyme is sometimes given off from limb-buds (five- and ten-day) in the form of disorganized masses of cells. Under other conditions reticulum and a corresponding membrane growth apparently also take their origin from limb-bud mesenchyme.

Heart-muscle. In one sectioned five-day culture the contents of the wall of the atrial canal is found to be moving out into a strand of a very coarse reticular growth, such as is common in cultures from four-day ventricle. Prmiitive myocardium of four- and five-day heart therefore apparently grows out as a coarse mesh but it is unlikely that heart-muscle of older ventricle has this power.

Endocardial cushion of ventricle. A growth of polj^hedral cells resembling those from sub-pericardial reticulum was traced in sections to the endocardial cushion (thirteen-day).

Scleretogenous tissue of Umh-bud. The scleretogenous tissue can move out into the plasma for a short distance but has little vitality (seven-day) .

Ectoder?)! of limb-hud. There is an extension of the ectoderm out into the plasma but this is due, in part at least, to a creeping of the original layer, as is shown by its marked thinning on the surface of the limb bud (five- and ten-day).

Pre-muscle tissue of limb-hud. The spindle-shaped premuscle cells of seven-day limb buds give a characteristic linear growth in the plasma and upon the cover-slip.


IDENTIFICATION OF CULTURES 359

LITERATURE CITED

Burrows, M. T. 1911 The growth of tissues of the chick embryo outside the

animal both' with special reference to the nervous system. Jour.

Exp. Zool., vol. 10. Carrel, A., and Burrows, M. T. 1911 Cultivation of tissues in vitro and

its technique. Jour. Exp. Med., vol. 13. H.\HRisoN, R. G. 1907 Observations on living, developing nerve fibers. Proc.

Soc. Exp. Biol, and Med., vol. 4. Ingebrigtsen, R. 1913 Studies of the degeneration and regeneration of axis

cylinders in vitro. Jour. Exp. Med., vol. 17. Lambert, R. A. 1912 Variations in the character of growth in tissue cultures.

Anat. Rec, vol. 6. Lewis, M. R., and Lewis, \V. H. 1912 a The cultivation of sympathetic nerves

from the intestine of chick embiyos in saline solutions. Anat. Rec,

vol. 6. Lewis, M. R., and Lewis, W. H. 1912 b Membrane formations from tissues

transplanted into artificial media. Anat. Rec, vol. 6.


THE ANATOMIC.VL RECORD, VOL. 9, NO. 5


PLATE 1


THE IDENTIFICATION OF TISSUES IN ARTIFICIAL CULTURES

E. D. COXGDOX



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Fig. 3 Section of thirteen-day ventricle; the fine reticular growth is coming from an endocardial cushion. X 570.

360


TTrE IDENTIFICATION OF TISSUES IN ARTIFICIAL CULTURES

E. D. CON'CnON


PLATE 2



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361


PLATE 3


THE IDENTIFICATIOX OF TISSUES IX ARTIFICIAL CLLTURES

E. n. rON'GDOX



Fig. 6 Cover-slip frrowth associated witli fine rcticuiuin ; nine-day ventricle; stained whole mounts. X 530.

Fig. 7 Cover-slip growth associated with fine mesh of five-daj^ liver; stained whole mount. X 350.

362


rHE IDENTIFICATION OF TISSUES IN ARTIFICIAL CULTURES

E. I). COXGDON


PLATl, 4



Fig. 8 Mesenchymal growth containing a few pre-muscle cells; spindle shaped pre-muscle cells are also seen projecting from the edge of the implanted tissue; stained whole mount. X 510.

Fig. 9 Cover-slip growth of pre-muscle cells from seven-day limb bud. X 410.

36;)


PLATE 5


THE IDENTIFICATION OF TISSUES IN ARTIFICIAL CULTURES

E. D. CONG DON



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Fig 10 Section of culture from ten-day liver, showing tine reticular growtJi. The cellular debris in the outer zone of the implanted tissue is made up of the remains of dead liver and sustentative cells. The inner zone shown at the right of the figure contains still uninjured liver cells. X 590.


364


THE ACTION OF ULTRA-VIOLET RAYS UPON THE

FROG'S EGG

I. THE ARTIFICIAL PRODUCTION OF SPINA BIFIDA

W. M. BALDWIN

From the Department of Anatomy, Cornell University Medical College, New York City

SIXTEEN FIGURES

While the method of the experimental embryological investigation detailed in the succeeding pages is of importance because of the constancy with which the condition of spina bifida may be produced in the embryo, the real value of the method and of its results lies in the interpretation which is thereby rendered possible of the physiological value of the several component portions of the fertilized ovum. The really fundamental problems to be determined by investigations of this nature are, first, whether the fertilized o^^um is to be regarded as a composite structure made up of various system- or organ-anlagen, or the chemical progenitors or 'ferments' of such, distributed in definite and, perhaps, constant positions throughout the cytoplasm. Or, second, is the ovum to be considered in the sense of a unicellular organism, differing in no great respect from the physiological structure of unicelhdar organisms in general but possessing that specific potential to elaborate 'ferments' and pro-anlagen at successive genetic stages, and, ultimately the anlagen of the later developmental stages? In the former instance it is presumed that the embryonic parts are pre-localized in the cytoplasm of the ovum and make their appearance, in the words of Lankester, as "a sequel of a differentiation already established and not visible." In the second assumption the embryonic parts are unrepresented in the ovum, the regions of the cytoplasm being

365


366 W. M. BALDWIN

then, so far as the future embryo is concerned, of equipotential vahie. It appeared to the author that a means by which a Umited area of cytoplasm could be destroyed and j^et left in its original relations to surrounding parts would afford a solution to this question. Accordingly, recourse was made to ultra-violet rays of such a degree of intensit}- as to cause the disorganization of the cj^toplasm in from one to thirt}^ seconds and of such a degree of concentration as to influence limited surface areas. Acting upon the suggestions made by Prof. E. H. Merritt, an apparatus was constructed which met these requirements fully.' This apparatus consisted of a large induction coil actuated by a 110-volt direct current reduced by an unknown resistance. The potential, moreover, was raised by means of several Leyden jars shunted between the electrode wires. The terminals were made of iron, and were spaced about 5.0 mm. The eggs used for the purpose were those of the various forms of frogs occurring in the neighborhood of Ithaca, New York. These were obtained early in the morning, as soon after laying as was possible. At the time at which they were influenced they were in the undivided stage. Development was allowed to progress in the laboratory in some instances, and the eggs influenced at several later developmental stages, but no egg further along in its cycle than about the 64-cell stage was used. Furthermore, care was taken to reject such eggs as were collected late in the laying season for that particular species of frog, and particularly those located near the center of the egg bunches, specifically to avoid dealing with those possessing a tendency towards abnormal development. In preparation for exposure to the rays, the eggs were freed from their jelly, which had been found impervious to the light, and placed under a i)erforated tinfoil diaphragm. The perforations differed in size in different experiments. After the egg had been rotated so that a predetermined part had been brought directly under the center of a circular ])erforatioii in the dia 1 At this ])oint I desire to express my indebtedness to Professor Merritt for helpful suggestions and to the Department of Pln'sics of the University for the use of the apparatus with which the experiments mentioned in this paper were conducted.


ARTIFICIAL PRODUCTION OF SPINA BIFIDA 367

pliragm, both were then brought under the electrodes of the apparatus and the circuit closed.

While in the numerous experiments conducted, the various portions of the white and of the black hemisphere and of the equator of the frog's eggs were influenced in order, the author decided to limit the scope of this present communication to those effects produced by the rays when influencing the white hemisphere and the equator of the egg. Indeed, in addition to the significance of the findings of the investigation in the interpretation of the larger problem of ovum structure, the immediate purpose in jiresenting this paper is to establish the fact that the condition of spina bifida may be produced at will l)v this method.



Figure 1

The aperture in tlie diaphragm used for this experiment was 0,4 mm. in diameter. The eggs averaged 1.7 mm. in diameter. Consequently but a small surface area proportionately of the total area of the egg was influenced. The latter amounted to 425.0 sq. mm. whereas but about 5.0 sq. mm. of this surface could be influenced by the rays. The relative sizes of these areas is brought out more clearly by reference to figure 1, which represents by a broken-line circle the portion of the surface area of the egg sphere ilhuninated. Further, it was found that the depth of penetration of the 0.4 mm. pencil of rays depended upon the length of exposure to the light. Uniform exposures of 30


368 W. M. BALDWIN

seconds were employed in this series. A section through an egg so influenced is shown in figure 2, in which the depth to which the ra^'s had penetrated is represented by the shaded portion on the right of the sketch. In this instance the rays passed in the plane of the section and at riglit angles to a tangent at the center of the surface of the affected area. The direct results of the illumination were corroborative of those previously observed by other investigators using violet rays, such as granulation of the chromatin and certain degenerative changes noted in the cytoplasm. Xo attempt was made, however, to study this aspect of the influence of the rays. It was noted in extremeh' long exposures of from 1 to 10 minutes, that masses of protoplasm



Figure 2 Figure 3

were in some instances extruded upon the egg surface, retaining, however, a slender connection with the main mass of the egg. In instances of such exovation, the egg died early after having made but little developmental progress. Such an exovate is shown in flgure 3. It is of importance to note the fact demonstrated by the sketch that the mass of the exovate was approximately equal to that of the influenced area of the egg (compare with figure 2). The most plausible inference to be drawn from this phenomenon, in the terms of tlic interpi-etation of the o\".ini as an organism, seems to be that of an effort on the part of the ovum to rid itself of the chemically altered or dead protoplasm which can only act as a hindrance to its further developmental progress.


ARTIFICIAL PRODUCTION OF SPINA BIFIDA 369

Reference to various series of experiments selected at random bring out the value of the method in the constancy of production of the condition of spina bifida. Tn one series of thirty-one 16-cell eggs used at the beginning of the experiments and exposed to the 0.4 mm. ra^' for 30 seconds each — various regions of the equator and of the white hemisphere being influenced — twenty-one developed abnormally, and but ten normally. Of the abnormal embryos, eight presented the condition of sphia bifida. In another and later series of fifteen eggs hi the 4-cell stage, influenced in the same manner, none developed normally. Most of these died during the early stages. Four, however, lived to swunming forms with two tails. Later in the spring, after the technique had been still further perfected and the eggs of the green frog were available, from which it was possible to remove the enveloping jelly more readily and more completely, the percentage of spina bifida embryos rose. In one set of five undivided eggs influenced in a suiiilar manner, one died about twelve hours after the experiment, having made no developmental progress, and the four others grew to swimming forms presenting the condition of spina bifida, each having two tails. This last instance is merely representative of the high percentage of these forms of malformation obtained when the white hemisphere is influenced by the ultra-violet rays.

As has been mentioned above, the most eflectual barrier to the penetration of the rays was the investing, jell}^ ^^ hen this was completely removed an exposure of 10 seconds was sufficient to influence the egg. The presence of a very thin layer, however, completely blocked the passage of the raj^s even during an exposure of as much as 10 minutes. The author attributes most, if not all, of the irregularities in percentage production of spina bifida embrj^os to the presence of this jelly. The later results of the expermients \^ere sufficiently assuring to warrant the conclusion that, when it could be positively known that the rays under the above conditions had actuall}^ penetrated the ovum in the regions above mentioned, the condition of spina bifida could be invariably brought about in the developing embryo. Taking these difficulties into consideration, however, the per


370


W. M. BALDWIN


centage production of the condition ranged between 85 and 90 per cent of the total number of eggs used.

An observation that recurred repeatedly was to the effect that the developmental period required by the eggs was lengthened as a result of the rays' influence. Under laboratory conditions ordinarily from 3 to 4 days were sufficient for the appearance




6

Fig. 4 A specimen of cauda bifida demonstrating the asj-mmetry of the tails. In this egg the rays had struck a portion of yolk farthest removed from the equator. The tails are provided, as is shown, with peculiar toe-like processes on their free extremities.

Fig. 5 In this tadpole the right tail encountered the body axis at an acute angle directed anteriorly. Two yolk plugs are to be seen, and the same splitting of the extremity of the left tail as was noted in figure 4.

Fig. 6 The lines 7 and 8 on this cauda bifida tadpole indicate the level of the cross-sections shown in the respective figures. In figure 7 the notochord lies ventral to the well differentiated neural tube. In figure 8 the asymmetry of the halved neural tube is shown, more particularly on the right side. Ventral to this lies the notochord, all traces of which are absent from the left halt of the sketch. This right neural tube-half lay in the more activeh' used tail.

of the free-swimming tadpole-forms of the green frog; in the case of the experimented eggs, howe\'er, 5 or 6 days were required and in some instances 8 days. Furthermore, it was noted that during the 12 hours immediatel}^ ensuing upon the experiment the eggs seemed to have entered into a condition of temporary suspension of development, later resuming that process but with greatly lengthened tempo.


ARTIFICIAL PRODUCTIOX OF SPINA BIFIDA


371


The further observation was made that free-swiinming forms, such as are represented in figures 4, 5, and 6, seemed to be able to move about by the use of either tail, but that the swimming movements were more vigorous in one than in the other. This is an interesting fact in connection with the results obtained by study of the microscopical sections of the same specimens. In these it was learned that in the more favored of the two tails the neural tube was greater in diameter and extended a longer distance towards the tip of the tail. In some of the specimens,









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as is to be seen in figure 8, the notochord was limited to one tail. Figures 7 and 8 are cross-sections of the tadpole represented by figure (5. The right was the more active of the two tails during life. In figure 7 the neural tube, cut just cephalic to its bifurcation, is seen to be well differentiated, with the notochord b^ng ventral and adjacent to it. The section of figure 8 was taken immediately caudal to the bifurcation and shows the notochord confined to one (the right) tail.

Several specimens presented a peculiar relation of one tail to the longitudinal axis of the body; such are figured in 5 and 9. In the latter figure the main axis of one tail joined that of the trunk at almost right angles, whereas the other tail coincided fairly well with the main body axis. In figure 5 the right tail


372


W. M. BALDWIN


met the body axis at an acute angle, looking forward. Such tails were, of course, useless from the functional standpoint; but their unportance cannot be o^'erestimated in furnishing exaggerated examples of the asymmetry of some of the types of spina bifida, such as were observed above in the cross-sections.

The study of the serial cross-sections demonstrated, furthermore, as these were followed in order caudally, that just posterior to the level of bifurcation of the neural tube each half tube des



lO

Fig. 9 This figure illustrates a marked instance of asymmetry with a division of the cord well anterior on the embryo. Here again the extremity of each tail is broken up into toe-like processes.

Fig. 10 In this embryo the rays had encountered an area well up on the equator in the median plane; hence, the bifurcation of the neural cord immediately posterior to the optic anlagen. The lines 11, 12 and 13 indicate the levels of the respective cross-sections illustrated by the succeeding figures.

tined for each tail presented an asymmetrical outline, the lateral wall being considerably thicker than the median. This is shown in part by the right neural tube in figure 8. As the series was followed farther caudally, however, a readjustment of the tube cells was observable, each half now becoming either a solid rod or a tube entirely synunetrical so far as the thickness of its walls was concerned; (see also figures 12 and 18).

The neural tube was caused to bifurcate at various levels, dependent upon tlie portion of the hemisphere influenced.






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^igs. 11, 12, 13 In figure 12 the marked asjTiimetry of the neural tube halves immediately posterior to the level of bifurcation of the cord is shown. The neuroblasts become adjusted farther posteriorlv, however (fig. 13) to form a more symmetrical tube or column of cells.

373


374


W. M. BALDWIN


Where the rays struck close to or on the equator in the median plane of the eg^ the subsequent bifurcation was noted well forward towards the head region; figure 10 well demonstrates this fact. In figure 9 the point encountered was much lower down on the hemisphere, while in figures 6 and 4 it was still farther posterior. Such are reallj^ instances of cauda bifida. Another fact of the utmost significance was gained from studies of the histological sections. Since it was definitely ascertained that the rays had killed the portion of the egg illuminated, in no specimen was there to be observed, however, a deficiency or falling out of a ]:)ortion of the neural tube, as one would expect



if the ])roanlagen or anlagen had been encountered by the rays. Notwithstanding the possibility of post-generation, with a replacement of the anlagen thus rendered inactive, the conclusion might be justified, tentatively at least, that the proanlagen are not located in the early stages of division of the ovum either in the yolk hemisphere or along the equator, but are confined wholly to a region well up on the black hemisphere. Before referring in detail to the results of other investigations dealing with spina bifida it will be well to emphasize some general considerations which must be taken into account in connection with the production of abnormalities.

It is taken for granted that there are many linking factors associating the develoi)mental processes concerned in the pro


ARTIFICIAL PRODUCTION OF SPINA BIFIDA 375

duction of spina bifida with tliose of other forms of malformation occurring in nature and produced experimentallj'-. Accordingly, one cannot well studj^ the one without taking into consideration those general fundamental phj^sico-chemical factors of development underlying both, upon the disturbance of which the production of anomalous conditions is dependent. The fact is well supported that the processes of differentiation in the tadpole, as in some other forms, appears to be dependent upon a series of complex and progressive chemical reactions which are of the nature of oxidations. In the later stages of development we are dealing with an organism whose chemical constitution differs considerably if not completely from that of the undivided ovum. The results of such reactions and chem.ical changes become apparent in the differentiation of the various anlagen. Eggs placed in pure water free from chemical compounds which might enter into the chemical structure of the organism, but supplied with a liberal amount of oxygen, can and do undergo the several processes of differentiation, finallj^ hatching and swinuning about. From that time on, however, when grovv^th of the differentiated parts is initiated the organism requires a supply of various chemical substances for its api^ropriation. In this connection, it is significant that the great majority of defects produced experimentally ai"e referable to changes in the differentiative stages of the embryo and only .secondarily to defective growth phenomena. Bearing in mind, then, the chemical modifications occurring during the differentiating cycle of the embryo, it is fair to assume that at certain specific times in the genesis of the anlagen their chemical composition is such as to render them more ready participants in chemical reaction with the chemical agent employed. Results so obtained cannot be cited without reservation as applying to the state of the undivided ovum, consequently much of the chemical work conducted along this line is subject to considerable qualification and limited in the insight which it furnishes into the constitution, chemical or physiological, of the ovum. Before the full truth can be established on this point, it must be demonstrated that the toxic action of the chemicals, employed was exerted upon the egg during the undivided state

THE ANATOMICAL KECORD, VOL. 9, NO. 5


376 W. M. BALDWIN

and not afterwards; or, in other words, upon the chemical 'ferments,' or proanlagen, and not upon the anlagen cells when they have attained what might be termed a condition of chemical completeness. Only by this means can we decide between the two conceptions of the ovmn; as an organism elaborating its organ anlagen at succeeding developmental periods, or as a composite, mosaic-like structure.

While the artificial production of defects has been known for a long while to be possible, but very few have succeeded in advancing any plausible explanations covering the instance of spina bifida embryos. There are two aspects to the problem of the artificial production of spina bifida which are brought out in a review of the literature dealing with this subject. The first consideration is whether we are dealing with the action of an external agent upon some specific substance in the egg; and the second, whether the nature of this reaction is specific, referable to the agent alone^ which possibly reacts upon the egg as a whole.

Morgan in 1894 and O. Hertwig in the year following were both successful in the production by chemical means of a large percentage of embryos showing the defect of spina bifida. That 0.625 per cent solutions of sodium chloride should produce so high as 50 per cent of this form, of malformation was an argument in favor of a definite specific chemical or physical property of the compound. Prior to this date observers had recorded only occasional instances of this defect and had failed to give a convincing indication of the nature of the upset in the physicochemical factors concerned. Roux was the first to call attention to the occurrence of spina bifida among frog's eggs, owing, apparently, to conditions found in nature. Panum recorded 38 instances of spina bifida in chicks, among 404 monsters produced. He, with Dareste and Fere, obtained monsters of various kinds by the employncient of variations in temperature (as did Hertwig), by varnishing the egg shells, by shifting the long, axis of the egg to the vertical, by traumatic injuries, shaking, magnetism, electrical means, various gases, vapors of lavender and by injecting different toxines and chemicals, such as turpentine, an


ARTIFICIAL PRODUCTION OF SPINA BIFIDA 377

iseed, absinthe, and cloves into the white of the egg. Their inabihty to associate any given deformity with a known and controllable cause led to a failure in the analysis of the normal developmental factors of the embryo. Richter found three instances of spina bifida among several hundred hen's eggs upon which he had experimented. Spemann, however, produced twotailed embryos by simply tying a ligature between the two blastomeres, demonstrating the bilaterality of the anlagen but throwing no light on the nature or antero-posterior extent of the organ-building substances. Fol, Rauber, Born, and O. Hertwig attributed the duplicity to double fertilization. This explanation was too compromising regarding the anterior portion of the embryo, and later was found to be unnecessary. Godlewski's experiments with reduced pressure, and Herbst's with lithium salts, Morgan's with the centrifuge, Samossa's with atmospheres of nitrogen and of hydrogen, and Wilson's with Ringer's solution and with sodium chloride, furnish additional evidence of the diversity of ways by which this abnormal condition may be produced.

In this connection, it is interesting to note that Mall has reported 12 instances of spina bifida among 163 pathological human embryos, attributing as a possible cause of the condition, faulty unplantation of the embryo. Analysed still further, however, by analogy to the conditions found among lower vertebrates, it seems possible that the hmnan ovum, too, requires but little else than a good supply of oxygen for its differentiation during the early stages of development. At this time the causal forces are operative for the production of spina bifida. Undoubtedly, a deficiency in the supply of oxygen could be brought about by the imperfect unbedding of the ovum in the uterine mucosa. Bearing this fact in mind in connection with the features of differentiation of the ovmii given on page 375, it seems superfluous to seek an explanation of the condition in man through the action of chemical substances or of altered temperature. Though the possibility of the direct or indirect dependence of the processes of oxidation upon the action of the latter agents must be


378 W, M. BALDWIN

admitted, reasoning from conditions as we find them in the frog, a sufficient and probably a more primal cause, at least, is referable to faulty oxidation.

Guthrie produced these defects by the use of strychnine, caffeine, and nicotine, as had Hertwig, but with concentration far below that of 0.625 sodium chloride. Jenkinson, however, tested out this question of the osmotic pressure of the salt solutions by employing a great variety of isotonic solutions of various salts, such as chlorides, bromides, iodides, nitrates, and sulphates of ammonium, lithium, sodium, potassium, calcium, barimn, strontium, and magnesium, and, in addition, solutions of cane sugar, dextrose, urea, and gmn arable. He obtained spina bifida with especial success in his sodium chloride and sodium nitrate solutions. His conclusions are best given in his own words: "There is very little room for doubt, that the malformations in question may be due to some property of a salt other than its osmotic pressure." Bataillon had previously come to the conclusion that malformations were not specific to the means employed. Gurwitsch's belief was that halogens affected the position and development of the blastopore and of the brain, sodium chloride acting upon both, and sodium bromide upon the brain alone, whereas lithium chloride seemed selective on archenteron and blastopore.

It would appear, considering the production of this malformation by the diverse methods outlined above in connection with that detailed by this paper, that we were justified in concluding that in the question of specificit}^ of reaction in the production of spina bifida the weight of argmiient at present refers the causative forces more particularly to an upset of a specific substance in the egg, rather than a specific action of the agent. It is in the conception of the changes which occur in the chemical composition of the ovum during its differentiation, as previously outlined, that we find support for this statement. It follows tiiat the composition of any particular proanlage or anlage may be such at different stages of its chemical elaboration as to possess a marked affinity for widely varying chemical reagents. The


ARTIFICIAL PRODUCTION OF SPINA BIFIDA 379

developmental end-product of the reactions so brought about would be the same, e.g., spina bifida, notwithstanding the wide diversity of character of the chemical reagents employed.

Furthermore, since we cannot deny, we must take into account the possibility of a two-fold manner of production of spina bifida; the one, owing to an upset in the contents of the cells of the unpigmented hemisphere whose yolk is intended for the nutrition or elaboration of the other component, viz., the proanlagen or chemical ferments restricted to the cells of the pigmented hemisphere. For the other, we can assume the possibility^ of an interference in the function of these proanlagen as the result of the chemical reactions experimentally induced, apart from an upset referable to the composition of the nutritive yolk particles. The author's work, however, points out clearly that in the white hemisphere alone are resident sufficient causes for the production of the malformation, so that, while the possibility of an involvement of the proanlagen exists, the weight of experimental evidence points to the yolk hemisphere as the more vulnerable of the two. Jenkinson observed, for instance, that as the result of chemical action the yolk cells were primarily affected, and Godlewski, employing reduced pressure, came to the same conclusion. The disturbing influences of insufficient aeration and cold, as ascertained by Morgan and others, were noted first in the yolk cells, and to this same region Morgan attributes the causative factors in the results of the centrifuge, while Hertwig drew the same conclusions from studies of overripe eggs.

The production of an area of altered protoplasm, which serves as a mechanical check to the approxunation of the lips of the blastopore during the backward progression of the latter, emphasizes very naturally the importance of synchronized tempo in the two processes directly concerned with the elaboration of the neural cord. Under normal conditions the differentiation of the neural anlagen (consequent upon the backward migration of the proanlagen) occurs apparently synchronously with the backward migration of the blastopore and fusion of its dorsal lips. These two processes are approxmiately cooperative in point of


380 W. M. BALDWIN

time, i.e., the anlagen of each half-tube become progressively differentiated in a backward direction at about the time when the half of the dorsal lip in which it is localized meets and fuses with its corresponding fellow of the opposite side. The two processes are not causally dependent upon each other, however, since differentiation takes place in the experimented eggs at about its former rate but now along the equator and not, as usual, parallel to the median plane.

The absence of the proanlagen and anlagen of the egg along the equator in the earliest stages of development of the ovum is sufficiently attested for by the ultra-violet method . Incidentally, it should be remarked that the restriction of these proanlagen at all times to the pigmented hemisphere seems to the author's mind a very significant fact. In this connection, it should be stated that ultimately the yolk mass is wholly drawn into the body of the embrj^o. Even though by this later process the neural tube halves may be approximated, subsequent fusion does not take place, however, since each half tube has postgenerated into a whole tube.

The conclusions reached by this method of experimentation upon the fertilized ovum, are, therefore; first, that the killing of a small localized area of the yolk hemisphere or of the region of the equator of the frog's egg produces invariabl}^ the condition of spina bifida in the embryo; and second, that the neural tube proanlagen, or formative substances, do not lie either in the yolk hemisphere or along the equator of the frog's egg, but are wholly restricted to the pigmented half of the egg. These proanlagen attain their definitive positions bj^ a process of backward migration, the rate of which is synchronous with that of the backward progression of the dorsal lip of the blastopore. The action of the ultra-violet rays in destroying a small localized area of the yolk hemisphere or equator results from mechanical causes in an upset of the synchronism of the two factors, i.e., differentiation of the neural anlagen and approximation of the lips. The former proceeds at its normal tempo, while the latter is retarded. Consequently, the former, always restricted to the pigmented hemi


ARTIFICIAL PRODUCTION OF SPINA BIFIDA 381

sphere, come to lie along the equator and are later carried towards the median plane by the subsequent approximation of the lips, but the half tubes, having already differentiated into whole tubes, do not subsequently fuse.

BIBLIOGRAPHY

Bataillon 1901 Arch. Entw. Mech., Bd. 12.

Born 1887 Bresl. arztl. Zeitschr. fur 1882, Bd. 14, Bd. 15.

Dareste 1891 Recherches experimentales sur la production artificielle des

monstruosites, Paris. F^RE 1893-1901 Compt. Rend. Soc. Biol. FoL 1879 Mem. de la Soc. de Phys. et d'hist. Nat., Genevd. GoDLEWSKi 1901 Arch. Entw. Alech., Bd. 11. GuRwiTSCH 1896 Arch. Entw. Alech., Bd. 3; Zeitschr. f. wissensch. Zool., Bd.

55, 1893. Herbst 1897 Mitt. d. Zool. Station zu Xeapel, 11, 1895; Arch. Entw. Mech.,

Bd. 5. Hertwig, O. 1896 Festschr. f. Karl Gegenbaur, Leipzig (Arch. f. mikr. Anat.,

Bd. 44, 1805). Jenkinson 1906 Arch. Entw. Mech., Bd. 21. Knower, H. McE. 1907 Anat. Rec, Amer. Jour. Anat., vol. 7. Lankester 1877 Xotes on embryology and classification. LoEB 1893 Pfliiger's Archiv... Bd. 54; Amer. Jour. Physiol., Ill, 1900. Mall, F. P. 1908 Jour, of Morph., vol. 19. Morgan, T. H. 1894 Anat. Anz., Bd. 9, Quart Journ. Micr. Sci., vol. 35, no. 5

1897 The development of the frog's egg.

1909 Anat. Rec. vol. 3. Pantjm 1878 L'ntersuchungen liber die EntstehungderMissbildungen, zunachst

in den Eiern der Vogel, 1860, and Virchow's Arch., Bd. 52. Ratjber 1878 Virchow s Archiv., Bd. 71, Bd. 73 and 74; Bd. 81, 1883. RiCHTER 1888 Verhand. der Anat. Gesellsch. Roux 1895 Gesammelte Abhandlungen, Leipzig. Spemann 1903 Zool. Jahrb. Suppl. Wilson, C. B. 1897 Arch. Entw. Mech. V.


ON THE PRESENCE OF INTERSTITIAL CELLS IN THE

CHICKEN'S TESTIS

t

T. B. REEVES

Anatomical Laboratory of the University of Virginia

THREE FIGURES

Since there is a difference of opinion as to whether interstitial cells are present in the testis of the domestic cock, and because of the obvious bearing of the question upon the theory which attributes to these cells an important influence upon secondary sex characters, it has seemed worth while to investigate the matter. To illustrate the difference of opinion I shall abstract briefly two very contradictory reports on the subject.

Alice M. Boring^ reports observations on testes of roosters from one day to twelve months of age. In the young as well as in the older testes she fails to differentiate any cells of the intertubular tissue from ordinary connective tissue cells. The variation in size, shape and character of the nuclei is attributed to mechanical conditions of pressure. The fat observed in the intertubular tissue was not found inside of the cell bodies, hence it was thought to be brought there by the circulation and deposited. Her conclusion is that there are no interstitial cells present at anj^ time.

In the summarj^ of the work done by J. des Cilleuls,- it is stated that the external differentiation of the rooster from the pullet begins to be apparent at about the thirteenth day; and that at this time interstitial cells first make their appearance in the testis. Des CiUeuls says the interstitial cells and cock characters increase pari passu and the cock characters are accentuated

1 Alice M. Boring. The interstitial cells and the supposed internal secretion of the chicken testis. Biological Bulletin, vol. 23, no. 3, August, 1912.

^ J. des Cilleuls. Interstitial testicular cells and secondary sex-character. Summary in Journal of the Royal Microscopical Society, December, 1912.

383


384 T. B. REEVES

while the seminal tubes still remain in an embryonic condition, until after the sixtieth day. The explanation offered is that the internal secretion of the interstitial cells serves as a stimulus for the development of the secondary sex characters.

This report is made after the study of testes from cocks three, five-and-a-half, nine and eighteen months old. T^he tissue was removed inmiediately after killing the fowl and fixed in the following solutions: formalin, Zenker's, Bouin's and Ciaccio's fixative :

5% potassium bichromate 20 cc.

formalin 4 cc.

acetic acid 1 cc.

Fix in the above forty-eight hours, then in 3 per cent potassium bichromate one week. Sections were stained chiefly with hematoxyhn, and congo red, iron hematoxylin, and Mallory's connective tissue stain. The Ciaccio fixative and Mallory's stain gave the best results for the study of the intertubular tissue, although the other preparations showed up fairly well.

For the study of fat I used frozen sections of tissue fixed in formalin. These were stained with Sudan III and hematoxyhn.

Microscopic examination of the sections from the eighteen months testis shows the seminiferous tubules in a state of active spermatogenesis. The intertubular tissue is small in amount and compact, allowing the tubules to he close together. Where three or more tubules come in juxtaposition small triangular or irregular areas are formed. In most of these areas there is a small blood vessel surrounded by connective tissue which contains both spindle- and oval-shaped nuclei. In other areas there are, in addition to the above structures, typical interstitial cells also, as shown in figure 1 . The nuclei are round or oval in outUne, rather rich in chromatin and contain an evident nucleolus. The cytoplasm is granular and in certain areas, especially around the nucleus, it is conden-sed, while near the periphery of the cell it is much less condensed or even vacuolated.

Sections from a five-and-a-half months' testis show the tubules in an inactive state, without spermatozoa, and the intertubular connective tissue shghtly greater in amount than in the preceding chicken. The intertubular areas are somewhat larger, but


INTERSTITIAL CELLS IN CHICKEN S TESTIS


385


in other respects the appearances are quite similar to those observed in the cock of eighteen months.

In the sections of the three months' testis, the tubules are much smaller and lined with SertoU cells, imbedded iq which are numerous young sex cells. Relative to the tubules the intertubular spaces are far larger than in any of the older testes. The connective tissue with its spindle-shaped nuclei is readily differentiated from the interstitial cells. The former surrounds the tubules very closely, while the interstitial cells are usually located in the irregular areas formed by three or more tubules



Fig. 1 C. t., connective tissue; s. I., seminiferous tubule; i. c, interstitial cell; 6. c, blood cell.

coming close together. In most of these areas there are several interstitial cells; often they form large groups (fig. 2). The cell boundaries are more distinct than in any of the older testes and the cytoplasm is very much more vacuolated. Indeed some of the cell bodies appear ahnost clear, containing only the nucleus and a small amount of granular cytoplasm.

On examination of the sections stained for fat the interstitial cells in the three months' testis appear to be almost completely filled with fatty material (fig. 3). Thus the vacuolated appearance of the cells in figure 2 is explained. Most of the fat is within the interstitial cells, though there is a good deal free in the intertubular tissue and also a very small amount in the tub


386


T. B. REE^'ES



i. C.





|>


Fig. 2 S. <., seminiferous tubule; i. c, interstitial cell; c.<., connectivetissue. Fig. 3 .S. i., seminiferous tubule;/., fat; i. c, interstitial cell.

ules. In the older testes the fat is very much less in amount and appears as very small particles both in and outside of the interstitial cells. No attempt was made to determine the nature of the fatty material; as it was not rendered insoluble by Ciaccio's fixative, it probably does not consist of phosphatid lipoids to any large extent.

The primary object of this short study was merely to determine the presence or absence of interstitial cells in the testis of the domestic cock; there can be no doubt but that they are present in all the stages examined.


A SIMPLE METHOD OF BRAIN DISSECTION

PAUL E. LINEBACK

Harvard Medical School

FIVE F13URES

Every instructor realizes how hard it is to make clear to students the deep or inner structures of the brain. It is difficult to give them a lucid description of even the simpler and more superficial parts, but when it comes to explaining the intricate mechanism, it is an almost hopeless task.

Efforts have been made to disclose the regions, parts, tracts, and nuclear masses by means of a series of cross sections or fiber tract dissections. To all but those well trained in technique and familiar with the general make-up of the brain, these methods are confusing and difficult. Tract dissection necessitates a general understanding of how and where a tract runs, and a series of cross sections presents to a student a mass of labyrinthian vagaries. Most students remember an important structure in a cross section series as it appears in a few well-defined segments, but do not have a clear mental picture or distinct understanding of its extent and relationship. With the following method a student, being guided l)}'^ a few easily located landmarks, can get the greatest degree of clearness and satisfaction from his work, and have the least amount of cutting and mutilating of tissue.

The procedure is as follows: Using one-half of the brain, clear away all pia mater from the regions to be cut; sylvian fissure, central fissure (Rolandi), post central fissure, superior frontal sulcus, and about the uncus and temporal pole. This is important to make the field of operation perfectly clear and prevent blocking the knife. It is also important to use a long scalpel the blade of which should be about 7 or 8 cm. long and not more than 1 cm. in width; 0.5 cm. is still better. Place the hemisphere with frontal region upward or toward the student and depress the temporal pole sufficiently clearly to expose the uncus. Now cut across the upper part of this convolution, going from within outward and slightly downward, extending the cut about 2 cm. lateralward and the same backward (fig. 1). Make further depression of the temporal lobe there by widening the sylvian fissure, and cut at nearly right angle to the first incision along the lower border of the island (fig. 1). When this cut is extended 2 or 3 cm. directly backward, the tip of a cavity can be exposed, the anterior extremity of the inferior horn of the lateral ventricle.

387


388


PAUL E. LINEBACK


J.Arej?/rj_


-^^-e



Fig. 1 Showing hemisphere in position, frontal pole forward and temporal pole depressed to make first and second cuts.

Fig. 2 Showing median surface with third and fourth cuts made and knife in position making fifth cut.


SIMPLE METHOD OF BRAIN DISSECTION


389



Fig. 3 Showing 'removable' portion, with hippocampus, fornix, and inferior horn of lateral ventricle.

Fig. 4 Showing 'basal' portion with lateral ventricle and its floor and lateral boundary structure in clear viev/.


390


PAUL E. LINEBACK


ust back °f th^ ff ^™2Lhere begtaning he incision at a point on 1? t: callosum (genu, thus -•^■>« -,° ^ f? n•taScutS:>^h1



Fig. 5 Showing lateral surface and dotted line marking, on the surface, the course of the shoulder of the knife in making the fifth cut.

and make the following incision with the shoulder of the knife^^^^^^^^^^ excised portion to give clear view of the he 1 ^^^^P;^2;^^-3hrrp curve

rn=„rbtcf.rtrttpii? n^^^^^^^^^^^^^^

at Us lateral-most boun,la.y where that cav.ty turns downward. When


SIMPLE METHOD OF BRAIN DISSECTION 391

the shoulder comes to the sylvian fissure, lift the handle to about 60° with the horizontal plane, thus forcing the point downward, at the same time turning the sharp edge forward.

Now make a little more bold depression of the temporal lobe through the S3'lvian fissure, and continue the incision forward along the lower border of the island to meet the original cut at the uncus, all the while holding the knife at about 60° with the horizontal plane.

The incisions have now been completed. With the median surface facing upward, grasp the frontal lobe in the right hand and the occipital lobe in the left hand (this is for the left hemisphere; if the right hemisphere is used, the hands will be reversed), and carefully separate the two portions to about 3 cm. This wall stretch out the choroid membrane which can be easily followed almost throughout its entire extent of attachment. When this is carefully studied, the removable portion containing the hippocampal lobe with its fornix can be entirely withdrawn, and a clear view of the lateral ventricle will be had (fig. 3). The complete separation of the two parts will rupture the choroid membrane, but the ragged edges will still give a clear view of the line of its attachment. On the basal portion, in plain view, will be the structures forming the floor and lateral Isoundary of the lateral ventricle, caudate nucleus, taenia semicircularis, thalamus, etc. The optic tract, geniculate bodies, quadrigeminal bodies, and pes pedunculus can also be easily seen (fig. 4). The two segments can be easily, quickly, and repeatedly separated with no harm whatever to continuity of tissue. When the sections are in place, the cuts are scarcely perceptible; when removed, there is the greatest amount of exposure of hidden structures. A special advantage in this method is that specimens too soft for filler tract dissection or cross sectioning, or hardened after being mashed or pressed out of shape, can still be used with a good degree of satisfaction when cut as outlined above. There is to be offered this last and most important point, that the removable segment comes off from the basal portion in approximately the same course the hemisphere pursued in its early stages of development. Following this course of development as displayed by such a method of removing part of the hemisphere, it is much easier for the student to see how the velum interpositum was at one time a part of the wall, the roof portion of the forebrain, of the neural tube, and its presence in the fully developed specimen, attached to the sharp edge of the fornix on the one side and the taenia semicircularis and thalamus on the other, makes a closed cavity of the lateral ventricle and its horn.

This method is not to be used for complete work; the nuclear masses and fiber tracts demand deeper dissection. But using the method on one hemisphere and cross section on the other, the student will have far greater and more gratifying results, and will have good material, easily kept, for future reference.

Finally, I wish to express mj- appreciation to Dr. Bremer and Mr. IMiller for their kindness in reviewing this paper and making valuable suggestions.

THE AXATO.MICAL RECORD, VOL. 9, NO. O


BOOKS RECEIVED

The receipt of publications that may be sent to any of the five biological journals published by The Wistar Institute will be acknowledged under this heading. Short reviews of books that are of special interest to a large number of biologists will be published in this journal from time to time.

THE ANATOMY OF THE DOMESTIC ANIMALS. By Septimus Sisson, S.B., V.S., Professor of Comparative Anatomy, Ohio State University, College of Veterinary Medicine. Second edition entirely reset. Octavo of 930 pages, 724 illustrations. Philadelphia and London: W. B. Saunders Company, 1914. Cloth, $7.00 net; Half INIorocco, $8.50 net.

Preface to first edition. The lack of a modern and well-illustrated book on the structure of the principal domestic animals has been acutely felt for a long time by teachers, students, and practitioners of veterinary medicine. The work here offered is the expression of a desire to close this gap in our literature.

The study of frozen sections and of material which has been hardened by intravascular injection of formalin has profoundly modified our views concerning the natural shape of many of the viscera and has rendered possible much greater precision in topographic statements. The experience of the author during the last ten years, in which almost all of the material used for dissection and for frozen sections in the anatomical laboratory of this University has been hardened with formalin, has demonstrated that many of the current descriptions of the organs in animals contain the same sort of errors as those which prevailed in regard to similar structures in man previous to theadopt ion of modern methods of preparation.

While the method of treatment of the subject is essentially systematic, topography is not by any means neglected either in text or illustrations; it is hoped tha^ this will render the book ol value to the student in his clinical courses and to the practitioner. Embryological and histological data have been almost entirely excluded, since it was desired to offer a text-book of convenient size for the student and a work of ready reference for the practitioner. * * *

Preface to second edition. This book supersedes the author's Text-book of Veterinary Anatomy. A comparison of the two will show the new title to be justified by the extent and character of the changes which have been made.

Continued observations of well-hardened material and frozen sections have led to a considerable number of modifications of statement. It is scarcely necessary to say that the recent literature, so far as available, has been utilized.

Many changes in nomenclature have been made. Most of the synonyms have been dropped or relegated to foot-notes. Exceedingly few new names have been introduced. Nearly all eponyms have been eliminated, on the ground that they are not designative and are usually incorrect historically. The changes made in this respect are in confomiity with the report of the Committee on Revision of Anatomical Nomenclature which was adopted by the American Veterinary Medical Association two years ago. Progress in the direction of a simplified and uniform nomenclature is much impeded by the archaic terminology which persists to a large extent in clinical literature and instruction. * * *

Septimi^s Sis.son.

The Ohio State University, Columbus, Ohio, September, 1914.

392


THE ROLES OF NUCLEUS AND CYTOPLASM IN MELANIN ELABORATION

DAVENPORT HOOKER

From the Anatomical Laboratories of the Schools of Medicine of Yale University and the University of Pittsburgh

ONE FIGURE

The more recent work on the formation of melanin seeks to derive this pigment from chromatin elements. In 1889 Mertsching attributed the formation of melanin to the breaking down of the cell and especiallj^ to the destruction of the nucleus. Jarisch ('92) makes the statement, "Das Oberhautpigment entwickelt sich ^us einer Kernsubstanz, dem Chromatin, oder einem diesem chemisch oder wenigstens raumlich nahe stehenden Korper." Rossle ('04), in the discussion of pigment formation in melanosarcomas, recognizes fives stages in the process, based on the appearance of the nucleus. He believes the melanin granules to be small particles of chromatin which are extruded from the nucleus, impoverishing the latter in the process.

Aurel von Szily ("11) has made a notable contribution to the theor}^ of pigment formation from chromatic elements. He worked on the elaboration of melanin in developing eyes of a variety of vertebrates and in melanotic tumors of the human eye. According to his results, the melanin granules arise as colorless rod-like bodies (Pigmenttrager) extruded from the nucleus, being derived directly from chromatic elements. These Pigmenttrager are typical for species and locality of production. They also correspond exactly with the size and form of the melanin particles met with in that species and location. After being freed from the nucleus and wandering to a more or less peripheral position in the cell, the colorless Pigmenttrager become colored probably by the action of cell ferments. The pigmentation of the Pigmenttrager begins at one end of it and proceeds to the other. The origin of the Pigmenttrager from the chromatin and their transition into the cell cytoplasm

393

THE AKATOMICAL RECORD, VOL. 9, NO. 5 JCXE, 1915


394 DAVENPORT HOOKER

may be followed step by step. The nucleus which gives rise to them may be either productive or degenerative. In the former case, no impoverishment of the nucleus takes place; in the latter, pigment formation is accompanied by marked degenerative changes in the nucleus.

In 1910 Harrison presented evidence of a new type upon the question of pigment formation. In his paper on nerve growth in vitro, he mentioned and figured certain cells which became pigmented during the life of the cultures. To quote, Harrison found that the pigment first arose as a round mass of granules lying just to one side of the nucleus. This (mass) gradually increased in size and then the pigment granules became scattered through the cytoplasm" ('10, p. 812).

In 1912, while working on the reactions to light of embryonic connective tissue melanophores, material for a careful study of the actual elaboration of the melanin granules themselves was found in the developing connective tissue and epithelial cells of embryos of Rana pipiens. For this study, Harrison plasma cultures, living embryos and serial sections of carefully fixed embryos were used. The development of the melanin was followed in embryos varying in length from 3 to 10 mm.

Though the melanophoric cells found in the epidermis of older frog larvae are certainly mesodermal in origin, many ectodermal cells of young embryos elaborate this pigment within themselves. The pigment, however, after existing for a time in the cells, gradually disappears. That connective tissue cells elaborate melanin has long been an established fact. The mode of its development in these two types of cells is the same.

Plasma cultures. Small pieces of mesenchyme and epithelium from Rana pipiens embryos 3 to 4 mm. long were implanted in the plasma of frogs of varying species. Seventeen primary cultures were made. These lived in good condition over periods varying from three to forty days. In the case of the older cultures, the plasma was changed at frequent intervals. From these primary cultures, secondary were made, to the number of sixteen, by removing fragments of tissue and reimplanting in new plasma, fti all, thirty-three cultures were studied.

At first (fig. 1, A) the cells were clear and translucent, without


MELANIN ELABORATION


395



C D E

Fig. 1 Diagrammatic sketch to show the different stages of melanin eh^boration. The heavily outlined circle in the center represents the nucleus of the cell, the smaller ovals represent oil droplets. The cell is represented in median section.

pigment granules, but contained fat droplets scattered throughout the cytoplasm and a more or less centrally placed nucleus. Then a few small, spherical, brownish granules became visible in the cytoplasm of the cell immediately adjacent to the nucleus, appearing simultaneously, or nearly so, on all sides of it. Their number gradually increased until a well defined hollow sphere surrounded the nucleus (fig. 1, B). On their first appearance, these melanin granules presented all the characteristics which are normal for them. No positive evidence of any increase in size of the individual particles of pigment was obtained. Owing, however, to their minuteness, an accurate determination of any such change presents alinost insurmountable difficulties.

No granules made their appearance at any time inside the nuclear membrane nor in the cytoplasm of the cell away from the nucleus. The region of production was limited to that zone of the cytoplasm which is in contact with the nucleus. Nor was there any sign of the presence of colorless granules, which, by a process of pigmentation, could be transformed into the particles of melanin. The most careful search for any morphological structure within the cell that might serve as a Pigmenttrager in von Szily's sense, was unavailing.

With each succeeding day, the number of melanin granules


396 DAVENPORT HOOKER

increased. During the earlier stages of this process, they remained concentrated in the center of the cell, the periphery of the cloud of densely packed granules becoming larger and further away from the nucleus (fig. 1, C). Then the granules began to spread throughout the cell. This process was gradual and was accomplished by the slow separation of the individual elements of the dense cloud about the nucleus. At first, but a few granules, widely separated from one another, detached themselves from the central mass and wandered among the oil droplets nearest at hand. As this process of distribution, accompanied by further production of new granules around the nucleus, continued, more and more of the pigment particles spread toward the periphery (fig. 1, D), in such a manner that the number of granules per unit area steadily decreased from within outward. The periphery of the cell always contained fewer granules than the center until the final stage of melanin elaboration was reached (fig. 1, E). At this time, the cytoplasm of the cell was filled, one might say, to 'saturation.' Through this cloud of granules, the fat droplets and the nucleus were visible as clear, translucent areas, absolutely free from pigment. The entire process here described is completed in a period of eight to fourteen days, on an average.

Living embryos. By carefully dissecting out scraps of mesenchyme and epidermis from embryos of different ages and mounting them in plasma or isotonic saline (0.4 per cent), the different stages of melanin elaboration may be observed. That the steps thus seen are not continuous, but isolated from one another, is true. This objection to the nlethod is obviated, however, by the check provided by the cultures. Every step in the elaboration of melanin observed in the cultures is exactly duplicated in the normal body. The light brown granules of melanin are found, at first, only in the region of the nucleus and then spread through the cytoplasm of the cell. They are colored on their first appearance, a fact which seems clearly to do away with the colorless Pigmenttriiger idea.

Serial sections. Like the study of fresh material from li\'ing embryos, that of serial sections serves principally as a check upon the cultures. A description of the findings here would


MELANIN ELABORATION 397

be but a repetition of facts already stated, with one important exception. The most minute examination of series fixed in all stages of melanin formation fails to show the slightest change in character and content or the least sign of degeneration or depletion in the nucleus. Nor can any evidence be found to show that the nucleus plays a part in the formation of melanin by a process of extrusion of any of its elements into the cj^toplasm. All the granules of pigment are found in the cytoplasm near the nucleus, but they have no visible, structural connection with the nucleus or any of its contents.

Certain very important objections to the chromatin idea of the origin of melanin are evident from the results set forth above.

The nuclei of the pigment-forming cells suffer no depletion during the process Though von Szily claims that certain nuclei which he terms 'active,' develop pigment without loss to their content, the actual depletion of many others was also seen by him. Rossle describes minutelj^ many changes which occur in the nucleus and states that after the extrusion of chromatin to form melanin, the nucleus is bladderlike, with a reduced amount of chromatin.

No colorless anlagen for the melanin granules are to be found in the form of 'Pigmenttrager' (v. Szily, '11) or Tigmentbildner' (Fischel, '96). That a chemical anlage in the form of a chromogen is present is almost certain in view of the work of Bertrand ('08) but that the melanogen exists in the frog as a definite morphological structure, which, without any other change than in its coloration, becomes the pigment granule itself, may be denied.

The process of pigmentation of a melanophore in the frog begins in the area nearest the nucleus and spreads from that point throughout the cell, that is to say, it progresses from the center of the cell to the periphery. This is in direct opposition to the observations of von Szily, who states that the pigmentation of the colorless Pigmenttrager takes place gradually while they are wandering about in the cytoplasm. Indeed, his figure 4 (plate 4) shows the process going on irregularly throughout the cell and figure 8 of the same plate illustrates a process directly the reverse of that noted in this paper, namely, the appearance


398 DAVENPORT HOOKER

of pigmented granules at the periphery of the cell before they are present near the nucleus.

The last, and probably the most important, objection to the supposed chromatin origin of melanin granules is the fact that no process of extrusion of chromatin nor any of the steps of such a process are to be observed. The pigment granules appear near the nucleus, in fact, in almost direct apposition to the nucleus, but no evidence was found in this work which even suggests a morphological relationship to either the nucleus or its contents.

It may safel}^ be concluded that, in the normal ontogenetic origin of melanin in the frog, the chromatin plays no direct role. On the contrary, all the evidence obtained goes to demonstrate that the melanin granules are formed in the cytoplasm, from elements already present in solution in it, through some action of the nucleus.

Bertrand ('96) isolated an enzyme in plants (Russula and Dahlia) which, by its oxidizing action on tyrosin, was named tyrosinase. Von Fiirth and Schneider ('01) found this same ferment in the haemolymph of Lepidopteran larvae and noted its occurrence in many animal forms. The action of this enzyme on tyrosin gives a melanin and von Fiirth suggested,

. . . . dass die physio logische Bildung melaninartiger Pigmente in den tierischen Geweben auf das Zusammenvvirken von zweierlei Fermenten zuruckzufiihren sei: durch ein autolytisches Ferment konnte ein aromatischer Komplex aus dem Eiweismaterial abgespalten und dieser sodann durch einc^ Tyrosinase in ein Melanin iibergeftihrt werden. (1901, p. 242). 1

The remarkable results of Bertrand's ('08) more recent work demonstrate the manner in which tyrosin and its derivatives may form the various types of the melanins usually met with in the animal body. He determined that many substances may be transformed into melanin by the oxidizing action of tyrosinase, each giving a characteristic color. During oxidation, a play of colors results, the earlier stages of the process giving lighter colors than the more advanced. The essential constitu ^ It is not within the province of this paper to review in detail the literature on the melanins. The reader is referred to the excellent Sammelreferat of von Fiirth ('04).


MELANIN ELABORATION 399

ent seems to be a benzene ring with an hydroxyl radicle. Tyrosin itself gives a black pigment, while paraoxyphenylacetic and paraoxyphenylpropionic acids give browns. It should be remembered, however, that the individual granules of ^black' melanin are brown; those of 'brown' melanins, yellowish in color. Gessard ('03) has given the strongest evidence yet adduced for the actual formation of melanin in the animal body from tyrosin. Working on melanotic tumors in horses, he determined the presence of free tyrosin and adds: "La tyrosine est done le chromogene dont I'oxidation par la tyrosinase determine la formation du pigment noir commun a divers produits physiologiques et pathologiques de I'economie animal." (p. 1088).

The recent work on protein digestion demonstrates that aminoacids are absorbed, unchanged, by the blood stream from the ahmentary canal and are distributed to the tissues (Folin, '14). Van Slyke and Meyer ('13) have shown that "the disappearance of intravenously injected amino-acids from the circulation is the result of neither their destruction, synthesis nor chemical incorporation into cell proteins. The acids are merely absorbed from the blood by the tissues, without undergoing any inmiediate chemical change." They have also demonstrated that there is a limit to the amourlt of amino-acids that may be absorbed by the tissues, so that a certain equilibrium exists between the blood and the tissues so far as the amino-acids are concerned. Further, Osborne and Alendel ('12) have shown that, while certain amino-acid groups will sustain life if fed as an exclusive diet, on the other hand it is clear that when certain aminoacid groups are lacking, nutritive equilibrium is impossible. The cyclic derivatives, tyrosin and trj^ptophane, appear to be included here" (p. 326).

Several of the protein putrefaction products mentioned by Bertrand as sources of melanin, as paracresol, paraoxyphenylacetic acid and others, all derivatives of tyrosin, also are known to be absorbed as such by the organism. There can be but little doubt that sufficient quantities of melanin-forming substances occur normally in the body.

" H. Eppinger ('10) isolated a melanogen from the urine of patients suffering from melanosarcoma which turned black on oxidation. This he believes to be derived, not from a tyrosin base, but from tryptophane.


400 DAVENPORT HOOKER

J. Loeb has repeatedly made the statement that oxidation is a prominent function of the nucleus in normal development and regeneration. Perhaps the most striking proof of this fact in specific tissues in the adult has been given by the work of R. S. Lillie ('02). By soaking thin slices of living tissues in solutions of substances which, colorless in the unoxidized condition, give brilliant color reactions on oxidation, he was able to determine the exact location in the individual cell where this reaction proceeds to the greatest extent. His findings furnish, it is believed, conclusive evidence that in many tissues the nucleus is the chief agency in the intracellular activation of oxygen; and, further, that the active or atomic oxygen is in general most abundantly freed at the surface of contact between nucleus and cytoplasm" ('02, p. 420).

The findings in the normal development of melanin in the embryonic frog furnish strong histological evidence that the nucleus of the cells elaborating this pigment provides something vitally necessary for its production. The melanin granules appear, not in haphazard manner throughout the cell, but in the cytoplasm immediately about the nucleus or, in Lillie's words, ^'at the surface of contact between nucleus and cytoplasm." Lillie's work seems to indicate clearly that 'the vitally necessary element for melanin elaboration provided by the nucleus is an oxidizer. Jaquet in 1892 demonstrated that the oxidizing action of the cell was not alone a property of living tissue, but was also evinced by broken-down cells which were no longer living. Nevertheless, the oxidases present in dead cells were originally elaborated by the nucleus. Lillie's work demonstrates this.

The particular form which the oxidizing action of the nucleus takes in melanin elaboration is that of an oxidase, perhaps of a type of tyrosinase. A host of investigators, following in the footsteps of Bertrand's ('96) original discovery of the presence of tyrosinase in plants, have isolated this enzyme in many animal forms and in such bodily positions as to serve normally for the manufacture of melanin.

The data derived from these various sources may be briefly summed up as follows:

1. Tyrosin, or its derivatives, acted upon by an oxidizing


MELAXIX ELABORATION 401

agent, tyrosinase, gives a melanin. (Bertrand, '96 and '08; von Ftirth and Schneider, '01, etc.)

2. Free tyrosin was discovered by Gessard ('03) in horses with melanotic tumors and it is now a well krfown fact that derivatives of tyrosin are absorbed by the animal body.

3. Lillie ('02) gave definite proof of the role played by the nucleus as a producer of oxygen or of an oxidase.

4. The normal presence of tyrosinase discovered in many parts of the body by Gessard ('01, '02, '03,) Przibram ('01), ^ Dewitz ('02), Durham ('04), Weindl ('07), etc.

When the histological data presented in this paper are considered in connection with the facts just reviewed, it will be seen that they are in full accord with one another. While no evidence has been obtained from this work that tyrosin is present in the cells under consideration, it is shown that the base from which the melanin granules are formed probably exists in a soluble condition in the cytoplasm. The role of the cytoplasm, then, is that of a carrier of the chromogen. That the nucleus plays an all important role is evident.

CONCLUSIONS

It is felt that the evidence here brought forward demonstrates conclusively the following points:

1. That the theory of the origin of melanin from chromatin elements extruded from the nucleus into the cytoplasm is untenable, at least in the frog.

2. That, however, the nucleus plays an essential part in pigment formation by some activity which greatly resembles an oxidizing action.

3. That melanin is formed in the cytoplasm of the cell at the point of known greatest efficiency of the nucleus as an oxidizing agent.

The following general conclusion from these facts seems justified: that, in the cells of embryo frogs, melanin is formed from some substance (probably tyrosin or its derivatives) in solution in the cytoplasm when acted upon by the nucleus (perhaps an oxidase reaction).

Anatomical Laboratory, University of Pittsburgh

^ Evidence given by von Fiirth and Schneider ('01, p. 241).


402 DAVENPORT HOOKER

LITERATURE CITED

Bertrand, G. 1896 Sur une nouvelle oxydase ou ferment soluble oxydant

d'origine vegetale. Compt. rend, de I'Acad. d. Sci., torn. 122, p. 1215.

1908 Recherche§ sur la melanogenesis : Action de la tyrosinase sur

la tyrosine. Ann. de I'lnst. Pasteur, torn. 22, p, 381. Dewitz, J. 1902 Recherches experimentales sur la metamorphose des insectes.

Compt. rend. d. 1. Soc. Biol., torn. 54, p. 44. Durham, F. 1904 On the presence of tyrosinase in the skins of some pigmented

vertebrates. Proc. R. S. London, vol. 74. Eppinger, H. 1910 Uber Melanurie. Biochem. Zeitschr., Bd. 28, p. 181. FiscHEL, A. 1896 Uber Beeinflussung und Entwicklung des Pigmentes. Arch.

f. mikr. Anat., Bd. 47, p. 719. FoLiN, O. 1914 Intermediary protein metabolism. Jour. A. M. A., Vol. 63,

p. 823. VON FtJRTH, O. 1904 Physiologische und chemische Untersuchungen liber

melanotische Pigmente. (Sammelreferat). Centralbl. f. allg. Path.

u. path. Anat., Bd. 15, p. 617. VON FtJRTH, O. UND ScHNEiDER, H. 1901 Uber tierische Tyrosinasen und

ihre Beziehung zur Pigmentbildung. Hofmeister's Beitrage z. chem.

Physiol, u. Path., Bd. 1, p, 229, 1901-02. Gessard, C. 1901 Etudes sur la tyrosinase. Ann. de I'lnst. Pasteur, torn.

15, p. 593.

1902 Tyrosinase animale. Compt. rend. d. 1. Soc. Biol., tom. 54, p. 1304.

1903 Sur la formation du pigment melanique dans les tumeurs du cheval. Compt. rend. d. 1. Soc. Biol., tom. 136, p. 1086.

Harrison, R. G. 1910 The outgrowth of the nerve fiber as a form of protoplasmic movement. Jour. Exp. Zool., vol. 9, p. 787.

Jarisch 1892 Uber die Bildung des Pigmentes in den Oberhautzelien. Arch, f. Dermat. u. Syphlis, Bd. 23, p. 223.

LiLLiE, R. S. 1902 On the oxidative properties of the cell nucleus. Am. Journ. Physiol., vol. 7, p. 412.

Mertsching 1889 Histologische Studien iiber Keratohyalin und Pigment. Virchow's Arch., Bd. 116, p. 484.

Osborne, T. B. and Mendel, L. B. 1914 Amino-acids in nutrition and growth. Jour. Biol. Chem., Vol. 17, p 325.

RossLE, R. 1904 Die Pigmentierungvorgang in Melanosarkom. Zeitschr. f. Krebsforschung, Bd. 2, p. 291.

Van Slyke, D. D. and Meyer, G. M. 1913 The fate of protein digestion products in the body. III. The absorption of amino-acids from the blood by the tissues. Jour. Biol. Chem., Vol 16, p. 197.

VON SziLY, A. 1911 Uber die Entstchung des melanotischen Pigmentes im Auge der Wirbelticrembryonen und in Chorioidealsarkomen. Arch. f. mikr. Anat., Bd. 77, p. 87.

Weindl, T. 1907 Pigmententstehung auf Grund vorgebildcter Tyrosinasen. Arch. f. Entw-mech., Bd. 23, p. 632.


ON THE NORMAL SEX RATIO AND THE SIZE OF

THE LITTER IN THE ALBINO RAT (MUS

NORVEGICUS ALBINUS)

HELEN DEAN KING AND J. M. STOTSENBURG

From the Wistar Institute of Anatomy and Biology

ONK FIGURE

Literature dealing with the early development of the albino rat contains references to but two papers that give information regarding the normal sex ratio and litter size in this animal (Cuenot '99; King '11). Marked differences in the results of these two sets of investigations, which were made on relatively small numbers of individuals, render it necessary that a large series of observations should be recorded in order to furnish adequate standards by which one can judge the effects of experiments aiming to modify the sex ratio or to alter the fertility of the albino rat. To supply the material for such standards the data given in the present paper were collected.

All of the records given are of litters cast by stock albino rats kept in the animal colony of The Wistar Institute. During the period when the data were being collected (1911-1914) all of the animals used for breeding were subjected to similar environmental conditions, and they all were fed on a mixed diet that experience has shown is necessary if rats are to be kept in good condition for any length of time.

THE NORMAL SEX RATIO IN THE ALBINO RAT

Practically all of the data were obtained by examining litters at or very shortly after their birth, since the sexes can readily be distinguished at this time as Jackson ('12) has shown. The removal of the young rats from the nest entails some risk that the mother will not care for them after they are replaced, but it is necessary that the records be taken at this time if one wishes

403


404


HELEN DEAN KING AND J, M. STOTSENBURG


an accurate determination of the sex ratio or of the Utter size. Not infrequently Utters contain one or more stiUborn young which are usuaUy eaten by the mother within a few hours after their birth. Often, too, some individuals in the litter, particularly^ if the Utter is large, will be killed by the mother when they are several days old, or if one or more of the young rats in a large litter are constitutionally weak they will die from lack of nourishment, being unable to cope with their stronger brothers in their efforts to obtain food.

Xo attempt was made to obtain the sex records for all of the litters of stock albino rats that were born in the colony during the years 1911-1913. The data that were collected during this period have been grouped together, according to the months when the Utters were cast, and are given in table 1.


TABLE 1


Showing the sex raiios and the average number of young in litters of stock albino rats born during 1911-1913. Data arranged according to the months when the litters were cast


January. . . February. .

March

April

May

June

July

August. . . . September. October. . . November. December.



NUMBER




NUMBER


AVERAGE


OF LITTERS


OF INDIVIDUALS


M.U-ES


FEMALES


MALES TO

100 FEMALES


NO. YOUNG

PER

LITTER


28


194


103


91


113.2


6.9


18


123


65


58


112.1


6.8


32


236 !


113


123


92.2


7.3


16


101 j


47


54


87.0


6.3


21


135


69


66


104.5


6.4


27


194


108


86


125.6


7.1


22


160


87


73


119.2


7.2


12


77


40


37


108.1


6.4


11


80


38


42


90.5


7.2


46


316


159


157


101.3


6.8


16


117


65


52


125.0


7.3


26


195 1


102


93


109.7


7.5


275


1928


996


932


106.9


7.01


One fact clearly brought out in the above table is that there is no restricted breeding season for the albino rat. Litters are cast during every month of the year, but, as the records for many thousands of litters show, relatively more litters are pro


NORMAL SEX RATIO AND LITTER SIZE IN RAT


405


duced in the spring than during other seasons of the year. In table 1 the sex ratios for the different groups of Utters do not show a very great range of variation considering the small number of litters involved. The highest sex ratio is that for the 27 litters cast during the month of June; the lowest sex ratio is found in the litters of the April group. For the entire series of 275 litters the sex ratio is 106.9 males to 100 females.

During the year 1914 an attempt was made to obtain the sex data for as many as possible of the litters of stock albino rats born in the colony. The cages containing the breeding animals were examined nearly every day throughout the year and practically all of the litters cast were recorded. The data obtained, arranged according to the months when the litters were cast, are given in table 2.

TABLE 2

Showing the sex ratios and the average number of young in litters of stock albino rats born during 191 4. Data arranged according to the months when the litters were cast




NUMBER




NUMBER


AVERAGE


MONTHS


OP

LITTEKS


OF IXDIVID. U.\I.S


MALEiS


FEM-\LES


MALES TO 100

FEMALES


NO. YOUNG

PER

LITTER


January


57


407


202


205


98.5


7.1


February


56


410


197


213


92.5


7.3


March


58


432


210


222


94.6


7.4


April


51


367


199


168


118.4


7.1


May


60


430


217


213


101.9


7.1


June


101


744


387


357


108.4


7.3


July


116


821


430


391


109.9


7.0


August


109


776


438


338


129.6


7.1


September


111


751


377


374


100.8


6 7


October


31


187


104


83


125.3


6.0


November


33


188


99


89


111.2


5.7


December


31


178


96


82


117.1


5.7



SI 4


5691


2956


2735


108.1


6.99


Although the number of records taken during the year 1914 is about three times greater than that collected during the period 1911-1913, the range of variation in the sex ratios of the Utters cast during the various months is only slightly greater than that given in table 1 . The lowest sex ratio in this series


406


HELEN DEAN KING AND J. M. STOTSENBURG


of records is found among the litters cast in February; the highest sex ratio occurs in the Utters born in August. The sex ratio of the 814 Utters examined during the entire year is 108.1 males to 100 females. This sex ratio is remarkably close to that found in the 275 litters previously recorded (table 1).

A summary for all of the data collected is given in table 3. In order to give equal value to the two sets of records the sex ratios in this table, and also the averages for the size of the litters cast in the various months, represent the arithmetical mean of the records as given in table 1 and in table 2; they have not been computed in any instance on a litter basis.

TABLE 3 A combination of the data given in table 1 and in table 2


NUMBER

OF LITTERS


.January 85

P'ebruary 74

March 90

April 67

May 81 June 128

July ; 138

August '■• 121

September 122

October 77

November. . . '. 49

December .57

1089


NUMBER




NUMBER


AVERAGE


OF INDIVID

M.VLES


FEM.'K.LES


MALES TO

100


NO. YOUNG PER


UALS




FEMALES


LITTER


601


305


296


105.7


7.0


533 •


262


271


102.3


7.0


668


323


345


93.4


7.3


468


246


222


102.7


6.7


565


286


279


103.2


6.7


938


495


443


116.9


7.2


981


517


464


114.6


7.1


853


478


375


118.8


6.7


831


415


416


95.6


6.9


503


263


240


113.3


6.4


305


164


141


118.1


6.5


373


198


175


113.4


6.6


7619


3952


3667


107.5


7.0


As arranged in table 3, the data show that the sex ratios are somewhat higher in the litters cast during the latter part of the year than in those cast in the early part of the year. With the exception of the record for. March the sex ratios for the litter groups from January to May show a variation of less than three points; and the sex ratios for the litters cast from June to December, omitting the record for September, vary less than four points. The pronounced drop in the sex ratio for the litters produced during September is found in both sets of records, and at present there is no satisfactory explanation for it.


NORMAL SEX RATIO AND LITTER SIZE IN RAT


407


In the total of 1089 litters examined there were 3952 males and 3667 females, giving a sex ratio for the series of 107.5 males to 100 females. This sex ratio is somewhat higher than that given by Cuenot, who found in 30 litters of albino rats a sex ratio of 105.6 males to 100 females, but it is practically the same as that given by King ('11) for 80 litters of albino rats (107.3 males to 100 females). The sex ratio found among adult rats is doubtless considerably lower than that given above, as growth experiments with the albino rat at present under way seem to indicate that female rats, as a general thing, live longer than male rats and show somewhat less susceptibility to disease at all stages of their growth.

It would be futile to make a comparison between the sex ratios of the various litter groups owing to the inequality in the number of litters recorded for the different months. For the purpose of a somewhat closer analysis than that given above, the two sets of records have been grouped in table 4 according to the season of the year when the litters were cast. The averages given for the two sets of records were obtained in the same manner as were the averages in table 3.

TABLE 4

Showing the data for sex ratios and size of the litters in the albino rat arranged

according to the season of the year when the litters were cast



1911-1913


1914


1911-1911


SEASONS


NUMBER OF LITTER3


NUMBER MALES TO

100 FEM.^LES


a S a ■^ a.


NUMBER

OF LITTERS


NUMBER MALES TO

100 FEMALES


la ^ a


NUMBER

MALES TO

100 .

FEMALES


a z a


March to May

June to August . . .

September to November

December to February


69 61

73

72


94.2 119.9

104.4

111.6


6.8 7.0

7.0

7.1


169 326

175.

144


103.8 115.6

106.2

99.0


7.2 7.1

6.4

6.9


99.0 117.7

105.3

105.3


7.0 7.05

6.7

7.0





275.


106.9


7.01


814


108.1


6.99


107.5


7.0


There is a very striking agreement between the corresponding sex ratios for the two sets of records, as is shown in table 4. In each case the sex ratio for the litters cast in the spring


408 HELEN DEAN KING AND J. M. STOTSENBURG



1 1 1 1 1 1 1 1 1 1 1 1













I









Number males to 100 females,



































































































/


\
































^


^/


V


\































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/


^^^


^





























li


^




■s


N


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110











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s


s








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90







































































































































Spring






Summer






Autumn






Winter








_


_


_






1 i i






1 1 1


L





1 1 1


1 1


Mar. -Way


June-Au9.


Sept -Nov.


Dec. -Feb.


Fig. 1 Graphs showing variations in the sex ratio of the albino rat at different seasons of the year. A, graph constructed from data for litters cast during 1911-1913; B, graph constructed from data for litters cast during the year 1914; C, graph constructed from the averages for the two sets of data.

is considerably below the normal sex ratio of 107 males to 100 females; the average for the two groups giving a sex ratio of only 99.0 males to 100 females. Each set of data shows likewise a sharp rise in the sex ratios of the litters born during the summer months and then a drop to below the normal ratio for the litters born in the fall. The two sets of records for the litters cast in the winter months do not, for some reason, show the same agreement as those for the litters produced in other seasons of the year, as in one case the sex ratio is somewhat above the normal and in the other case it is below the normal.

Figure 1 shows graphs, constructed from the data given in table 4, which bring out very clearly the changes in the sex ratio that are found to occur among rats born at different seasons of the year.

Judging from observations and from the records for several thousand litters cast in our colony during the past six years.


NORMAL SEX RATIO AND LITTER SIZE IN RAT


409


the rat breeds more readily in the spring than in any other season of the year, and there is a second, less pronounced, period of sexual activity in the early fall. The lowest points in the graphs shown in figure 1 are found to coincide with the period in which the greatest sexual activity occurs. Lacking adequate means for heat regulation the rat suffers greatly from heat during the summer months, and for years the highest mortality among the animals in our colony has occurred in July and in August while relatively fewer litters are produced at this time than at other seasons of the year. It is during the hot weather when the breeding animals are not in the best physical condition that the litters produced show the highest sex ratio, as is indicated by the graphs in figure 1.

The seasonal variation in the sex ratios that is shown by these records cannot be ascribed to environmental conditions other than temperature, since the routine of caring for the animals in our colony is the same throughout the year and there is no change in the character of the food.

That the sex ratios in various mammals seem to show a pronounced variation at different seasons of the year has long been known. From the large body of statistics examined by Diising ('83) it appears that relatively more boys are born during the winter than during the summer months. Table 5, compiled from data collected by Wilckens ('86) and by Heape('08), shows the apparent seasonal variation in the sex ratio that occurs in the young of various kinds of domestic animals.


TABLE 5

Showing seaso7ial variations iti the sex ratios of some dornes tic animals. Data

collected by Wilckens and by Heape



NUMBER IXDIVIDU.\LS


NUMBER MALES TO 100 FEMALES



Birth in warm Birth in cold

mos. mos.

1


Birth during entire year


Horses

Cattle

Sheep

Swine

Greyhounds


16,091

4,900 6,751 2,357*

17,838


96.6 97.3 114.1 103.0 102.9 94.0 115.0 109.3 116.3 122.1


97.0 107.3

97.4 111.8 118.5


THE ANATOMICAL RECORD, VOL. 9, NO. 6


410 HELEN DEAN KING AND J. M. STOTSENBURG

Except in the dog, and in the horse where these statistics are at variance with those collected by Schlechter ('84), the sex ratios as given in table 5 are relatively high among the animals born in the warm months and correspondingly low where the births occurred during the cold months. To be available for analysis by any current theory of sex-determination, however, these records would have to be arranged according to the time when conception occurred, since it seems most probable that sex is determined at or before the time of the fertilization of the ovum and cannot be altered by the nutritive or other environmental conditions to which the embryo is subjected. The gestation period in the rat is so short, only 21 days, that the time of conception and the time of birth may be said to take place in the same season of the year. Since the gestation periods in the various animals for which sex ratios are given in table 5 vary so greatly, the sex records cannot be arranged on any basis except that of the time of birth, and they are of value, therefore, merel}^ as indicating that there is apparently a seasonal variation in the sex ratio of other animals as well as in that of the albino rat.

If it can be shown bj^ a sufficiently large body of statistics that the sex ratio in various animals changes in a definite direction with the time of year at which conception occurs it will indicate that some metabolic process occurs in one or the other or in both of the parent organisms at stated periods which tends to swing the sex ratio in one direction rather than in the other. Assuming that sex is determined by the chromatin constitution of the spermatozoan that fertilizes the egg, we must add to this theory the probability that some form of chemical attraction or repulsion exists between each ovum and one kind of spermatozoan in order to account for the constantly increasing mass of evidence that under changed environmental conditions sex ratios in various animals can be altered in a definite direction. Chance, therefore, cannot play as important a role in the process of sex-determination as some investigators, have maintained, and any egg is not fertilized by any spermatozoan that happens to come in contact with it. The laws of chance, according to our


NORMAL SEX RATIO AND LITTER SIZE IX RAT 411

present conception, are not subject to periodic changes in their action, and while they offer a very attractive explanation for the existence of an equality of the sex in certain species, they utterly fail to explain sex ratios that vary in a definite direction, whether as the result of seasonal changes or as the outcome of experimental attempts to modify the sex ratio.

THE EFFECTS OF THE AGE OF THE MOTHER OX THE SEX RATIO

OF HER YOUXG

It has been stated by many investigators that the age of the mother has a pronounced influence in determining the sex of her young. According to a considerable body of statistics collected by Punnett ('03) the sex ratio among the first children in a family is 140 boys to 100 girls. This ratio falls to 117 boys to 100 girls for the second births among the children of these same mothers, and it then declines steadily until, at the ninth birth, the chances for the two sexes are about even. In a compilation of birth statistics for the first born of women of various ages, Bidder (78) found that the sex ratio was 122.2 boys to 100 girls when the mothers were under 19 years of age; this ratio falls to 104.6 boys to 100 girls for the children of women between 20-30 years of age and it then rises to 131 boys to 100 girls when the first conception occurs after the woman has reached 40 years of age. Conditions closely paralleling these for man are found in the horse according to "Wilckens, but this investigator states that heifers predominate among the first offspring of cattle.

Data given by Copeman and Parsons ('04) from their inbreeding experiments with mice show the relation between the age of the mother and the sex of the offspring as given in table 6. Normally there is about an equal proportion of the sexes in mice as is shown by the investigations of Schultze ('03) and of Welden ('06).

The sex records for the mouse, as given in table 6, agree with those for man and for the horse in that they show that the sex ratio in the young is at its lowest point when the mother is at


412


HELEN DEAN KING AND J. M. STOTSENBURG


the height of her reproductive powers. Schultze, on the other hand, states that young female mice tend to produce a slight excess of females among their young, and he concludes that the age of the mother has no effect whatever on the sex of her offspring.

TABLE 6

Showing the effects of the age of the mother on the sex ratio of mice. Data collected by Copeman and Parsons

AGE OF FEMALE AT NUMBER OF NUMBER OF M.VLES

CONCEPTION LITTERS TO 100 FEMALES

2mos 21 103.7

3-5 mos 27 96.5

6mos 21 123.3


For comparison with the records given by Copeman and Parsons and by others we have the sex data for 75 litters cast by 21 stock albino rats. These data, arranged according to the location of the litter in the litter series, are given in table 7.

TABLE 7

Showing the sex ratios and average number of young in 75 litters of stock albino rats. Data arranged according to the position of the litters in the litter series


LITTER SERIES


NUMBER

OF LITTERS


NUMBER

OF INDIVIDUALS


M.\LES


FE.MALES


NUMBER M.\LES TO

100 FEMALES


AVERAGE

NO. YOUNG

PER

LITTER


1

2

3


21 21 18 15


131 '

162

127

96


72 85 64 41


! 59 77 63 55


122.0

110.4

101.6

74.5


6.2

7.7 7.0


4


6.4





75


516


262


254


103.1


6.8


At the time that the first litter was cast each of the 21 females was about three months old. As shown in table 7, the sex ratio in the j^oung rats belonging to the first litters is 122.0 males to 100 females. For the individuals in the second litters the sex ratio drops to 110.4 males to 100 females, and it goes down to 101.6 males to 100 females for the rats belonging to the third litters. At the time that the females cast their fourth litters the majority of them were seven to nine months old.


NORMAL SEX RATIO AXD LITTER SIZE IN RAT 413

The female albino rat, if she is in good physical condition, will continue to bear young until she is about fifteen months old. The third and the fourth litters of an albino female, therefore, are usually cast during the period when the female is at the height of her reproductive power. In the above table the sex ratio for the fourth Utters is much lower than that for the first three litters, being only 74.5 males to 100 females.

The records given in table 7 are, of course, too few to furnish evidence from which very definite conclusions can be drawn. As far as they go, however, these records indicate that the sex ratio among the first offspring of very young females is higher than that found among the offspring of the same females at a period of life when they are at the height of their reproductive power. The results, therefore, are in agreement with those obtained by Piinnett, by Bidder and by Copeman and Parsons. In what way the age of the mother can affect the sex of her offspring is not known as yet. The fact that female rats at the height of their sexual activity in the spring and fall and also at the zenith of their reproductive powder tend to produce relatively more female than male young would seem to indicate that the physical condition of the female, either as the result of age or of environment, produces changes of metabolism that tend to affect the sex of the young. It is possible that anabolic processes predominating in the female at certain periods might affect the ova in such a way as to cause them to be more easily fertilized by a female-producing than by a male-producing spermatozoan. In very young females, on the other hand, and in females not in good physical condition, katabohc processes that would give the male-producing spermatozoa an advantage over the female-producing spermatozoa in the fertilization of the ova, might be assumed to occur. Until, however, our knowledge of the mechanism of sex determination rests on a more secure foundation than it does at the present time, it seems useless to offer even tentative suggestions as to the manner in which this mechanism can be influenced.


414 HELEN DEAX KING AND J. M. STOTSENBURG

THE RELATION BETWEEN THE SIZE OF A LITTER AND THE SEX

OF ITS MEMBERS

E\TLdence for man as to whether one sex or the other tends to predominate in large f amihes is conflicting. According to Nichols (/07), it has been shown by several investigators, particularly bj' Geissler ('89), that in large f amihes there is a greater proportion of sons than in small famihes. Geissler's statistics show that in 159,042 families containing more than seven children the sex ratio was 106.8 boj's to 100 girls, while in 839,719 families ha\'ing from two to seven children each there were only 105.8 boys to 100 girls. From the statistics of a very much smaller number of families, Punnett ('03) comes to the opposite conclusion that girls tend to predominate more in large families than in small ones.

Copeman and Parsons's breeding experiments with mice show that the percentage of males is shghtly less in large litters (containing more than 6 young) than it is in small litters. Welden, on the contrary, states that in a given generation of mice there seems to be a positive tendency for large litters to contain more males than females.

The sex data for 1089 litters of albino rats have been arranged on the basis of litter size in order to ascertain if, in this animal, there is any relation between the sex of the individuals and the size of the Utters to which they belong. For the purpose of this analysis the litters have been arbitrarily divided into three groups: large litters containing nine or more young; medium litters with six to eight young; small Utters having Uve or less members. The records collected during the year 1914 are sufficiently numerous to warrant their separation into groups according to the months when the litters were cast; the data obtained during 1911-1913, being too few to be divided in a similar way, have been grouped together. The results of this arrangement of data are given in table 8.

As shown in table 8, the results obtained bj^ this analysis are so conflicting that no definite conclusions can be drawn from them. The data for the year 1914, arranged according to the months when the litters were cast, show that the highest sex


NORMAL SEX RATIO AND LITTER SIZE IN RAT


415


TABLE 8


Showing the sex ratio in different sized litters of albino rats. Data collected during 1914 arranged according to the months when the litters were cast


9 OR MORE YOUNG


January. . . February. .

March

April

May

June

July

August. . . . September. October. . . November. December.


Number litters


14

19

24

14

23

34

36

29

28

1

3

3


Number males to

100 females


108.7

98.9

87.1

112.3

104.6

100.6

97.7

129.9

100.0

125.0

93.8

130.8


6 TO 8 YOUNG


O OR LESS YOUNG


Number [ Number

Number 1 males to Number I males to

litters : 100 litters 100

females ; females


27 25 22 24 19 42 56 57 46 18 15 15


93.1

87.6

98.7

144.3

85.9

109.9

120.6

134.1

98.1

119.3

123.4

106.3


16 12 12 13 18 25 24 23 37 12 15


91.7 87.5 125.0 75.8 126.5 131.3 116.7 111.4 107.8 140.9 100.0


Data for 1911-1913.


228


65


Total.


293


103.7 109.9 106.8


366


110.7


142 508


110.5


110.6


13 220


133.3


111.7


68


90.2


288 ! 100.7


ratio occurs in the members of the largest htters in onl}^ two cases, while in six cases it is found in the individuals comprising the smallest litters. In the records for the entire year the highest sex ratio, 111.7 males to 100 females, occurs in the indi\dduals composing the smallest litters; the lowest sex ratio, 103.7 males to 100 females, being found in the rats belonging to the largest litters. The records fol- 1911-1913, on the other hand, give the highest sex ratio, 110.5 males to 100 females, in the indi\dduals belonging to htters of medium size; the records for the small litters show a sex ratio of only 90.2 males to 100 females. For the entire series of data, litters of medium size show the highest sex ratio, 110.6 males to 100 females, and the lowest sex ratio occurs in the individuals of the small litters.

The lack of uniformitj' in the results of this arrangement of data indicate that apparently there is no well defined relation between litter size and sex in the albino rat.


416 HELEN DEAN KING AND J. M. STOTSENBURG

THE NORMAL SIZE OF THE LITTER IN ALBINO RATS

Available data concerning litter size in the rat indicate that the average number of young in a litter varies considerably in different species. Miller ('11) finds for the common gray rat (Mus norvegicus) that there is a range of 7 to 12 young in the litter and that, on the average, a Htter contains 10.5 young. Data recorded by Lantz ('10) give 8.1 as the average number of young in a large series of pregnant females of this species killed in India. Litters of the black rat (Mus rattus) are apparently much smaller than those of the gray rat. Lantz states that 5.2 young is the average for the Utters of this species. This average is practically the same as that given by Lloyd ('09).

But few observations have been recorded regarding litter size in the albino rat. Crampe ('84) states that the average size of a litter of albino rats is 5.6 young, which is exactly the result obtained by one of us (King '11) from an examination of 80 litters of stock albino rats. Cuenot records 8.5 as the average number of young in 30 litters of albino rats, but this is undoubtedly a higher average than would be found in a larger series of litters.

In addition to the sex ratios tables 1-4 give the average number of young in the various litters examined during the years 1911-1914. The records for the period from 1911-1913, as given in table 1, show that there is very little variation in litter size in the various groups of litters cast during the different months of the year; the range being from 6.3 young, the average size of the litters cast during April, to 7.5 young, the average of the litters produced during December. The largest litter examined contained 14 young, the smallest contained only two individuals. For the series of 275 litters the average size of the litter was 7.01 young.

A similar analysis of the data collected during the year 1914, as given in table 2, shows for the entire series of 814 litters an average of 6.99 young per litter, which is remarkably close to the average for the litters examined in 1911-1913. While the records for 1914, as a whole, show a great uniformity in the


NORMAL SEX RATIO AND LITTER SIZE IN RA.T 417

average size of the litters cast in the various months, there seems to be a tendency for the Utters cast during the first part of the year to be sUghtly larger than those produced during the latter half of the year. A similar tendency, however, is not noted in the records of table 1, so that it can have little, if any, significance.

Records for the entire series of 1089 litters give 7.0 young as the average number of indi\iduals in a Utter. According to these observations, therefore, the size of a litter of albino rats is, on the average, greater than that of the black rat, but it is smaller than that in the gray rat of which it is the domesticated variety.

The data for litter size, arranged according to the season of the year when the litters were cast, are given in table 4. A marked uniformity in the various series of records is again e\'ident. In the final averages the Utters cast during the fall of the year show a relatively small size. This result probably has Uttle, if any, meaning, since it is due entirely to the low average size of many of the Utters cast during the fall of 1914. Records for the litters cast in corresponding months of the years 19111913 give 7.0 young as the average number of individuals per litter. It is evident, from these results, that there is no pronounced seasonal variation in the size of the litters at all comparable to the evident change that occurs in the sex ratio at stated periods in the year. Seasonal changes in the sex ratio are independent of litter size just as the normal sex ratio is independent of litter size.

Crampe ('83) states that the first litter of an albino rat is not as large as the second and that the second litter is an index of the size of subsequent litters. The first part of this statement can be corroborated by our records, but the latter part of it needs to be modified. A large second litter gives no indication whatever as to the size of the following litters, as the records for litters from many hundreds of females coUected by one of us shows. In many cases a large second litter is followed by an unusually small Utter, and there are marked individual differences in females regarding the size of the litters they pro


418 HELEN DEAN KING AND J. M, STOTSENBURG

duce. Some females never have over five or six young in a litter; other females invariably cast litters containing eight or more j^oung.

The average size of 75 Utters cast by 21 stock albino rats is given, with other data, in table 7. In these records the average size of the first litter is found to be considerably less than that of the second, whUe the second of the four litters is the largest of the group, containing an average of 7.7 young per litter. In this particular series of records the average size of the third litters is considerably below that for the second litters, but in a larger series of data it would probably be found that the third litter is nearly, if not equal, to the second in size. The fourth litters are, as shown in table 7, only a little larger than the first, as a rule.

For the entire series of 75 litters the sex ratio is below normal, and the average size of the litters is somewhat small, being only 6.8 young per litter. The number of young in a given litter is dependent to a marked extent on the age and physical condition of the female (King '15), and it is not improbable, as previouslj^ stated, that these factors also have an effect on metabolic processes that play an important role in determining the sex of the embryo.

SUMMARY

1. Albino rats breed throughout the entire year, but the periods of greatest sexual activity are in the spring and autumn.

2. The sex ratio in the 1089 litters of albino rats examined was 107.5 males to 100 females.

3. There is, apparently, a seasonal variation in the sex ratio of the albino rat. Litters cast in the spring and early fall show a relatively low sex ratio; those cast in summer have a much higher sex ratio (fig. 1).

4. Data for 75 litters produced by 21 albino females indicate that the sex ratio among the first offspring of young females is higher than that found among the offspring of the same females when they are at the height of their reproductive power.


NORMAL SEX RATIO AND LITTER SIZE IN RAT 419

5. There is apparently no relation between the size of a litter of albino rats and the sex of its members.

6. The 1089 litters examined contained an average of 7.0 young per litter. Litters of albino rats, therefore, are smaller than those of the gray rat and larger than the litters of the black rat.

7. There is no pronounced seasonal variation in the Utter size comparable to the seasonal variation noted in the sex ratios.

8. As a rule the first of an albino female's four litters is the smallest; the second and the third litters are the largest; the fourth litter is a little larger than the first.


420 HELEN DEAN KING AND J. M. STOTSENBURG

LITERATURE CITED

Bidder, F. 1878 Ueber den Einfluss des Alters der IMutter auf das Geschlecht

des Kindes. Zeitschr. Geburtshiilfe und Gjiiakologie, Bd. 11. CoPEMAN, S. M., and Parsons, F. G. 1904 Observations on the sex in mice.

Proc. Royal Soc. London, vol. 73. Crampe, H. 1883 Zucht-Versuche mit zahmen Wanderratten. I. Resultate

der Zucht in Verwandtschaft. Landwirthschaftliche Jahrb., Bd. 12.

1884 Zucht-Versuche mit zahmen Wanderratten. II. Resultate der

Kreuzung der zahmen Ratten mit wilden. Landwirthschaftliche

Jahrb., Bd. 13. Cu^NOT, L. 1899 Sur la determination du sexe chez les animaux. Bull. Sci.

de la France et de la Belgique, t. 32. DusiNG, K. 1884 Die Regulierung des Geschlechtsverhaltnisses bei den Ver mehrung der Menschen, Tiere und Pflanzen. Jen. Zeitschr. Natur.

Wiss., Bd. 17. Geissler, a. 1889 Beitriige zur Frage des Geschlechtsverhaltnisses der Gebo renen. Zeitschr. d. k. sachsischen statistischen Bureaus, Dresden,

Bd. 35. Heape, W. 1908 Notes on the proportion of the sexes in dogs. Proc. Cambridge Phil. Soc, vol. 14. Jackson, C. M. 1912 On the recognition of sex through external characters in

the young rat. Biol. Bull., vol. 23. King, Helen Dean 1911 The sex ratio in hybrid rats. Biol. Bull., vol. 21.

1915 On the weight of the albino rat at birth and the factors that

influence it. Anat. Rec, vol. 9. Lantz, D. E. 1910 Natural history of the rat. U. S. Bull. Public Health and

Marine Hospital Service. Lloyd, R. E. 1909 Relation between fertility and normality in rats. Report

6f the Indian Museum, vol. 3. Miller, N. 1911 Reproduction in the brown rat (Mus norvegicus). Amer.

Nat., vol. 45. Nichols, J. B. 1907 The numerical proportions of the sexes at birth. Mem.

Amer. Anthropological Assoc, vol. 1. Ptjnnett, R. C. 1903 On nutrition and sex-determination in man. Proc.

Cambridge Phil. Soc, vol. 12. Schlechter, J. 1884 L^eber die Ursachen welche das Geschlecht bestimmen.

Biol. Centralbl., Bd. 4. Schultze, O. 1903 Zur Frage von den Geschlechtsbildenden Ursachen. Arch.

mikr. Anat., Bd. 43. Wklden, W. F. R. 1906 On heredity in mice. I. On the inheritance of the sexratio and of the size of the litter. Biometrika, vol. 5. Wilckens, M. 1886 Untersuchung ueber das Geschlechtsverhiiltniss und die

Ursachen der Geschlechtsbildung bei Haustieren. Biol. Centralbl.,

Bd. 6.


AN INSTANCE OF ACIDOPHILIC CHROMOSOMES AND CHROMATIN PARTICLES

IVAN E. WALLIN

Anatomical Laboratory, Cornell University Medical College, New York City

ONE PLATE (twelve FIGURES)

Studying the cytological literature, I have been unable to find a record of acid staining chromosomes in a normally dividing cell. In an investigation of sections of petromyzon larvae numerous mesenchyma and blood cells are seen which contain nuclei staining a uniform and brilliant red. These cells are scattered among other cells having nuclei of exactly the same structure, yet staining the usual deep blue color with the hemotoxilyn eosin stain. After studying these cells more closely, I found that the cells with the red nuclei were able to undergo mitotic division in the same manner as the cells with blue nuclei, the chromosomes in such cases staining red rather than the characteristic deep blue or black seen in the neighboring cells.

Such cells have been found as free blood cells in the blood vessels and also as mesenchyma cells in the pharyngeal and head regions of the larvae. Wherever found, aside from the peculiar property the nuclei show in the absorption of the acid dye, these cells are exactly similar to others in the region in which the nuclei stain characteristically with the basic dye (hematoxylin). The accompanying plate shows the two types of cells in the resting condition and in different stages of mitosis.

It is of interest that these cells have been found only in the 5 mm. larvae of my collection. These particular 5 mm. larvae were procured at Naples by Professor Stockard in the spring of 1910. They were fixed at the time of collection in picroacetic and preserved in 80 per cent alcohol. I received them

421


422 IVAN E. WALLIN

in the fall of 1914, sectioned and stained them in hematoxylin and eosin. The remaining specimens of my collection, which comprise developmental stages ranging from the segmentation sphere up to an including a transforming larva and the adult, have been kindh' supplied to me by Professor Gage. They were collected from the waters in the neighborhood of Ithaca, X. Y. Unfortunately, I do not have any 5 mm, larvae of the American species so am unable to say whether these cells are peculiar to the European species and to this age of larvae. Several specimens of these 5 mm, larvae show cells with nuclei taking the acid stain. They are not equally numerous nor do they take the stain equally well in all cases. In one specimen, for instance, such cells are difficult to find while in others they are distinct and plentiful. Embryos in which these cells are prominent may show more than half of the blood cells containing nuclei in which the chromatin has absorbed the acid dye.

Cells have been found in which both kinds of chromatin are present. Figure 7 represents such a cell in the resting state. Two lumps of chromatin in the central part of the nucleus have taken the basic stain while the chromatin at the periphery is stained with the acid dye, Heidenhain ('07) has shown a chromatolytic nucleus which somewhat resembles this, but in which the acid-staining chromatin was in the central part of the nucleus while the basic-staining chromatin was at the periphery. Figures 5 and 6 represent cells with two kinds of chromatin in the process of mitosis. Figure 6 shows that a small part of. the acid-staining chromatin has apparently been taken over with the basic-staining group. Figure 5 represents the separation of the two kinds of chromosomes in the daughter nuclei which appears to have been complete. The great majority of these cells with acid-staining chromatin, however, are pure in regard to their staining reaction. Figures 1, 4, 8, 9 and 10 show nuclei containing no granule or any other part which absorbs the basic dye.

Stockard ('06) confirmed the observations of Schniewind-Theis ('97) in which it was shown that some nuclei in the deeper layers of actively secreting nectar glands of Vicia faba take the plasma


AN INSTANCE OF ACIDOPHILIC CHROMOSOMES 423

stain. In the living gland some rows of cells have a blue while others have a red coloration. By introducing alkaline and acid fluids to sections of the living gland, Stockard found that these cells responded to the fluids in the same way that litmus does to alkalies and acids. This experiment shows quite conclusively that the chemical reaction of the glandular plant cell is not constant during ^'arious physiological phases. The staining reaction also indicates that the nuclei apparently respond to the stain according to their physiological state. The stain used was Auerbach's (methyl green and acid fuchsin) which gives a delicate differentiation of the acid and basic qualities. It was determined in these investigations that materials were formed by the nucleus and passed out into the cytoplasm, the cytoplasm in such cases finally accumulating enough of the nuclear products to stain with the nuclear dye. Further, when the secreting activities of the nucleus had apparently been spent the nucleus stained with the plasma stain. These reactions occurred only in vegetative cells, the dividing cell always contained chromatin which stained in the normal way with the basic dye. In these studies the tissues had been carefullj^ fixed with neutral fluids so as to preserve the chemical reaction of the living cell. The fixation used in my specimens, as was pointed out above, was an acid fluid, yet the differences in the reactions of the cells and portions of some nuclei were sufficient to maintain their character and to respond to the ordinary hematoxylin-eosin stain in the pecuhar ways shown in plate 1.

The presence in the same section of the lamprej' larva of cells with acidophilic nuclei together with cells which stain in the normal way, and the fact that both kinds of chromatin are present in a single cell, make it difficult to give any other interpretation of these reactions than that they represent the result of physiological changes which occurred during life.

As far as I can ascertain this is the first account of a case where the chromosomes in a dividing cell have definitely taken the acid stain.


424 IVAN E. WALLIN

LITERATURE CITED

Heidenhain 1907 In Bardeleben's Handbuch der Anatomie Des Menschen.

Schniewind-Thies, J. 1897 Beitrage zur Kenntniss der Septalnectarien, Jena (cited from Stockard (1906) ) .

Stockard, C. R. 1906 Cytological changes accompanying secretion in the nectar-glands of Vicia faba. Bull, of Torrey Bot. Club, vol. 33, pp. 247262.


PLATE 1

EXPLANATION OF FIGURES

All figures were drawn with the aid of the camera lucida to the same scale of magnification (1/12 oil inmaersion objective, compensating occular No. 12). Higgins' carmine and true blue inks were used in reproducing the colors of the stained specimens.

Figures 1, 2 and 5 are mesenchjTna cells; all other figures represent blood cells.


AN IXSTAXCE OF ACIDOPHILIC CHROMOSOMES

IVAN E. WALLIN


PLATE 1





r.


(<?VJ


a




1


10


.^


%


12


425


THE ( ONXECTING SYSTEMS OF THE REPTILE HEART

HENRY LAURENS

From the Osborn Zoological Laboratory, Yale University

EIGHT FIGURES (tWO PLATES)

THE SINO-VENTRICULAR CONNECTION

A sino-^'entriclllar bundle, or dorsal ligament, has already been described by me in the hearts of Lacerta agihs, and L. viridis, of Clemmys lutaria and Chelopus insculptus. By observing this ligament in living hearts under the binocular microscope, and from the study of transverse, frontal and sagittal sections, it was seen to be a band of connective tissue, containing nerves and blood vessels, running between the sinus and the ventricle well over to the right side of the heart, (Laurens '13 a and '13 b). In my first paper it was further shown that this ligament had no significance for the coordination of the heart beat. This band of tissue had previously been described and experimented with b^' several investigators, and a discussion of their various views as to its structure and physiological importance will be found in my papers and in a recent publication by Mangold (;14).

Mackenzie ('13) has recently described in the heart of the salempenter, a South American lizard, a ' ' sinu-auricular bundle" of specialised muscle, connecting the sinus with the specialised tissue lying in the floor of the auricle. Although from my earlier studies of the lizard and tortoise hearts it was certain that such a bundle did not exist in the hearts of the reptiles examined by me, this publication of Mackenzie's induced me again to go over my preparations, to which had been added in the meantime sections of the heart of the fence lizard (Sceloporus undulatus) and of the spotted tortoise (Chelopus guttatus). A part of this later material was fixed and stained by the same methods as were earlier used ('13 b) — fixation in strong Flem 427

THE AXATOMICAL RECOn'>, VOL. >J, N'O. 6


428 HEXRY LAURENS

ming or in concentrated corrosive sublimate, and staining with iron hematoxylin and picric acid fuchsin. The remainder consisted of sections of hearts treated with methylen blue according to various methods, by CajaFs double impregnation method, as given by Hofmann r02), and by the silver reduction method, as given by ^leikeljohn CIS).

From this further study of these lizard and tortoise hearts no doubt has been thrown on the truth of the statement that the dorsal ligament is here a sino-ventricular bundle. But from Mackenzie's descriptions and from his figures it can also not be doubted that in the heart of the salempenter conditions are diiTerent. As he has himself pointed out, the conditions in this respect shown bj^ the hearts of different reptiles are not the same and various stages can be recognized. We shall see that the conditions found in the hearts of the reptiles Usted above represent still another stage in addition to those whi'ch he has described.

According to Mackenzie fp. 129) the sinu-auricular-ring" of the fish heart is represented in the heart of the salempenter by a bundle or leash of fibres which hes in the groove between the left venous valve and the spatium intersepto-vahailare." The sinu-auricular bundle courses round the posterior and under aspect of the sinus venosus just where the left duct of Cuvier enters the sinus and runs ... a short distance as a free bundle to become continuous with the .speciahsed tissue h'ing in the floor of the auricle, this tissue becoming in turn continuous with the auricular canal." In the heart of the crocodile (p. 130) the sinu-auricular muscle" is present at the base of the left venous valve at the junction of the sinus with the spatium. There is no direct continuity between the sinu-auricular bundle and the auriculo-ventricular bundle in the crocodile. The interruption takes place in the region of the sinus septum where the left duct of Cuvier enters the sinus." Later ^p. 135) he goes on to say:

The .sinu-auricular nodal tissue appears to become lost in this septum. It would appear that there are reptiles which in respect of this point exhibit an intermediate stage between the lizard (salempenter) and the crocodile. An example of this is the iguana, in which the sinuauricular bundle is interrupted by a cord of fibrous tissue with iso


COXXECTING SYSTEMS OF THE HEART 429

lated muscle fibres and large nerve trunks. This cord occupies a corresponding position to the continuous muscle structure in salempenter and in front appears again as a short isolated muscle bundle which in turn becomes continuous ^^1th the muscle of the auricular canal.

The conditions found in the lizard and tortoise hearts listed above represent another intermediate stage between that found in the iguana and that found in the crocodile, as described bj' Mackenzie. In these hearts there is no isolated muscle bundle" which becomes continuous with the auricular cajial. At the left venous valve, near its upper portion, there is, in the fibrous tissue a large group of nerve cells, which represents the endings of a branch of the right vagus nerve. The nerve fibers connected ^^dth these nerve cells can be followed for quite a distance along the right vein, as far as it is present in the sections, being connected with other large ganglia here and there along the vein. From this portion of the left valve there runs a band of connective tissue, a fold of the pericardium, which bending under the left vein becomes free from the dorsal surface. From this point it is continued downward as a free band, superficially over the dorsal surface of the right auricle to the ventricle, over the anterior dorsal surface of wliich it spreads, being wider at its point of attachment than elsewhere. Sometimes the bundle, before it reaches the ventricle, divides into two, or even three, parts, and often under these circumstances a fine branch can be seen bending still further to the right and running in the auricular-ventricular groo\'e to the ventral side.

In the bundle there are numerous blood vessels and large nerve trunks with several groups of nerve cells. Sometimes these nerve cells are single and scattered, but there are also many large ganglia. By studying ^Mackenzie's figures of sagittal sections (plate 2, figs. 1-3) one sees on the dorsal surface of the hearts a mass of tissue which extends from the sinus region to the anterior dorsal portion of the ventricle. This tissue Mackenzie has not labelled, but it has a position very similar to the continuous sino-ventricular bundle m the hearts of the Uzards and tortoises which I have studied. From figure 3 of this same plate of ^lackenzie's, however, it is seen that the sinu-auricu


430 HENRY LAURENS

lar bundle" does go over direct I3' into the auricular funnel musculature, the latter being, according- to his representation, on the dorsal side a continuation of the " sinu-auricular bundle." A glance at the figures which are presented with this article will show that this is not the case in the animals with which we are dealing. The figures are untouched photographs of sagittal sections of the heart of the tortoise Chelopus guttatus. The hearts of the other tortoises and of the lizards show the same conditions. Drawings of the lizard heart have already been given (Laurens '13 b) and for that reason the tortoise is selected for the illustrations here.

After reaching the ventricle, the sino-ventricular bundle spreads out over its anterior dorsal surface. A portion of it runs to the back of the ventricle, while another portion goes down into the space between the funnel musculature and the inner wall of the ventricle. This space is filled \vith connective tissue containing blood vessels, nerves and ganglia (Laurens '13 b, fig. 4), and the portion of the sino-ventricular bundle which goes down into this space becomes continuous with this connective tissue, which is also, of course, a portion of the pericardium. The nerves in the sino-ventricular bundle, two of which are shown in figure 6, are also distributed, some of them to the anterior dorsal surface of the ventricle, and some to the connective tissue filled space between the funnel musculature and the inner wall of the ventricle. The latter innervate the auriculo-ventricular funnel and also supply the inner wall of the ventricle. Quite often the nerves in the sino-ventricular bundle are insignificant, and even entirely lacking, a fact which was also noted by Gaskell.

There is no muscle tissue, either continuous or isolated, in the sino-ventricular bundle. At its beginning (sinus end) and ending (ventricular end) a few isolated striated muscle fibers can sometimes be seen in the connective tissue (as in the sections from which figures 3 and 4 are taken). But it is clear that these muscle fibers have been pulled into this position by the knife tearing them away from the walls of the sinus and of the ventricle. In its free course there is only fibrous tissue in the bundle, in which nerve fibers, ganglion cells and blood vessels are found.


CONNECTING SYSTEMS OF THE HEART 431

As the sino-ventricular bundle is followed in transverse and sagittal sections it is seen to be nothing more than a portion of the pericardium which is folded off as a free band to run between the sinus and the ventricle. In some places it is even connected with the pericardium proper over the right auricle by fine strands (fig. 5). By studying the figures, which represent sections in order from left to right, the manner in which the sino-ventricular bundle is folded off from the continuous pericardium can be made out. Figures 1 and 2 are sections to the left of the median line, and the dorsal ligament does not show at all. In figure 2, however, one of the large nerve trunks is seen running from the sinus, under the pericardium on the dorsal side of the auricle, to the ventricle across the auriculo-ventricular groove (Laurens '13 b and Dogiel and Archangelsky '06) to end in the auriculo-ventricular funnel musculature, after it has gone through the connective tissue in the space between the funnel and the ventricle. In figure 3 we see the beginning of the free portion of the sino-ventricular bundle in an out-folding of the pericardium on the anterior dorsal surface of the ventricle, and opposite to it a corresponding outfolding on the sinus wall. In figure 4 these folds have advanced further and in figure 5 they have met to form the continuous band of connective tissue, which can here be followed up along the sinus until bending over to the right it disappears from the section. Figure 6 gives another view of the sino-ventricular bundle further to the right. In this section a large nerve trunk is seen in the Hgament coming from the sinus and going dowTi into the connective tissue filling the space between the funnel and the ventricle. It also shows to the extreme right a portion of a smaller nerve going over to the outer wall of the ventricle. Figures 7 and 8 serve to illustrate the appearance of the ligament further over to the right hand side of the heart. From a study of these figures it will be clear, I believe, that the dorsal hgament is simply a fold of the pericardium, which, retaining its connection with the sinus and with the ventricle, runs free over the dorsal surface of the right auricle from the sinus to the ventricle, and is therefore strictly a sino-ventricular bundle.


432 HENRY LAURENS

THE SINO-AURICULAR COXXECTION

The connection between the smus and the right auricle is a direct muscular one in the reptile hearts described in this paper. Gaskell pointed out the fact that this was the case in the tortoise with which he was working, though the details concerning the manner in which the connection was actually brought about do not hold here. Kiilbs and Lange TIO) also describe a direct muscular connection between the sinus and the right auricle in the lizard. But in the heart of the salempenter (Mackenzie) the ring of specialized muscle with numerous nerve cells and fibers at the ' sinu-auricular junction' in the fish is represented by a bundle or leash of fibers which lies in the groove between the left venous valve and the spatium intersepto-valvulare." In the reptile hearts that I have examined there is a complete muscular ring. Nerve cells, in larger and smaller gangha, and nerve fibers are all around this ring in the connective tissue. The musculature of the sinus goes over into that of the right auricle in much the same way that the musculature of the auriculo-ventricular funnel goes over into that of the ventricle. At the junction of the sinus with the auricle there are the two valves which completely close the oval shaped opening which runs obhquely from the upper right hand side to the lower left, as Mackenzie shows in his figure on plate 3. At the right, or lower, valve, the musculature of the sinus goes over into that of the auricle at the free edge, the two kinds of musculature being here continuous. At the left, or upper, valve the conditions are somewhat different. In its upper portion the valve is a continuation of the wall of that portion of the sinus, and the musculature of the sinus joins directlj^ with that of the auricle along the valve (fig. 7). But the extreme lower portion of the left valve, which, in sagittal sections taken from the left to the right comes first into view, is formed from a portion of the auricular septum, being really a continuation of it (fig. 3), and the wall of the sinus here goes directly over into this portion of the septum, the left valve being here separated from the wall of the auricle by a layer of fibrous tissue, a condition particularly clearly shown in transverse sections.


CONNECTING SYSTEMS OF THE HEART 433

THE AURICULO-VENTRICULAR CONNECTION

Attention may be here again called to this connection in the hearts of lizards and tortoises, since, from Mackenzie's description, there appear to be slight differences between the conditions found in the salempenter and those found in other Uzards and in tortoises. In the salempenter, the auricular canal, according to Mackenzie, is specialized, an assumption also made by Kiilbs and Lange ('10) for the lizard (L. viridis and L. muraUs) and by Kiilbs ('12 and '13) for the lizard and tortoise. It has already been pointed out (Laurens '13 b) that the musculature of the auriculoventricular funnel is not very different from the musculature of other portions of the auricles. The fibers and nuclei are similar to those of the auricles, though there is more sarcoplasm and fewer fibrillae. However, the funnel musculature is richly supplied with nerves and contains numerous capillaries, and in between its fibers, which are arranged circularly, there is a considerable amount of connective tissue. The striation of the fibers is distinct but fine, and is quite similar to that of the auricles. The striation of the ventricular fibers is coarser and the nuclei are much elongated and narrower than are those of the auricles and of the funnel.

The function of the auriculo-ventricular funnel in co-ordinating the contractions of the auricles and of the ventricle was very carefully worked out in the hzards, L. viridis and L. agilis, and in the tortoise, Clemmys lutaria. From this work (Laurens '13 a) it is evident that there is here a physiological differentiation in that certain portions of the funnel are more efficient than others in allowing the passage of the contraction wave from the auricles to* the ventricle, and furthermore, in preserving the co-ordination of ventricular with auricular beat, when other portions of the connection between these parts of the heart are cut away. The portions showing this greater efficiency are the right and left sides of the funnel. Later (Laurens '13 b) it was shown that this physiological speciaUzation had an anatomical basis in that, at these two portions, there was a more intimate connection between the funnel musculature and the musculature of the ventricle.


434 HENRY LAURENS

In the salempenter (Mackenzie, p. 129) the auricular canal is described as a tube invaginated into the ventricle, becoming at its lower end continuous with the ventricular musculature in the region of the papillary muscles to which the auriculoventricular valves are attached. This invagination does not of course occur at that part of the orifice where the auricular canal is continued on to the bulbus musculature." In all the lizard and tortoise hearts studied by me the invagination does take place around the whole circumference of the orifice, the funnel being only broken through at its entrance into the ventricle, by the bulbus with the musculature of which the funnel musculature becomes continuous. The direct continuity between the musculature of the funnel and that of the ventricle does not, of course, occur at this place.

Mangold ('14) points out that on the dorsal side the funnel musculature in the salempenter, as described by Mackenzie, extends further into the cavity of the ventricle, before the fusion of the two kinds of musculature takes place, than it does in the hearts of the reptiles which were described by me, where it very soon becomes broken through by its fusion with the ventricle. This difference, however, is I think, very slight. By comparing Mackenzie's figures with mine it will readily be seen that the length of the ventricle of the salempenter is relatively, when compared with its dorso-ventral thickness, less than that of the lizards and of the tortoises here described. Moreover, that the attachment of the auriculo-ventricular valves as represented in the salempenter is much nearer the apex, and that the auriculoventricular funnel extends further into the cavity of the ventricle, than in the other lizards and tortoises. From a glance at figure 4 (Laurens '13 b) it will be apparent that on the dorsal side the funnel musculature is continued, although quite thin, almost to the attachment of the auriculo-ventricular valves to the papillary muscles, and the figures presented with the present article show this quite plainly. On the right and left sides, however, the funnel musculature is continued further into the ventricle, before the fusion between the two kinds of musculature finally takes place, the connection at these parts being


CONNECTING SYSTEMS OF THE HEART 435

therefore more intimate than at other portions. Mackenzie does not mention whether the final continuity between the auriculoventricular funnel and the ventricle takes place at all portions at the same level.

There is one other matter concerning the auriculo-ventricular connection, and that is its innervation. Nerve fibers can be seen extending downward from the sinus in the pericardium and can be followed across the auriculo-ventricular groove. For the past two years I have been studying the innervation of the reptile heart, and particularly of the auriculo-ventricular funnel muscle, by means of the special methods mentioned earlier. Although perfect results have not yet been obtained, it has been seen that the auriculo-ventricular funnel is richly supplied with nerves, in the form of a net-work of fine fibers, which come to it from branches of nerves descending along the back of the auricles in the way described earlier by me ('13 b), and by Dogiel and Archangelsky ('06). Nerve fibers and cells are also found on the inside of the auricles, running along the inner edge of the walls and along the septum, and which come into the heart along or near the entrance of the pulmonary vein and of the left duct of Cuvier. These nerves also give off branches which run down between the auriculo-ventricular valves and the inner side of the funnel to finally become distributed to the latter. In the funnel musculature itself, nerve cells are scarce, only a few scattered ones being found here and there. But in the connective tissue of the groove, and of the space between the funnel and the inner wall of the ventricle, ganglia are numerous, particularly on the dorsal side, though in sections of some hearts the number of ganglia found on the " ventral side, especially near the bulbus, and on the right and left sides of the funnel is also quite large.

The nerves which run over the dorsal surface of the auricles and of the auriculo-ventricular groove to be continued into the connective tissue between the funnel and the ventricle can also be easily seen in sagittal sections of material fixed in Flemming and in corrosive sublimate. In figure 2 one of these nerves is shown running down to finally become distributed to the auriculoventricular funnel musculature (see also fig. 6).


436 HENRY LAURENS

THE PROBABLE FUNCTION AND FATE OF THE SINO-VENTRICULAR

BUNDLE

The sino-ventricular bundle, contrary to the view of Imchanitzky ('09), has nothing to do with the coordination of ventricular and auricular contraction (Gaskell '84 and Laurens '13 a). Furthermore it has no function in bringing about a possible sino-ventricular rhythm. In the salempenter, however, according to Mackenzie, 'the sinu-auricular bundle' is made up of specialized muscle. In support of which statement, we have no physiological evidence.

The contraction wave begins in the walls of the sinus and spreads to the auricles along the sino-auricular junction, and from there along the auriculo-ventricular funnel to the ventricle. Can the 'sinu-auricular bundle' in the salempenter be a pathway for impulses passing direct from the sinus to the auriculoventricular connection and to the ventricle, and if so, what is the nature of these impulses? That they have anything to do with coordination can hardly be claimed owing to the physiological evidence against such an assumption. Gaskell (p. 83) showed that when the peripheral end of the 'coronary nerve' was stimulated that the rate of beat of the heart was not changed, although when the central end was stimulated a decided slowing of auricular rate took place. By the stimulation of either end of the nerve the force of the auricular contractions was diminished (p. 92). Further, Gaskell showed (p. 85) that, when the connection between the sinus and the auricles is severed so that the 'coronary nerve' remains intact and as the only connection between the auricle and ventricle and the body of the animal and an independent auriculo-ventricular rhythm is set up, stimulation of the right vagus brings about a decrease in the force of the auricular contractions alone. In one experiment, out of several, Gaskell obtained an inhibition of this independent auriculo-ventricular rhythm, when the right vagus nerve was stimulated. His explanation of this was that "when the coronary nerve happens to contain fibers which supply the particular muscles which originate the independent rhythm.


CONNECTING SYSTEMS OF THE HEART 437

then stimulation of the vagus can inhibit that rhythm." Moreover, as Gaskell also pointed out, the 'coronary nerve' is only one of several nerve trunks, branches of the vagus nerves, which pass from tlie sinus to the ventricle and to the auriculo-ventricular funnel musculature, and it is therefore but natural that the auriculo-ventricular rhythm should be controlled by it when it happens to innervate the muscles which originate this rhythm, just as the other branches of the vagus nerves do.

The 'coronary nerve,' when the vagus is stimulated, is also no more able to conduct an impulse to the ventricle by which its force of contraction can be diminished, than are any of the other nerve trunks passing from the sinus to the ventricle (Gaskell, p. 91). It has also another function in common with the other branches of the vagus nerves in that it carries impulses, upon stimulation of the vagus which improve the conduction power of a strip between the auricle and the ventricle during a condition of partial block, though it may also have a function occasionally in increasing such a block by diminishing the conducting power of the connecting strip (Gaskell, p. 96).

The 'coronary nerve' is not always present, and is often very insignificant. From what has just been said it apparently has no particular function that the other nerve trunks do not have, and we are forced to the conclusion that its function is relatively unimportant, or perhaps better, no more important than that of the other branches of the vagus nerves.

From physiological evidence then, the effect of the 'coronary nerve,' like the other branches of the vagus nerves, are on the auricles, and it may be assumed to have an additional regulatory effect when, for any reason, the rhythm producing power of the auriculo-ventricular funnel is brought into prominence above that of the sinus. As we have seen, some of the nerve trunks which run in the sino-ventricular bundle go into the connective tissue between the funnel and the ventricle, which is a condition that was not reahsed at the time of my earher publication. It is highly probable that the nerves of the ' sinu-auricular bundle' of the salempenter have the same function as the 'coro


438 HENRY LAURENS

nary nerve' in the heart of the tortoise described by Gaskell. But what the function of the 'speciahzed muscle' of this bundle is, must remain for the present an unanswered question.

As to the probable fate of the sino-ventricular bundle, Mackenzie has given the steps leading up to the condition found in the reptile hearts described in the present article. In the salempenter there is a ' ' sinu-auricular bundle of specialised muscle;" in the iguana the bundle is interrupted by a cord of fibrous tissue, a short isolated muscle bundle, which is continuous with the muscle of the auricular canal, being all that is left. In the hearts of the lizards and tortoises here described, the sino-auricular junction is a ring of muscle completely surrounding the opening of the sinus into the right auricle, and running from this region there is a band of connective tissue which goes to the anterior dorsal surface of the ventricle. In this band of connective tissue there are large nerve trunks and blood vessels some of which go to the ventricle, others into the connective tissue between the funnel and inner wall of the ventricle to become distributed to the musculature of both. In the crocodile, all that there is of the ' sinu-auricular muscle' according to Mackenzie, is at the base of the left venous valve at the junction of the sinus with the spatium.

Mackenzie speculates on the probable fate of the fibrous cord and of the distal isolated muscle bundle found in the iguana. He considers it not improbable that it becomes incorporated in the auricular floor, and that it is represented in the higher reptilian and mammalian hearts by a bundle of fibrous tissue which runs in the basal wall of the auricle at the line of attachment oftthe septum between the region of the coronary sinus and the septum fibrosum." As we have seen, however, in the hearts of other lizards and tortoises; the 'distal muscular bundle' has disappeared, while the 'fibrous cord' is still present as a sinoventricular bundle.

In this connection attention may be called to the recent publication of Stanley Kent in which it has been shown that in man "the auriculo-ventricular bundle is not the only path by which the functional connection between the auricle and ven


CONNECTING SYSTEMS OF THE HEART 439

tricle may be established/' (Kent '14 a). In a series of papers Kent describes and figures a specialized tissue on the right lateral aspect of the heart, as a neuro-muscular connection between the auricle and the ventricle, with large nerve trunks in the fat and connective tissue of the groove, and also in the muscular tissue. He also shows ('14 c) that, when all other "connections between the auricles and ventricles are severed, contractions of the auricles are still ca