Difference between revisions of "American Journal of Anatomy 22 (1917)"

From Embryology
(Created page with "{{Header}} {{Historic Disclaimer}} {{Amer. J Anat.}} =THE AMERICAN JOURNAL OF ANATOMY=")
 
m (THE AMERICAN JOURNAL OF ANATOMY)
Line 5: Line 5:
  
 
=THE AMERICAN JOURNAL OF ANATOMY=
 
=THE AMERICAN JOURNAL OF ANATOMY=
 +
The page has been created.
 +
Embryology
 +
Navigation
 +
Teaching
 +
Movies
 +
Embryonic
 +
Systems
 +
Abnormal
 +
Explore
 +
 +
 +
Talk:American Journal of Anatomy 22 (1917)
 +
Jump to:navigation, search
 +
Skip to main content web texts movies audio software image logosearch
 +
 +
 +
upload UPLOAD person SIGN IN ABOUT
 +
 +
CONTACT
 +
 +
BLOG
 +
 +
PROJECTS
 +
 +
HELP
 +
 +
DONATE
 +
 +
JOBS
 +
 +
VOLUNTEER
 +
 +
PEOPLE Full text of "The American journal of anatomy" See other formats THE AMERICAN JOURNAL
 +
 +
 +
 +
OF
 +
 +
 +
 +
ANATOMY
 +
 +
 +
 +
EDITORIAL BOAliD
 +
 +
 +
 +
Charles R. Bardeen
 +
 +
University of Wisconsin
 +
 +
Henry H. Donaldson
 +
 +
The Wistar Institute
 +
 +
Simon H. Gage
 +
 +
Cornell University
 +
 +
 +
 +
G. Carl Huber
 +
 +
University of Michigan
 +
 +
George S. Huntington
 +
 +
Columbia University
 +
 +
Henry McE. Knower,
 +
 +
Secretary University of Cincinnati
 +
 +
 +
 +
Franklin P. Mall
 +
 +
Johns Hopkins University
 +
 +
J. Playfair McMurrich
 +
 +
University of Toronto
 +
 +
George A. Piersol
 +
 +
University of Pennsylvania
 +
 +
 +
 +
VOLUME 22 1917
 +
 +
 +
 +
THE WISTAR INSTITUTE OF ANATOMY AND BIOLOGY PHILADELPHIA, PA.
 +
 +
 +
 +
Uf^n
 +
 +
 +
 +
1% io^
 +
 +
 +
 +
CONTENTS
 +
 +
No. 1. JULY
 +
 +
George L. Streeter. The factors involved in the excavation of the cavities in the cartilaginous capsule of the ear in the human embryo. Twelve figures 1
 +
 +
L. BoLK. On metopism. Nine figures 27
 +
 +
Franklin P. Mall. On the frequency of localized anomalies in the human embryos
 +
 +
and infants at birth. Eighteen figures 49
 +
 +
Rhoda Erdmann. Cytological observations on the behavior of chicken bone marrow
 +
 +
in plasma medium. Two text figures and nine plates 73
 +
 +
Ivan E. Wallin. The relationships and histogenesis of thymus-like structures in Ammocoetes. Three text figures and four plates 127
 +
 +
No. 2. SEPTEMBER
 +
 +
Warren H. Lewis and Margaret R Lewis. Behavior of cross striated muscle in tissue
 +
 +
cultures. Fourteen figures 169
 +
 +
J. A, Myers. Studies on the mammary gland. II. The fetal development of the mammary gland in the female albino rat. Twelve figures 195
 +
 +
Charles R. Stockard and George N. Papanicolaou. The existence of a typical oestrous cycle in the guinea-pig— with a study of its histological and physiological changes. One text figure and nine plates 225
 +
 +
H. E. Jordan and J. B. Banks. A study of the intercalated discs of the heart of the
 +
 +
beef. Fifty-one figures (four plates) 285
 +
 +
No. 3. NOVEMBER
 +
 +
Aimee S. Vanneman. The early history of the germ cells in the armadillo, Tatusia
 +
 +
"novemcincta. Three plates and two text figures 341
 +
 +
E. A. Baumgartner. The development of the serous glands (von Ebner's) of the vallate papillae in man. Ten figures 365
 +
 +
James Crawford Watt. Anatomy of a seven months' foetus exhibiting bilateral absence of the ulna accompanied by monodactyly (and also Diaphragmatic hernia) Four text figures and four plates 385
 +
 +
Leslie B. Arey. The normal shape of the mammahan red blood corpuscle. One figure 439
 +
 +
Andrew T. Rasmussen. Seasonal changes in the interstitial cells of the testis in the
 +
 +
woodchuck (Marmota monax). Twenty-six figures (three plates) 475
 +
 +
 +
 +
THE FACTORS INVOLVED IN THE EXCAVATION OF
 +
 +
THE CAVITIES IN THE CARTILAGINOUS CAPSULE
 +
 +
OF THE EAR IN THE HUMAN EMBRYO
 +
 +
GEORGE L. STREETER
 +
 +
Department of Embryology, Carnegie Institution of Washington, Baltimore,
 +
 +
Maryland
 +
 +
TWELVE FIGURES
 +
 +
The main mass of the cartilaginous capsule of the ear matures into true cartilage when the human embryo reaches a length of 20 to 30 mm., at which time it has acquired what may be considered its adult form with characteristic chambers and openings. From this time on, throughout its whole cartilaginous period, and even after ossification has begun, it undergoes continuous growth, maintaining at the same time, however, its general form and proportions. Such a growth involves both an increase in the surface dimensions of the capsule and a gradual enlargement or excavation of its contained cavities. It is to the manner in which this excavation is accomplished that the T\Titer wishes to call attention and particularly to the factors concerned in its progress whereby a suitable space is always pro\'ided for the enlarging membranous labyrinth. The actual amount of increase in size of the labyrinth is graphically pictured in figure 1. The outlines are made so that they show on the same scale of enlargement a series of wax-plate models of the left membranous labyrinth of human embryos having a crown-rump length of 20, 30, 50, 85 and 130 mm., as indicated in the figure. This covers the period during which the otic capsule is in a cartilaginous state. Ossification begins when the fetus has attained a crown-rump length of about 130 mm. The growth from then until the adult condition is reached may be judged by comparing the above with the final stage, labelled
 +
 +
1
 +
 +
THE AMERICAN JOURNAL OF ANATOMY, VOL. 22, NO. 1 JULY, 1917
 +
 +
 +
 +
GEORGE L. STREETER
 +
 +
 +
 +
adult, which is taken from Schonemann's reconstruction^ and reprotlucecl here so as to be on the same scale of enlargement as the younger stages. Since the cartilaginous labyrinth corresponds closely in form to the membranous labyrinth, particu
 +
 +
 +
20 mm
 +
 +
 +
 +
30 mm.
 +
 +
 +
 +
50mmr
 +
 +
 +
 +
 +
Fig. 1 Median views of wax-plate models of the left membranous labyrinth in human embryos having crown-rump lengths as indicated in the figure. The largest one is taken from Schonemann ('04) and represents the adult condition. They are all on the same scale of enlargement (4.4 diameters) and thus comparison of them shows graphically the amount of growth the labyrinth experiences during this period.
 +
 +
larly as regards the canals, one can see from figure 1 that there is a progressive increase in the size of the cartilaginous chambers throughout the whole embryonic period.
 +
 +
In addition to this increase in size, there is a change in the form of the cartilaginous labyrinth. The general proportions
 +
 +
1 Schoenemann, A. Die Topographic des menschlichen Gehororganes. Verlag von Bergmann, Wiesbaden, 1904. Plate 2, figure 20.
 +
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE 6
 +
 +
are maintained but there are alterations in the detailed form. As the canals become larger and longer they describe arcs of lesser cm'vature. If one compares the superior canal of an 80 mm. fetus with that of a 30 mm. fetus it will be found that in the former it has doubled its diameter and trebled its length. There is, moreover, a constant change in the relative position of the cartilaginous canals. The lateral canal, for instance, progressively recedes from the lateral wall of the vestibule. In studying this canal, therefore, one may know that it is steadily becoming larger by means of a process of excavation, but this is so managed that the canal as a whole moves in a lateral direction through the substance of the cartilaginous capsule. The topography of the cartilaginous labyrinth is so well provided with known landmarks that these changes in its size and form can be accurately followed. It is possible to determine deductively at what points new cartilage is being laid down and at what points it is being removed. On this account the cartilaginous capsule of the ear is a particularly favorable place for determining the histological features of the growth of cartilage.
 +
 +
As has been noted above the growth of the cartilaginous otic capsule resolves itself into an increase in its external dimensions with a simultaneous hollowing out and reshaping of its contained chambers. It at once becomes evident that this cannot be accounted for on the basis of a simple interstitial increase in the mass of cartilage together with its passive rearrangement to allow for the enlarging cavities, due for instance to a mechanical expansive pressure from the growing membranous labyrinth with its surrounding tissue and fluid. Such a passive rearrangement could only occur in a tissue that is very plastic, whereas cartilage is one of the least plastic of the embryonic tissues. Moreover the histological picture is not that of mechanical pressure. The cartilaginous chambers are always excavated slightly in advance of the space actually required by the membranous labyrinth, and there is no evidence of the labyrinth being cramped or of the creation of pressure grooves in the margins of the cartilage. Nor is the situation improved by the introduction of the conjectured activity of the perichondrium, either in
 +
 +
 +
 +
4 GEORGE L. STREETER
 +
 +
explanation of the deposit of new cartilage or of the excavation of the old, since the perichondrium, as will be shown, does not make its appearance until after a considerable amount of the growth and hollowing-out of the labyrinth had been already completed. Therefore there is involved in the development of the cartilaginous capsule something more than interstitial and perichondrial growth, in the ordinary sense of the terms. On account of its bearing upon this problem, it is the purpose of the present paper to call attention to the occurrence of dedifferentiation of cartilage in the human embryo, and to point out the important part which this process normally plays in the hollowing out and reshaping of the otic capsule during its development.
 +
 +
The term dedifTerentiation is applied here in the sense of a regression of certain areas of cartilaginous tissue to a more embryonic form, the same areas being subsequently rebuilt or redifferentiated into quite a different type of tissue. Dedifferentiation is defined by Child as a process of loss of differentiation, of apparent simplification, of return or approach to the embryonic or undifferentiated condition." In his noteworthy review of this subject he makes the assertion that the wide occurrence and significance of dedifTerentiation in the lower animals and plants "must at least raise the question whether similar processes do not occur to some extent in higher forms. "2 From the context it is evident that he refers to man as well as other mammals. The materialization of his prediction is here at hand in the development of the cartilaginous capsule of the ear. Before entering into this further it will be necessary to outline the earlier steps in the histogenesis of this particular tissue.
 +
 +
THE THREE STAGES IN THE DEVELOPMENT OF CARTILAGE
 +
 +
The cartilage of the otic capsule in its transition from embryonic mesenchyme to true cartilage passes through three fairly definite phases: firstly, the condensation of mesenchyme
 +
 +
^^hild, C. M. Senescence and rejuvenescence. University of Chicago Press, 1915. Page 293.
 +
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE 5
 +
 +
around the otic vesicle; secondly, the differentiation of the condensed mesenchyme into precartilage; and thirdly, the conversion of precartilage into true cartilage. These three histogenetic stages merge more or less diffusely into one another and one must bear in mind that such a subdivision is necessarily, arbitrary and tends to result in an exaggeration of the distinctness of the lines of their demarcation. Their points of difference, however, are here emphasized because the reversal of one state of development into a previous state is the feature to which it is desired to call especial attention.
 +
 +
STAGE OF CONDENSED MESENCHYME
 +
 +
When a human embryo is 4 to 5 mm. long the mesenchymal tissue surrounding the otic vesicle differs very little from that in other regions. The nuclei, however, are quite sparse in the regions ventral to the neural tube in the median line, and they become perceptibly more numerous as one explores laterally into the neighborhood of the otic vesicle. This sHght increase in the number of nuclei around the vesicle marks the beginning of the mesenchymal condensation that is to form the otic vesicle. A definite layer of such nuclei is not found until the embryo reaches a length of about 9 mm. ; it is then possible to recognize a fairly well outlined zone of mesenchyme which represents the otic capsule in its first stage of development. In figure 2 is shown a sketch indicating the relations which exist at that time. It represents a transverse section through the otic vesicle at the level of the attachment of the endolymphatic appendage. The zone of condensed mesenchyme forming the primordium of the otic capsule abuts directly against the lateral wall of the vesicle and extends from there to a point about one-half the distance between the vesicle and the ectoderm. On the median side of the vesicle this zone is lacking, although there is a considerable number of mesenchyme cells clustered around the vascular plexus ensheathing the central nervous system, and among the nerve rootlets of the acoustic complex. When this zone is analyzed under higher magnification it is found that it still consists essentially of a mesenchymal syncytium. It differs
 +
 +
 +
 +
6
 +
 +
 +
 +
GEORGE L. STREETER
 +
 +
 +
 +
morphologically from the adjacent mesenchyme, with which it is directly continuous, only in its more numerous and more C()nii)a('tly ari'anged nuclei and its somewhat richer network of internuclear processes. This is shown in figure 3 which is taken from an embryo a little larger than that in figure 2, but which in its general form is apparently in about the same stage of development.
 +
 +
 +
 +
Otic copsule
 +
 +
 +
 +
Ect o d e rm
 +
 +
 +
 +
G.petros f/-^^,
 +
 +
 +
 +
 +
GoOC?,^
 +
 +
 +
 +
 +
Med. oblo na.
 +
 +
 +
 +
Fig. 2 Section through the region of the otic vesicle in a human embryo 9 mm. long (Carnegie Collection, No. 721) enlarged 66.6 diameters. The primordium of the otic capsule, consisting of condensed mesenchyme, can be seen enclosing the vesicle on its lateral surface.
 +
 +
During the period of growth represented by embryos between 9 mm. and 13 mm. long, that is, up to the time when the semicircular ducts begin to separate from the main labyrinth through the apposition and absorption of the intervening membranous wall, the zone of condensed mesenchyme around the otic vesicle increases in extent and compactness, thereby forming a sharply defined capsule which completely encases the labyrinth. This capsule of condensed mesenchyme has the same openings and corresponds closely in form to the cartilaginous capsule into which it is destined soon to be converted.
 +
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE
 +
 +
 +
 +
' • m4S^ ^vM^^jf otic vesicle
 +
 +
 +
 +
 +
^mmMm-f
 +
 +
 +
 +
► Capsule
 +
 +
 +
 +
C^'
 +
 +
 +
 +
Ad) ac e nt
 +
 +
m es en c hyme
 +
 +
 +
 +
•"CS)
 +
 +
 +
 +
Fig. 3 Camera lucida drawing of a portion of the otic capsule while it is the state of condensed mesenchyme. It is taken from a human embryo 13.5 mm. long (Carnegie Collection, No. 695). The section is 10 microns thick and is enlarged 950 diameters. The syncytial character of the capsule can be seen and also its relation to the epithelial wall of the otic vesicle and to the surrounding mesenchyme.
 +
 +
STAGE OF PRECARTILAGE
 +
 +
The histogenetic changes which initiate the conversion of the capsule of condensed mesenchyme into a cartilage-hke tissue make their first appearance just after the separation of the semicircular ducts from the main vestibular pouch. This occurs when the embryo is about 14 mm. long. The conversion of the
 +
 +
 +
 +
8.
 +
 +
 +
 +
GEORGE L. STREETER
 +
 +
 +
 +
capsule into a true cartilage with a characteristic tinctorial reaction of its matrix is not completed until the embryo attains a length of 30 mm. Thus in embryos between 14 and 30 mm. long the otic capsule consists of a tissue in an intermediate condition between condensed mesenchyme and cartilage. This inter
 +
 +
 +
Otic cap s u le
 +
 +
 +
 +
 +
Ec t o de rm
 +
 +
 +
 +
Skull
 +
 +
 +
 +
—D. sc.p&st.
 +
 +
 +
 +
Sinus t r.
 +
 +
 +
 +
Med. ^^
 +
 +
 +
 +
 +
7^
 +
 +
 +
... _
 +
 +
 +
o b 1 o n Q . i-A^/Ss
 +
 +
 +
 +
 +
^ o
 +
 +
 +
 +
 +
9m
 +
 +
 +
-Cl\ sJV
 +
 +
 +
^>
 +
 +
Gana. nodos
 +
 +
 +
 +
 +
Appendix'
 +
 +
 +
 +
 +
 +
N. IX
 +
 +
Fig. 4 Section through the region of the otic capsule in a human embryo 15 mm. long, (Carnegie Collection, No. 719). Enlarged 66.6 diameters. The epithelial portions of the labyrinth are shown in solid black and it will be noted that they are in direct contact with the substance of the capsule; there is as yet no periotic reticular tissue. The section passes through the superior and posterior semicircular ducts and through the utricle near its junction with the crus commune.
 +
 +
mediate form is known as precartilage. It constitutes the second of our three stages of cartilaginous growth.
 +
 +
The general form and relations of the otic capsule at the beginning of its conversion from condensed mesenchyme into precartilage is shown in figure 4, which represents a horizontal section through this region in a human embryo 15 mm. long (Carnegie
 +
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE
 +
 +
 +
 +
9
 +
 +
 +
 +
Collection, No. 719). It will be noted that the capsule abuts directly against the epithelial wall on the labyrinth. Around the margins of the capsule there is a vascular network the branches of which, however, do not penetrate into its substance. In its form it is essentially the same as its antecedent capsule of condensed mesenchyme, but in structure it can be seen to be undergoing certain characteristic alterations. These do not occur uniformly throughout its substance but appear
 +
 +
 +
 +
 +
Fig. 5 Camera lucida sketches showing characteristic fields in sections of the otic capsule while it is in the precartilage state. Enlarged 950 diameters. The groups labelled A are taken from an embryo 17 mm. long (Carnegie Collection, No. 576). Group B is taken from an embryo 18 mm. long (Carnegie Collection, No. 409).
 +
 +
earlier in some areas than in others. They consist of an increase in distance between the nuclei, together with an alteration in the internuclear protoplasmic network and its spaces. Whereas the capsule, as seen in prepared sections, has previously consisted of a mesenchymal syncytium, it now gradually loses its syncytial appearance. Most of the branching processes disappear and are replaced by a homogenous mass. Some of the processes, on the other hand, persist, and become thicker and more sharply outlined. These persisting larger processes usually exhibit a characteristic relation to the nuclei. Two or more of
 +
 +
 +
 +
10 GEORGE L. STREETER
 +
 +
them unite in the formation of a loop at one side or at one or both ends of a nucleus, thereby creating a perinuclear space which soon takes on a more transparent appearance than the surrounding homogeneous material that accumulates in the place of the disappearing processes. These changes can be seen in the sketches shown in figure 5, which represent characteristic areas in the otic capsule while in the precartilage stage in human embryos 17 and 18 mm. long. In the two sketches marked A the contrast beween the permanent and disappearing protoplasmic processes is already noticeable. In the sketch marked B the transition is more advanced although one can still recognize in the homogeneous matrix remnants of branching processes which have not yet disappeared. The persisting processes enclose characteristic capsular or perinuclear spaces. Similar spaces are shown in figure 6 which presents a series of isolated nuclei with their associated permanent processes such as are found in sections of maturing precartilage. In some of these (figure 6, C and figure 5, B,) there is a beginning accumulation of granular protoplasm at the margin of the nucleus which constitutes the so-called endoplasm and becomes enclosed with the nucleus in the capsule. After the formation of the spaces the endoplasm gradually accumulates and forms the cell body of the encapsulated nucleus. Thus in precartilage we find all stages in the transition, from a mesenchymal syncytium to a tissue consisting of partially encapsulated cell-islands separated from each other by a homogenous matrix.
 +
 +
CARTILAGE STAGE
 +
 +
The transition from precartilage into cartilage gradually takes place in the otic capsule when the embryo is between 25 and 30 mm. long. This maturation is characterized by an increase in the amount of matrix combined mth a more complete encapsulation of the nuclei, or cartilage-cells, as they may now be designated. With the increase in the amount of the matrix there is also a change in its chemical composition, so that it becomes possible to stain it differentially. This tinctorial reaction constitutes an arbitrary point at which it may be said
 +
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE 11
 +
 +
that the precartilage becomes cartilage. In embryos 30 mm. long the greater portion of the otic capsule reacts tinctorially and has the histological character of young cartilage. With this stage we reach the third and final phase of the process with which we are dealing. The further changes from younger cartilage to
 +
 +
 +
 +
 +
K:m) \^a
 +
 +
 +
 +
Fig. 6 Characteristic precartilage cells showing the manner in which spaces become enclosed around them, eventually becoming encapsulated cells of true cartilage. Enlarged 950 diameters. Group A is from the otic capsule of an embryo 17 mm. long (Carnegie Collection, No. 296) ; Group B is from an embryo 24 mm. long (Carnegie Collection, No. 455) ; and Group C is from an embryo 23 mm. long (Carnegie Collection, No. 453).
 +
 +
older cartilage, and the conversion of cartilage into bone, are doubtless a continuation of the same general process but in the present paper they will not be taken into consideration.
 +
 +
PERIOTIC RETICULUM
 +
 +
It has been pointed out elsewhere by the writer^ that there is derived from the condensed mesenchyme surrounding the otic capsule not only the cartilaginous capsule but also the periotic
 +
 +
' Streeter, G. L. The development of the scala tympani, scala vestibuli and perioticular cistern in the human embryo. Am. Jour. Anat., vol. 21, 1917.
 +
 +
 +
 +
12 GEORGE L. STREETER
 +
 +
reticulum which eventually intervenes between the capsule and the epithelial labyrinth. The relation existing between this reticulum and the three stages of cartilage that have just been defined must therefore now be referred to. The formation of the periotic reticulum is first indicated by a cluster of deeply stained nuclei that can be seen along the central edge of the semicircular ducts in embryos soon after the ducts are formed, and at about the time the otic capsule begins to change from condensed mesenchyme into precartilage. These nuclei constitute a focus at which the development of the reticulum and its blood vessels takes origin. Here the tissue of the capsule gradually takes on an appearance less like a cartilage-forming tissue and more like embryonic connective tissue. Spreading from this focus a narrow area is established which soon encircles the semicircular ducts and becomes the open-meshed vascular reticulum which in embryos 30 mm. long everywhere bridges the space existing between the epithelial labyrinth and the surrounding cartilage.
 +
 +
While in the stage of condensed mesenchyme and in the earlier part of its precartilage period the tissue of the otic capsule to all appearances abuts directly against the epithelial wall of the labyrinth as shown in figures 2, 3 and 4. It is possible, however, that some of the cells directly adjacent to the epithelium do not properly belong to the tissue of the otic capsule. It is conceivable that such cells may represent indifferent mesenchyme and perhaps angioblasts which were originally enclosed, along with the otic vesicle, by the condensed tissue of the capsule where they remain in contact with the epithelial wall in a resting condition until the embryo attains a length of 20 mm. We might regard as an indication of their resumed activity the formation of the deeply stained foci along the central margins of the canals which have been described above. It might thus be maintained that the periotic reticulum is derived from a few predestined mesenchyme cells which after a latent period undergo proliferation and occupy the space vacated by the receding precartilage. On the other hand one may also maintain that the reticulum is derived from cartilage-forming tissue; that it is not
 +
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE 13
 +
 +
a predetermined tissue but is simply precartilage that has undergone dedifferentiation. In the early stages when only a few cells are concerned this matter cannot be so well determined, the histological difference between early precartilage and indifferent mesenchyme cells not being sufficiently great for their certain recognition. In the later stages, however, it is quite evident that precartilage tissue is actually converted into a reticulum, and that the replacement of precartilage by a reticular connective tissue is accomplished by a process of dedifferentiation. By identifying a special area through its relation to a particular canal, and comparing this selected area in a series of stages, it is possible to observe the conversion of precartilage into reticulum, and to trace histologically step by step the manner in which a space occupied by precartilage in a younger stage is replaced by a reticulum in an older stage. This is the same procedure which occurs in the conversion of cartilage into precartilage and in the latter case, on account of the more highly specialized structure of the tissues, the picture is even more striking, as will be seen in the following outline in which the main features of the process will be pointed out.
 +
 +
DEDIFFERENTIATION OF CARTILAGE
 +
 +
It has been noted that in embryos 30 mm. long the main capsular mass consists of true cartilage possessing encapsulated cartilage cells and an intervening matrix that is differentially stainable. A section passing transversely through the lateral semicircular canal of an otic capsule of this age is shown in figure 7. This, and figures 8 and 9, form a series showing at the same enlargement the same canal, i.e., lateral, cut in the same plane at three successive stages in its development. A direct comparison of these figures can thus be made and there is thereby seen the histological changes that occur with the growth of the canal. The successive figures may be superimposed upon each other and in this way the relative amount and position of the constituent tissues be determined. When this is done it is found that in the process of enlargement the true cartilage around the margin of the canal becomes replaced by precartilage
 +
 +
 +
 +
14
 +
 +
 +
 +
GEOKGE L. STREETER
 +
 +
 +
 +
and the precartilage in its turn becomes converted along its inner margin into the reticular mesenchyme which finally becomes the periotic reticulum. In other words, cartilage of the third stage as above described, reverts or is dedifferentiated into cartilage of the second stage and this in turn is dedifferen
 +
 +
 +
."Ductus semicirc. lai".
 +
 +
 +
 +
 +
•/Carrilaqe
 +
 +
 +
 +
Precarhilaqe
 +
 +
 +
 +
'. ' •' ' ■ .• ' ■' -Reticulum
 +
 +
 +
 +
Fig. 7 Section passing transversely through the lateral semicircular canal in a human embryo 30 mm. long (Carnegie Collection, No. 86), enlarged 100 diameters. The canal at this time is only slightly larger than the contained epithelial duct, but the zone of temporary precartilage marks out an area that is soon to be excavated by the process of dedifferentiation through which it becomes converted into a reticular connective tissue.
 +
 +
tiated into a tissue approximating the first stage. It is this retrogressive adaptability of its tissues combined with their progressive development which render possible the enlargement of the otic capsule and the alteration in form and position of its contained cavities.
 +
 +
In the 30 mm. embryo shown in figure 7, the first of these three figures, it will be seen that the epithelial duct is sep
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE
 +
 +
 +
 +
15
 +
 +
 +
 +
arated from the main cartilaginous mass of the capsule by a surrounding zone of precartilage and intervening between the latter and the duct is a narrow zone of mesenchymal tissue which is somewhat reticular in character. This zone of reticulum has attained its greatest width on the median side of the duct, toward the right, being at this point about twice as wide as the
 +
 +
rDu.ctus semiclrc. lat.
 +
 +
 +
 +
•i^Precartila(^e
 +
 +
 +
 +
-^r-^. — Reticuki m
 +
 +
 +
 +
 +
' . ■ .■ ■ " A!'. ' ■ . ■ ■
 +
 +
 +
 +
Fig. 8 Section passing transversely through the lateral semicircular canal in a human fetus 43 mm. long (Carnegie Collection, No. 886). Enlarged 100 diameters. The epithelial semicircular duct is larger in diameter than the one in figure 9, but that is the accidental result of its having been fixed while in a distended condition. The size of these ducts cannot be compared without taking account of this variation in their distension.
 +
 +
thickness of the duct wall. It is characterized by its reticular arrangement and by the presence of small blood vessels which are not found in the precartilage, although they lie closely against its inner margin. The area of precartilage stands out conspicuously in material that has been intensely stained in hematoxylin without any counter-stain. A series of this kind is represented by No. 199 in the Carnegie Collection. In that series
 +
 +
 +
 +
16 GEORGE L. STREETER
 +
 +
the true cartilage is deep blue on account of the avidity with which its matrix takes the stain, whereas the precartilage shows only a nuclear stain and therefore is only faintly colored, as compared with the sharply demarcated and almost opaque cartilage surrounding it. The negative of this picture is presented in material where there has been an intense nuclear stain with subsequent decolorization of the cartilaginous matrix. Such a condition exists in figure 7 but is more marked in specimens where the stain is more intense, such as the series No. 972 of the Carnegie Collection. Under such circumstances the area of precartilage appears as a dark field in the midst of the faintly stained true cartilage. Depending upon the management of the technique it is thus possible in embryos about 30 mm. long to display the future cartilaginous canals; that is, the precartilaginous areas which approximately correspond to them, either as dark fields in a light background or as light fields in a dark background.
 +
 +
In the second figure of the series, figure 8, the area representing the future cartilaginous canal, is appreciably larger. Its perimeter, compared with that of the canal in figure 7, is in the proportion of 152 to 115, which are measurements in millimeters made on photographs taken at 100 diameters. By comparing the two figures it will be seen that the increase in size is obtained by the encroachment of the precartilaginous area upon the surrounding cartilage. The amount of this encroachment represents the amount of true cartilage which has reverted or dedifferentiated into precartilage. In a similar manner the reticular zone surrounding the membranous duct has enlarged at the expense of the precartilage. The reticular zone as shown in this figure, taken from a human embryo 43 mm. long, forms a distinct and characteristic eccentric vascular field, but it undergoes its greatest expansion soon after this period.
 +
 +
In the 50 mm. embryo, as can be seen in the third figure of this series, figure 9, the area of the reticular zone is about the same in size as the whole precartilage area in the 30 mm. embryo of figure 7. On comparing these two figures it becomes apparent that there is just as much, and even more, precartilage
 +
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE 17
 +
 +
in the latter but it has moved outward into the area that was previously true cartilage. At this period the outer perimeter of the precartilage is 192 mm. as compared with 115 mm. in figure 7. As the old area of precartilage disappeared, a new and more peripheral area became established. Thus it may be seen
 +
 +
Ductus semicirc. lat.
 +
 +
Cartilaqe
 +
 +
 +
 +
Precarlilaqe"
 +
 +
 +
 +
 +
,^: - " . ;!vv?.i' ./'/'•'; ' T ?eticulum
 +
 +
 +
 +
Fig. 9 Section through the lateral semicircular canal in human fetus 50 mm. long (Carnegie Collection, No. 95). Enlarged 100 diameters. This section is taken at the same relative position and at the same enlargement as those in figures 7 and 8, so that they may be directly compared. It will be seen that the area of precartilage in figure 7 is now entirely replaced by reticulum, whereas a new and more peripheral area of precartilage has formed at the expense of surrounding cartilage. This more peripheral precartilage likewise in the end becomes reticulum.
 +
 +
that true cartilage has been dedifferentiated into precartilage and this in turn into the periotic reticulum. It is in this way that the enlargement of the canals is accomplished, a process of excavation based on the dedifferentiation of a specialized tissue into a more embryonic type, followed by a readjustment of redifferentiation of this simpler form into a tissue adapted to the new conditions.
 +
 +
THE AMERICAN JOUR.N'AL OF ANATO.MY, VOL. 22, NO. 1
 +
 +
 +
 +
18 GEORGE L. STREETER
 +
 +
In addition to the excavation of cartilage there occurs, in connection with the growth and alteration of form of the otic capsule, the deposit of new cartilage. As the lateral cartilaginous canal, for instance, enlarges it also moves laterally, so that the distance between it and the cartilaginous vestibule increases, thereby producing a lateral migration of the space as a whole. Such a migration must involve an excavation of the established cartilage on its lateral margin and the formation of new cartilage on its median margin. Therefore on the lateral margin we find true cartilage being dedifferentiated into precartilage and on the median margin precartilage being differentiated into true cartilage. The margins of the cartilaginous canals throughout the whole embryonic period are in an unstable condition and are constantly undergoing changes. These are either in the nature of a uniform excavation throughout their whole contour, resulting in a simple enlargement of the canal, or of an excavation in certain parts combined with a deposit of additional cartilage in others resulting in a change of form and position of the canal. On account of the well defined landmarks that characterize the labyrinth, it is possible to orient points at which excavation and new deposit respectively are occurring. Thus one can follow the histological phenomena of these two processes with great accuracy. Where new cartilage is being deposited, the tissue shows all the stages of development from an embryonic connective tissue on its central margin through an aj^ea of precartilage to a true cartilage on its more peripheral margin. These different grades merging into one another repeat stages which characterized the whole capsule in embryos between 14 and 30 mm. Where the cartilage is undergoing excavation the same transitions exist, but the changes are more abrupt and there is a sharper line of transition between the different zones. The \\ddth, however, and the sharpness of the zones vary somewhat, being relatively ^\'ider and less abrupt in youngef stages and becoming narrower and more abrupt in their transition in older fetuses. It is quite possible that these changes occur in waves and when the zones are wider and less abrupt it is due to the greater acti\aty of this process of dedifferentiation and when the zones are nar
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE 19
 +
 +
rower and more sharply outlined, as is common in older fetuses, the alteration is then proceeding more slowly.
 +
 +
The dedifferentiation of cartilage into precartilage involves first of all changes in its matrix including the loss of its tinctorial reaction, a decrease in its amount and an alteration in its structural appearance, in that it becomes less homogeneous and begins to show the presence of branching processes. As a result of these changes in the matrix, the encapsulated cartilage cells come to lie closer together, pressing to some extent directly against each other. The combined edges of the overlapping margins of flattened capsules give the appearance of wavy refractile lines running through the transition zone parallel to the margin of the canal. With these changes the capsules of the cartilage cells rapidly become incomplete and take on the appearance of branching processes. With the disappearance of the capsules the tissue assumes the appearance of a mesenchymal syncytium which then takes on a reticular character and becomes part of the general periotic reticulum. The question as to whether there is an active proliferation of the nuclei in the tissues subsequent to their alteration from cartilage to precartilage has not been definitely detennined. The material at hand is inadequate for a satisfactory solution of this point, although in some specimens there seems to be an increase in the number of nuclei in the transition zones of precartilage, over and above the apparent increase associated with the absorption of the intervening matrix, which could only be explained in that way. It would seem very probable that with its dedifferentiation there should be associated a renewed proliferative vitality of a given embjTonic tissue, sufficient at least for its reconstruction into the newer form.
 +
 +
DEVELOPMENT OF THE PERICHONDRIUM
 +
 +
In studying the cartilaginous canals one must take into consideration the perichondrium and its relation to the continual transformations occurring along their margins. Reasoning from the prevaihng conceptions, concerning the activity of periosteum in bone growth, one might expect to find in the perichondrium
 +
 +
 +
 +
20 GEORGE L. STREETER
 +
 +
an important factor in the growth and changes in the cartilage. In later periods its influence on cartilaginous changes cannot be easily determined, but fortunately for the solution of this point it happens that the perichondrium is late in making its appearance and therefore cannot take any part either in the deposit of new cartilage or in the excavation of the old until after a considerable part of this transformation is already completed.
 +
 +
The zone of precartilage surrounding the margins of the canals in embryos about 50 mm. long might be mistaken for perichondrium, such for instance as is shown in figure 9. If this area, however, is followed to a slightly older stage it will be found to be converted almost entirely into reticulum. The section shown in figure 10 is through the posterior semicircular canal of an embryo of the same length, 50 nnn., but a little older in development. It is just at this age that precartilage very rapidly reverts to reticulum, much more rapidly than the surrounding cartilage in reverting to precartilage; and therefore in sections at this period we find only a thin rim of precartilage around the margins of the canals. The real perichondrium makes its first appearance when the fetus has reached a length of about 70 mm. A photograph of a section of the posterior semicircular canal of a fetus 73 mm. long (Carnegie Collection, No. 1373) is shown in figure 11. Examination of this section reveals along the outer margin of the periotic reticulum a condensation of its trabeculae resulting in the formation of a thin fibrous lamina or membrane near the margin of the cartilage. This is the perichondrium in its early form. It does not abut directly against the cartilage but is separated from it by a zone of transition tissue which consists partly of precartilage and partly of reticulum. This transitional precartilage-reticular zone, becomes narrower and more abrupt in later stages. In all of the specimens studied, however, it was found intervening between the perichondrium and the surrounding cartilage. It will thus be seen that the perichondrium is a derivative of the periotic reticulum. It forms an outer limiting membrane along the cartilaginous margin of the latter in a manner somewhat similar to that in which the membrana propria forms an inner one along its epithe
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE
 +
 +
 +
 +
21
 +
 +
 +
 +
lial margin. The reUition of the perichondriuiu to the reticular tissue surrounding the labyrinth, as seen under higher magnification, is shown in figure 12. The section is a portion of the one shown in figure 11 and includes the successive strata
 +
 +
 +
 +
 +
Ductus semicirc. post.
 +
 +
 +
 +
•^Cartilac^e
 +
 +
 +
 +
-Precartilaqe
 +
 +
 +
 +
X'X
 +
 +
 +
 +
.• •• •^^^"^"7— R e t i c u 1 u nn
 +
 +
 +
,o
 +
 +
 +
P^ig. 10 Section through the posterior semicircular canals in a human fetus 52 mm. long (Carnegie Collection, No. 96). Enlarged 100 diameters. Here the replacement of precartilage by reticulum has been more active than that of cartilage by precartilage so there remains only a narrow zone of the latter. The reticulum begins to show an alteration in its trabeculae. Due to the retraction and rearrangement of the protoplasm of some of the trabeculae there results a coalescence of adjacent intertrabecular spaces. There are thus formed larger fluid spaces that are devoid of traversing trabeculae. As yet there is no perichondrium.
 +
 +
from the epithelial wall of the labyrinth to the true cartilage. It will be seen that the membrana propria consists of a narrow meshed syncytium, such as is found in embryonic fibrous connective tissue, and constitutes a supporting coat for the epithelial wall of the semicircular duct. The main part of the periotic connective tissue consists of a wide-meshed reticulum and arbor
 +
 +
 +
22
 +
 +
 +
 +
CKOliClO L, STIlEF/nOll
 +
 +
 +
 +
iziiifi; through it arc Mic loops of small blood vessels. The pcrichoiulriuiu forms in tiu' outer part of this reticuhim as a compact fibrous uieiubrano. l\^rii)luvral to the ])('rich()n(lrium tlio tissue is still of a roticuUir ty]io but passes hi rapid transition hito precartilage and then into a, tiiie cartilaginous tissue.
 +
 +
After making its first a|)i)eai'ance, the ix'richondrium ra])idly becomes more consi)icuous. In fetuses 80 mm. CU length (Car
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
enchonciriur
 +
 +
 +
 +
V\\l,. II l'li(it(ifir;i|)li (if seel ion lliiou^li I lie posi ciior scinicircul;! r cm nal in a liunian fclus 7.'{ imn. loii^ (C'aincfiic ( 'olloction, No. 1873). JMilarficd 100 diameters. It siuiws I lie pcticlioiKlriiiiii in its cai'liest form.
 +
 +
negie Collection, No. 172) it consists of a dense hbrous coat more than twice as thick as that shown in Hgiu'e 12. It is clearly separated trom the cartilage by a narrow zone of transitional precartihige-i"(>ticular tissu(\ In slightly older fetuses, S5 nun. CH length, (CaTn(>gi(> ( \)ll(H'tion, No. 14()()-3()) it has become a (Umisc broad zone sei)arat(Hl from lh(> surroundhig cartilage only by a, narrow cleft of transitional tissue which still, however, can be recogniz(Hl as reticular in character. In fetuses 130 nun. CR long (Carnegie Collection, No. 1018) the perichondrium presents
 +
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE
 +
 +
 +
 +
23
 +
 +
 +
 +
a relatively inatinx^ a])pearance. As observed under lower magnifications, one is apt to conclude that the perichondriini is in direct contact with the true cartilaj2;e. Under higher powers, however, a narrow zone of transitional precartilage can be seen intervening between them. In this dcHlifferentiating zone the matrix has largely disappeared and the cartilaginous capsules have collapsed and ar(^ flattened out. Thus the elongated endoplasm of adjacent cartilage cells is brought into contact, being separated only by
 +
 +
 +
 +
s>
 +
 +
 +
^^
 +
 +
 +
 +
^,^ Epithelium
 +
 +
 +
 +
® ^' -^•'..:j^'®f^^^ .. r, Membr.prop.
 +
 +
 +
 +
i^.^^ '^" :M
 +
 +
 +
 +
to
 +
 +
 +
 +
^.^
 +
 +
 +
 +
^
 +
 +
 +
 +
-.fc ■. 7^->— ." \ ^ff'- Reticulum
 +
 +
 +
 +
W'**'
 +
 +
 +
 +
 +
^ «
 +
 +
 +
 +
"m
 +
 +
 +
 +
^■'^i^^^f -m^^ Perichondrium
 +
 +
 +
 +
Precart.- retic.
 +
 +
 +
 +
Cartilage
 +
 +
 +
 +
Fig. 12 Detailed drnwinf-- of n port ion of flic sniiic sect ion shown in figure 11. Enlarged 500 diameters. It, can he seen liere that the perichoTulriuni is a condensation of the meshes in the peripheral part of the periotic reticulum and that it separated from the true cartilage by a transitional area of precartilage and reticulum.
 +
 +
 +
 +
24 GEORGE L. STREETER
 +
 +
the reiuiuints of tlu^ capsiihir margins. The appearance of activity in this zone corresponds to the unstable condition of the margin of the cartilage which is still undergoing gradual excavation.
 +
 +
SUMMARY
 +
 +
From a study of the development of the cartilaginous capsule of the ear in human embryos it is found that the changes in size and form which it undergoes during its development are accomplished in part by a progressive and in part by a retrogres.sive differentiation of its constituent tissues. Throughout the entire period of growth, as far as material was available for study, it was found that the margins of the cartilaginous cavities "undergo a process of continual transformation. They exhibit a state of unstable equilibrium, in respect to the opposing tendencies toward a deposit of new cartilage on the one hand and toward the excavation of the old on the other. The margins thereby are always either advancing or receding and in this way are produced the progressive alterations in their size, shape and position. In this manner a suitable suite of chambers is always provided for the enlarging membranous labyrinth.
 +
 +
The general tissue mass of the otic capsule during the period represented by embryos from 4 mm. to 30 mm. long passes through three consecutive histogenetic periods, namely, the stage of mesenchymal syncytium, the stage of precartilage and the stage of true cartilage. In the subsequent growth of the capsule it is found that in areas where new cartilage is being deposited the tissues of the areas concerned follow the same progressive order of development. In areas, however, where excavation occurs, where cartilage previously laid down is being removed, it is found that the process is reversed. The tissue in such areas returns to an earlier embryonic state, that is it undergoes dedifferentiation. Tissue that has acquired all the histological characteristics of true cartilage can thus be traced in its reversion to precartilage and from precartilage in turn to a mesenchymal syncytium. In the latter form it redifferentiates into some
 +
 +
 +
 +
EXCAVATION OF THE CARTILAGINOUS OTIC CAPSULE 25
 +
 +
more specialized tissue — in this case for the most part into a \-asciihir reticuhmi.
 +
 +
The perichondrium is a derivative of the periotic reticuhmi and forms an outer Umiting membrane along its cartilaginous margin. During the foetal period the perichondrium does not rest dhectly against the true cartilage but is separated from it by a zone of transitional tissue consisting partly of precartilage and partly of reticulum. This transitional zone intervening between the perichondrium and the surrounding cartilage was observed in all of the specimens that were studied, which includes fetuses up to 130 mm. CR length. Owing to the fact that the perichondrium is late in making its appearance, being first seen in fetuses about 70 nun. long in can take no part in the early changes in the cartilaginous capsule either as regards deposit of new cartilage or the excavation of cartilage that had been previously laid down.
 +
 +
 +
 +
ON METOPISM
 +
 +
L. BOLK
 +
 +
Director of the Anatomical Institute, University of Amsterdam
 +
 +
NINE FIGURES
 +
 +
It is a well-known fact that in man the two frontal bones in a certain number of individuals do not coalesce. In normal circumstances the frontal or metopical suture begins to disappear during the last quarter of the first year, and is completely closed before the end of the second year, the anterior fontanelle disappearing during the third year. The phenomenon of a persisting frontal suture generally is designed as metopism.
 +
 +
Many publications on metopism are contained in the anthropological and anatomical literature. Several reasons have induced me to add the present paper to them. Firstly, I am able to deal with data unknown till now regarding the numerical occurrence of the phenomenon in Dutch skulls. Such a communication is not wholly superfluous because the frequency of metopism varies not inconsiderably among different peoples or races. The second reason for the publication of this paper is given by the fact that in many points the results of my investigations contradict those of other investigators, and, as to the etiology of the phenomenon, I differ from the current opinion. Commonly an increased intracranial pressure, caused by the somewhat more strongly developing frontal brain, is regarded as the mechanical factor preventing the fusion of the two frontal bones. So Martin in his Manual of Anthropology says:
 +
 +
All this shows that a more considerable growth of the frontal cerebrum, as occurring in some brachy cephalic groups, is to be considered the cause of metopism. By the internal pressure the normal concrescence of the frontal bones is prevented, likewise in hydrocephalic skulls, in which regularly the metopical suture persists.
 +
 +
27
 +
 +
 +
 +
28 L. BOLK
 +
 +
After having- cominuuicated the results of my own investigation I will enter into some critical remarks ujion this opinion.
 +
 +
The above mentioned explanation of metopism gives rise to a more extended point of view. Some authors believe that a large brain indicates intellectual superiority. And it is easy to understand that to such a metopical suture too, should be a symptom of such a superiority, being a suture caused by a strongly developed brain. This opinion has in fact the approval of Schwalbe. In an investigation into the occurrence of a frontal sutiu-e in apes and monkeys this author, after having mentioned the current opinion with regard to the etiology of metopism, says: "This hypothesis agrees with the idea that persons with metopical crania are to be considered as being intellectually on a higher level."
 +
 +
The partisans of this hypothesis surely may advance the following anthropological fact, in favor of their view. It is incontestable that metopism occurs more frequently in culture races than in those possessing a lower degree of civilization. The differences are sufficiently pointed out in the following table, most of whose data are taken from Martin's Manual of Anthropology.
 +
 +
Frequency of metopism
 +
 +
per cent
 +
 +
Australian 1.0
 +
 +
Negroes 1.2
 +
 +
Malayan 2.8
 +
 +
Papuan 4.3
 +
 +
Slaves 6.4
 +
 +
Alsatians 6.5
 +
 +
Bavarians 6.4
 +
 +
Swiss 7.1
 +
 +
Hamburgher 9.5
 +
 +
Scotchman 9.5
 +
 +
Parisian 9.7
 +
 +
The difference between the civilized and uncivilized people is a very obvious one. And even when rejecting the hypothesis of any relation between metopism and intellectual development, this difference still retains its anthropological significance to the full.
 +
 +
 +
 +
ON METOPISM 29
 +
 +
Furthermore it is clear that even among the Europeans the ratio is not at all constant in crania of the inhabitants of the MidEuropean region (Bavarians, Alsatians and Swiss), and in the Slavs the frontal bone seems to oe divided less frequently than n crania of the inhabitants of the North-European regions (Hamburgher, Scotch, and, as will be demonstrated further on, also Amsterdamian). I draw special attention to this fact, which does not agree with the not seldom expressed contention, that metopism occurs more frequently in brachycephalic than in dolichocephalic skulls. As far as I am aware, it was Welcker who first pointed out this idea. And it is found in most treatises on metopism. But I think in most of these it is a mere statement of a current opinion, and not a result of definite investigation. The results of research do not confirm this hypothesis. This will be demonstrated by my own research in the course of this paper, and the investigations of Bryce on Scottish crania give similar results. As is well known these are very dolichocephalic, and yet the author found 9.5 per cent metopical skulls among them. Therefore among the dolichocephalic Scotchmen the metopical skulls are more numerous than is the case among the more broad-headed inhabitants of the Mid-European region. This contradicts the assumed prevalence of metopism in brachycephalic skulls.
 +
 +
Before finishing these introductory remarks it is necessary to give a brief account of some of the principal points in the comparative anatomy of the frontal suture. A knowledge of these points is necessary for the thorough understanding of my explanation of metopism, which, as already mentioned, differs from the current one. That the frontal bone in the human embryo arises by two points of ossification situated symmetrically is due to the fact that originally this bone was a paired one. As a rule this condition persists not only in the lower vertebrates, but even among mammals there are many groups in which the metopical suture does not disappear. In Prosimiae as a rule the frontal suture persists as long as the other sutures of the skull. In case of an early closure of the system the frontal suture also disappears earl}^, in case of a persistence of the system till an advanced age, the frontal suture also persists. There is considerable va
 +
 +
 +
30 L. BOLK
 +
 +
riability as to the age at which the skull bones unite in Prosimiae. In monkeys the ossa frontalia unite and a persisting metopical suture is an individual and rare exception. Finally, in Anthropoids a metopical suture in an adult skull has never been seen.
 +
 +
The history of the metopical suture therefore is a somewhat complicated one. Originally the suture was always present, later it disappears, and finally in man it reappears as a not infrequent variation.
 +
 +
I wish to emphasize, that in consequence of this behavior of the frontal suture in the course of evolution, two possibilities must be taken into consideration when trying to account for its reappearance in man. Firstly this reappearance can be explained as due to a quite new influence acting only in man, namely the increased development of the brain which prevents the two frontal bones from uniting. But there is another point of view of a more physiological nature, claiming our full attention in no lesser degree. In primitive Primates the metopical suture persisted. In the further course of evolution certain causes, to which I intend to return, exerted their influence in such a way that both frontal bones were compelled to unite and the metopical suture disappeared. Now, I believe, the possibility presents itself that the metopical sutm-e in man reappears, just because the factor, which once caused its disappearance in monkeys, no longer exerts its influence in the human skull. From this point of view the problem has not yet been examined.
 +
 +
In the foregoing it is made clear that the metopism of the human skull is the starting point of some very interesting problems, to which I will shortly refer in the order in which they are treated on the next pages. Firstly the question about the frequency of the anomaly in Dutch skulls will be discussed, then the question whether the metopical suture occurs more frequently in brachycephalic skulls, and whether it is true that a persisting frontal suture is of some influence upon the shape of the skull. Thereupon we will examine if there exists any relation between metopism and intellectual development, particularly if it is true that the anomaly is more frequent in large skulls, containing a
 +
 +
 +
 +
ON METOPISM 31
 +
 +
heavier brain than usual, and finally we will enter into the question of the aetiology of metopism in men.
 +
 +
The material I used for this research consists of 1400 adult skulls of inhabitants of Amsterdam who died during the second half of the last century. It was gathered from one of the cemeteries of this town.
 +
 +
In this collection I found 134 skulls with a persisting metopical suture, that is 9.5 per cent. This relation equals that found by Bryce in Scottish skulls and by Simon in Hamburghian skulls, and agrees nearly with that found by Broca among the old Parisian skulls.
 +
 +
As mentioned in the introductory remarks, it is often claimed in the literature that the metopical suture occurs more frequently in brachycephalic than in dolichocephalic skulls. Now, we will examine in the fii^st place whether this statement agrees with the results of my own research. As a dolichocephalic skull I mean in the following pages all those with an index cephalicus lower than 80, omitting therefore a more detailed classification in mesocephalic, hyperdolichocephalic, etc.
 +
 +
The number of brachycephalic crania present in the whole collection of 1400 skulls, amounted to 420, or just 30 per cent, and among the 134 metopical skulls, there were 55 or 41 per cent brachycephalic. The number of brachycephalic skulls among metopical crania surpasses, therefore, that among the collection as a whole and the difference of 11 per cent really seems to be very considerable. Only the fact merits mention that the absolute number of metopical skulls (134) is a relatively small one, and hence a few skulls more or less exert a perceptible influence upon the percentage. Altogether the above described relation proves that the majority of the metopical skulls is not brachycephalic. And therefore I do not agree with the statement of Anntchin that "metopical dolichocephalic skulls are relatively rare." This conclusion, moreover, does not agree with the results of the investigation of Bryce who, among his material of Scottish skulls, only met with two brachycephalic crania. Yet in another way the eventual influence of a persisting metopical suture upon the shape of the skull may be verified, namely in
 +
 +
 +
 +
32 L. BOLK
 +
 +
comparing the average index cephalicus in normal and metopical skulls. In doing so the following averages were found. That of the total number of 1400 skulls amounted to 78.3 and that of the 134 metopical skulls, 78.9. This difference is such an insignificant one that it does not prove anything as to a supposed more brachy cephalic character of metopical skulls. And the average index cephalicus is such a low one that it by no means justifies the opinion that brachycephaly is a characteristic of metopical skulls, or that metopism in general is favorable to the formation of brachycephalic skulls.
 +
 +
Finally I wish to advance still another proof of the absence of any relation between the shape of the skull and the persistence of a frontal suture. Among the 1400 skulls there were 23 with the very low index cephalicus of 71, an indication of a very narrow skull. And among the 134 metopical skulls, five were found with the mentioned low index. This fact demonstrates clearly that metopism occurs even frequently in skulls which are dolichocephalic in high degree.
 +
 +
It is well known that for the characterization of a skull its index cephalicus is a very insufficient indicator, because for instance the height of two crania with quite the same index can differ considerably, or the curvatures of the calvarium can be very dissimilar. And finally this index furnishes not a single indication as to the absolute dimensions of the skull, a very large and a very small skull may have an equal index cephalicus. Hence a comparison of this index in regard to persisting metopical sutures is a very insufficient means of recognizing the existance of an eventual relation between the shape of the skull and the frequency of metopism. It is necessary to prosecute our investigation in still another direction.
 +
 +
First we will examine whether the three principal dimensions of the skull in average are different in normal and metopical crania. A comparison of the sum of these averages in both groups of skulls will enable us moreover to answer the question whether it is true that metopical skulls commonly are larger, including a heavier brain than nonmetopical crania.
 +
 +
 +
 +
ON METOPISM
 +
 +
 +
 +
33
 +
 +
 +
 +
In the next table the averages are dealt with of the three principal dimensions of the 134 metopical skulls and of the total number of 1400 skulls.
 +
 +
 +
 +
 +
 +
.WERAGE LENGTH
 +
 +
 +
AVERAGE BREADTH
 +
 +
 +
AVERAGE HEIGHT
 +
 +
 +
134 metopical skulls
 +
 +
1400 skulls.:
 +
 +
 +
182 183.3
 +
 +
 +
144.8 143.8
 +
 +
 +
128.4
 +
 +
128.6
 +
 +
 +
 +
The height of the skull was measured from the bregmapoint to the casion.
 +
 +
As is clearly shown by the table, the height of metopical skulls does not differ from the usual measure, for a decrease of 0.2 mm. is of no consequence. Regarding this dimension it is certain that there exists no preponderance in metopical skulls. And also the two other dimensions scarcely testify in favor of such a supposition. For though it is true that metopical skulls average 1 mm. broader than normal skulls, their length, on the contrary, is a somewhat smaller one. The metopical skulls seem to be shorter and broader than normal skulls. But the differences are so insignificant that the capacity of metopical skulls equals that of crania with united frontal bones. And an equality of capacity includes an equality of brain weight.
 +
 +
Thus it is obvious that neither in the shape, nor in the absolute dimensions is there a striking difference between the two groups of crania. In this regard the results of my investigation does not agree with that of some other authors. The metopical skulls which I examined were not more brachy-cephalic and were not larger than the normal skulls with which they were compared. And not without reason I consider the results of my own researches to be of a greater value than the contradictory results of some other investigators. For the 134 metopical skulls belonged to the same group as the non-metopical with which they were compared, the whole collection originating from one source. And this was not always the case with the material used hitherto by other investigators.
 +
 +
The result of my research does not harmonize with the alreadjmentioned views upon the cause of metopism. I summarize that
 +
 +
THE AMERICAN JOURNAL OF ANATOMY, VOL. 22, NO. 1
 +
 +
 +
 +
34 L. BOLK
 +
 +
a heightened intracranial pressure during growth due to a greater development of the brain, is considered to be the cause of metopism. Now, I cannot agree with this opinion, for as clearly shown in the foregoing pages, metopism is independent of the shape as well as of the size of the skull. And if there really existed some relation between the degree of development of the brain and the frequency of metopism, one should expect among the largest skulls an increased number of metopical specimens and higher average values of the mean dimensions in metopical skulls. This is not at all the case. The averages of the three dimensions in metopical skulls are nearly the same as in the nonmetopical. Therefore a noticeable difference between the capacity of both groups of skulls cannot be accepted, and consequently the average weight of the brain must be the same.
 +
 +
An objection of more general theoretical nature against the current opinion about the etiology of metopism may be adduced. Is it really true that an increase of the intracranial pressure may prevent the coalescence of two bones of the skulls whose normal fate is to unite together? Martin, the renowned anthropologist, accepts this view, founding his opinion upon hydrocephalic skulls, in which, as he says, metopism is a common phenomenon.
 +
 +
I do not know how far this statement of the painstaking investigator is based upon observations by himself, or is merely the expression of a doctrine propagated in craniological literature. I am inclined to believe the latter. For the experience gained by myself upon this matter is in contradiction with the idea mentioned. There is no concurrence of hydrocephaly and metopism, hydrocephaly being not at all a condition propitious for the persistance of the frontal suture. I have examined carefully the hydrocephalic skulls present in the anatomical Museum of Amsterdam, and the results of this investigation are dealt with in the next table. This table informs us of the state of the frontal suture the horizontal circumference of the skull and the age. With regard to the circumference it may be remarked, that in normal Dutch skulls it amounts to 516 mm.
 +
 +
 +
 +
ON METOPISM
 +
 +
 +
 +
35
 +
 +
 +
 +
NO.
 +
 +
 +
CIRCUMFERENCE
 +
 +
 +
AGE
 +
 +
 +
SUTURA FRONTALIS
 +
 +
 +
 +
 +
m m .
 +
 +
 +
peats
 +
 +
 +
 +
 +
1
 +
 +
 +
684
 +
 +
 +
8
 +
 +
 +
Disappeared
 +
 +
 +
2
 +
 +
 +
673
 +
 +
 +
20
 +
 +
 +
Disappeared
 +
 +
 +
3
 +
 +
 +
616
 +
 +
 +
32
 +
 +
 +
Existing. Sut. sagittalis entirely closed
 +
 +
 +
4
 +
 +
 +
600
 +
 +
 +
adult
 +
 +
 +
Disappeared
 +
 +
 +
5
 +
 +
 +
582
 +
 +
 +
adult
 +
 +
 +
Disappeared
 +
 +
 +
6
 +
 +
 +
570
 +
 +
 +
5
 +
 +
 +
Disappeared
 +
 +
 +
 +
By this table it is clearly shown that the assertion that hydrocephaly regularly is accompanied by metopism, is a false one. Only in the third case the suture was still open. But it is a question whether in this case the presence of the suture was due to supposed mechanical influence of .the hydrocephaly. For as mentioned in the table, in this case the sagittal suture was already entirely closed. And this fact justifies the supposition that in this case the skull was a metopical one by inheritance, in which therefore the suture also should have persisted, if the development of the brain had been quite normal. But, I admit, this to be a mere supposition, although I believe that this case may scarcely be accepted as a proof that metopism is caused by hydrocephaly. It seems better to disregard this case in a discussion of this matter. Furthermore the other data of the table afford a strong proof against the existence of such a casual relation. The first two crania are of an extraordinary size, with a circumference met with rarely, even in hydrocephalic skulls. Surely in both individuals the intracranial pressure must have been an excessive one. And notwithstanding this circumstance the frontal sutures vanished without leaving a single trace. And the same occurred in the other cases mentioned in the table.
 +
 +
I believe the data of this table to be sufficient to justify my statement, that hydrocephaly by no means produces, as a rule, metopism. Hence it seems to me an error to pretend that an increased intracranial pressure — caused by a marked development of the brain — is the cause of metopism. For, if the considerable increase of this pressure, as surely occurred in the skulls
 +
 +
 +
 +
36 L. BOLK
 +
 +
of the first two individuals of the table, was unable to prevent the coalescence of the two frontal bones, it is wholly unthinkable that a somewhat increased development of the brain will suffice to prevent these bones from uniting.
 +
 +
One may advance still another more weighty question with regard to the influence of the growing brain upon the skull. It is assumed that the pressure exercised by the growing brain upon the inner surface of the skull rises, when the brain is developing in a greater degree. Is this assumption true? I do not believe it. It seems to me more probable that with regard to the expansion due to their grow^th, the brain and the skull form one entity, the same hereditary factors determining the growth intensity of the brain as well as of the cranium. I do not believe that the dilatation of the latter is a mere mechanical phenomenon, depending on the pressure exercised by its contents. To some degree this may be the case in pathological circumstances, as in hydrocephaly or in premature closure of some suture or other, but under normal circumstances, I believe the intracranial pressure always to be the same, varying only between its physiological limits.
 +
 +
As a further argument in favor of the assumed influence of the growing brain upon the expansion of the skull, the fact is advanced that the forehead in metopical skulls is broader than in those with normal closure of the frontal suture, this increase of the transverse frontal measure being another result of the more strongly developing frontal lobes of the brain. Without doubt, the observation made f. i. by Welcker and Papillante is right, and I am able to confirm the same, the metopical skulls of my collection having an average breadth of the forehead of 99.7 mm. and the nonmetopical one of 96.5 mm. But I cannot agree with the interpretation of the phenomenon given by the above mentioned authors. I think in this matter they are confusing cause and effect. The difference may be elucidated in the following way. If the frontal suture does not disappear during the second year, the apposition of bony tissue in it is continued during a longer space of time than in case of its disappearance in the normal way, and therefore there is a very favorable
 +
 +
 +
 +
ON METOPISM 37
 +
 +
opportunity for the forehead to grow broader than usual. It seems therefore quite reasonable that in metopical skulls the forehead is broader, this being the natural consequence of the fact that the growth-centrum remains longer in an active state.
 +
 +
With regard to the problem of metopism, observations as well as theoretical considerations have convinced me, that the common opinion about the aetiology of this phenomenon is an erroneous one. As to the facts, I have been unable to confirm the existence of any relation between metopism and a particucular shape of the skull, the frontal suture persisting in dolichocephalic crania as frequently as in brachycephalic ones, and the index cephalicus being in average equal in metopical and nonmetopical skulls. Furthermore, the metopical crania of my collection were not larger than the normal specimens, consequently the average of the brain-weight should be equal in both groups. There is but one fact which I was able to confirm, namely the greater breadth of the forehead in metopical skulls, a phenomenon easily understood as a logical consequence of the protracted activity of the frontal suture.
 +
 +
And as to the theoretical side of the problem, I do not agree with the current opinion that metopism is caused by an increased intracranial pressure, the result of a greater development of the brain. First, because the least indication of such an increased development is wanting, and secondly because in pathological cases, as in hydrocephaly, in which undoubtedly the intracranial pressure had considerably risen, the frontal suture disappears as in normal circumstances.
 +
 +
Before entering into an explanation of my views upon the aetiology of metopism, I wish to discuss briefly the argument that metopism is less frequent in the lower races. As mentioned in the introduction to this paper, this fact is utilized as a proof that metopism, caused by a larger expansion of the brain, should be a symptom of higher intelligence. I think this opinion cannot withstand a serious analysis. If one accepts the principle that metopism is a symptom of intellectual superiority as true, because it is more frequent in culture races, than in uncivilized ones, one must accept also the consequence of this principle, that
 +
 +
 +
 +
38 L. BOLK
 +
 +
amongst the culture nations those are psychically the most favored in which metopism is the most frequent. Now in the middle region of the continent and in Russia metopism occurs in about 6.5 per cent, according to Schwalbe, Ranke, Gruber and others. In the northern part of Europe, the phenomexion is more frequent, and attains 9.5 per cent according to Bryce, Simon and myself. In Frisians, occupying the northern region of the Netherlands, metopism amounts even to 11.4 per cent. Though the acceptance of the principle should be very flattering for the Dutch people, I do not accept its exactness, metopism having nothing to do with intelligence. I think the interpretation of the different frequency of metopism in the inhabitants of the central and the northern region of the continent to be this : that it is simply a racial difference, the phenomenon occurring more frequently in the Homo nordicus than in the Homo alpinus.
 +
 +
• The opinion that the difference in frequency of metopism in the human race is a mere physical anthropological character also holds good with regard to a comparison of civilized and uncivilized races. In the former, metopism is commonly very rare. What may be the reason of it? The authors, who hold that the metopism is the result of an increased intracranial pressure, caused by a somewhat hypernormal growth of the brain, adduce this difference as a proof of the exactness of their doctrine, obviously supposing that such a hypernormal growth does not occur in uncivilized races. In this argument there is a very obvious mistake. Surely the average weight of the brain is a lower one in uncivilized races. But the individual weight of the brain differs in uncivilized races as well as in culture races. Not only among white men, but also among Negroes and Papuans there are individuals with sub-normal, normal and hypernormal volume of their brain. And if really a strongly developed brain should cause an increased pressure upon the. inner surface of the skull, this condition is realized as well in a Papuan with, a hypernormal development of his brain, as in an European. Nevertheless in Papuans and Negroes, metopism is rare. I consider this a further proof that the persistence of the frontal suture
 +
 +
 +
 +
ON METOPISM 39
 +
 +
has nothing to do either with brain development, or with the higher or lower degree of intellectual evolution.
 +
 +
Now I wish to express my opinion upon the aetiology of metopism. In the introduction to this paper a brief account is given of the phylogenetic history of the frontal suture, principally in Primates. I summarize that among the Prosimiae in some families the frontal suture, as a rule, persists, while in others, on the contrary, it disappears. In monkeys both frontal bones unite together at a very early stage of development, but in some individuals the suture may persist. In Anthropoids till now the suture has never been seen in an adult specimen. This summary shows that in the course of the phylogenetic evolution of man, originally both frontal bones remained separated; thereupon in the higher degree of evolution the bones coalesced, and finally in man the primitive state presents itself again in a number of individuals. These facts form the basis for a conception of the aetiology of metopism differing from those previously advanced. For it seems to me necessary to begin by discovering the cause which caused the suture to disappear in monkeys. Having elucidated this point, we have approached more closely to the solution of the metopical "problem in man. For the possibility must be taken into consideration that the influences which were acting on lower Primates and caused the concrescence of the two frontal bones, have lost their significance and activity in man. If this really happened, it is quite comprehensible that the frontal suture reappears. For in each individual both frontal bones arise separately, the bilateral condition being the rule in the younger stages of development even in such forms in which the individual is born with an already single frontal bone. The metopical suture in an adult individual hence represents no new condition, no alteration of a primitive state, but simply the continuation of an original condition. There must be a special cause for a union of the bones whereas there is no new factor required for the explanation of the fact that they may remain separated. Let us therefore try to find out the primary cause of the concrescence of the frontal bones in monkeys, afterwards we can examine whether this cause became inactive in man or not.
 +
 +
 +
 +
40 L. BOLK
 +
 +
It is a well established fact that the shape of a bone and especially its internal structure, are the results of the mechanical and muscular forces acting upon it. In accordance with the mechanical principle of securing the maximum of strength with the minimum of material, the cancellous tissues of each bone is so arranged as best to withstand the strains and stresses to which the bone is usually subjected. So the internal architecture of each bone is quite in accordance with the fundamental laws of physics; systems of 'pressure lamellae' running in definite direction are crossed by sets of 'tension lamellae.' A great number of investigators have tried with good results to analyze the structure of the different bones of the human skeleton from this point of view. Only in regard to the skull in general, and particularly the cranial vault, are we without definite knowledge as to the structure of the bony framework of the different bones of the skull and the relation between the statical and dynamical external forces to which it is subjected. The whole of our knowledge is confined to the fact that the structure of the plate-like bones of the cranial vault exhibits the following appearance : the outer and inner surfaces are formed by two compact layers, having sandwiched between them a layer of cancellous tissue.
 +
 +
Nevertheless concerning the cranial vault we find ourselves under relatively favorable circumstances, because the general conditions are so very simple here that the problem can be elucidated sufficiently from a mere theoretical standpoint. For the function of the cranial vault being principally a protective one, the number of mechanical stresses to which the frontal half of the skull is subjected is slight. There are but two factors to take in consideration, namely the weight of the facial cranium with the soft parts of the face as a constant working factor, and the pressure effectuated by the temporal muscle during its contraction. The weight of the facial cranium is transferred surely for the greatest part by means of the zygomatic arches to the middle of the base of the cranium, and so there remains as the only important external force acting upon the anterior and lateral part of the skull, the pressure of the temporal muscles, when the jaws are firmly closed. Surely this
 +
 +
 +
 +
ON METOPISM 41
 +
 +
stress will determine the arrangement of the cancellous tissue in the frontal bone. And the variations in the arrangement and the course of the pressure and tension lamellae in different animals, without doubt is caused by the variable relation between the frontal bone and the Musculus temporalis. If the muscle arises largely from the frontal bone the internal structure of the anterior region of the cranial vault will be largely influenced by the same. It is obvious that in such a case the frontal and sagittal suture are primarily subject to this influence, as their course is perpendicular to that of the fibers of the muscle.
 +
 +
I think this idea is sufficient to demonstrate why in lower Primates the frontal suture persists, while in the higher Primates it regularly disappears. For the stress of the masticatory muscles tends to compress the skull in a transverse direction and the vault of the skull will withstand this force by a system of trajectories, running on a frontal plane. Now it is not difficult to understand that it is of advantage that the trajectories do not meet with an open suture in their course. And so the fate of the metopical suture in Primates will depend upon the topographical relation between the temporal muscle and the frontal bone. If the muscle arises from the frontal bones a system of pressure and tension lamallae will be developed in it crossing the median line and hence necessitating the union of the tw^o primary frontal bones. If on the contrary, the bone remains free from the dynamical influence of the muscle, there is no reason for the union of the two bones.
 +
 +
In figure 1 an attempt is made to elucidate the above described idea by means of a very simple scheme. It represents a frontal section of the anterior part of the vault of the skull, wdth the temporal muscle on both sides. The direction in which the vault will be narrowed by the stress of the contracting muscle is indicated by two arrows. It is obvious that in order to withstand this stress pressure trajectories will be developed in the vertical parts of the vault, under the direct influence of this force. The compression in the indicated direction will produce a tension in the top of the vault. And while in the vertical parts of it the cancellous tissue will arrange itself in pressure
 +
 +
 +
 +
42
 +
 +
 +
 +
L. BOLK
 +
 +
 +
 +
lamellae, on the top a system of tension lamellae will arise. In the figure both systems are represented by some simple lines. I admit it is a purely theoretical construction, which I have tried, however, to bring in accordance with the principles of mechanics. The point upon which I will lay some stress, is that the tension lamellae necessarily must cross the median plane. And because an interruption in their course by a suture would be contrary to their mechanical function, the two frontal bones unite together. Now we will examine in how far the anatomical conditions in the different Primates agree with the principles worked out above.
 +
 +
It is needless to give a long description of the anatomical conditions in several specimens, for the inspection of some few
 +
 +
 +
 +
 +
crania suggests the regularity in the special groups of the Primates. I will confine myself therefore to treat each group as a whole.
 +
 +
The examination of the prosimian skull shows that in this lowest group of Primates the frontal suture is a constant element in the system of sutures, disappearing nearly at the same time as the other sutures. I regret to have at my disposal only a small number of skulls of prosimiae. Hence it is impossible for me to give a summary of the age at which the metopical suture disappears in the different genera of this group of Primates. The small number of skulls in my possession indicate that a considerable variability exists as to this point in the different genera of the Prosimiae. So I found among five adult skulls of Lemur only one specimen with the system of sutures still wholly
 +
 +
 +
 +
ON METOPISM 43
 +
 +
intact, including the metopical suture. In the others the system had completely disappeared. In three adult crania of Avahis on the contrary, apparently of old individuals, all sutures including the metopical, were still present, and so it was in two old crania of Nycticebus. It thus seems that the sutures in Prosimiae close at a very different stage in the different genera of this family. But for the present it suffices to know that the disappearance of the metopical suture takes place simultaneously with that of the other elements of the system. There is no special factor necessitating the same to close at an earlier period than the other sutures. In this respect the Prosimiae differ from the monkeys and apes in which the closure of the frontal suture always precedes those of the other sutures, and often very considerably. From this we may conclude that the influence compelling the metopical suture in monkeys and apes to disappear, is absent in Prosimiae. Now a comparison of the topographical relations between the temporal muscle and the frontal bone in the lower and higher Primates, reveals that in Prosimiae the muscle does not arise from the frontal bone at all. The reason for this is obvious. In Prosimiae the lateral wall of the orbit is a very incomplete one, and frequently also the floor of this fossa is restricted to a foremost part. As a rule the outer wall only is represented by an arch extending from the facial root of the zygomatic arch to the parietal margin of the frontal bone. This insertion of the orbital arch at the hindermost border of the frontal bone causes the latter to be situated completely in front of the temporal fossa, hence the temporal muscle cannot extend its origin forward upon the frontal bone. In monkeys, as in apes and man, the outer wall of the orbit is a complete one, formed partly by the orbital surfaces of the zygomatic bone and the great wing of the sphenoid bone. By this outer wall the orbit is separated almost completely from the temporal fossa and the plane of entrance of the orbit is considerably turned. In Prosimiae the inclination of the latter is more a lateral than a frontal one, the axis of the orbit making a more open angle with the median plane. But in monkeys the plane of entrance is turned, being directed principally forward and but slightly out
 +
 +
 +
44 L- BOLK
 +
 +
ward. The axis of the orbital fossa is making therefore a more acute angle with the median plane. In consequence of the rotation of the plane of entrance of the orbit, the insertion of the primitive orbital arch at the frontal bone was shifted from the hindermost border of the bone forward, so that a part of the outer surface of the frontal bone is added to the temporal fossa. By this enlargement of the fossa the temporal muscle was enabled to arise to a smaller or greater extent from the frontal bone.
 +
 +
The differences between Prosimiae and the higher Primates are clearly shown by the figures 2 to 9. In these figures the lateral and superior view of some prosimian and simian skulls is drawn. The course of the main sutures and also the extension of the temporal muscle is indicated. Figures 2 and 3 represent lateral views of the cranium of Avahis sinavensis and of Stenops gracilis respectively. In both it is obvious that the frontal bone is completely excluded from the temporal fossa, and that there are no fibers of the temporal muscle arising from this bone. Hence it is easy to understand that in those crania the frontal suture persists, as is shown in figure 4, representing the superior view of the skull of an Avahis niger. The frontal bone remains free from the dynamical influence of the temporal muscle, its anatomical significance is a restricted one. It functions only as roof of the orbits and the foremost narrow part of the cavity of the skull. In consequence of the absence of forces acting upon this bone, its system of trajectories cannot be strongly developed. Hence there is no reason for both frontal bones to unite.
 +
 +
Quite the contrary happens in the skulls of monkeys from the Old and New World, as is illustrated by figures 5, 6, 7, and 8. Figure 5 represents a side view and figure 6 a superior view of the skull of Chrysothrix, a platyrrhinic monkey, figure 7 a side V ew of the skull of Macacus, and figure 8 such a one of a female Gorilla. The extension of the temporal muscle and the course of the sutures in the cranial vault are drawn. These figures require but little comment. In all it is clear that the frontal bone participates in the formation of the temporal fossa, and that no small part of the temporal muscle takes origin from this bone.
 +
 +
 +
 +
ON METOPISM
 +
 +
 +
 +
45
 +
 +
 +
 +
 +
46 L. BOLK
 +
 +
In Macacus and Gorilla the origin of the muscle reaches to the median line, so that there is but a small triangular part of the outer surface of the bone uncovered by the muscle, while in Chrysothrix a narrow strip on both sides of the median line remains free from the origin of the muscle. It requires no special argument to show that the forces executed by the contracting muscle upon the frontal bone must give rise to a system of trajectories in it, able to withstand the strains on its outer surface. And it is important to draw attention to the fact that the fibers of the muscle are directed perpendicularly to the median line and consequently also with regard to the frontal suture, the forehead being directed horizontally immediately behind the superciliary arch. This condition surely favors the formation of trajectories crossing the median line and causing the frontal suture to disappear, as really occurs in all monkeys and apes. In man the condition is greatly changed, though a small part of the frontal bone is still participating in the formation of the temporal fossa, as shown in figure 9. There are two circumstances by which the relation between the temporal muscle and the frontal bone became altered from that obtainmg in monkeys. Firstly, the frontal bone in man is much larger, and the surface of it occupied by the origin of the temporal muscle is considerably smaller in man than in apes. The pressure of the muscle upon the outer face of this bone in man cannot be a very strong one, hence its influence upon the inner structure surely is of little importance. In this respect the condition in man is getting closer to that in Prosimiae.
 +
 +
The second circumstance peculiar to man is the well-pronounced curve of his frontal bone. By this curve the greater part of this bone rises vertically above the orbits. In apes, as pointed out, the fibers of the temporal muscle are directed perpendicularly to the whole length of the fronta^ suture. In man th's condition is altered, for in consequence of his strongly curved forehead the greater part of the frontal suture is situated in front of the anterior border of the temporal muscle, and moreover is directed nearly parallel to this border.
 +
 +
 +
 +
ON METOPISM 47
 +
 +
By these two circumstances the frontal suture in man becomes independent from the dynamical influence of the temporal muscle. Hence in man there is a return to the conditions as met with in Prosimians, though the anatomy of the skull and the muscles is quite different. The mechanical cause for the disappearance of the suture in monkeys having fallen out, the circumstances become very favorable to the persistence. Now it is obvious that these conditions act most favorably in individuals with a more prominent forehead and a less pronounced development of the masticatory musculature. In the white race therefore, the possibility for the persistance of the suture is far greater than in the races with a more flattened forehead, a higher development of the dentition and of the temporal muscle. And this may be considered the cause, accounting for the fact that commonly metopism is more frequent in Europeans than in Negroes or Australians.
 +
 +
 +
 +
ON THE FREQUENCY OF LOCALIZED ANOMALIES IN HUMAN EMBRYOS AND INFANTS AT BIRTH
 +
 +
FRANKLIN P. MALL
 +
 +
EIGHTEEN' riGTRES
 +
 +
111 a paper published nine years ago on the causes underlying the origin of human monsters, I made the assertion that localized anomalies were more common in embryos obtained from abortions than in the full term fetus, without, however, adducing conclusive evidence in support of this theory. ^
 +
 +
In a footnote on page 27 of that publication I gave a list of embryos with their chief defects, comparing them ^\dth the percentage of frequency of monsters born at full term. An objection to be raised to such a statement is the fact that there is not a complete correspondence between anomalies in the embryo and those found in the fetus at the end of pregnancy. For instance, spina bifida in young embryos is always complete while at full term the open canal is covered over with skin. Cyclopia and exomphaly are the same in the embryo as at birth, but the deformities of the head and neck of the embryo are of such a nature that it cannot live long enough to admit of comparison with like malformations found at term. With these difficulties clearly before me, I have made an effort to define sharply the anomalies in embryos, so that a satisfactory comparison might be made with those found in monsters at the end of pregnancy, as described in the literature.
 +
 +
I shall mention first cyclopia, for it seems to me that it is the type of monster which is now best understood. This clearer conception is due largely to the excellent experimental work of Stockard, and partly to the fact that the cj^clopean state can exist quite independently of other marked deformities of the
 +
 +
^ Mall, F. P. A study of the causes underlj^ing the origin of human monsters. Jour. Morph., vol. 19, 1908.
 +
 +
49
 +
 +
THE AMERICAN JOUnXAL OF ANATOMY, VOL. 22, NO. 1
 +
 +
 +
 +
50 FRANKLIN P. MALL
 +
 +
onihryos. T haAo pi-fniously discussed tho rjuostion of cyclopia in a sr])ai'at(^ puhlicatiou, and it is not therefore necessary for me to dilate further ui)on it at ])resent."- Hare lip is also sharply defined in the embryo and is as readily recognized as exomphaly. Other anomalies, however, are more difficult to recognize as sharply defined malformations in the embryo.
 +
 +
We have in our collection about 2000 embryos. The pathological specimens of the first 400 were reported in my paper on the origin of human monsters mentioned above. Since the collection was taken over by the Carnegie Institution of Washington, it has gTown at a very rapid rate, about 400 specimens being added to it each year. I have in preparation a more extensive study of pathological embryos, and during the past year have practically completed a careful study of the first thousand. While this was in progress, another thousand specimens were added to the collection. At present, however, only the first thousand will be considered, the remainder not having been sufficiently tabulated to be of statistical value.
 +
 +
We have introduced and are gradually perfecting a system of classification of the embryos which will enable us to locate any specimen in our collection and the record thereof by means of a card catalogue. Reasons for adopting this S3stem were given in a circular recently published.-^ The specimens can clearly be divided into two groups according to their origin, i.e., uterine and ectopic. In both of these, the embryos which are normal in form are catalogued according to their sitting height, which we call crown-rump (CR). All embryos therefore which are apparently normal, say 10 mm. long, are entered upon one card. What happens to these specimens subsequently, whether they are dissected, sectioned or preserved permanently as whole specimens, may also be entered upon this card without interference with the system of classification. The chief difficulty is to determine what constitutes a normal embryo, and
 +
 +
- Mall, F. P. Cyclopia in the human embryo. Contributions to Embryology, vol. 6, Publication No. 226, Carnegie Institution of Washington, 1917.
 +
 +
^ Mall, F. P. Embryological collection of the Carnegie Institution, Circular No. 18, 1916.
 +
 +
 +
 +
LOCALIZED ANOMALIES IN HUMAN EMBRYOS 51
 +
 +
here we must rely largely upon our experience in human and in comparative embryolog3^ A sharply defined, well formed white embryo, with blood vessels shining through its transparent tissues, is considered normal. If it is partly stunted and opaque or disintegrating, it is considered pathological. A further study of the normal embryo, however, shows that in many of these specimens the membranes are decidedly pathological. For instance, the villi may be deformed, diseased, atrophic or hypertrophic, or the contents of the amnion and the exocoelom may be unusual. Nevertheless, in all of these cases we still classify the embryos as normal, although fully cognizant of the fact that the surrounding membranes are pathological; otherwise it would be difficult to account for the great number of spontaneous abortions. The theory is that the embryo was developed under pathological conditions, but that the chorion was not sufficiently affected to cause any apparent change in the embryo. If an embryo included in this group is apparently normal in all respects save one, we still consider it normal with a localized anomaly. In fact we are gradually forced into this position, as an embryo, considered at first to be normal, may later on prove to have a localized anomaly, such as spina bifida or cyclopia. As far as we can determine, such an embryo would have been able to sur\'i\'e longer had not something happened to its membranes, thus causing its expulsion. I am inclined to believe that pregnancies of this sort, if carried to term, would produce the ordinary monsters described by teratologists. As the study of our collection of specimens is continued by different members of the staff, localized anomahes, wlien found, are recorded in our card catalogue, without, as stated above, necessitating any rearrangement. WTien these anomalies are present in normal embryos, the embryos are classed as normal, with localized anomalies.
 +
 +
The second group of specimens, which are termed pathological, are in a way more interesting, and their study justifies our method of classifying localized anomalies with normal embryos. We have in this group a variety of changes ranging from those found in fetus compressus down to complete disin
 +
 +
 +
52 FRANKLIN P. MALL
 +
 +
tegratioii of the ovum, leaving only a few villi. Having made numerous efforts to classify these s]ieeimens, I have finally lesolved them into seven groups which I shall consider in their reverse numerical order.
 +
 +
The seventh group, shown in figure 7, is composed mostly of larger specimens which are either dried up and deformed, or macerated and soft. These, of course, apparently merge into each other, and for this reason we have had to consider them as a single group. We hope, however, in the course of time to be able to subdivide them, for it is well known that fetus compressus is extremely rare in pigs and other lower animals, w^hile edematous and macerated embryos are quite common. It appears that the type of fetus in this group develops as a normal embryo during the first portion of pregnancy, and then dies slowly, either undergoing maceration, or being transformed into a fetus compressus. In the latter the cord is long, thin and greatly twisted The structures of the embryo show that there has been a slow^ tissue growth w^hich has not been sufficiently rapid to allow the normal development of the extremities. Instead the hands and feet are club-shaped, and in several instances there are adhesions beween the extremities and the body We also find very pronounced and quite characteristic changes in the placenta of the fetus compressus, there being bcw^een the villi lage masses of chromatin substance presenting much the same picture as the photograph of a comet, a central nucleus with scattered granules extending from it. Generally in our notes we speak of this substance as nuclear dust.
 +
 +
The sixth group of specimens we term stunted (fig. 6). The form of the embryo is easily recognized, but the head is atrophic as are also usually the extremities. At the time of the abortion the tissues are quite transparent, giving every appearance of a living embryo, but with, increasing knowledge concerning tissue cultures and growing isolated cells, we can see in specimens of this sort an active but circumscribed tissue culture of a clump of differentiated tissues. In other words we have a tissue culture of the entire embryo, w^hich on account of faulty or arrested circulation, growls in an irregular manner. Changes
 +
 +
 +
 +
LOCALIZED ANOMALIES IN HUMAN EMBRYOS 53
 +
 +
of tliis sort ill an embryo I have designated in my paper on monsters as a dissociation of the tissues. I picture to myself something Hke the following sequence: when the ovum comes into the uterus which is more or less diseased, it becomes somewhat poisoned and consequently does not implant itself well. This naturally results in an irregular growth of the chorionic villi; in turn the embryo is affected and it is only natural to infer that the most direct influence would be through the vascular system, soon ending in poisoning of the heart and frequently in the interruption of the circulation. In such specimens the nutrition would reach the embryo through the exocoelom. In fact one of the earliest indications of a pathological specimen is an increased amount of magma in the exocoelom. Embryos, which are thus cut off from the chorion, continue to grow in an irregular manner; the tissues are more or less dissociated, and the specimen as a w^hole is stunted. Hence the designation.
 +
 +
In the fifth group (fig. 5), the process of stunting has progressed to such an extent that the extremities are almost entirely lacking and only the head end can be recognized with certainty. On account of their shape, due to this extreme stunting, we speak of these specimens as cylindrical embryos. Falling frequently into this group are embryonic remnants which, however, really do not belong there, since a primary examination with a binocular microscope does not permit of a sharp differentiation between this and other cylindrical forms of stunted embrj^os. Close examination wdth a microscope reveals specimens of this sub-group to be, composed of a naked umbilical cord belonging to an older embryo which had disintegrated, or as seen in a few instances the embryo has been torn off by mechanical means during abortion. As rapidly as the sub-type is recognized, it is labeled in the card catalogue in parenthesis (cord) so that in stud^dng these specimens we may distinguish between the naked cords and the true cylindrical forms of pathological embryos.
 +
 +
\Mien the process of dissociation of the embryo begins in still earlier stages than those belonging to the older groups (Xos. 0, 6, and 7), the result is a nodular body representing the embryo,
 +
 +
 +
 +
54 P^KANLKIN P. MALL
 +
 +
Imt tho cliango in it is so complete that it is difficult to recognize the diffei'cnt ])arts of the embryo except in a general way (fig. 4). The coelom, heart and central nervous system can readily be made out. Sometimes there are pigmented spots in one or two of the sections, marking the position of the eyes. This group again divides into two quite sharply circumscribed sub-groups: first, those with an umbilical cord to which the dissociated embryo is attached together ^vith the umbihcal vesicle; and second, a vesicular group composed of specimens in which there is only the remnant of the umbilical vesicle, the embryo being nearly or entirely destroyed. Had it been possible in every instance to differentiate between these two types of specimens in the primary examination, they would, of course, have been recorded as separate groups; but this could not be done without sections and a microscopic examination. Therefore, for the present we must consider them together. In our ordinary laboratory parlance we speak of them as the nodular group.
 +
 +
In the third group, both embryo and umbilical vesicle are completely destroyed, but we can see within the degenerated chorionic sac a more or less complete amnion. This group is designated as the one in which the specimens are composed only of the chorion and the amnion (fig. 3).
 +
 +
In the second group the amnion is destroyed and there remains only the chorionic vesicle containing the coelom. This is usually filled with reticular magma and scattered cells, which may represent all that is left of the embryo (fig. 2).
 +
 +
Finally in the first group the form of the ovum is destroyed and the specimen consists only of the \dlli which have undergone fibrous or mucoid degeneration. Sometimes only a few of the \dlli are found, at other times there is a large cluster clinging to a single stem, and some specimens are composed of large masses of villi which form malignant hydatidiform moles. Such a mass may weigh a kilogram (fig. 1).
 +
 +
It can be readily seen that the above classification into subgroups is arranged somewhat in the order of the age of the ovum when it began to degenerate. Generally these changes are so pronounced that the embryo cannot live through the duration of pregnancy and this accounts for the abortion.
 +
 +
 +
 +
LOCALIZED ANOMALIES IN HUMAN EMBRYOS
 +
 +
 +
 +
DO
 +
 +
 +
 +
As far as localized anomalies are concerned, we naturall do rot find them in the first four groups, while in the remaining three groups we encounter only such as are very pronounced and stand out clearly in spite of other changes in the emtryo.
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
 +
Fig. 1 lllustratinji (Jroup 1, composed exclusively of villi. Specimen Xo. 749 received from Dr. G. C. McCormick. Sparrows I'oint, Md. X 2. These hypertrophic villi came from a hydatiditorm mole weighing over a kilcgr: m.
 +
 +
Fig. 2 Illustrating Group 2, chorion with coelom. No. 12S9 from Dr. J. R. Cottell, Louisville, Ky. X 2. The picture shows the coelom filled mostly with granular magma.
 +
 +
Fig. 3 Illustrating (jroup 3. chorion with amnion. Xo. 813 from Dr. H. D. Taylor, Baltimore. X i The cavity of the ovum is filled with a dense mass of granular magma.
 +
 +
 +
 +
5G
 +
 +
 +
 +
FRANKLIN P. MALL
 +
 +
 +
 +
Thus, for instance, with fetus compressus we frequently recognize club-foot; in stunted forms, hare lip and spina bifida, and in cyUndrical forms, spina bifida. Of course, if cyclopia is encountered in any of these forms, it is looked upon as a localized anomaly in a pathological embryo. On the other hand, a single anomaly in an embryo called normal can easily be recog
 +
 +
 +
 +
 +
4
 +
 +
1 ig. 4 Specimen illustrating Group 4. The ovum contains a nodular embryo; Ko. 1140b from Dr. George T. Tayler, Greenville, S. C. X U Fig. 5 Illustrating Group 5. Ovum containing a cylindrical embryo; No. 839 from Dr. W. S. Miller, Madison, Wis. X li
 +
 +
nized, and it is from this group that we should expect the development of monsters had the pregnancy progressed to term.
 +
 +
A few illustrations of localized anomalies are given in the figures in order to show that they are identical with those found in infants at birth. Figures 8 and 9 are specimens of cyclopia and double monsters in normal embryos. Figure 10 a and
 +
 +
 +
 +
LOCALIZED ANOMALIES IN HUMAN EMBRYOS
 +
 +
 +
 +
57
 +
 +
 +
 +
10 b show an embryo and a fetus with hare lip. Figure 11, 12 and 13 have pronounced localized anomalies and need no further explanation. Finally figures 14 to 18 show anomalies of the hand the first and last are of the hereditary variety, and figures 15 and 16 show acquired anomalies, that is, they were subsequentl}^ formed in an embryo which started its development normally. It is proper to remark here that these illustrations are mostly from specimens from the second thousand of our
 +
 +
 +
 +
 +
6g
 +
 +
Fig. G Group 6. Three stunted embrj-os to illustrate this group. 6a, No. 1295d from Dr. B. T. Terry, Brooklyn, N. Y. X 4. 6b, No. 1523 from Dr. G. B. Ward, Gilman, Iowa. X 2. 6c, No. 1477 from Dr. H. B. Titlow, Baltimore. X 3.
 +
 +
 +
 +
collection but this is for the reason that recently we have made many more photographs and secondly, many of the specimens in the first thousand have already been figured in my paper on monsters.
 +
 +
In order to render possible a comparison between localized anomalies found in pathological and those found in normal embryos, the following six tables have been constructed. Table
 +
 +
 +
 +
58
 +
 +
 +
 +
FRANKLIN P. MALL
 +
 +
 +
 +
1 gives the classified distribution of the first 1000 embryos in the Carnegie Collection. The primary division comprises two classes — pathological and normal. The pathological in turn is arranged in the seven groups just described. The normal are arranged in groups to correspond as nearly as possible with the
 +
 +
 +
 +
 +
7a
 +
 +
 +
 +
 +
7b
 +
 +
 +
 +
Fig. 7 Croup 7, giving two specimens of fetus compressus. 7a, No. 996 from Dr. H. B. Titlow, Baltimore, X r. 7b, No. 868 from Dr. E. H. Egbert, Washington. X 2.
 +
 +
 +
 +
ages of the embryos in lunar months. In order to define clearly which embryos belong to a given month, I have inserted their probable lengths for each month in table 6. Thus, for instance, the second month includes all specimens from 2.6 mm. to 25 mm. in length, etc. (Data upon the estimated age of embryos
 +
 +
 +
 +
LOCALIZED ANOMALIES IN HUMAN EMBRYOS
 +
 +
 +
 +
59
 +
 +
 +
 +
may be found in my chapter on the age of embryos, contained in the Manual of Human Embryology.)^
 +
 +
It will be noted in these tables that the specimens are arranged in centuries; that is, each line in the table includes exactly 100 specimens. The first century includes specimens Nos. 1 to 98, the second, Nos. 99 to 205, and so on. This adjustment was necessary for the reason that frequently a single number is given to two or more specimens. Sometimes the
 +
 +
 +
 +
 +
 +
9
 +
 +
 +
 +
Fig. 8 Normal embryo with cyclopia; in front of the eye is seen the Cyclopean snout. No. 559 from Dr. B. J. Merrill, Stillwater, Minn. X 5.
 +
 +
Fig. 9 Normal double monster. No. 249 from Prof. L. Hektoen, Chicago. Natural size.
 +
 +
 +
 +
first is called a and the second, b; or the first may be given the number, and the second the letter a, etc. The second century passing from Nos. 99 to 205 includes more than 100 numbers, because specimens which are given a number are frequently found upon further examination not to contain any remnants of the ovum, and for this reason they are to be discarded. In our catalogue they are later marked as 'no pregnancy.' Finally the full 1000 ends with embryo No. 900g. The individual entries are percentage records. Thus in the fifth century, there
 +
 +
^ Determination of the age of human embryos and fetuses. Human Embryology, Keibel and Mall, vol. 1, Chap. 8. 1910.
 +
 +
 +
 +
60
 +
 +
 +
 +
FRANKLIN P. MALL
 +
 +
 +
 +
 +
iUa
 +
 +
 +
 +
10 b
 +
 +
 +
 +
Fig. 10 Two specimens of hare lip. 10a, No. 364 from Dr. B. .1. Merrill, Stillwater, Minn. X 3. There is also exencephaly in this specimen. 10b, No. 9S2 from Dr. G. C. ^NlcCormick, Sparrows Point, Md. X 2.
 +
 +
 +
 +
 +
11
 +
 +
 +
 +
12
 +
 +
 +
 +
15
 +
 +
 +
 +
Fig. 11 Stunted fetus with a large hernia in umbilical cord, also spina liifida. No. 1330 from Dr. A. R. Mackenzie, Capitol Heights, Md. X H.
 +
 +
Fig. 12 Normal embryo with exencephaly and spina bifida (the latter opposite the arrow). No. 1315 from Dr. J. C. Bloodgood, Baltimore, X 2.
 +
 +
Fig. 13 Normal fetus with hernia of midbrain. No. 1690 from Dr. P. F, Williams, Philadelphia. X 9.10.
 +
 +
 +
 +
LOCALIZED ANOMALIES IN HUMAN EMBRYOS
 +
 +
 +
 +
61
 +
 +
 +
 +
are 41 normal specimens of the second month; that is, of this hundred, 41 per cent of the specimens are normal embryos of the second month, whereas the total for the full 1000 has been brought down this percentag;e to 24.5.
 +
 +
 +
 +
 +
14
 +
 +
 +
 +
15
 +
 +
 +
 +
Fig. 14 Anomaly of the left hand in which only the thumb and little finger are normal. No. 306a from Dr. F. A. Conradi, Baltimore. X f.
 +
 +
Fig. 15 Left hand which is club-shaped from a fetus compressus. No. 230, CR 57 mm., from the late Dr. J. P. West, Bellaire, Ohio. Natural size.
 +
 +
 +
 +
 +
Fig. 16 Deformed wrist with atrophic radius in a normal embryo. No. 789, CR 50 mm., from Dr. H. F. Cassidy, Roland Park, Aid. X 2. The same kind of wrist is seen in the specimen illustrated as figure 11.
 +
 +
Fig. 17 Right hand with six fingers from macerated specimen. No. 1749 from Dr. S. M. Wagaman, Hagerstown, Md. X 2. This specimen had six digits on all four extremities.
 +
 +
Fig. 18 Double little finger of the left hand of the same specimen. X 2.
 +
 +
 +
 +
62
 +
 +
 +
 +
FRANKLIN T. MALL
 +
 +
 +
 +
TAIiI.E 1
 +
 +
(iin'ntj llic ilixirllmtioti (if 1001) specinicin
 +
 +
 +
 +
IT.
 +
 +
 +
CATALOGUE
 +
 +
 +
PATHOLOGICAL, IN GKOUPS
 +
 +
 +
 +
 +
 +
 +
NORMAL
 +
 +
 +
i\
 +
 +
 +
MONTHS
 +
 +
 +
 +
 +
 +
 +
BS
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
NfMBER
 +
 +
 +
1
 +
 +
 +
2
 +
 +
 +
3
 +
 +
 +
4
 +
 +
 +
5
 +
 +
 +
6
 +
 +
 +
7
 +
 +
 +
"3
 +
 +
 +
1
 +
 +
 +
2
 +
 +
 +
3
 +
 +
 +
4
 +
 +
 +
5
 +
 +
 +
6
 +
 +
 +
7
 +
 +
 +
8
 +
 +
 +
9
 +
 +
 +
10
 +
 +
 +
"ci
 +
 +
 +
Ed u
 +
 +
 +
 +
 +
1
 +
 +
 +
5
 +
 +
 +
1
 +
 +
 +
6
 +
 +
 +
4
 +
 +
 +
3
 +
 +
 +
4
 +
 +
 +
24
 +
 +
 +
3
 +
 +
 +
41
 +
 +
 +
17
 +
 +
 +
8
 +
 +
 +
7
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
H
 +
 +
 +
1
 +
 +
 +
1- {'8
 +
 +
 +
76
 +
 +
 +
2
 +
 +
 +
99-205
 +
 +
 +
 +
 +
 +
g
 +
 +
 +
1
 +
 +
 +
8
 +
 +
 +
6
 +
 +
 +
13
 +
 +
 +
6
 +
 +
 +
43
 +
 +
 +
 +
 +
 +
25
 +
 +
 +
21
 +
 +
 +
7
 +
 +
 +
2
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
57
 +
 +
 +
3
 +
 +
 +
206-295
 +
 +
 +
2
 +
 +
 +
5
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
9
 +
 +
 +
11
 +
 +
 +
7
 +
 +
 +
37
 +
 +
 +
1
 +
 +
 +
24
 +
 +
 +
28
 +
 +
 +
7
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
63
 +
 +
 +
4
 +
 +
 +
296-380
 +
 +
 +
1
 +
 +
 +
7
 +
 +
 +
1
 +
 +
 +
4
 +
 +
 +
9
 +
 +
 +
16
 +
 +
 +
7
 +
 +
 +
45
 +
 +
 +
1
 +
 +
 +
21
 +
 +
 +
12
 +
 +
 +
14
 +
 +
 +
2
 +
 +
 +
2
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
55
 +
 +
 +
5
 +
 +
 +
381-476
 +
 +
 +
4
 +
 +
 +
2
 +
 +
 +
3
 +
 +
 +
4
 +
 +
 +
7
 +
 +
 +
9
 +
 +
 +
3
 +
 +
 +
32
 +
 +
 +
3
 +
 +
 +
41
 +
 +
 +
11
 +
 +
 +
11
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
68
 +
 +
 +
6
 +
 +
 +
477-571
 +
 +
 +
4
 +
 +
 +
10
 +
 +
 +
7
 +
 +
 +
7
 +
 +
 +
9
 +
 +
 +
8
 +
 +
 +
6
 +
 +
 +
51
 +
 +
 +
 +
 +
 +
21
 +
 +
 +
16
 +
 +
 +
4
 +
 +
 +
5
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
49
 +
 +
 +
7
 +
 +
 +
572-652C
 +
 +
 +
3
 +
 +
 +
5
 +
 +
 +
4
 +
 +
 +
3
 +
 +
 +
5
 +
 +
 +
5
 +
 +
 +
8
 +
 +
 +
33
 +
 +
 +
 +
 +
 +
28
 +
 +
 +
21
 +
 +
 +
10
 +
 +
 +
3
 +
 +
 +
2
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
67
 +
 +
 +
8
 +
 +
 +
652d-729
 +
 +
 +
4
 +
 +
 +
7
 +
 +
 +
3
 +
 +
 +
7
 +
 +
 +
12
 +
 +
 +
7
 +
 +
 +
4
 +
 +
 +
44
 +
 +
 +
1
 +
 +
 +
18
 +
 +
 +
18
 +
 +
 +
10
 +
 +
 +
4
 +
 +
 +
3
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
56
 +
 +
 +
9
 +
 +
 +
730-8 16b
 +
 +
 +
8
 +
 +
 +
13
 +
 +
 +
1
 +
 +
 +
5
 +
 +
 +
7
 +
 +
 +
4
 +
 +
 +
11
 +
 +
 +
49
 +
 +
 +
1
 +
 +
 +
12
 +
 +
 +
15
 +
 +
 +
15
 +
 +
 +
7
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
51
 +
 +
 +
10
 +
 +
 +
817-SOOg
 +
 +
 +
9 36
 +
 +
 +
8 71
 +
 +
 +
 +
21
 +
 +
 +
4 51
 +
 +
 +
7 75
 +
 +
 +
4 80
 +
 +
 +
6 62
 +
 +
 +
38 396
 +
 +
 +
1 11
 +
 +
 +
14 245
 +
 +
 +
21
 +
 +
180
 +
 +
 +
7 93
 +
 +
 +
8 41
 +
 +
 +
 +
 +
18
 +
 +
 +
2
 +
 +
8
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
3 6
 +
 +
 +
62
 +
 +
 +
 +
 +
 +
 +
604
 +
 +
 +
 +
In determining the normality of specimens, the criterion used was the shape of the embryo, judging this as best we could by our own knowledge of human and comparative embryology, as well as by the experience of other students of human embr^^ology, and we have used freely the atlases of His, Hichstetter and Keibel and Else in making our decisions on this point. How
 +
 +
 +
table 2
 +
 +
Specimens obtained from the uterus
 +
 +
 +
 +
2
 +
 +
Eh
 +
 +
o
 +
 +
 +
CATALOGUE NUMBER
 +
 +
 +
1 1
 +
 +
 +
2
 +
 +
5
 +
 +
 +
3 1
 +
 +
 +
4
 +
 +
6
 +
 +
 +
5
 +
 +
4
 +
 +
 +
6
 +
 +
3
 +
 +
 +
7
 +
 +
4
 +
 +
 +
EO E 24
 +
 +
 +
1 3
 +
 +
 +
2
 +
 +
41
 +
 +
 +
17
 +
 +
 +
4
 +
 +
8
 +
 +
 +
5
 +
 +
7
 +
 +
 +
6
 +
 +
 +
 +
7
 +
 +
 +
 +
8
 +
 +
 +
 +
9
 +
 +
 +
 +
 +
10
 +
 +
 +
 +
Eh
 +
 +
 +
 +
1
 +
 +
 +
1- 98
 +
 +
 +
76
 +
 +
 +
2
 +
 +
 +
99-205
 +
 +
 +
 +
 +
 +
8
 +
 +
 +
1
 +
 +
 +
8
 +
 +
 +
6
 +
 +
 +
12
 +
 +
 +
6
 +
 +
 +
41
 +
 +
 +
 +
 +
 +
22
 +
 +
 +
20
 +
 +
 +
6
 +
 +
 +
2
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
52
 +
 +
 +
3
 +
 +
 +
206- 295
 +
 +
 +
2
 +
 +
 +
5
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
9
 +
 +
 +
11
 +
 +
 +
7
 +
 +
 +
37
 +
 +
 +
1
 +
 +
 +
23
 +
 +
 +
27
 +
 +
 +
7
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
61
 +
 +
 +
4
 +
 +
 +
296-380
 +
 +
 +
1
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
8
 +
 +
 +
15
 +
 +
 +
6
 +
 +
 +
36
 +
 +
 +
1
 +
 +
 +
19
 +
 +
 +
12
 +
 +
 +
14
 +
 +
 +
2
 +
 +
 +
2
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
53
 +
 +
 +
5
 +
 +
 +
381-476
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
3
 +
 +
 +
3
 +
 +
 +
7
 +
 +
 +
9
 +
 +
 +
3
 +
 +
 +
27
 +
 +
 +
3
 +
 +
 +
34
 +
 +
 +
8
 +
 +
 +
11
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
58
 +
 +
 +
6
 +
 +
 +
477-571
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
5
 +
 +
 +
7
 +
 +
 +
7
 +
 +
 +
6
 +
 +
 +
3
 +
 +
 +
29
 +
 +
 +
 +
 +
 +
18
 +
 +
 +
14
 +
 +
 +
3
 +
 +
 +
5
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
43
 +
 +
 +
7
 +
 +
 +
572-652C
 +
 +
 +
1
 +
 +
 +
4
 +
 +
 +
4
 +
 +
 +
3
 +
 +
 +
5
 +
 +
 +
5
 +
 +
 +
8
 +
 +
 +
30
 +
 +
 +
 +
 +
 +
24
 +
 +
 +
21
 +
 +
 +
10
 +
 +
 +
3
 +
 +
 +
2
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
63
 +
 +
 +
8
 +
 +
 +
652d-729
 +
 +
 +
1
 +
 +
 +
4
 +
 +
 +
3
 +
 +
 +
7
 +
 +
 +
10
 +
 +
 +
7
 +
 +
 +
3
 +
 +
 +
35
 +
 +
 +
1
 +
 +
 +
13
 +
 +
 +
18
 +
 +
 +
10
 +
 +
 +
4
 +
 +
 +
3
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
51
 +
 +
 +
9
 +
 +
 +
730-816b
 +
 +
 +
2
 +
 +
 +
5
 +
 +
 +
1
 +
 +
 +
5
 +
 +
 +
6
 +
 +
 +
4
 +
 +
 +
10
 +
 +
 +
33
 +
 +
 +
1
 +
 +
 +
8
 +
 +
 +
15
 +
 +
 +
15
 +
 +
 +
7
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
47
 +
 +
 +
10
 +
 +
 +
817-900g
 +
 +
 +
2 12
 +
 +
 +
4 39
 +
 +
 +
 +
18
 +
 +
 +
3
 +
 +
48
 +
 +
 +
5 67
 +
 +
 +
2
 +
 +
74
 +
 +
 +
5 55
 +
 +
 +
21 313
 +
 +
 +
1 11
 +
 +
 +
11 213
 +
 +
 +
18 170
 +
 +
 +
7 91
 +
 +
 +
8 41
 +
 +
 +
6 18
 +
 +
 +
2
 +
 +
8
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
3 6
 +
 +
 +
56
 +
 +
 +
 +
 +
 +
 +
560
 +
 +
 +
 +
LOCALIZED ANOMALIES IN HUMAN EMBRYOS
 +
 +
 +
 +
63
 +
 +
 +
 +
ever, many of thevse specimens are enclosed in membranes which have undergone very marked changes. Thus, an embryo, normal in form, may be found surrounded by an excessive amount of magma, and the chorion may have undergone very pronounced changes; but for purposes of classification we have found it necessary to arrange them all according to the shape of the embryo. A fairly large number of our specimens were
 +
 +
TABLE 3
 +
 +
Ecotopic specimens
 +
 +
 +
 +
■t
 +
 +
H S
 +
 +
a o
 +
 +
 +
CATALOGUE NUMBER
 +
 +
 +
I
 +
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
 +
 +
4
 +
 +
 +
 +
 +
5
 +
 +
 +
 +
 +
6
 +
 +
 +
 +
 +
 +
 +
 +
< o
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
2
 +
 +
 +
 +
3
 +
 +
 +
 +
4
 +
 +
 +
 +
 +
5
 +
 +
 +
 +
 +
6
 +
 +
 +
 +
 +
 +
 +
 +
s
 +
 +
 +
 +
9
 +
 +
 +
 +
 +
10
 +
 +
 +
 +
 +
< o
 +
 +
 +
1
 +
 +
 +
1- 98
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
99-205
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
5
 +
 +
 +
3
 +
 +
 +
206-295
 +
 +
 +
 +
 +
 +
C
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
4
 +
 +
 +
296-380
 +
 +
 +
 +
 +
 +
4
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
9
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
5
 +
 +
 +
381-476
 +
 +
 +
3
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
5
 +
 +
 +
 +
 +
 +
7
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
10
 +
 +
 +
6
 +
 +
 +
477-571
 +
 +
 +
3
 +
 +
 +
10
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
2
 +
 +
 +
3
 +
 +
 +
22
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
2
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
6
 +
 +
 +
7
 +
 +
 +
572-652C
 +
 +
 +
2
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
4
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
4
 +
 +
 +
8
 +
 +
 +
6o2d-729
 +
 +
 +
3
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
9
 +
 +
 +
 +
 +
 +
5
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
5
 +
 +
 +
9
 +
 +
 +
730-8 16b
 +
 +
 +
6
 +
 +
 +
8
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
16
 +
 +
 +
 +
 +
 +
4
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
4
 +
 +
 +
10
 +
 +
 +
817-900g
 +
 +
 +
7
 +
 +
 +
4
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
2
 +
 +
 +
2
 +
 +
 +
1
 +
 +
 +
17
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
6
 +
 +
 +
 +
 +
 +
 +
24
 +
 +
 +
32
 +
 +
 +
3
 +
 +
 +
3
 +
 +
 +
8
 +
 +
 +
6
 +
 +
 +
7
 +
 +
 +
83
 +
 +
 +
 +
 +
 +
32
 +
 +
 +
10
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
44
 +
 +
 +
 +
TABLE 4
 +
 +
Specimens showing localized anomalies (a be compared with table 1
 +
 +
 +
 +
■Ji
 +
 +
 +
CATALOGUE NUMBER
 +
 +
 +
PATHOLOGICAL
 +
 +
 +
NORMAL
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
3
 +
 +
 +
 +
 +
4
 +
 +
 +
 +
 +
5
 +
 +
 +
 +
 +
6
 +
 +
1
 +
 +
 +
7 1
 +
 +
 +
"3 2
 +
 +
 +
] 1
 +
 +
 +
2 4
 +
 +
 +
3
 +
 +
 +
 +
 +
4
 +
 +
 +
 +
 +
5
 +
 +
 +
 +
 +
6
 +
 +
 +
 +
 +
7
 +
 +
 +
 +
 +
8
 +
 +
 +
 +
 +
9
 +
 +
 +
 +
 +
10
 +
 +
 +
 +
3
 +
 +
 +
1
 +
 +
 +
1- 98
 +
 +
 +
5
 +
 +
 +
2
 +
 +
 +
99-205
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
2
 +
 +
 +
1
 +
 +
 +
4
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
3
 +
 +
 +
206-295
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
3
 +
 +
 +
5
 +
 +
 +
1
 +
 +
 +
3
 +
 +
 +
2
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
7
 +
 +
 +
4
 +
 +
 +
296-380
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
3
 +
 +
 +
1
 +
 +
 +
7
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
6
 +
 +
 +
5
 +
 +
 +
381-476
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
6
 +
 +
 +
477-571
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
4
 +
 +
 +
7
 +
 +
 +
572-652C
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
4
 +
 +
 +
5
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
8
 +
 +
 +
652d-729
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
9
 +
 +
 +
730-816b
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
1
 +
 +
 +
3
 +
 +
 +
5
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
1
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
6
 +
 +
 +
10
 +
 +
 +
817-900g
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
2
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
3
 +
 +
 +
3
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
11
 +
 +
 +
13
 +
 +
 +
14
 +
 +
 +
38
 +
 +
 +
2
 +
 +
 +
22
 +
 +
 +
3
 +
 +
 +
4
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
1
 +
 +
 +
 +
 +
 +
4
 +
 +
 +
37
 +
 +
 +
 +
64 FRANKLIN P. MALL
 +
 +
obtained from hysterectomies, and we believe with Hochstetter that we shall ultimately have to determine what constitutes a normally formed human embryo from specimens obtained in this way. However, even by this method we have found among about 25 specimens 3 markedly pathological ones undergoing abortion.
 +
 +
The second table includes all specimens that were obtained from the uterus, and the third, all ectopic specimens. Thus, in making a comparison of these three tables it will at once be noted that among the entire 1000 nearly 40 per cent are pathological embryos and ova. Of this number, 31 per cent were obtained from the uterus alone while slightly more than 8 per cent were ectopic. The comparative frequency of pathological and normal embryos can be ascertained, however, by comparing them within a given century, or for the whole thousand together. In the uterine specimens about one-third of the ova and embryos are pathological, as compared to two-thirds in the actopic. In other words, pathological specimens are twice as frequent in ectopic as in uterine pregnancy.
 +
 +
The fourth table includes all the specimens in which there are pronounced localized anomalies. The character of the anomaly is given with the individual specimens which are recorded in tables 5 and 6. It is interesting to note that these tables show that there are about as many anomalies among the normal as among the pathological specimens, but when these figures are compared with the total of specimens both normal and pathological, it becomes e\ddent that localized anomalies occur about twice as frequently in the pathological as in the normal embryo. Thus, there are 38 locahzed anomalies among 396 pathological specimens or about 10 per cent, while the occurrence of localized anomalies in 604 normal specimens is about 6 per cent. The table shows further that the 38 pathological specimens with locahzed anomahes abort in the early part of pregnancy and only one of them (No. 649) grew to a sitting height of 90 mm., that is, about the middle of the fourth month.
 +
 +
Among the normal embryos, those with localized anomalies usually disappear before the fifth month, there being but one in the sixth, one in the eighth, and four in the tenth month or
 +
 +
 +
 +
TABLE 5 Localized anomalies in pathological embryos
 +
 +
 +
 +
GROUP
 +
 +
 +
o
 +
 +
 +
So
 +
 +
w «
 +
 +
 +
<«2 •a «  o o
 +
 +
S o 3
 +
 +
 +
<
 +
 +
 +
LOCALIZED ANOMALT
 +
 +
 +
 +
 +
 +
 +
m m .
 +
 +
 +
m m .
 +
 +
 +
days
 +
 +
 +
 +
 +
 +
 +
785
 +
 +
 +
2
 +
 +
 +
15x12x10
 +
 +
 +
64
 +
 +
 +
Spina bifida
 +
 +
 +
 +
 +
874b
 +
 +
 +
3
 +
 +
 +
35x30x20
 +
 +
 +
80
 +
 +
 +
Hydrocephalus
 +
 +
 +
 +
 +
189
 +
 +
 +
4
 +
 +
 +
28x25x15
 +
 +
 +
 +
 +
Spina bifida
 +
 +
 +
 +
 +
228
 +
 +
 +
4
 +
 +
 +
60x25x25
 +
 +
 +
99
 +
 +
 +
Hydrocephalus
 +
 +
 +
Group 5
 +
 +
 +
302
 +
 +
 +
4
 +
 +
 +
25x20x15
 +
 +
 +
 +
 +
Hydrocephalus
 +
 +
 +
(Cylindrical
 +
 +
 +
466
 +
 +
 +
4
 +
 +
 +
29x23x16
 +
 +
 +
 +
 +
Spina bifida
 +
 +
 +
Embryos)
 +
 +
 +
328
 +
 +
 +
4.5
 +
 +
 +
 +
 +
 +
 +
Hydrocephalus
 +
 +
 +
 +
 +
842
 +
 +
 +
5
 +
 +
 +
 +
 +
 +
 +
Eye detached from brain
 +
 +
 +
 +
 +
653
 +
 +
 +
11
 +
 +
 +
80x50x35
 +
 +
 +
 +
 +
Amyelia-Ectopia of heart
 +
 +
 +
 +
 +
710
 +
 +
 +
13
 +
 +
 +
95x55x55
 +
 +
 +
228
 +
 +
 +
Amyelia
 +
 +
 +
 +
 +
365
 +
 +
 +
14
 +
 +
 +
 +
 +
 +
 +
Anencephaly — Spina bifida
 +
 +
 +
c
 +
 +
 +
433a
 +
 +
 +
3
 +
 +
 +
27x25x15
 +
 +
 +
49
 +
 +
 +
Hydrocephalus
 +
 +
 +
 +
 +
413
 +
 +
 +
5
 +
 +
 +
35x35
 +
 +
 +
 +
 +
Spina bifida
 +
 +
 +
 +
 +
510
 +
 +
 +
10
 +
 +
 +
60x45
 +
 +
 +
 +
 +
Spina bifida
 +
 +
 +
 +
 +
338c
 +
 +
 +
11
 +
 +
 +
 +
 +
35
 +
 +
 +
Spina bifida
 +
 +
 +
 +
 +
276
 +
 +
 +
13.5
 +
 +
 +
70x35x35
 +
 +
 +
80
 +
 +
 +
Anencephaly i
 +
 +
 +
 +
 +
81
 +
 +
 +
15
 +
 +
 +
65x55x35
 +
 +
 +
 +
 +
Anencephaly
 +
 +
 +
 +
 +
344
 +
 +
 +
16
 +
 +
 +
45x45x45
 +
 +
 +
 +
 +
Rounded head — Club leg
 +
 +
 +
Group 6
 +
 +
 +
364
 +
 +
 +
16
 +
 +
 +
90x50x40
 +
 +
 +
89
 +
 +
 +
Exencepahaly — Hare lip —
 +
 +
 +
(Stunted
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
Exomphaly — Spina bifida
 +
 +
 +
Embryos)
 +
 +
 +
499
 +
 +
 +
17
 +
 +
 +
45x45x40
 +
 +
 +
 +
 +
Hare lip — Spina bifida
 +
 +
 +
 +
 +
201
 +
 +
 +
20
 +
 +
 +
80x60x50
 +
 +
 +
 +
 +
Cyclopia
 +
 +
 +
 +
 +
124
 +
 +
 +
35
 +
 +
 +
90x75x50
 +
 +
 +
 +
 +
Club foot and hand
 +
 +
 +
 +
 +
797
 +
 +
 +
35
 +
 +
 +
65x35x35
 +
 +
 +
 +
 +
Clul) foot and hand
 +
 +
 +
 +
 +
649
 +
 +
 +
90
 +
 +
 +
 +
 +
 +
 +
Spina bifida — Exomphaly — Without radii and without thumbs
 +
 +
 +
 +
 +
182
 +
 +
 +
5.5
 +
 +
 +
 +
 +
 +
 +
Head defective — Spina bifida
 +
 +
 +
 +
 +
802
 +
 +
 +
6
 +
 +
 +
19x26x16
 +
 +
 +
 +
 +
Anencephaly
 +
 +
 +
 +
 +
212
 +
 +
 +
15
 +
 +
 +
 +
 +
 +
 +
Head atrophic
 +
 +
 +
 +
 +
732
 +
 +
 +
19
 +
 +
 +
 +
 +
88
 +
 +
 +
Exomphaly
 +
 +
 +
 +
 +
94
 +
 +
 +
20
 +
 +
 +
 +
 +
 +
 +
Spina bifida
 +
 +
 +
 +
 +
226
 +
 +
 +
24
 +
 +
 +
60x60x30
 +
 +
 +
87
 +
 +
 +
Anencephaly — Spina bifida
 +
 +
 +
Group 7
 +
 +
 +
651a
 +
 +
 +
27
 +
 +
 +
70x45x45
 +
 +
 +
 +
 +
Spina bifida
 +
 +
 +
(Macerated
 +
 +
 +
868
 +
 +
 +
39
 +
 +
 +
 +
 +
193
 +
 +
 +
Club foot
 +
 +
 +
and fetus
 +
 +
 +
316
 +
 +
 +
44
 +
 +
 +
 +
 +
 +
 +
Club hand and foot. Hand
 +
 +
 +
compressus)
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
adherent to head. Skin nodulas
 +
 +
 +
 +
 +
627
 +
 +
 +
45
 +
 +
 +
80x50x35
 +
 +
 +
 +
 +
Club hand and Club foot
 +
 +
 +
 +
 +
740
 +
 +
 +
56
 +
 +
 +
 +
 +
 +
 +
Club foot
 +
 +
 +
 +
 +
230
 +
 +
 +
57
 +
 +
 +
75x60x50
 +
 +
 +
 +
 +
Club hands and feet
 +
 +
 +
 +
 +
622
 +
 +
 +
70
 +
 +
 +
 +
 +
 +
 +
Club foot
 +
 +
 +
 +
 +
646
 +
 +
 +
85
 +
 +
 +
90x60x50
 +
 +
 +
 +
 +
Exencephaly
 +
 +
 +
 +
65
 +
 +
 +
 +
THE AMERICAN JOURNAL OF ANATOMY, VOL. 22, No. 1
 +
 +
 +
 +
TABLE 6 Localized anomalies in normal embryos
 +
 +
 +
 +
1
 +
 +
(0-25mm.)
 +
 +
 +
 +
(2.6-25mm.)
 +
 +
 +
 +
(26-68 mm.
 +
 +
 +
 +
(69-12 mm.)
 +
 +
 +
 +
-i D
 +
 +
 +
o o
 +
 +
K »
 +
 +
 +
 +
 +
mm.
 +
 +
 +
250
 +
 +
 +
2
 +
 +
 +
12
 +
 +
 +
2.1
 +
 +
 +
779
 +
 +
 +
2.75
 +
 +
 +
164
 +
 +
 +
3.5
 +
 +
 +
186
 +
 +
 +
3.5
 +
 +
 +
112
 +
 +
 +
4
 +
 +
 +
808
 +
 +
 +
4
 +
 +
 +
80
 +
 +
 +
5
 +
 +
 +
552
 +
 +
 +
6
 +
 +
 +
676
 +
 +
 +
6
 +
 +
 +
796
 +
 +
 +
6
 +
 +
 +
371
 +
 +
 +
6.6
 +
 +
 +
651f
 +
 +
 +
7
 +
 +
 +
559
 +
 +
 +
8
 +
 +
 +
511
 +
 +
 +
14
 +
 +
 +
338a
 +
 +
 +
18
 +
 +
 +
293
 +
 +
 +
19
 +
 +
 +
242a
 +
 +
 +
23
 +
 +
 +
242b
 +
 +
 +
23
 +
 +
 +
6
 +
 +
 +
24
 +
 +
 +
10
 +
 +
 +
24
 +
 +
 +
31
 +
 +
 +
24
 +
 +
 +
314
 +
 +
 +
24
 +
 +
 +
584a
 +
 +
 +
25
 +
 +
 +
249a
 +
 +
 +
37
 +
 +
 +
249b
 +
 +
 +
37
 +
 +
 +
789
 +
 +
 +
50
 +
 +
 +
768c
 +
 +
 +
80
 +
 +
 +
768b
 +
 +
 +
85
 +
 +
 +
306a
 +
 +
 +
100
 +
 +
 +
295
 +
 +
 +
110
 +
 +
 +
 +
2 °
 +
 +
W 6,
 +
 +
So
 +
 +
 +
 +
mm,
 +
 +
10x9 x8 18x18x18
 +
 +
16x14x12 17x17x10 25x20x15
 +
 +
 +
 +
24x18x8 40x28x28 35x20x17 30x20x15
 +
 +
 +
 +
25x20x15
 +
 +
20x15x12
 +
 +
38x32x32
 +
 +
45x45
 +
 +
50x50x70 50x50x70 40x40x40
 +
 +
50x30x20
 +
 +
50x42x40
 +
 +
 +
 +
 +
 +
 +
days
 +
 +
 +
 +
41
 +
 +
 +
 +
44
 +
 +
 +
 +
47
 +
 +
 +
 +
52
 +
 +
48
 +
 +
 +
 +
54
 +
 +
 +
 +
62
 +
 +
 +
 +
117
 +
 +
 +
 +
LOCALIZED ANOMALY
 +
 +
 +
 +
Cytolysis
 +
 +
Ancncephaly — Spina bifida
 +
 +
Spina bifida
 +
 +
Spina bifida
 +
 +
Anomalous tracheal diverticulum
 +
 +
Hydrocephalus
 +
 +
Spina bifida
 +
 +
Deformed tail
 +
 +
Spina bifida
 +
 +
Spina bifida
 +
 +
Leg hypertrophic — Head atropic
 +
 +
Hydrocephalus
 +
 +
Spina bifida
 +
 +
Cyclopia
 +
 +
Spina bifida
 +
 +
Constricted cord
 +
 +
Spina bifida
 +
 +
Double monster
 +
 +
Double monster
 +
 +
Cyst of spinal cord
 +
 +
Hernia of liver
 +
 +
Hernia of liver
 +
 +
Atrophic head
 +
 +
Hernia of liver
 +
 +
Double monster Double Monster Extremities deformed — Left
 +
 +
radius probably absent.
 +
 +
Head acbophic
 +
 +
Stub coccyx
 +
 +
Left forearm and hand
 +
 +
wanting Only 2 fingers on right
 +
 +
hand Pounded head — Thickened
 +
 +
scalp
 +
 +
 +
 +
66
 +
 +
 +
 +
LOCALIZED ANOMALIES IN HUMAN EMBRYOS
 +
 +
 +
 +
67
 +
 +
 +
 +
 +
 +
 +
 +
T.VBLE 6— Concluded.
 +
 +
 +
 +
 +
MONTHS
 +
 +
 +
Is
 +
 +
o
 +
 +
 +
o c X «
 +
 +
 +
DIM1N8IONS OF CHOKION
 +
 +
 +
 +
 +
LOCALIZED ANOMALY
 +
 +
 +
 +
 +
 +
 +
mtti.
 +
 +
 +
7nm.
 +
 +
 +
days
 +
 +
 +
 +
 +
5
 +
 +
(122-167 mm.)
 +
 +
 +
No sp
 +
 +
 +
3cimen
 +
 +
 +
 +
 +
 +
 +
 +
 +
6
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
(168-210 mm.)
 +
 +
 +
335
 +
 +
 +
190
 +
 +
 +
 +
 +
 +
 +
Anencephaly
 +
 +
 +
7
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
(211-245 mm.)
 +
 +
 +
No specimen
 +
 +
 +
 +
 +
 +
 +
 +
 +
8
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
(246-284 mm.)
 +
 +
 +
558
 +
 +
 +
250
 +
 +
 +
 +
 +
 +
 +
Spinia bifida
 +
 +
 +
9
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
 +
(285-316 mm.)
 +
 +
 +
No specimen
 +
 +
 +
 +
 +
 +
 +
 +
 +
f
 +
 +
 +
370 After b
 +
 +
 +
irth
 +
 +
 +
 +
 +
Enormous tail
 +
 +
 +
10 1
 +
 +
 +
862 At birth
 +
 +
 +
 +
 +
Ectopia of bladder
 +
 +
 +
(317-3.36 mm.) |
 +
 +
 +
862a At birth
 +
 +
 +
 +
 +
Spina bifida
 +
 +
 +
I
 +
 +
 +
862b At birth
 +
 +
 +
 +
 +
Stunted eyes
 +
 +
 +
 +
at the end of pregnancy. In other words, all pathological specimens, either with or without localized anomalies, abort in the first half of pregnancy ; while nearly all so-called normal embryos with slight malformations are also aborted before the middle of pregnancy, very few of them reaching full term.
 +
 +
We have made an especial effort to collect specimens of full term monsters as well as abortion material from all months of pregnancy. Only the first 100 specimens of the collection show an unusually large percentage of normal embryos. Although at first an effort was made to collect only good normal specimens the last 900 specimens, including all sorts of material, of the collection carry about the same percentage of normal specimens throughout. The first 1000 specimens of our collection is short of fetuses from the second half of pregnancy, but we are now endeavoring to collect material covering all months of
 +
 +
 +
 +
68 FRANKLIN P. MALL
 +
 +
pregnancy. One monster at term, a sympus belonging in about the third hundred, was not recorded in our catalogue, and should be added to the four full term specimens given in table 4. This means that among 1001 specimens there were five monsters at term, while among 1000 specimens there were 71 with localized anomalies, most of which w^ere aborted early in pregnancy.
 +
 +
According to the table on the frequency of abortions given in my monograph on monsters,^ there are 80 full term births for each 20 abortions; therefore, the 1000 abortions under consideration were probably derived from 5000 pregnancies.
 +
 +
As we have calculated that there should be approximately 30 full term monsters in 5000 pregnancies, and as 5 of these were observed in our 1000 specimens, it is apparent that the remaining 25 should be encountered in 4000 additional full term births. When these figures are compared with the fact that 75 localized anomalies occurred in 1000 abortions — 7.5 per cent, it becomes apparent that in any similar numbers of abortions, localized anomalies should be noted twelve times as frequently as monsters at term. A similar result is obtained if the number of localized anomalies of the tenth month, as given in table 4, is compared wdth all of the localized anomahes of pre\dous months, as given in the same table."
 +
 +
Our studies seem to justify the conclusion that pathological embryos, as well as those which are normal in form, are very frequently associated with localized anomalies and that abortion usually follows as a result of serious lesions in the chorion, as well as in its environment. Should the alterations in the embryo and in the chorion be very slight, and the condition of the uterine mucous membrane, which may be expressed by the term inflammation, be overcome, the pregnancy in all probability would go to term and end in the birth of a monster or an infant presenting a well recognized malformation.
 +
 +
^ Also in a resume of the paper on monsters in the article entitled: Mall, F. P. Pathology of the human ovum. Chapter 9, Human Embryology, Keibel and Mall, vol. 1, 1910.
 +
 +
® Records are now being made of about 50,000 births in Baltimore, including the frequency of abortions for each mother. When these are completed, the above mentioned ratio of 1 to 4 will probably be changed.
 +
 +
 +
 +
LOCALIZED ANOMALIES IN HUMAN EMBRYOS 69
 +
 +
I have already pointed out the difference in, frequency of malformations and destructive changes as observed in the ovum in tubal and in uterine pregnancies. Since the pubhcation of my monograph on monsters, I have reconsidered the question of tubal pregnancy, and the specimens mentioned in the present paper are recorded in detail in a book on tubal pregnancy recently published.^
 +
 +
It seems to me that the studies based upon our collection of embryos as well as recent investigations in experimental embryology, set at rest for all time the question of the causation of monsters. It has been my aim to demonstrate that the embryos found in pathological human ova and those obtained experimentally in animals are not analogous or similar, but identical. A double monster or a cyclopean fish is identical with the same condition in human beings. In all cases, monsters are produced by external influences acting upon the ovum; as, for instance, varnishing the shell of a hen's egg or changing its temperature; traumatic and mechanical agencies magnetic and electrical influences, as well as by alteration of the character of the surrounding gases, or by the injection of poisons into the white of an egg. In aquatic animals, monsters may be produced by similar methods. Whether in the end all malformations are brought about by some simple mechanism, such, for instance, as alteration in the amount of oxygen or some other gas, remains to be demonstrated. The specimens under consideration show such marked primary changes in the villi of the chorion and in the surrounding decidua that the conditions in the human may be considered equivalent or practically identical with those created artificially in the production of abnormal development in animals.
 +
 +
It would have been quite simple to conclude that the poisons produced by an inflamed uterus should be viewed as the sole cause, but when it is recalled that pathological ova occur far more commonly in tubal than in uterine pregnancy, such a theory becomes untenable. Moreover, monsters are frequently
 +
 +
' Mall, Franklin P. On the fate of the human embryo in tubal pregnancy. Publication No. 221, Carnegie Institution of Washington, 1915.
 +
 +
 +
 +
70 FRANKLIN P. MALL
 +
 +
observed in swine and other animals without any indication of an inflammatory environment. For this reason I have sought the primary factor in a condition buried in the non-committal term fault}^ implantation. It would seem to be apparent that lesions occurring in the chorion as the result of faulty implantation, can and must be reflected in the embryo. For example, before circulation has developed, in a human embryo, pabulum passes from the chorion to the embryo directly through the exocoelom, and probably on this account we always encounter, as a first indication of pathological development, a change in the magma. In older specimens before any other changes are noticeable in the ovum, the magma become markedly increased, and a variety of changes are found between the villi. I shall not dwell further upon magma as I have recently dealt with the subject in detail.^
 +
 +
It is perfectly clear that monsters are not due to germinal and hereditary causes, but are produced from normal embryos by influences which are to be sought in their environment. Consequently, if these influences are carried to the embryo by means of fluids which reach it either before or after the circulation has become established, it would not be very far amiss to attribute these conditions to alterations in the nutrition of the embryo. Probably it would be more nearly correct to state that change in environment has affected the metabolism of the egg. Kellicott, who has recently discussed this question, seems to be disinclined to accept such an explanation, but I do not see that he has added materially to it by substituting the word disorganization for nutrition as one might as easily say that the altered nutrition causes the disorganization. ^
 +
 +
In my paper on monsters I stated that on account of faulty implantation of the chorion the nutrition of the embryo is affected, so that, if the ovum is very young the entire embryo is soon destroyed, leaving only the umbilical vesicle within the
 +
 +
Mall, Franklin P. On magma reticule in normal and in pathological development. Contributions to Embryology, vol. 4, Publication No. 224, Carnegie
 +
Institution of Washington, 1916.
 +
 +
3 Kellicott, W. E. The effect of lower temperature upon the development of Fundulus. Am. Jour. Anat., vol. 20, 1916.
 +
 +
 +
 +
LOCALIZED ANOMALIES IN HUMAN EMBRYOS 71
 +
 +
chorion, and this also soon disintegrates, leaving only the chorionic membrane which in turn collapses, breaks down and finally disappears entirely. In older specimens, on the other hand, the process of destruction takes place more slowly and thus we account for a succession of phenomena which correspond with the seven groups of pathological ova recognized and given in the various tables appended.
 +
 +
In my original study, I really went, I believe, a step farther than Kellicott in his discussion of monsters, as he dropped the subject by stating that the embryo is a monster simply because it is disorganized. I attempted to analyze the process of disorganization more thoroughly and demonstrated that when disorganization begins it is accompanied by cytolysis, but as it progresses more rapidly it results in histolysis, and that these two processes do not act with equal severity on all parts of the embryo. When we consider the whole ovum, it is the embryo itself which is first destroyed; while within the embryo the central nervous system or the heart is the portion which is first affected. Morphologically, these changes are accompanied by a destruction of certain cells and tissues, leaving other portions which continue to grow in an irregular manner. For this reason I speak of the tissues which are first affected as more susceptible than the others. The entire process of disorganization, resulting in an irregular product, I have termed dissociation. In a general way this explanation is accepted by Werber in his recent studies, but he employs the term blastolysis instead.^"
 +
 +
At the time I prepared my paper on monsters, Harrison was just beginning his interesting experiments in tissue culture in our laboratory. Since then this method of study has given us clearer insight into the independent growth of tissues. I was fully convinced from the study of pathological embryos that tissues continue to grow in an irregular manner, thus arresting normal development; but since we are more familiar with the
 +
 +
10 Werber, E. I. Experimental studies aiming at the control of defective and monstrous development. A survey of recorded monstrosities with special attention to the ophthalmic defects. Anat. Rec, vol. 9, 1915. Also: Blastolysis as a morphogenetic factor in the development of monsters. Anat. Rec, vol. 10, 1916.
 +
 +
 +
 +
72 FRANKLIN P. MALL
 +
 +
growth of tissues, as revealed by Harrison's method, we can understand a Uttle better the process of dissociation. In fact we have in our collection two striking examples of tissue culture in human embryos. In one, the cells had formed an irregular mass which is growing actively, but the contour of the organs has been entirely lost. In the other, from a tubal pregnancy, for some unknown reason, the ovum had been completely broken into two parts, which in turn had cracked the embryo, and from each piece had been a vigorous independent tissue growth, or, as we may now say, a tissue culture. Accordingly, when an embryo through changed environment is profoundly affected, the development of one part of the body may be arrested, while the remaining portion may continue to grow and develop in an irregular manner. In very young embryos tissues or even entire organs become disintegrated, as can easily be recognized by the cytolysis and histolysis present, and the resultant disorganized tissue cannot continue to produce the normal form of an embryo. If this process is sharply localized, for instance, in a portion of the spinal cord or in the brain, spina bifida or anencephaly results. To produce a striking result, as in cyclopia, a small portion of the brain must be affected at the critical time, and I think the work of Stockard has shown clearly that this is before the eye primordia can be seen. Consequently, in order to produce a human monster, which is to live until the end of gestation, the altered environment must be reflected from the chorion to the embryo, so that the tissue to be affected is struck at the critical time in its development. It is inconceivable that cyclopia should begin in an embryo after the eyes are once started in normal development. Moreover, the same is true regarding hare lip, for after the upper jaw has once been well formed, the abnormality cannot develop. We may extend this statement to include club-foot, spina bifida occulta, and other types of malformation. In fact, in discussing the origin of merosomatous monsters, hardly more has been stated by most authors than that there has been an arrest of development, but I have attempted to point out that the primary cause is in the environment of the egg and that the arrested development is associated with destruction of tissue.
 +
 +
 +
 +
CYTOLOGICAL OBSERVATIONS ON THE BEHAVIOR OF CHICKEN BONE MARROW IN PLASMA MEDIUM'
 +
 +
RHODA ERDMANN
 +
 +
Osborn Zoological Laboratory, Yale University, New Haven, Connecticut, and
 +
 +
Rockefeller Institute for Medical Research, Department of Animal
 +
 +
Pathology, Princeton, Neiv Jersey
 +
 +
TWO TEXT FIGURES AND NINE PLATES
 +
 +
The writer, employing the bone marrow of the chicken for attenuating the virus of cyanolophia (Erdmann '16^), by culture of the marrow and the virus in a medium of chicken plasma, has observed some interesting facts concerning the cytological changes in the bone marrow cells.
 +
 +
The morphology and development of chicken bone marrow and its relation to blood formation have been described by few authors. Dantschakoff ('09, pp. 859-65) gives an extensive review of the literature on these questions and establishes our knowledge of the origin of the different elements of chicken bone marrow\
 +
 +
In studying the cells of bone marrow in plasma culture medium, we must take into consideration the fact, that we add to the plasma in which the tissue culture is cultivated a heterogeneous mixture of highly differentiated cells. Chicken bone marrow has a loose framework of slender connective tissue cells, in the meshes of which blood and fat cells are scattered. The blood cells — eosinophils, erythrocytes, and myelocytes — form, according to Foot ('13, p. 45) strands and circles between and around the fat cells. The blood islands represent collections of cells of microlymphocytic and macrolymphocytic types, of more or less ripe erythrocytes and of young connective tissue cells. It must be clearly kept in mind that all these different
 +
 +
^ Received for publication March 14, 1917.
 +
 +
2 Erdmann, Rh. 1916 Attenuation of the living agents of cyanolophia, Proceedings of the Society for Experimental Biology and Medicine, vol. 8, pp. 189-193.
 +
 +
73
 +
 +
 +
 +
74 RHODA ERDMANN
 +
 +
elements behave differently in the tissue cultures and may, after having undergone important changes in the plasma, offer some difficulties in interpretation.
 +
 +
The only observations of normal chicken bone marrow in plasma are those made by Foot '12 and '13. In the first series of experiments he studied especially the behavior of the fatty elements of chicken bone marrow, recording the following results. Six hours after implantation numerous cells leave the tissue center. They form rays of cells liquefying the plasma. These rays are formed by polymorphous leucocytes wdth eosinophile granules and by eine Art von mononuklearen basophilen Zellen" (p. 450). Foot gives the latter the name of X cells; they are the most important and they contain only fat according to his observations of 1912. They form, he says in 1912, the bulk of all cells migrating into the surrounding plasma. These X cells, the origin of which Foot tries to elucidate, are true phagocytes They include small fatty droplets and other particles which are dispersed in the cytoplasm. On the fourth day, these cells, after having been enlarged by the amount of fat which they have taken up during the first three days in the culture, form either syncytial masses or a widely spread network of anastomosing cells. The former may divide, after having lost most of their fatty granules, and form the final 'ruhende X Zelle' (Foot '12, fig. 8, pi. 22) : or the latter, after having been highly vacuolized, as stated by Foot '12, may form fibrils (fig. 18, pi. 22). If these X cells do not form resting X cells or cells which produce fibrils, they take the shape of 'Riesenzellen.' These ' Riesenzellen' are not identical, in Foot's opinion, with the 'giant' cells of the normal bone marrow. They are represented in his figures 11, 16, 17, 19. They are only X cells which have fused together, form no fibrils, and may later break up in small cells (figs. 12 to 14), which have generally one nucleus. Das Ergebnis der Aufteilung der Riesenzellen ist sozusagen eine neue Zellrasse" (p. 460) — cells adapted to the condition of the medium.
 +
 +
Foot believes that the X cells are transformed cells of the 'mesenchyme' and "Zwar indifferent gewordene Mesenchymzel
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 75
 +
 +
len" (p. 4()G). He reasons as follows: Because these cells have the potentiality of forming fibrils they must belong to those cells which can form connective tissue, and therefore these X cells without any intermediate stages take their origin from mesenchymal or endothelial cells. In a postscript to this paper he changes his opinion entirely and says (p. 475): "Was die Herkunft der X Zellen betrifft, so scheint es als ob die Hauptmasse derselben entweder direkt oder indirekt von den lymphocytaren oder myeloblastischen Elementen des Knochenmarkes abstammte," promising to give the reasons for this change of opinion in his second communication.
 +
 +
After a careful study of Foot's second publication ('13), which is rather difficult to understand because he does not very often connect his first publication with the second, I restate in his own words his revised opinion of the origin of those cells which form X cells ('13, pp. 46-47). The deductions as to the transformation of the lymphocytes from one form to another, which form the basis of the following descriptions, were made from the observation of transition forms. The later transformations of these cells into forms resembling fat and giant cells or cells of the connective tissue have been considered in my previous article." So it appears that the so-called X cells of this author ('12) — the name does not often appear in the paper of 1913 — are not directly transformed cells of the mesenchymal type but are said to be of lymphocytic origin. He observes that as early as three hours after implantation of the bone marrow a considerable number of microlymphocytes emigrate from the tissue particle. Their transformation occurs in the following way:
 +
 +
The small microlymphocytes are first transformed into macrolymphocytes, later into large mononuclear forms, then into myelocytes. At last the polymorphonuclear leucocytes appear, after having undergone difi"erent changes in the form and structure of the nucleus. The nucleus is at first horseshoe-shaped, later polymorphonuclear and even polynuclear. Finally the cells, by rounding off and dechromatization of the nucleus coincident with the rarification and a change in the staining
 +
 +
 +
 +
70 RHODA ERDMANN
 +
 +
properties of the plasma, are transformed into the cell culture type (p. 56). This cell culture type (see his fig. 2, pi. 3, and his fig. 3, pi. 4) represents small polymorphonuclear leucocytes (p. 49) which have undergone the transformation, but not only does the cell culture type originate from lymphocyte forms, but this 'stem cell' can also be transformed through the transition stage of amoeboid forms into 'giant cells,' syncytia, and, as said before, into the cell culture type (table 1, p. 56).
 +
 +
Thus it is clear that, according to this author's view, all the different forms described by Foot in 1912 and 1913 originate from the microlymphocytes. Until the present time ('16) this important fact lacked verification, but by the cultivation of the virus of cyanolophia in chicken bone marrow an opportunity was afforded of observing the changes which Foot describes. A careful study of the morphological and cytological characters of the cells figured in the above mentioned papers, soon showed a lack of transition stages, which are needed as proof of Foot's final theory. Further, the nuclei of cell forms which are said to be transformed into each other do not show close resemblances, e.g., the cells in figures 1 and 3, 1913, which are said to be eosinophil leucocytes at different stages of incubation, have different nuclear structure as well from each other and from the cell of the cell culture type (fig. 2, left side, 1913). The nuclear structure of this particular cell (fig. 2, left side, 1913), however, has a certain resemblance to the nuclei shown in 1912, figures 5 and 6. These cells are considered by Foot as stages connecting the ' Riesenzellen' with "eine Art von monnuklearen basophilen Zellen" (1912, p. 450). But here, as far as could be judged from the draA\ings, the cytoplasm of the cells in figures 5 and 6 is very different. Figure 5 has granules, figure 6 does not show them; only traces of digested nuclei of other cells are visible. These contradictory facts present a priori difficulties in accepting the views of Foot. But they appeared far more disconcerting on examining the cells themselves.
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 77
 +
 +
TECHNIQUE OF CULTIVATING, PRESERVING, AND STAINING BONE
 +
 +
MARROW
 +
 +
It is not necessary to describe in detail the technique of these cultures, since the writer followed the same methods as those used by Harrison ('10), Burrows ('11), and particularly Foot ('12 and '13). For storing the plasma it was deemed important to use the methods described by Walton ('12) for keeping mammalian plasma in good condition for long periods of time. Great stress was laid on the study of the living cells, and a warm stage was used to follow out the transitions of one cell form into another. The bone marrow of very young chickens, those of medium age, and of old individuals was studied; observations were also made on bone marrow which contained a very small amount of fat, as well as that which had a large amount of fat.
 +
 +
The method described below gave the best results in identifying and showing the stages of the individual cell types in stained preparations. A small particle of bone marrow was put into the plasma medium. The cells in the tissue were then allowed to migrate out of it. At periods of either 2, 4, 6, 12, or 24 hours, the original particle of bone marrow was extracted, and the fate of those cells which had emigrated was studied. The writer found that from the original particle of tissue numerous cellforms had been sent into the surrounding plasma clot. Having thus extracted the bone marrow, it could be determined with absolute exactitude which cell-forms emigrated first, and the history of those cell types which had emigrated after 2, 4, 6, 12, or 24 hours, or at any given period, could be recorded. The extracted particle of bone marrow was now transferred to a new plasma medium and the cell forms which emigrated after the transfer were also observed. This was repeated several times, until practically all emigration of cells into the surrounding plasma had ceased. The structure of the remaining particle of bone marrow was of course studied. Smears and sections were made at every stage of the emigration process and a more complete history of this complicated process was thus obtained.
 +
 +
In staining the pieces of bone marrow, the methods used by Foot in 1912 and 1913 were followed and other methods for the
 +
 +
 +
 +
7S RHODA ERDMANN
 +
 +
discovery of fat were added (see descriptions of plates, page 118. Besides these, the Giemsa stain after moist fixation according to the prescription of Giemsa proved to be very satisfactory. No dry smears of bone marrow were used.
 +
 +
THE FATE OF LIVING BONE MARROW CELLS IMPLANTED IN
 +
 +
PLASMA AT 38°C.
 +
 +
The experiments from which the drawings on plates 1 and 2 were made were started on December 25, 1915, and on January 3, 1916. The bone marrow was taken from a full-grown chicken which had a large amount of fat, so that the pieces of marrow have a yellowish-white appearance. The first cells to leave the tissue after 40, 60, and 90 minutes incubation are, as Foot rightly remarks in his publication of 1913 (p. 49), small mononuclear or larger polymorphonuclear leucocytes (fig. 1). The forms have a very dark, granulated cytoplasm and are actively amoeboid (fig. 1). Pale mononuclear forms without granulations but with their characteristic vesicular nucleus, follow closely the emigrating polymorphonuclear leucocytes. The fourth cell from the left (fig. 1) represents an erythroblast. The structure of the nucleus makes this evident. Besides these forms figured in figure 1, red blood corpuscles and a few fat cells were present in those parts of the plasma clot which surround the implanted bone marrow particle. The network of the bone marrow was injured by the process of cutting and tearing the particle into small pieces, and it is therefore not surprising that a large number of red blood corpuscles and some fat cells were scattered into the surrounding plasma clot. They are not figured in figure 1.
 +
 +
After 24 hours various other cell types have migrated into the surrounding plasma.
 +
 +
Figure 2 shows bone marrow which has been in the plasma for 24 hours, from January 3 to January 4, 1916. We can easily distinguish two different kinds of granulocytes: big cells which have round, shining granules, the nucleus nearly half as big as the cell and half-moon shaped; and smaller forms, with very dark granules, the latter not rounded but more rod-shaped, the
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 79
 +
 +
nuclei spherical and very often dividing. It is impossible to define without doubt the exact type of these granulocytes before the relation of their granules to basic or acid stains develops the true character of these cells. Therefore we do not venture any interpretation of the bigger type of these granulocytes but point out only that the smaller forms must be eosinophil leucoC3'tes after their morphological structure, though their granules appear rather darker than those in non-incubated leucocytes of chicken-bone marrow. Also they have less distinctly round or less rod-shaped granules. These two observations are important. The big cell in the center of the figure 2 does not contain any granules but is from the large nongranular mononuclear lymphocyte type. Very often these cells break into pieces during observation.
 +
 +
Two other cells, one on the right, the other on the left side of figure 2 are of a different type They contain large shining droplets, the fatty nature of which seems doubtless. Their nuclei have a vesicular structure and appear at this stage of the culture as often dividing. They are less numerous than the eosinophil leucocytes which form, in the first 24 hours, the bulk of all cells migrating into the surrounding plasma medium.
 +
 +
Figure 3 represents bone marrow which has been incubated for 48 hours (January 3 to January 5, 1916). Here a 'Riesenzelle' is rapidly moving; its cytoplasm is spread over a great area on the cover-glass and contains fat droplets and glistening granules. This ' Riesenzelle' shows in its cytoplasmic structure a close resemblance to the fat droplet containing cells on figure 2. To account for the larger size, we can either suppose that several of these cells have fused together or the cytoplasm of a single cell is thinned out by the method of cultivation.
 +
 +
The structure of the granulocytes is not very much changed. The larger forms with glistening granules and half-moon-shaped nucleus have diminished in number but smaller cells of the same type can be discovered now and then. In these forms sometimes fat droplets are visible. The eosinophil leucocytes are still abundant, but are surpassed in number by small ungranulated cells. These form now the bulk of the cells migrating into
 +
 +
 +
 +
80 RHODA ERDMANN
 +
 +
the surrounding plasma clot from the implanted tissue particle. They have either vesicular, less refractive or very shining and highly refractive nuclei.
 +
 +
In plate 2 we can follow in detail the further changes of the 'Riesenzellen.' The bone marrow (fig. 4) has been implanted 72 hours, from January 3 to January 6, 1916. Three round cells with big fat droplets can be seen, which seem to protrude out of the cell or cover its surface. The nuclei are therefore very seldom visible. When visible, they appear dark. A few granules are contained in the cytoplasm besides round or irregularly shaped masses, which seem to be remnants of other cells. On the third day after implantation these cells immediately attract the attention of the observer. They seem to have taken the place of the 'Riesenzellen;' this could be demonstrated by observation of the living cells. Some ' Riesenzellen' break apart, take on a round shape and completely extrude the fat droplets. These may be small or larger (fig. 5, second cell, left side) and show very fine pseudopodia. They are round cells which can survive an indefinite time in the plasma medium, the so-called 'cell culture type.'
 +
 +
Many 'Riesenzellen' however (fig. 5), the similarity of which to the round cells seen in figure 4 can be easily discovered, show all signs of degeneration. The cytoplasm has a 'curdled' appearance and is torn. The fat droplets have been thrown out into the plasma clot, and the granules have acquired a dark appearance. This regressive process takes place on the fourth or fifth day after implantation. These decaying cell masses are surrounded by small ' granulated and ungranulated cells and seem to be able to phagotise, because their cytoplasm shows in some places 'curdled granules.'
 +
 +
During the next days of incubation, no striking changes take place. The number of living cells diminishes and few tjrpes of cells are in healthy condition.
 +
 +
Fig. 6 shows cells which have been incubated in the same plasma medium 216 hours (from December 25 to January 3). They have small distended nuclei which do not seem to contain much chromatin, and the cytoplasm is filled with shining
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 81
 +
 +
droplets. They belong to the so-called 'cell culture' type. Besides these cells we find others with oblong nuclei and elongated cytoplasmic bodies full of glistening fine granules. These move slowly and show fine pseudopodia formed by their delicately granulated cytoplasm.
 +
 +
To summarize: Fat containing bone-marrow of chicken when incubated for 9 days in a plasma medium, undergoes the following changes which can be observed in the living preparation: The signet-like fat cell disappears, it is transformed to 'Riesenzellen' and finally to the 'cell culture' type. This type includes round cells with coarsely granulated cytoplasm, big shining droplets and oblong, less refractive nuclei. The other prevailing cell-form is distinguished by its finel}^ granulated cytoplasm, elongated or round cell body, and oblong nucleus.
 +
 +
These two cell types (not widely different in their morphological bearing) are always to be found among the cells which have migrated from the implanted bone-marrow particle into the plasma clot. Besides these cell forms, — capable as it seems of metabolism for long periods, — we see all forms of disintegrated cells. The cytoplasm and nucleus separate and the preparation is filled with debris. Fat droplets of different sizes which are freed from the cell fill the preparation. Nuclei of small granulocytes and lymphocytes without cytoplasm are often seen. Also shadows of blood corpuscles and granulocytes of all sizes are present.
 +
 +
It is certain that in non-renewed tissue culture retrogressive and progressive processes take place. It will be necessary to investigate the more intimate phenomena of these changes in stained preparations specially adapted to the study of each different cell type by different methods of cultivating and staining.
 +
 +
THE FATE OF THE MONONUCLEAR AND POLYMORPHONUCLEAR
 +
 +
EOSINOPHIL LEUCOCYTES OF THE BONE MARROW IN
 +
 +
TISSUE CULTURE
 +
 +
While describing the changes of the living bone-marrow cells after they had been 1, 24, 42, 72, 96, and 216 hours in the plasma medium, — the present author could give little or no definite
 +
 +
THE AMERICAN JOURNAL OF ANATOMY, VOL. 22, NO. 1
 +
 +
 +
 +
82 RHODA ERDMANN
 +
 +
interpretation of the changes observed in the different types. Some exact knowledge could be acquired only by comparing and combining the phenomena observed in bone-marrow cells in preserved and stained preparations after they had been in the plasma medium for, well defined periods.
 +
 +
In figure 7, an exact microscopic field of a bone marrow preparation, after 36 hours incubation, is shown. The implanted tissue particle would be (if shown on the drawing) on the left side of the preparation. The cells shown have migrated to the zone next to the implanted bone-marrow tissue particle whichwas taken from a full-grown chicken and contained fat
 +
 +
Eosinophil leucocytes in various developmental stages are numerous. They are in rapid amoeboid movement, and by continued fragmentation diminish in size and multiply in number. Their plasma is slightly basophil. The nuclei are strongly chromophil and the nuclear leucocytic structure in most forms is indistinctly developed. By comparing the nuclear structure wdth that of eosinophil leucocytes which have been 24 hours in cultivation (fig. 9) we can better distinguish the typical leucocytic network of chromatin particles and threads. The plasma of these leucocytes and of those figured in figure 8, which have been only one hour in the plasma medium, is acidophil and the round granulations are very distinctly recognizable.
 +
 +
Besides the changes in the cytoplasm of the leucocytes from acidophily to basiphily, other phenomena are noticeable. After one hour and still more after 36 hours incubation, the leucocytes of all sizes are losing and expelling the granulations. The nuclei of these forms have either become pale and indistinct (fig. 7, right side, below) or condensed and strongly chromatic (figs. 12 to 14). They may fade out to mere shadows and disappear.
 +
 +
The farther the polymorphonuclear eosinophil leucocyte advances into the plasma clot, the more its cytoplasm spreads out in the tissue culture. The granulations in consequence no longer appear lying closely together, but seem widely scattered in the cytoplasm. The leucocytes finally lose their power of cytoplasmic division. This happens generally on the margin of the plasma clot where the culture medium is thinly spread. The horseshoe — or kidney-shaped nuclei separate, become
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 83
 +
 +
pyknotic and form round, chromatic bodies " (figs. 11 to 19). The acidophil granules become more and .more indistinct, the cytoplasm is again acidophil, and partly vacuolized. In this stage, long chains of these forms closely lying together cover the outer zones of the preparation, gi\ing it a reddish halo. Later these cells without granules flatten out entirely, lose their nuclei or their chromatic particles, and undergo total destruction.
 +
 +
To summarize: most mononuclear and polymorphonuclear eosinoiphil leucocytes with either round, kidney-shaped, or lobulated nuclei, during the first hour of their emigration (fig. 8, and fig. 43) into the surrounding plasma, divide rapidly. They form smaller cells with fewer granules and a more basophil cytoplasm. Later by dividing and moving to the outskirts of the plasma clot, they finally form rays and layers of partly acidophil, vacuolized 'cells' without nuclei and granules. Another group of these eosinophil leucocytes, before diminishing in size in the zone near the implanted bone-marrow particle, had extruded its granules at a very early period. They fade out and leave their more basophil cell bodies in the plasma clot. The mononuclear or polymorphonuclear eosinophil leucocytes undergo a regressive development in tissue cultures.
 +
 +
These conclusions agree with the writer's own observations of the cells in living preparations. On the first and second day of incubation the eosinophil leucocytes are numerous and of normal size (fig. 2, left side, above). On the fourth and the fifth day the few forms, which have not undergone the flattening-out process and which have not changed their character, are small, with fine granules and an ellipsoid nucleus (fig. 5, left side, below). Foot ('13, pp. 49-51), in his account of the changes of the eosinophil leucocyte in the culture medium, reports that these cells finally take on the same form as that assumed later by the large mononuclear lymphocytes, and cannot be distinguished from them. With this conclusion the present MTiter cannot agree. In figure 8, the emigration of small leucocytes is shown. The lean, almost fat-less bone-marrow orginated from a young, not full-grown chicken. After an hour in an identical preparation the tissue was extracted and only the emigi-ated cells were allowed to develop. All cell types which
 +
 +
 +
 +
S4 RHODA ERDMANN
 +
 +
are pictured in figures 11 to 26 are cells which have emigrated early from the bone-marrow particle, advanced to the border of the plasma medium, and changed in different ways.
 +
 +
Figin-es 11 to 19 show the regressive development of the polymorphonuclear leucocyte which is inserted in the plasma, either as a younger form, with spherical nucleus, or as an older form with kidney — or horseshoe-shaped, or lobulated nucleus always recognizable because of its acidophil granules. The long chains of these deformed cells in all transitions are easy to identify in preparations, where only a few cell types have been allowed to emigrate into the plasma. Here they never take on the character of the 'cell culture type' (Foot).
 +
 +
When bone marrow is taken from a young, poorly fed chicken and treated as above described, few ' mononucleare basophile Zellen' emigrate in the first half hour, and the bulk are only eosinophil leucocytes (fig. 43). If these preparations are allowed to develop two or three days the rays of cells consist for the most part of these eosinophil leucocytes and few X cells or forms of the cell culture type are visible. If the process of extracting and again implanting the bone-marrow particle is repeated and the cells of the succeeding emigrations are controlled, few eosinophil leucocytes are observed in the second and third stage and after the third implantation approximately no eosinophil leucocytes are to be seen.
 +
 +
Therefore, no new formation of this cell type from a stem cell could be observed in the plasma clot, but only a process of emigration, multiplication, transformation and degeneration of those forms which were implanted with the bone marrow in the plasma clot.
 +
 +
THE FATE OF THE ERYTHROCYTES AND THE ERYTHROBLASTS IN THE BONE MARROW TN TISSUE CULTURE ^
 +
 +
The general rule for the behavior of cells in tissue culture: the more they are differentiated, or adapted to certain functions,
 +
 +
^Erdmann, Rh. 1917 Some observations concerning chicken bone marrow in living cultures, Proceedings of the Society for Experimental Biology and Medicine, vol. 14, pp. 109-112.
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM , 85
 +
 +
the quicker they undergo destruction holds true in the case of erythrocytes. The red blood corpuscles appear often without a nucleus or without a shadow of a nucleus. The plasma seems perforated. This indicates that the haemoglobin has disappeared. Those cells in which we can trace only the shadow or a faint remainder of the nucleus are apt to deceive the observer. The remainder of the nucleus appears like a small parasite but is nothing more than the nucleus of the cell, as can be proved by numerous intermediate forms. These bodies resemble the Cabot's bodies which are described by Juspa ('14, p. 429) in certain diseases of men. Also the nuclei may become pyknotic in other forms and the plasma may disappear. Foot ('12, p. 461, and 1913, p. 46) notes these same two different ways of degeneration in erj^^throcytes. Their dead nuclei or their plasma is often incorporated into phagocytic cells (figs. 34 and 35) the origin and types of which will be discussed later.
 +
 +
The non-elongated round or irregularly shaped erythroblasts have a pale yellowish or colorless plasma (figs. 1 to 3). Well developed erythroblasts are distinguished when stained by their wheel-like, highly chromatic nucleus. Unstained cells show a whitish appearance of the nuclear membrane which seems crowded with the content of the nucleus and ready to break. Figures 3 and 7 represent erythrocytes and erythroblasts in various stages of their retrograde development. Their plasma-less nuclei cover the microscopic field and are often seen incorporated into cells of phagocytic character. Unripe, young erythroblasts are figured in figure 8. They have larger nuclei in proportion to their basophil plasma than the erythrocytes and are scattered, through the tearing apart of the bone-marrow network, in large quantities into the surrounding plasma. They are recognizable in stained preparations by the smooth surface of their plasma and their chromatic nuclei and cannot be confused with eine Art von basophilen mononuclearen Zellen" which, according to Foot '12, form the X cells and the cell culture type.
 +
 +
But the difficulty begins when very young, i.e., small cells characterized in the first day of incubation by their situation near the bone-marrow network, are to be isolated and cultures
 +
 +
 +
 +
86 RHODA ERDMANN
 +
 +
from young living erythroblasts and from young basophil cells with vesicular nuclei are necessary, for deciding different questions. My experiments only proved, after isolating young cells near to the bone-marrow network that they underwent no transformation into erythroblasts but showed the phenomena fully described later on page 94-100 the transformation into cells of connective tissue cell type. It is naturally not excluded that erythroblasts — when they are already erythroblasts in a strict sense- — divide in the tissue cultures, but I never could isolate this cell type with any certainty just at the point in being transformed from its 'stem cell' into erythroblasts. This phenomenon seems not to take place in tissue cultures.
 +
 +
THE FATE OF THE IMPLANTED MICROLYMPHOCYTES IN TISSUE CULTURES OF BONE MARROW
 +
 +
The microlymphocytes in chicken bone marrow are found in great quantities. Their small protoplasmic brim and condensed, highly chromatic nuclei allow us to distinguish them easily from the small basophile round cells "with vesicular and achromatic nuclei, closely situated to the network of the bone marrow. The microlymphocytes seem to be present in the tissue cultures from the first day of the incubation of the bone marrow, mthout apparent changes, until the last day of cell life in the culture. But are those the same forms which were incubated or newly originated forms? The microlymphocytes implanted with the bone marrow particle must be capable of active movements, because they are no longer visible in the meshes of the bone marrow network after several days' incubation, but are always present in the plasma clot. In the preparations where only a few cells are allowed to emigrate and to stay several days in the plasma medium, the microlymphocytes are widely scattered. Their own cytoplasm expands in a star-like manner, often forming long cytoplasmatic raj^s. After a fortnight in the culture medium, they have the appearance of forms such as the cells pictured in figure 25. One cell appears normal; the other has a torn cytoplasmatic body. Figure 27 shows the remaining nuclei which will soon undergo complete destruction. Foot '13, page 43, believes that besides numerous microlymphocytes.
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 87
 +
 +
which die, a large number 'steadily increase in size' and either form cells of the macrolymphocytic type or of the large mononuclear lymphocytic type, after the latter has undergone nuclear enlargement and dechromatization." Foot presents no dra^^^[ngs of these highly important forms, but considers it sufficient to record the measurements of microlymphocytes of different sizes, measuring from 3.5 to 9.6 in diameter. The nuclear structure of these transition forms is not described by him. The present author has never seen cells with typical microlymphocytic condensed nuclei in all sizes, only cells with vesicular achromatic nuclei in every possible size. In the later discussion these contradictory reports of Foot and of the present author must be borne in mind.
 +
 +
Some authors hold the theory that microlymphocytes originated from the large mononuclear lymphocytes by multiple simultaneous divisions. Only in very recently incubated tissue cultures, as recorded on page 79 a breaking of large lymphocytic forms into pieces was observed. But the isolated cultivating of these small cells afforded no definite results. Multinucleated forms with ragged or torn cytoplasmic structure and nuclei with highly condensed chromatin may be observed in the case illustrated, of which three have a condensed chromatic structure (fig. 8). The younger the implanted bone marrow is, the more numerous these forms appear to be. They have a slight resemblance in their plasma to very young connective tissue cells, as, e.g., Maximow ('10) pictures them in figure 43, from a guinea pig, but they seem to have no connection with the formation of bone marrow lymphocytes.
 +
 +
To summarize: The microlymphocyte belongs to those cell types which undergo no progressive development in the tissue culture.
 +
 +
THE FATE OF THE IMPLANTED MYELOCYTES IN TISSUE CULTURES OF CHICKEN BONE MARROW
 +
 +
From the first to the sixth day after incubation large cell types can be observed in the tissue culture of bone marrow when the experiment is conducted with a full-grown, over a half year old ehicken. These cell types have, as described on page 79,
 +
 +
 +
 +
88 RHODA ERDMANN
 +
 +
before staining and preserving, a half-moon shaped, or elongated nucleus, and their plasma is either granulated, or the granules are invisible dining cell life. The cells shown in figure 2, two granulocytes and one ungranulated large cell, have only been one day in the culture. The first type appears to divide; we can observe smaller forms on the following days, with larger granules than the eosinophil leucocytes possess. The other represented cell type is a large lymphocyte. These forms may break in pieces during observation. After six days incubation we discover in stained preparations the changed form of the myelocytes (figs. 39 to 42). The reddish ripened nucleus of these forms has all the characteristics of a myelocytic nucleus. But in eosinazur stains such nuclei are generally supposed to have a more bluish color. This must be explained by the rising acidity of the culture medium in growing tissue cultures (Rous, '13, p. p. 183-86). The cells in figures 39 and 41 must be considered eosinophil myelocytes, those in figures 40 and 42 mononuclear lymphocytes. In earlier stages of their degeneration process these large forms often have very fine acidophil granules in their cytoplasma when observed on the second or third day of incubation; but they are never seen to divide. Their plasma loses its granulations, flattens out, and vacuolizes. The eosinophil myelocytes and lymphocytes have only a regressive development in the tissue culture medium.
 +
 +
THE FATE OF THE FAT CELLS OF THE BONE MARROW IN TISSUE
 +
 +
CULTURE
 +
 +
But one observation of the behavior of fat cells in tissue culture is given by Foot, who writes ('12, p. 447,) that the cultivation of subcutaneous or subepicardial adipose tissue was without success, growth of considerable amount could not be observed. The present writer repeated Foot's experiments. Adipose tissue of the omentum of the chicken showed, after three days incubation, almost a complete disintegration; further, the formation of few cells of the 'cell culture type' and the survival of connective tissue cells could be observed. It may be conceived that some connective tissue cells may have originated
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 89
 +
 +
from fat cells losing their fatty contents and assuming the character of the known type of connective tissue cells. Or the connective tissue cells, implanted together with the adipose tissue may have developed and multiplied. This is a separate question which has not been sufficiently studied in true adipose tissue.
 +
 +
The changes of the fat cells of bone marrow in tissue culture, though not considered by all authors to be real fat cells, have a great resemblance to phenomena seen in rapidly growing embryonic adipose tissue, as Foot remarks (p. 48, '12). But he himself, neither in 1912 nor in his later publication of 1913, states the ultimate fate of the implanted, so-called fat cells, which, together* mth the other cells of the bone marrow, are in the culture medium and are numerous in the white bone marrow of the adult chicken. The typical signet-ring cell may apparently remain unchanged for 24 hours in the plasma medium, as it is shown on a photograph (fig. 46, right side, above). But the observed facts do not agree in most cases with this view. After three hours incubation all fat cells show still their accustomed shape. The big fat -globule surrounded by a brim of cytoplasm flattens out and the large globule of fat separates into small droplets. Or the fat cell divides into two parts, and even a process of budding may be observed (figs. 29 and 30). If the cell has not divided up, the fat globule diminishes in size and does not fill the whole cell. With a specific fat stain it can be shown that the cytoplasm is filled with small fat droplets and strands (fig. 28). Later foamlike masses of cytoplasm, in the meshes of which the fat is easy to identify, protrude from the cell margin and separate themselves partially or totally from their 'mother cell.' Cells of this kind may offer the appearance of cells figure in figure 2, left side, in unstained preparations. In a tissue culture of 24 hours incubation, preserved with Orth's fluid and stained with Giemsa stain; they appear as cells with highly chromatic nuclei, and perforated cytoplasm (figure 7, right side and figures 33 and 34) ; also weblike masses, apparently without nuclei, are frequent (fig. 7) which are often surrounded by microlymphocytes and polymorphonuclear leucocytes. Text-figure A gives
 +
 +
 +
 +
90
 +
 +
 +
 +
RHODA ERDMANN
 +
 +
 +
 +
the most striking phases of the activation of a fat cell. The original fat cell, the fat cell which has extended fine pointed processes, and the final stage that comprehends cells containing vacuoles which may still have traces of fat in them. (Compare cells on figure 2; figure 7, cell right side, above; and figures 45 and 46.)
 +
 +
 +
 +
 +
Text fig. A. Fat cells after 6 and 12 hours incubation.
 +
 +
 +
 +
 +
It must be kept in mind that these changes occur during the first 24 hours or 48 hours of incubation. Figures 45 and 46 show that in a 30 hours culture the dissolving of the big fat globules and the dividing up of the fat cells has been in progress. The cells form chains, typical for the stage of the culture of 24 to 48 hours of fat containing bone marrow. These cell chains flatten out, fine processes are extruded which cover great areas and may fuse with other cells in web-like masses. Figures 45 and 46 give a good surview of this process and such a cell is also represented in figure 33. We note its enormous size, its big vacuoles, its slender processes, its phagocytic capacity and its small nucleus. In short, we see a so-called 'Riesenzelle' of Foot
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 91,
 +
 +
which is already present after 24 hours of incubation. Now Foot ('12, p. 459, fig. 5) gives the photograph of a preparation of bone marrow after 5 days of incubation in a plasma medium. This is a descrepancy for which no explanation could be found.
 +
 +
It is of importance to state that all vacuoles do not contain fat in such a condition as to make it visible by the osmium process. The cell (fig. 32) shows still some fine traces of fat, but in many preparations which were treated with Scharlach or Sudan stain after adequate fixation, the vacuoles were devoid of fat. It is conceivable that fatty acids or other products of related character fill the vacuoles, but even after trying the most complicated stains (Ciaccio, Benda) to elucidate the nature of the contents in the vacuoles, no final decision could be I'eached.
 +
 +
From the third to the fifth day, the number of 'Riesenzellen' has diminished; we see smaller round or oblong cells with one or several vacuoles, with oblong faintly chromatic nuclei (fig. 34). They are the products of the breaking up of the 'Riesenzellen' and seem to be identical with Foot's cell culture type. They are capable of phagocytosis and move slowly toward the periphery of the plasma clot.
 +
 +
How can we interpret these extraordinary changes in the fat cells? The only similar observation was made by Maximow ('04, p. 108), describing the changes occurring in the cells of inflamed connective tissue of the rat. There he gives a good description of the involution of the fat cells. The process shows the same phenomena in the involution of the fat cells in the connective tissue of the living animal after inflammation as are to be seen in tissue culture. The flattening out of the cytoplasm, the dividing up of the big fat globule into small droplets inside the cell (Maximow, plate 3, fig. 9; Erdmann, text-fig. A) and the transformation of the plasma in a honeycombed mass (Maximow, Plate 3, fig. 11; Erdmann, fig. 7, left side, above), are identical processes in both cases. Maximow believes ('04, p. 119) that some of these cells become fibroblasts. The present author ventures no opinion on the subject, though a striking similarity exists between the fibroblasts of Maximow (text-fig. B) and the cell in figure 7, right side above.
 +
 +
 +
 +
92
 +
 +
 +
 +
RHODA ERDMANN
 +
 +
 +
 +
We find after the second day in our cultures: (1) cells of the fibrotjlast type; (2) cells of the 'Riesenzellen' type; (3) cells of the cell culture type, after Foot. All three types can originate from the implanted fat cell.
 +
 +
Besides these progressive changes we must state that many implanted fat cells undergo destruction. This is shown by the observation of the living cells as described on pages 79 to 81. Figure 4, shows such a disintegrating mass of fat cells from an unstained preparation, and fig-ure 7, shows the mass in a stained preparation. Here two cells of the honeycombed type are recogniza
 +
 +
 +
 +
Text fig. B Maximow, 1914, figure 8, plate 3. area of inflammation into a fibroblast.
 +
 +
 +
 +
Involution of a fat cell in an
 +
 +
 +
 +
ble (left side, above), one of which is intact, the other has expelled the contents of the plasma. Microlymphocytes are gathered around the disintegrating fat masses and the transformed fat cells. Maximow describes how his polyb asts, cells of the lymphocyte order, crowd around the fat cells and destroy them by phagocytosis (page 120). The same phenomenon occurs in the tissue culture; between the second and the fifth day the destruction and resorption of the dying fat cells is finished and the tissue culture gradually assumes a different aspect, as will be described later.
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 93
 +
 +
But together with these retrograde processes, easily observed in the Uving culture, small parts of the irregularly-shaped, large, disintegi-ating fat cells isolate themselves. They become spherical in shape and begin to wander away from their 'mother cells.' They can be recognized by their small nuclei, their coarse glistening plasma. They are identical with small fat cells. This 'rejuvenation' of the fat cell was only observed when bone marrow tissue of younger well-fed animals was implanted. Bone marrow from very young chickens and tissue from old hens seldom rejuvenate the fat cells, when such are present. In tissue from older hens the disintegration of the fat cells often obscures the observation of the other cell types.
 +
 +
THE FATE OF THE MONONUCLEAR BASOPHIL CELLS OF THE BONE MARROW IN TISSUE CULTURES
 +
 +
\\'Tien implanted in the plasma medium, the bone-marrow particle itself appears basophil after preservation with Orth's fluid and staining with Giemsa stain. For a long period, up to 14 days, it shows a strong basophilic character. We have shown how fat cells and their derivatives generally have a strongly basophil nucleus and often a basophil plasma. Erythrocytes, erythroblasts, and eosinophil leucocytes, which show a strong basophily of the nucleus, emigrate or are washed out of the tissue particle and either perish or undergo the changes described. The eosinophil leucocytes, diminishing the size of their nuclei and acquiring an acidophil cytoplasm, later form, together with the erythrocytes, the reddish halo around the implanted particle.
 +
 +
After the first emigration or washing out of the cell types mentioned, the tissue particle consists almost solely of basophil cells, which are very young, small, unripe erythroblasts, small lymphocytes, connective tissue cells of the bone marrow network, and basophil cells of all sizes and forms, the character of which is not at first recognizable. The thickness of the tissue particle prevents the closest examination, but these cells have always ungranulated plasma. In figure 8, a general survey of these basophil cells is given, as they appear after one hour's in
 +
 +
 +
94 RHODA ERDMANN
 +
 +
cubation in bone marrow of a young nearly fat-less chicken. Two types besides the erythroblasts with their more or less pinkish plasma and their wheel-like nuclei are distinguishable — cells with crude irregular cell plasma, as if it has been torn They possess small, condensed, highly chromatic nuclei (fig. 8 left side, above), or their cytoplasm has well-rounded contours and a very big nearly chromatinless nucleus. This type and its changes will now be described.
 +
 +
In figures 11 to 27, different emigrated cell types of a similar bone-marrow particle are represented. The particle itself was twice extracted during an incubation period of 24 hours. The emigrated cells of each extraction stayed 12 days in the plasma until they were preserved and stained and later analyzed, so no new rear guard of eosinophil leucocytes and those mononuclear basophil cells, the fate of which Foot tried to elucidate, need be considered. According to this experiment, which was repeated several times, besides the eosinophil leucocytes the changes of which (fig. 11 to 19) have been fully treated on page 85, six different cell types are recognizable after the second extraction.
 +
 +
1. Cells which resemble fat cells (figs. 20 and 21).
 +
 +
2. Cells which, by their nuclear structure but not by their cell plasma, resemble true connective tissue cells (figs. 22 to 24).
 +
 +
3. Cells which are true connective tissue cells, from the type of endothelial cells (fig. 27).
 +
 +
4. Cells which are true connective tissue cells not shown in figures 20 to 27 but in figure 9, with star-like, fine protoplasmatic processes and elongated, often cone-like shapes, and a more mesenchymelike character.
 +
 +
5. Cells which are microlymphocytes (fig. 25 and also fig. 27).
 +
 +
6. Cells which are lymphocytes (fig. 26).
 +
 +
Cell types 3, and 6 are not often found in preparations made according to the prescribed method. The lymphocyte with its fine red granules (fig. 26) shows all signs of degeneration. It appears highly probable that in the plasma clot the normal ripening out of the large mononuclear lymphocyte began but could not be fully accomplished owing to the conditions of the culture medium. The endothelial cell and the elongated connective tissue cells
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 95
 +
 +
(figs. 27, 9, and 38) have not changed their characters. They abeady appear on the first day after incubation, because they could be observed in bone marrow culture of 24 hours incubation. The elongated connective tissue cell is highly amoeboid, and shows in its plasma, on the first days of incubation, fine and bigger fat droplets, which are coarser when stained with specific fat stains. Later their plasma looks as if pulverized with small fat droplets, still later they lose their fat and appear highly vacuohzed. They repeat on a smaller scale the changes of embryonic subcutaneous connective tissue that had been incubated 14 days in a plasma medium. Because these cells appear after the first day of incubation (the present author has observed them after but five hours' incubation) it appears highly improbable that they originated from the basophil spherical cells in question. They are cells of the bone marrow network or the vessels of the bone marrow, which have been torn apart by the cutting of the bone marrow. They can be also observed in tissue cultures of true adipose tissue and are distinguished by their rapid division rate.
 +
 +
In most cultures of connective tissue made by various authors these cells have been described. Lambert and Hanes ('11) mention the accumulation of fat and the vacuolization of the cytoplasm in cells of mesenchymal origin. They represent tumor cells in their publication of 1911, plate 66, figures 4 and 5, of this character. Lambert himself in 1912, on plate 72, figure 3 and plate 74 figures wandering cells from the chick spleen. Some of these forms are more related to the connective tissue cell type in question, some resemble more the cell type seen in bone marrow cultures when the fat cells have begun the disintegration. In 1914, plate 44, figure 6, he gives a good proof of this.
 +
 +
In figure 9, Carrel and Burrows, ('11), represent also fat storing cells of this type. They are said to be originated from an adult chicken spleen, while the first author must have seen the elongated vacuohzed type ('13, plate 17, figure 16), in cultivated connective tissue. Lewis, R. M., and Lewis, H. W., '11, show on their figure 20, left side, in a chicken liver culture, highly vacuohzed cells of the same type.
 +
 +
 +
 +
96 RHODA ERDMANN
 +
 +
This comparison could be continued but the facts prove already that among connective tissue cells of the most varied parts of the chicken body these elongated, finely vacuolized, slender cells appear with a true connective tissue cell nucleus. They are all similar to the figures of Foot representing his X cells (cf. Foot '12, plate 22, figures 8, 16, 19). The connective tissue cell represented by the present writer in figure 9, is taken from a young chicken and is not of the same size as some of those cells which Foot shows. When cells, however, were taken from the bone marrow of a full-grown chicken, they were of the same dimensions as those given by Foot, '12, plate 22, figure 8.
 +
 +
Also, in the development of embryonic bone marrow tissue of the chicken, Dantschakoff, '09, depicts mesenchyme cells (plate 44, figures 5 and 6) which have a close resemblance to the above mentioned cell type (fig. 9). They are identical types, except that the latter may contain fat, the first are fatless. In this group must also be included the elongated forms of Foot's Riesenzellen which have pointed pseudopods.
 +
 +
To summarize: Though fat containing and often vacuolized the elongated cells with connection tissue like nuclear structure which appear in Foot's figures among his 'Riesenzellen' are true connective tissue cells. There can be no doubt that the granular lymphocytes, the elongated cells of connective tissue character, and the endothelial cells did not originate de novo in the tissue culture.
 +
 +
In studying the cells close to the connective tissue network of the bone marrow the present wTiter could only distinguish one well defined cell type (figs. 36 and 37). Small round cells with strongly basophil cytoplasm and large, faintly staining nucleus with two nucleoli are abundant. They are neither microlymphocytes nor mononuclear lymphocytes nor erythroblasts. They differ from the microlymphocytes by their vesicular nuclei, from the mononuclear lymphocytes by their size and their cytoplasm, from the erythroblasts by their nearly chromatinless nuclei and also by their size. In living cells the nuclei of erythroblasts appear whitish, the nuclei of these cells dark. If these cells, which migrate from the tissue particle after the leucocytes are
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 97
 +
 +
washed out by continued changing of the plasma, on the second incubation are allowed to develop we find after a fortnight two different types: figures 20 and 21, and figures 22 to 24. The cell represented in figure 21 differs from the basophil cells which had been implanted into the tissue culture (fig. 8, and figs. 36 and 37) onlj^ by its size and by the more chromatic contents of its nucleus. These forms are numerous; they later contain fat or vacuolize, forming chains, the cells of which are always to be distinguished by their nuclear structure from the eosinophil leucocyte. The nucleus has a close resemblance to that in fat cells; it is vesicular with round bulky, chromatic contents.
 +
 +
The next group (figs. 22 to 24) have a true connective tissue cell-like nuclear structure. The nuclei are elongated and fine threads of chromatin form a true connective tissue nucleus network. The cytoplasm is basophil in most cases, but in certain parts of the culture and in very old cultures it becomes acidophil. The basophily or acidophily of cells is no constant character in tissue cultures. Rous ('13, page 183) points out the changes in acidity of growing cells. The cells themselves become acid in the culture medium, after having been basophil. Later they may regain their basophil character. The cells in question are true phagocytes (fig. 23). They contain fat, blood corpuscles, dead nuclei, and other disintegrating particles. They are sometimes polynuclear; as the cell body does not divide they form also the so-called 'Riesenzellen' of Foot. They are more agile after the first days' of incubation. In older cultures they assume round, spherical and oblong shapes, and their enormous protoplasmatic body divides up. They then form the cell culture type (fig. 6) the nuclei of which are always vesicular and not very chromatic.
 +
 +
Therefore, in the group of Foot's 'Riesenzellen' do belong besides the products of the involution of the fat cells and the implanted elongated connective tissue celltype with its finely vacuolized plasma, these forms (figs. 22 to 24) in which the nearly fat-less bone marrow of a young chicken was used. This gave conclusive proof that the small mononuclear basophil cell
 +
 +
THK AMKHK AN JOIKNAL f)r ANATOMY, VOL. 22, NO- 1
 +
 +
 +
 +
98 RHODA ERDMANN
 +
 +
(figs. 8, 35, 36 and 37) after leaving the bone marrow network, can form 'Riesenzellen' which by their nuclear structure resemble connective tissue cells. They later become the cells to which Foot gave the name cells of the cell culture type." They are enlarged, fat-storing or vacuolized cells capable of phagocytosis.
 +
 +
The results here presented, i.e., the change of the small vesicular basophil cell into true phagocytes and later into 'Riesenzellen' or cells of the cell culture type — were attained by using the bonemarrow of a young, fat-less chicken and the washing out of the undesired cell types, as polymorphonuclear leucocytes. But even if we use the fatty bone-marrow of a full-grown chicken and control the daily changes, the same fact is demonstrated. The first day after incubation (fig. 7) we observe a large number of basophil mononuclear lymphocytes. Three are shown in one microscopic field. Their pale nuclei, often of a lighter blue than the plasma, the irregular shape of their plasmatic body in which sometimes a few fine -acidophil granules are visible, and their large size, make them conspicuous. Examining preparations of the same series a day later, the lymphocytes are very scarce. On the fifth day of incubation, when the disintegrated fat has been disposed of by the phagocytic acti\dty of these basophil cells, characterized by their close position to the network of the bone marrow, they are by far the most numerous types in our tissue cultures. In the following days they grow and divide rapidly forming 'Riesenzellen' which can store fat, become vacuolized, and end in rounding off and becoming cells of the cell culture type, their nuclei with a fine thread-work of chromatin becoming more like true connective tissue nuclei. They can even lose their basophily but may always be distinguished by their nuclear structure from the products of the regressive development of the eosinophil leucocyte in tissue cultures.
 +
 +
It might be possible to interpret Foot's text-figure 5, (page 459, '12) as representing a tissue culture preparation just in such a stage; because the time for formation of these features is the same. But then it is not explained why Foot does not describe the formation of the 'giant cells' and cells of 'cell culture' type after 24 hours' incubation.
 +
 +
 +
 +
CHICKEN BONE MARROW IN PLASMA MEDIUM 99
 +
 +
In the above mentioned preparations the bulk of all cells, with their fat storing and phagocytic capacities, their vacuolized cytoplasm have now left the implanted bone marrow particle. They advance with their fine, pointed, plasmatic pseudopodia to the outskirts of the plasma clot. Their faintly chromatic nucleus has only two nucleoli. This character is evident in the youngest cells of that kind w^hich are close to the network of the bone marro^v (figs. 36 and 37) and is also found in 'Wanderzellen' after Dantschakoff (cf. Dantschakoff, '09, page 133), plate 7, figures 2 to 5. These 'Wanderzellen' w^hich originate from a mesenchyme or endothelial cell can, according to Dantschakoff, either be histiotypic or lymphocytic. They form in the embryonal development specific elements of the connective tissue or the hematopoetic apparatus, according to the conception of the monophyletic school. In older cultures nearly all basophil cells have nuclei of true connective tissue cell character, e.i., the chromatic granules of the nucleus are connected with fine threads. They are identical with those nuclei figured in figures 22 to 24. Not so frequent are types of nuclei figured in figures 20 and 21.
 +
 +
The 'Wanderzellen' in the tissue culture lose, in the later days of their existence, especially in unrenew^ed tissue cultures, their fine cytoplasmatic processes but are — by the structure of their nuclei and their cytoplasm — connective tissue cells of a more mesenchymelike character. They are transformed to cells of the cell culture type.
 +
 +
That these cells are descendents of the implanted cells, which were lying close to the bone marrow, is further proved by the following experiment. After all loose cells in the meshes of the bone marrow are w^ashed out by repeated changing of the plasma medium, cells of the type in figures 20 to 24, can be formed. After three changes of the culture medium, with a period of two days between, the cells close to the netw^ork formed vacuolized cells w^hich could be interpreted in no other way except as 'Wanderzellen.' Their nuclei had become nearly chromatinless, and their plasma acidophil; they sometimes assumed the character of fat cells, but were generally of the 'Wanderzellen' type.
 +
 +
 +
 +
UK) KHODA EUDMANN
 +
 +
No large mononuclear lymphocytes could be seen. It is, therefore, also evident that a new formation of this cell type, the niononuchar hir^e lymphocyte of the bone marrow, does not occur in i\\v tissue culture. The smaller and larger basophil cells with a vesicular nucleus near the bone marrow network, and the cells which later leave the network are 'Wanderzellen,' a type closely related to the mesenchymal cell. They can be kept alive for longer periods in renewed culture-medium.
 +
 +
The empty network of the bone marrow, consisting of slender connective tissue cells, has lost its power of sending new cells into the surounding plasma clot. The network cells remain living for long periods in renewed medium changing only their cytoplasma in the same manner as other connective tissue cells do in plasma culture. It becomes perforated with sieve-hke vacuoles which may stor