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==Racial And Sexual Differences In The Appendix Vermiforaiis==
==Studies In The Development Of The Opossum Didelpbys virginiaua L.==


Henry Bayon
V. The Phenomena Of Parturition


Department of Anatomy of Tulane University
Carl G. Hartman


About thirty years ago the appendix had practicalh' no history, either physiological or pathological.
The University of Texas, School of Zoology


Howard Kelly in his extensive work on the vermiform appendix and its diseases, recalls that only in 1824 was the appendix recognized as an organ susceptible to disease arising primarihin its own structure, although mention was made of isolated cases such as ]\Iestiviei's recorded in 1759 in which a postmortem examination revealed a pin (t)ncealed in the appendix, which had caused inflammation resulting in the death of the patient. This and other similar cases related in Kelly's work show that even in the eighteenth century the appendix was recognized as susceptible to inflammatory lesions, but it was not until 1886 that the appendix was placed in the category of organs susceptible to surgical disease. From that time the daily harvest of appendices has steadily increased. At the beginning of that period we hear Frederick Treves, one of the pioneers of appendectomy, clamoiing against the indiscriminate removal of the appendix, which he brands as a needless and illogical recklessness.
THE METHOD OF TRANSFER OF YOUNG TO THE POUCH


Since that time a number of speculative statements have appealed regarding the purpose of the appendix, usually more or less fanciful and sometimes positively grotesque. From the high otiice of abdominal tonsil we find it elsewhere relegated to the abject role of the ordinar}^ mechanical grease cup. In studying the minute structure of the appendix, it is true that large numbers of lymphocj'te accumulations are found within its walls, but at best these amount to little compared with similar accumulations found elsewhere in the intestinal canal and are in no way diff'erent from the solitary and aggregated lymphatic nodules.
The literature


241
So far as the writer has been able to discover, there exists in the nterature only one account of the actual birth of any marsupial, notwithstanding the abundance of opossums in America and the variety of all marsupial fauna in Australia. Nor does that foremost of all students of marsupial embryology, Prof. J. P. Hill, refer to this topic, although on one occasion ('00, p. 371) he killed a specimen of Dasyurus after "one only of the young had been born." ^leigs ('47) and Selenka ('87) examined pouch young of the opossum immediately after birth, but made no observation on parturition.


The single recorded observation referred to is that of Dr. Middleton Michel, of South CaroUna ('50), who, on January 28, 1847, witnessed the copulation of a pair of opossums, and fourteen days and seventeen hours later saw the birth of the foetuses. In order to show, however, that Doctor ^Michel failed to see the actual passage of the 3'oung to the pouch, two essential paragraphs on the point at issue are here quoted:


' Parts 1 and 2 (History of the early cleavage — Formation of the blastocyst) appeared in the Journal of Morphology, volume 27, number 1, March, 1916; and Parts 3 and 4 (Description of new material on maturation, cleavage and entoderm formation — The bilaminar blastocyst) appeared in the Journal of Morphology, volume 32, number 1, March. 1919. These four parts may be obtained from the publishers.


242 HENRY BAYON
* Contributions from the School of Zoology, the University of Texas, no. 143.


Nceilless to say that the grease-cup theory (imls no support from whatever aiiRlo the organ is vioweil. It evidentl}' originated in 174^ from an old theory of J. Vosse, who ohiimed that the ghmds of the cecum were not sufficient to moisten its contents antl that tlie function of the apjiendix was to provide additional secretion.


It is not the jjurposenf tlie ])resent study, however, to discuss the function of the api)endix nor the conditions which call for its removal. It was undertaken with a view to possible difTerences in .structure, both as to race and as to sex.
The pregnant female was found standing on her hind legs; her body was much bent, and propped up against the rornor of the cage; her muzzle in immediate contact with the cloacal opening, which was red, tiunefied and distended: a young ap|)eared at the opening, and was conveyed by the mother's mouth to the pouch, or perhaps was rather licked in, as her tongue seemed busily employed within, around and about the pouch.


In considering disea.se of the appendix, the following (juestions suggested them'selves: Is appendicitis more frequent in the white race than in the negro? Is the disease more prevalent in one or the other of the sexes? .\nd if there are racial and sexual differences, is there anything in the structure of the appendix to account for such difTerences?
The young are expelled first into the vaginal cul-<le-sac, in which they remain for a short time, on the contraction of which they are forced along the vaginal canals one by one; parturition is thus ver>' much prolonged, owing to the circuitous route which the young are obliged to take, and the delay therein- occasioned between the birth of each is the object of the peculiar modification of these parts in this animal, as it affords the requisite time emjiloyed in the convej'ance of the young to the pouch and their adaptation to the teat.


The first question, if records and Surgical experience are given consideration, is answered decided!}' in the affirmative. The statistics, however, on this, as unfortunately on a great many other subjects, are totally unrelial)le, even though tabulated intelligent h' and in good faith.
It is quite clear from the language of this quotation that Doctor Michel did not actuallj- witness the migration of the embryos and that he merely guessed at the method emploj-ed by the mother, since he was not sure whether she used her mouth or her tongue. It will, moreover, be shown below that Doctor Michel was also mistaken in presuming that the young at birth pass out by way of the lateral vaginal canals. The observations recorded below indicate that the marsupial female does not actually transfer the foetuses to the pouch and that Doctor Michel's interpretation, as well as the prevailing notion in accordance therewith, is not borne out by the facts.


The eagerness displayed bj' the medical i)rofession in coming before the public, both in print and in lecture, no doubt in a great manj- instances with very laudable intent and good effect, places Avithin reach of the more intelligent hwman much of the interpretation of his own ills and jiains. He seldom ignores the signs and symptoms of appendicitis. As a result, the first tinge of pain in the right iliac region will sound a loud note of warning, followed b}' a rush to the surgeon, who at once proceeds to remove the aj)pcndix, in which postoperative examination frequently reveals little or no inflammatory change. This statement, however, is made with due regard to surgical prudence svhich takes no chances in a condition where prompt treatment means so much to the patient's safety. At this juncture it may not be inappropriate to refer to the opinion so frequently exjire.ssed, that apjiendicitis is on the increase. That the number of appendectomies has increased there can be no question, but that appendicitis is increasing is more than doubtful.
So7ne preliminary observations


A series of observations and experiments during the last four or five breeding seasons of the opossum had enforced the conviction that the young reach the pouch and find the teat by their own efforts and are not placed on the teats by the mother's tongue or lips, ^^h^• should it be necessary, one may ask, in the absence of actual observation, to presume such undue skill and sensitivit}- in the adult when a pure instinctive reaction on the part of the young will suffice?


On several occasions I experimented with newly born pouch young, gently removing them from the teats to which they had firmly attached themselves by means of their powerful tongues.


RACIAL DIFFERENCES APPENDIX VERMIFORMIS 243


In contrast with the alertness of the better classes and their readiness to part with an offending organ, is the ignorance and apathy of the poor negro concerning his disease and the counterindifference of his medical attendant. Acute indigestion or heart failure are con^-enient and readj' forms for his death certificate. Acute gangrenous appendicitis maj' have caused his death, but his tardiness in seeking medical aid or the lack of interest of his doctor, who comes in when the patient is dying or dead, are in many instances responsible for the error in diagnosis. Hence a possible flaw when records are considered, in passing judgment as to the racial susceptibility to appendicitis.
I quote from mj^ notes in one case (no. 301, experimented upon in the presence of Dr. C. H. Heuser, of The Wistar Institute, January 20, 1917) :


But if statistics are negative in deciding susceptibility, might there not be some structural peculiarity which would make certain appendices more vulnerable than others? Some time ago, in a casual examination of appendices in the dissecting-room, I was struck with the stout musculature of the negro organ as compared with the flabby membranous appearance of the white appendix. Obviously, a fecal stone or a foreign bodj^ would have far less chance of becoming impacted or retained in a robustly muscular appendix with active peristalsis possible than in one whose weaker walls would not only fail to rid the organ of its offending contents, but in consequence of the organ's easier distention would favor the storing up of enormous numbers of pathogenic bacteria.
Female tied do^ii and pouch opened. Young which were removed from teats crawled about, moving hands alternately, as in swimming. Were able to crawl among hairs and find teats by their own efforts. One specimen, removed three times, found teat each time and three others found teats after wandering about.


Hoping to arri\-e at some tangible facts regarding structm-e which might cast some light on racial and sexual peculiarities, I have examined 100 appendices and tabulated them according to race and sex. The specimens emploj^ed comprised 53 negro appendices, 31 male and 22 female, and 47 wliite appendices, 11 nude and 36 female.
These experiments certainly argued strongly in favor of some little independence of action on the part of these 'embryos,' a term that Doctor Meigs ('47) would have us abandon when speaking of these breathing, sanguiniferous, digesting pouch young."


METHOD OF PREPARATION
On February 6, 1917, on opening specimen no. 402 under anesthesia, I was surprised to find a collapsed but very vascular uterus, as if birth had just taken place. This proved to be the case, for on remo\'ing the animal from the table I found that the entire litter of foetuses had been expelled during the operation. They were mostlj' still ali\'e, entangled in foetal envelopes and immersed in the foetal fluid. To some of the foetuses the umbilicus was still attached ; others were free, but no navel could be seen in any case. None of the foetuses, even after being freed of membranes and liquids, could crawl about, as they were apparently drowned in their own embryonic fluid. It seemed likely, therefore, that the emlsryos, on emerging from the vagina, need the assistance of the mother to lick away the fluid expelled from them, and this w-as later verified by actual observation.


The appendices were at first fixed in 10 per cent solution formahn, then mordanted in the following fluid:
Embryos near term were also removed from the uterus, freed of their envelopes, and allowed to crawl about over the mother, which they did for at least fifteen minutes.


35 per cent aqueous solution bichromate of potash 92
On one occasion I removed one uterus three days before term (no. 131), and about the time that birth was to be expected from the remaining uterus I injected, some pituitrin subcutaneously, hoping to witness parturition thus brought on. But owing to the fact that abortion had pre\dously taken place, as was afterward learned, onlj' mucus was extruded from the genital orifice.


Formalin (40 per cent formaldehyde) 4


Glacial acetic acid 5
It is intorpstinp; to note, however, that after the injection of pituitrin the female Uctced out the pouch at freciuent intervals, an act which probably always precedes parturition.


The birlh of the opossum


Specimen no. 443 was broupiht to the laboratory February 2, 1920, having been captured uninjured several nights before. She was a healthy female of medium size, and In' palpation of the mammary glands, after the method which I have described at another place ('19, p. 24), T recognized her as pregnant and Hkely to give birth within several days. I removed her to my home, where she was kept under observation night and day, and the success which attended the undertaking is largely due to my wife's enthusiasm and perseverance.


244 HENRY BAYON
The animal was i)laced just outside a window in a cage illuminated within by a red electric light, which arrangement was least disturbing to the animal as she was insulated against noises from within the room; the sight of persons moving about in the room caused little response on the part of the animal, but slight noises near the cage startled her great h'.


The appendices were then imbedded and sectioned in celloidin, stained by Delafield's hematoxylin and counterstained in eosin.
At 10:30 P.M., February (>, 1920, the animal showed signs of restlessness and soon began cleaning out the pouch, which she did about four times. Then began a short series of spasmodic contractions of the abdominal wall, after which she came to a sitting posture with legs extended. .\t no time did she stand on her hind legs, as Doctor Michel seems to have observed, for such


LEVELS AT WHICH STAINED SECTIONS WERE TAKEN
t po.sition is certainly strained and unnatural. I once had an
opossum give birth while she was confined in a Inulaji sack in which she was carried to the laboratory. In this case it was assuredly' impo.s-sible for her to stand on her hind legs during parturition.


In order to oljtain more reliable data, dissecting-room appendices were not considered. Appendices so diseased as to show disorganization or destruction of their tissues were avoided. Only recently removed appendices gathered from autopsies and abdominal operations at ("harit}- Hospital and Touro Intirmary of this city and preserved in formalin solution were used. The material included twenty-five slides of cross-sectioned a]ipentlices l)orr()wed from the pathological department of Charity Hospital. Each appendix was measured in length and in width and cross-sectioned two or three times from base toward the apex.
After assuming the sitting i)osture, our specimen bent her body forward and licked the vulva: however, her position at this time was such that we could not see the embryos, which very likely passed into the pouch with the fust licking of the genital opening. Hence we went to the outside where we could plainly hear her lap up the chorionic fluid; then suddenly a tinj- bit of flesh appeared at the vulva and scampered up over the entanglement of hair into the pouch to join the other foetuses, which now could be seen to have made the trip without our having observed them. Unerringlj' the embryo tra^'eled by its own efforts; without any assistance on the mother's part, other than to free it of liquid on its first emergence into the world, this ten-day-old embryo, in appearance more like a worm than a mammal, is able, immediately upon release from its liquid medium, to crawl a full three inches over a difficult terrain. Indeed, it can do more: after it has arrived at the pouch it is able to find the nipple amid a forest of hair. This it must find — or perish.


The average length, in all cases considered regardless of race or sex, was 9.2 cm. in seventj'-one specimens (table 1) and the average width 6.2 mm. in ninety-eight specimens. The length and width of the 100 aj)])eiidices were not all available. The length was not mentioned in the histories of the twenty-five Charity Hospital slides, and in four of the specimens prepared by myself part of the organ was missing. The width was taken fiom the mounted cross-.sections in all ca.ses except in two, the specimens having been previously opened by the pathologist for inspection.
Having now satisfied ourselves as to the manner in which the 3'oung opossum reaches the pouch, we etherized the female, hoping still to find some of the embryos within the genital tract. But it happened that we had witnessed the last of the litter make the journey. The pouch contained a squirming mass of eighteen red embryos of which twelve were attached, though thirteen might have been accommodated. The remainder were, of course, doomed to starvation. Even some of these unfortunates, however, held on with their mouths to a flap of skin or to the tip of a minute tail, while several continued to move about.


Tallies 2 and 3 show a sexual difference in favor of the male, giving an average of 9.6 cm. (length) and 6.5 mm. (width) in the male against 8.7 cm. (length) and 6 mm. (width) in the female, tables 4 and o. the racial difference fin the two tables) show an average of 7 cm. (length) and 6.5 mm. (width) in the white and 11.3 cm. (length) and 6 mm. (width) in the negro.
With the mother under the influence of ether, we now gently pulled off a number of embrj'os from the teats in order to test their reactions. The teats had ah-eady been drawn out from about a millimeter in height to double that length, doubtless bj' the traction of the embryo itself, for the bottom of the pouch certainly presented a busy scene with each member of the closepressed litter engaged in verj^ active breathing and sucking movements.


It may well l)e oiijectccl that in tables 2, 3. 4, and 5 the inferences mu.st be unreliable, the nunilier of cases being too restricted. In table 1, however, which deals with the average length of the appendix, regardle.ss of race or sex, the same objection does not prevail. The slight difference in size between the male and female appendix is all that might have been expected, although that,
One detached young, placed near the vulva, crawled readily back into the pouch. Two or three others regained the teats after some delaj^, and one wanderer, which lost out in the first scramble, found a vacated teat and attached itself even after twenty minutes' delay, showing that the instinct to find the teat . persists for some time. If the skin be tilted, the embryos, can
be made to travel upward and even away from the pouch, for they are negatively geotropic.


For locomotion the embryo employs a kind of 'overhand stroke,' as if swimming, the head swajnng as far as possible to the side opposite the hand which is taking the jiropcUing stroke. With each turn of the head the snout is touched to the mother's skin as if to test it out, and if the teat is touched, the embryo stops and at once takes hold.


It is thus ajiparent that the opossum embryo at birth possesses not only fairly well-developed respiratory and digestive systems, but that it has attained a neuromuscular development sufficient to enable it to find its place in the pouch where food and shelter await it.


TABLE 1
The 7iu7nber of pouch young


Racial and sexual
Most female opossums possess thirteen teats, of which usualljonlj' the posterior eleven are functional. I have often found as many as eleven pouch yovmg attached, but only in two cases as many as twelve. Doctor ^leigs ('47) on one occasion found thirteen. I have seen litters consisting of fifteen, seventeen, and eighteen newlj- born j'oimg in the pouch, with as few as seven attached to teats, and have removed from pregnant uteri as many as twenty-two normal foetuses near term. Such overproduction with consequent mortality has already been pointed out for the opossum and other marsupials (Hill, '10, '11: Hartman, '19).


Folklore


In the popular mind the generation of no animal is so shrouded in mystery as that of the opossum. From New Jersey to Texas several beliefs are current which it might be well to state at this point.


There is a wide-spread notion that copulation takes place in the nostril of the female and that the 'fruit of conception' is blown into the pouch. This superstition rests upon two observed facts: first, that the opossum penis is dichotomous and, second, that the female licks out the pouch immediately prior to parturition.


Another notion is that the pouch young is organically connected with, or 'grown to,' the teat, in fact so intimatelj^ that bleeding results from the forced separation of the pouch young. Doctor Meigs ('47) already showed that this is not the case.


LENGTH
Doctor ]Meigs mentions and refutes the idea prevailing in his time that the pouch young produces a teat wherever it happens to take hold of the skin in the pouch.


Finalh', it is often stated that the marsupial mother pumps milk into the pouch young. Whether or not this is true the writer does not know, but certain it is that from the very beginning the young opossum engages in active sucking movements.


WIDTH
THE PASSAGE OF THE FOETUSES FROM THE UTERUS


As is, of course, well known, the opossum, as a member of the order Marsupalia, possesses two uteri. These do not communicate posteriorly, but open each into a separate shallow cul de sac, on either side of a median partition. Each cul de sac communicates laterallj' with a loop, the 'lateral vaginal canal' (Hill, '97), which cur^-es laterad, then caudad and mediad, until near the midline the two canals almost touch; and from this point backward they Ue parallel until they empty into the 'median vaginal canal' (Hill, '97) or urogenital passage (Owen, '68). The lateral vaginal canals thus resemble two question marks placed face to face; the curved portions lie in the body cavity, the 'stems' are imbedded in the connective tissue of the urogenital strand. The urethra forms a third parallel tube, lying in the midline ventrad to the straight portion of the lateral A-aginal canals and emptying with them into the median vaginal canal.


White male . .
In two Austrahan species Hill (Parameles, Dasj-urus; Hill, '98, '00) made the surprising discovery that the embryos at birth do not pass out through the lateral vaginal canals, but break through by a cleft-like rupture, the 'pseudo vaginal canal, directly into the median vaginal canal from the culdesac into which the os uteri opens. The new passage is described as a split in the connective tissue, at no time lined with epithelium and containing fragments of foetal membranes together with leucocvtes and maternal blood clots.




9 cases — ■ 8 cm. 20 cases — 11.3 cm. 37 cases — 6.1 cm.
I have on several occasions demonstrated in the opossum the existence of the pseudovaginal passage discovered by Hill. In sjiecinien no. 402. aheady iiiontioiiod as aborting under an abdominal operation, one could follow a bloody trail direct into the median vaginal canal exactly as Hill had described it The hemorrhage was less severe in no. 443, the birth of whose young has been described above, but the new passage was ea.sil}- demonstrable. The organs were fixed in Bouin's fluid and sectioned. The findings are quite in accord with those of Hill. The pseudovaginal canal is seen to be simply a slit in connective tissue between the bladder and urethra voiitrally and the caudal ends of the lateral vaginal canals dorsally. In formaldehyde preparations of the organs taken from non-pregnant females such a pseudovaginal passage can with great ease be pushed through; that is, the urethra maj- very readily be separated from the parts dorsal to it. It appears quite certain that the contraction of the alxlominal and the uterine walls is sufficient to force the new passage at the tune of birth.


5 cases — 11 3 cm.
The embryonic envelopes are partly retained within the uterus, a fact already noted by Osborn ('87) for the opossum, and partly scattered along the median vaginal canal. None were found in tiie lateral vaginal canals either by Osborn or by the writer. It is possible that an embryo may even drag parts or all of its foetal membranes to the exterior, in which case the mother may lick it free; but my only evidence on this point is the presence of the foetal membranes about many of the embryos in the case of one abortion.


The opossum should therefore lie added to the list of marsupials which force the 'pseudovaginal canal' at parturition.


11 cases — 7 mm.
One might suppose from this that the lateral vaginal canals would pos.sess a special function. The writer believes with Hill that the}' function as rcceptacula scminis, .since in the marsupials several days elapse between copulation and ovulation. In the opossum the enlargement of the canal is one of the striking features of the prooestrus period. .\t oestrus they "have attained an enormous size and are filled to turgidity with a thin, lymi)li-like fluid. Soon after ovulation thej' shrink almost to the resting
stage and are filled with cheesy masses of cpithehal cells, which remind one of a similar phenomenon described bj^ Stockard and Papanicolaou ('17) for the guinea-pig at oestrus.


ADDENDUM


Negro male
Several months after the foregoing paper had been received by the editor of this journal the writer received a note from Dr. H. H. Donaldson, of The Wistar Institute, in which he stated that he had learned from Dr. N. Hollister, Superintendent of the National Zoological Park, Washington, D. C, of a pubhshed account of parturition in Macropus rufus, the deer kangaroo. The article in question is in the nature of a communicatioii by the observer, Mr. A. Goerling, to the 'Western ]\Iail,' of Perth, Australia, and was published January 3, 1913. Doctor Hollister's kindness in having the article copied makes it possible to present this interesting account to the readers of The Anatomical Record and thus render it more generally available to zoologists. The accounts of the birth of Didelphys virgiiiiana, as detailed above, and of INIacropus rufus, as reported by ^Ir. Goerling, are seen to be in perfect agreement on the one essential point, namel}^ that the young reach the pouch and find the teat by their own efforts and entirely without the assistance of the mother. It would seem, therefore, that this will be found to hold universally among the numerous species of the ]Marsupialia. The following are Mr. Goerling's notes dated December 19, 1912:


THE BIRTH OF THE KANGAROO


28 cases — 6 mm.
The question of how the young kangaroo comes into the pouch has long been looked upon as answered. According to obscivations made, the young is born and placed on the pap by its mother, and this view has been accepted In" zoologists.


On the 25th of February, 1906, 1 had the good fortune to make the most interesting and astounding obseivation. I had a number of Macropus rufus and M. cervinus in my possession, caged in varioussized cages. On the morning of the above mentioned date I was attracted by the peculiar behavior of a female M. rufus. She refused the feed placed before her; and on seeing blood marks in the cage, I


White female
'The italics are mine.




37 cases — 6 mm.
came to the cont'lusic^n tliat the nniinal liad just given birth to a young one. Shi' was sittiinj in tliat resting ]iosition in which kangaroos can often be seen. Tlie tail pas.<eii forward through the legs, thus she was sitting almost entirely on the thick part of her tail. 8hc took no notice of my presence, although not more than three weeks in captivity, and was busy licking and cleaning herself. Presently she lifted her head, when I was astonished to see a young kangaroo clinging to the long fur about four inches below the opening of the pouch.


It moved about slowly, ven- slowly, through the fur upwards, using the arms in its progress, and conlittiuiUy moving the head from side to side, thus a.ssi.sting the upward movement. Nearly 30 minutes were required by the little wanderer to reach the top of the pouch, the last end in a semicircle. During the whole of this time the mother paid no attention to her offspring, offering no ass-istance, ami leariny it entirely to its own exertions. She then became restless; and not wishing to disturb her, I moved a short distance away, when she at once started to feed. A little later I paid another visit to her cage. She was sitting upright, the young one had disajjpeared, but the fur was still bearing evidence of the struggle, a plain visible track leading to and ending on the top of the pouch.


Now I had the explanation of a previous observation, but which I misconstrued at the time. I had a female ]\Iacropus woodwardi — Woodward's kangaroo — in captivity; and noticing blood stains in the cage. I beheved the animal was hurt. I then noticed just such a young kangaroo clinging to the fur below the pouch, and thought the mother by restless movements had dislodged it.


My obser\-ation of the 25th of Februaiy, 1006, proves that the new born kangaroo has to look after its own safety and reach the pouch mthotd the mother's as.vstance.


The anns of the new born kangaroo are strongly developed, the small hands open and close hke a cat's ])aw, and by these strong little anns and hands the young one is enabled to labour its way to the pouch, the place of safety and nourishment.


The cjuestion now presents itself, how can the young, with such a hard and firmly closed mouth, attach itself to the pap? I am convinced that at the time of birth the mouth has a wider opening and is perhaps more ela.stic than such specimens po.^.sess which are found in the pouch of the mother. Once a young kangaroo is removed from the pap, it is unable to reattach it.self.


As concluding proof that all newly born marsupials must reach the pouch by their own exertions, I mention that bandicoots, native cats and those very smallest of marsupials, the i)0uched mice, have the opening of the pouch in a reversed po.sition to the kangaroos and phalangers. I had once in my pos-scssion a ver>' small specimen of pouched mouse, having ten young ones in the pouch, each one not lugger than a grain of wheat. (Jnly through the opening of the pouch being reversed are these .smallest of boi-n mammals enabled to reach it with saftitv and without much exertion.


LITERATURE CITED


71 cases av. 9.2 cm.
Hartman, Carl G. 1919 Studies in the development of the opossum (Didelphys virginiana L.)- Parts III and IV. Jour. Morph., vol. 32, no. 1, pp". 1-UO.


Hill, J. P. 1895 Preliminary note on the occurrence of a placental connection in Parameles obesula, and on the foetal membranes of certain macropods. Proc. Linn. Soc, New South Wales, vol. 10 (2nd ser.), part 4. 1897 The placentation of parameles (Contributions to the embryology of the Marsupialia I). Quart Jour. Micr. Sci., vol. 40, pp. .385-142. 1899. 1900 Contributions to the morphology and development of the female urogenital organs in the Marsupialia, no. 1. On the female urogenital organs in Parameles, with an account of the phenomena of parturition. Proc. Linn. Soc. N. S. Wales, vol. 24, pp. 42-82. Part I, March 29; nos. 2-5, id., vol. 25, pp. 519-532.


98 cases av. 6 2 mm.
1900 Contributions to the embryology of the Marsupialia. Quart. Jour. Micr. Sci., vol. 43, pp. 1-22.


1900 On the foetal membranes, placentation and parturition of the native cat (Dasyurus viverrinus). Anat. Anz., Bd. 18, s. 364—373.


Hill and O'Donoghue 1913 The reproductive cycle in the marsupial Dasyurus viverrinus. Quart. Jour. Micr. Sci., vol. 59.


TABLE 2 Racial, male
Meigs, Dr. Charles D. 1847 Reproduction of Didelphys virginiana. Proc. Am. Philosophical Soc, Philadelphia, vol. 4, pp. 327-330.


Michel, Dr. Middleton 1850 Researches on the generation and development of the opossum. Proc. Am. Assn. Adv. Sci., vol. 3, Charleston, S. C.


OsBORN, H. F. 1888 The foetal membranes of the marsupials: the yolk sac placenta in Didelphys. Jour. ^lorph., vol. 1, pp. 373-382.


White male. Negro male.
Owen, Richard 1868 Anatomy of vertebrates, vol. 1, p. 682.


Selenka, E. 1887 Studien ueber Entwioklungsgeschiehte der Thiere. IV (1 and 2), Das Opossum (Didelphys virginiana). Wiesbaden.


Stockard, Charles R., and PAPANicoLAor, George N. 1917 The existence of a typical oestrous cycle in the guinea-pig with a study of its histological and physiological changes. Am. Jour. Anat., vol. 22, pp. 225265.


LENGTH




niDTH
Resunien por el autor, Frank Charles Mann. Clinioa Mavd, Rochester, ^linnesota.


Psincreas accesorio.


9 cases — 8 cm. 20 cases — 11.3 cm.
En el present e trabajo se describen dos pancreas accesorios hallados en perros. En uno de los casos la ghindula aberrante estaba situada a corta distancia distal del ligamento de Treitz, en la inserci6n nicsentcrica del yeyuno. La glandula presentaba fomia triangular, niidiendo 27 X 20 X 15 nun. Poseia un conducto definido que desembocaba en el yeyuno. Su estructura histol6gica coiTesjionde a la del tejido pancreatico normal, pero existe una cantidad relativaniente pequena de tejido insular, y los islotes son muy pequefios.


La segunda gldndula aberrante estaba situada en la pared del duodeno, a corta distancia de la entrada del conducto pancredtico menor. Presentaba forma de disco y media 5x3 mm. Su estructura histol6gica revela la presencia de acmi y conductos normales, pero hay una ausencia casi completa de tejido insular. En este ultimo caso es interesante la estrecha relaci6n entre el tejido pancreatico y la nuisculatura lisa de la pared duodenal.


11 cases — 7 mm. 28 cases — 6 mm.
TransUtioD by Joe6 F. Xonidex Comfll Mfdiml CoIIoitc. Nrw York
 
author's abstract of THI3 PAPER ISSUED BT THE BIBLIOGRAPHIC SERVICE, SEPTEMBER 13
 
29 cases av. 9.6 cm.
 
 
39 cases av. 6.5 mm.
 
 
 
T^VBLE 3 Racial, female
 
 
 
 
 
LENGTH
 
 
WIDTH
 
 
White female
 
Negro female
 
 
37 cases — 6 1 cm. 5 cases — 11.3 cm.
 
 
37 cases — 6 mm. 22 cases — 6 mm.
 
 
 
 
42 cases av. 8.7 cm.
 
 
59 eases av. 6 mm.
 
 
 
TABLE 4 Sexual, white
 
 
 
 
 
LENGTH
 
 
WIDTH
 
 
 
 
9 cases — 8 cm. 37 cases — 6.1 cm.
 
 
11 cases — 7 mm.
 
 
White female
 
 
37 cases — 6 ram.
 
 
 
 
 
 
 
 
46 cases av. 7 cm.
 
 
48 cases av. 6.5 mm.
 
 
 
T^VBLE 5 Sexual, negro
 
 
 
 
 
LENGTH
 
 
WIDTH
 
 
 
 
20 cases — 11.3 cm. 5 cases — 11.3 cm.
 
 
28 cases — 6 mm.
 
 
Negro female
 
 
22 cases — 6 mm.
 
 
 
 
 
 
 
 
25 cases av. 11.3 cm.
 
 
50 eases av. 6 mm.
 
 
 
245
 
 
 
246
 
 
 
HENRY BAYON
 
 
 
together with racial differences, would seciu to otter no sohitit)n to the problem at issne. namely, structural peculiarity bearinjj; an susce|)tihility to inflannnation. The tabulations were simply included as a matter of general interest.
 
The field which .seemed most promising was the microscopic survey of the transverse sections. This consisted in measuring the thickness of the longitudinal and circular muscular tunics exprcs.sed in terms of microns together with noting the relative amount of h-mphocytes, fat and crypts and the vascularity of each appendix, classifying the specimens into three categories, rich, moderate anil poor, as indicated in table G.
 
TABI.K 6 Based upon 100 specimens
 
 
 
 
 
UUSCDLA
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TURE
 
 
LTUPBOCrTES
 
 
 
 
F-AT
 
 
 
 
CBIPTS
 
 
VASCCIABITT
 
 
 
 
IN UICRON8
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
S
 
 
 
 
 
 
s
 
 
 
 
 
 
fi
 
 
 
 
 
 
O
 
 
 
 
 
 
 
 
 
 
 
 
s
 
 
 
 
 
 
s
 
 
 
 
 
 
P
 
 
 
 
 
 
«
 
 
 
 
 
 
e 9
 
 
£
 
 
•s
 
 
1
 
 
S
 
 
■s
 
 
b
 
•a c
 
 
R
 
 
 
 
1
 
 
^
 
 
L.
 
 
 
 
 
^
 
 
 
 
O
 
 
per
 
 
per
 
 
ptr
 
 
per
 
 
7per
 
 
per
 
 
per
 
 
5per
 
 
per
 
 
per
 
 
per
 
 
 
 
 
 
 
 
 
 
per
 
 
 
 
 
 
 
 
cent
 
 
cent
 
 
ernt
 
 
cent
 
 
cent
 
 
cent
 
 
cent
 
 
cent
 
 
cent
 
 
cent
 
 
cent
 
 
cent
 
 
X. .M.-31 C.
 
 
247 B
 
 
3.50 8
 
 
16
 
 
22
 
 
62
 
 
23
 
 
32
 
 
45
 
 
19
 
 
,5.5
 
 
26
 
 
64
 
 
29
 
 
7
 
 
X. F. -22 C.
 
 
270 4
 
 
37.5 3
 
 
14
 
 
64
 
 
T2
 
 
41
 
 
41
 
 
18
 
 
14
 
 
36
 
 
50
 
 
54
 
 
27
 
 
19
 
 
W. .M.— 11 C.
 
 
270 4143.5 9
 
 
64
 
 
18
 
 
18
 
 
27
 
 
55
 
 
18
 
 
36
 
 
9
 
 
65
 
 
IS
 
 
18
 
 
64
 
 
W. F. -36 C.
 
 
241 2 392 8
 
 
47
 
 
44
 
 
9
 
 
59
 
 
29
 
 
12
 
 
62
 
 
23
 
 
15
 
 
16
 
 
21
 
 
73
 
 
 
A glance at the figures disproves the first impression regarding musculature. It is. therefore, quite evident that inmumitj' from ajjpendicitis in the negro, if such exists, cannot be accounted for by a stronger i)eristaltic wave. Indeed, the measurements show a preponderance of muscular tissue in the white appendix.
 
The racial and sexual dilTerences in the percentage ot fat conform with the general distribution of fat elsewhere in the sexes and in the two races. The negro as a race carries less fat in the average than the white, and in both races the female carries more than the male.
 
The dilTerence in the number (tf crypts retained is decidedly in favor of the white appendix. This would seem to indicate ie.ss
 
 
 
RACIAL DIFFERENCES APPENDIX VERMIFORMIS 247
 
susceptibility to iiifiammation. Hence, the study of structure in this particular feature, far from confirming disease statistics, offers decided opposition and is quite suggestive to the reverse.
 
The difficulty, however, presented by the crypts is offset very singularly by the findings regarding both the lymphocytes and vascularity. In the white appendices, 64 per cent male and 47 per cent female were found rich in lymphocytes, and 18 per cent male and 16 per cent female were found rich in vascularity. Comparing this with the findings for the negro appendix, 16 per cent male and 14 per cent female were rich in lymphocytes and 64 per cent male and 54 per cent female were found rich in vascularity.
 
In the cases here examined the ratio in the two races between lymphocytes and vascularity is inverted — the richer in lymphocytes, the poorer the vascularity seems a characteristic of the white appendix, whereas the reverse obtains for the negro appendix, in which the scarcity of lymphocytes corresponds with rich vascularity. From the figures the fact stands out that the white appendix is richly lymphatic and poorly vascular and the negro organ just the reverse.
 
In the white appendix are found two conditions predisposing to inflammation more especially of the gangrenous type — a rich supi^ly of lymphocytes indicating predisposition to inflannnation and poor vascularity favorable to gangrenous changes.
 
It may be objected that since the cases were tabulated regardless of health or disease, the prevalence of the appendices rich in lymphocytes might result from inflammatory action. The objection is met by the fact that, although in some cases operation was performed for appendicitis, in a great many other cases operation was performed for disease other than appendicitis, the appendectomy being performed simply as a matter of prudent routine in anticipation of possible future appendical trouble. But even if on that account, the high percentage of organs rich in lymphocytes found in the white cases be considered of negative \alue, the fact remains that these specimens show a low percentage of \-ascularity, and if inflammation alone could suggest increased lymphatic richness, it should also accentuate vascularity, which is (luite contrary to the fiiuling.
 
 
 
248 HENUV HAYON
 
Racial differences in tlie appendix suggested that corresponding differences might also exist in other diseases of the lymphatic system. Statistical inquiry into the relative number of tonsil and adenoid disease in the two races demonstrated that in 47ol) jiatients admitted into the Charity Hospital during the first three months of 1917, 2258 were negroes and 2501 were whites. In the 22r)S negro cases there were 35 tonsil cases and 8 adenoid cases. In the 2501 white cases there were 95 tonsil cases and 21 adenoid cases.
 
Table 7 .shows that the numl)er of tonsil ca.ses was more than twice as great in the white than in the negro and that the number of adenoid cases was twice as large in the white.
 
TABLE 7
 
 
 
22.58 negro patients. 2501 white patients
 
 
 
TONSIL CA8F.S
 
 
 
35 (0.015 per cent) 95 (0.037 per cent)
 
 
 
ADENOID CASES
 
 
 
9 (0.004 per cent) 21 (O.OOS per cent)
 
 
 
In these tonsil and adenoid cases figures may hold out equivocal interpretation : we are well aware that more whites than blacks are prone to l)ecome nervous al)out health conditions and the same suggestion regarding the advisabilitj' of parting with the appendix j)rcvails for tonsils and adenoids. It rests with the specialist whether the organs show sufficient evidence of disease to justify operation and the administration of an anesthetic — alwaj's a grave re.sponsibilit}'. Be that as it may, if each tonsilectomy and adeiioidertomy means disea.sed jialatiiie or pharyngeal tonsil, the unavoidable and iiidisputal)lr inference is that tonsil and adenoitl disease is more prevalent in the white than in the negro.
 
The .same Ciiarit}' Ilo.spital records for the first three months of 1917 show a total of twenty-three negro cases of aj)pendicitis against eighty-five white cases, ^^■ith due allowance for the doubtful trustworthiness of statistics considered from the standpoint of their face value, it may he safely assumed that when viewed in the liglit of histological findings above submitted, they
 
 
 
RACIAL DIFFERENCES — APPENDIX VERMIFORMIS 249
 
are at least ((uite suggestive of greater susceptibilit}^ of the white race than the negro to appendicitis.
 
Differences in the lymphatic system of the white and negro races may also be inferred from the findings of Bean and Baker, which appear in the Journal of Physical Anthropology, vol. 2, no. 1, 1919, under the title of "Some Racial Characteristics of the Spleen Weight in JNIan." 0\'er 1500 white and about the same number of negro spleens are considered, showing a decided difference in weight in favor of the white spleen.
 
These findings are well correlated to those submitted in the present study and seem to prove that the white race is more subject to lymphocytic stasis than the negro.
 
SOIMARY
 
1. The musculature of the white appendix is not weaker. Indeed, it seemed slightly stronger than that of the negro.
 
2. The female appendix is richer in fat than the male.
 
3. The white appendix is richer in crj-pts.
 
4. The white appendix is rich in lymphocj^tes and poor in vascularity and the negro appendix rich in vascularity and poor in lymphocytes.
 
5. The average size of the appendix is 9.2 cm. in length and ().2 mm. ill width.
 
6. The white appendix is shorter and wider than the negro appendix.
 
7. The male appendix is longer and wider than the female apjjendix.
 
 
 
HUMAN PAKASITOLOGY, with xotks ox Bacteuiolocy, Mycology, Lahokatouy Diagnosis, Hematology and Serology, l.y Damos Kivas, B. S. Riol. M.S., M.D., Ph.D., Uiiivcrsily of rciinsvlviinia. Illustrated. 71t> i)agps, W. B. Saunder.s Coini)aiiv. Philadelphia. Pa. 1920.
 
extracts from preface
 
A half century ago nieilieine was more an art than a science. The doors of American medical colleges stood wide open to welcome all who came as students, and if they showed a desire to learn, possessed enough elementary eilucatioii to eiiahle tlum to read their text-lmok anil write their examination papers no questions were asked as to their acquaintance with the physical and hiologic sciences.
 
There was no science of parasitology. Parasites were zoologic curiosities that occasionally intruded into the si)h(>re of medical activity.
 
Now all has changed. The necessities of commerce have led to such extensive geographic explorations that the entire surface of the earth has been explored and charted. Ethnologic investigators have uncovered the location, life and habits of many formerly unknown peoples.
 
The general rapid advance of scientific knowledge, especially the progress of physics, chemistry and biology, inevitably reaetetl upon metlicine, stimulating the scientific spirit, demanding research upon its obscure ]jroblems. and re(juiring a new tVpe of student whose jm'paration for medicine must include at least an elementary knowledge of the collateral and fundamental sciences.
 
The author has for twenty years interested himself in i)arasitology and has had the good fortune to have studied in public health laboratories at home and abroad, an<l to have served on sanitary commissions. Aftrr years of tcacliing he now endeavors to bring together tlie facts of ])arasitology in a form suital)le to the needs of the student and jihysician. The following pages reflect his personal experiences and present the facts of the sul)ject in a fonii sufficiently brief to make it a text-liook — the modern tendency is to be encyclopeilic- and sufficiently full not to omit any imjiortant fact or method.
 
 
 
250
 
 
 
',-"
 
 
 
THE ANATOMICAL RECORD, VOL. 19, NO. 5 OCTOBER, 1920
 
 
 
Resumen por el autor, Carl G. Hartman. Uuiversidad de Texas.
 
Los fen6nienos del parto en el opossum.
 
Ell oposici6n a lo que se cree generalmente, el embri6n del opossum, al final del periodo de gestaci6n, que dura diez dias, caniina por sus propios esfuerzos desde el orificio vajiinal hasta la bolsa marsupial, en la que encuentra la mama. La madre no ayuda al embri6n durante su paso desde la vagina a la bolsa, pero le lame para despojarle del liquido cori6nico, cuando sale por la vulva. Lo mismo que en el caso de las especies australianas Perameles y Dasyurus, descrito por Hill, los embriones alcanzan el canal vaginal medio no por los canales vaginales laterales, sino por un tuncl ([ue aparece de novo en el tejido conjuntivo situado entre la uretra y los canales vaginales laterales.
 
Translation by Joa& F, Xonides Cornell Medical College, New York
 
 
 
AUTHOR S ABSTRACT OF THIS PAPER ISSUED BY THE BIBLIOGRAPHIC SERVICE, SEPTEMBER 13

Latest revision as of 11:08, 2 February 2020

Studies In The Development Of The Opossum Didelpbys virginiaua L.

V. The Phenomena Of Parturition

Carl G. Hartman

The University of Texas, School of Zoology

THE METHOD OF TRANSFER OF YOUNG TO THE POUCH

The literature

So far as the writer has been able to discover, there exists in the nterature only one account of the actual birth of any marsupial, notwithstanding the abundance of opossums in America and the variety of all marsupial fauna in Australia. Nor does that foremost of all students of marsupial embryology, Prof. J. P. Hill, refer to this topic, although on one occasion ('00, p. 371) he killed a specimen of Dasyurus after "one only of the young had been born." ^leigs ('47) and Selenka ('87) examined pouch young of the opossum immediately after birth, but made no observation on parturition.

The single recorded observation referred to is that of Dr. Middleton Michel, of South CaroUna ('50), who, on January 28, 1847, witnessed the copulation of a pair of opossums, and fourteen days and seventeen hours later saw the birth of the foetuses. In order to show, however, that Doctor ^Michel failed to see the actual passage of the 3'oung to the pouch, two essential paragraphs on the point at issue are here quoted:

' Parts 1 and 2 (History of the early cleavage — Formation of the blastocyst) appeared in the Journal of Morphology, volume 27, number 1, March, 1916; and Parts 3 and 4 (Description of new material on maturation, cleavage and entoderm formation — The bilaminar blastocyst) appeared in the Journal of Morphology, volume 32, number 1, March. 1919. These four parts may be obtained from the publishers.

  • Contributions from the School of Zoology, the University of Texas, no. 143.


The pregnant female was found standing on her hind legs; her body was much bent, and propped up against the rornor of the cage; her muzzle in immediate contact with the cloacal opening, which was red, tiunefied and distended: a young ap|)eared at the opening, and was conveyed by the mother's mouth to the pouch, or perhaps was rather licked in, as her tongue seemed busily employed within, around and about the pouch.

The young are expelled first into the vaginal cul-<le-sac, in which they remain for a short time, on the contraction of which they are forced along the vaginal canals one by one; parturition is thus ver>' much prolonged, owing to the circuitous route which the young are obliged to take, and the delay therein- occasioned between the birth of each is the object of the peculiar modification of these parts in this animal, as it affords the requisite time emjiloyed in the convej'ance of the young to the pouch and their adaptation to the teat.

It is quite clear from the language of this quotation that Doctor Michel did not actuallj- witness the migration of the embryos and that he merely guessed at the method emploj-ed by the mother, since he was not sure whether she used her mouth or her tongue. It will, moreover, be shown below that Doctor Michel was also mistaken in presuming that the young at birth pass out by way of the lateral vaginal canals. The observations recorded below indicate that the marsupial female does not actually transfer the foetuses to the pouch and that Doctor Michel's interpretation, as well as the prevailing notion in accordance therewith, is not borne out by the facts.

So7ne preliminary observations

A series of observations and experiments during the last four or five breeding seasons of the opossum had enforced the conviction that the young reach the pouch and find the teat by their own efforts and are not placed on the teats by the mother's tongue or lips, ^^h^• should it be necessary, one may ask, in the absence of actual observation, to presume such undue skill and sensitivit}- in the adult when a pure instinctive reaction on the part of the young will suffice?

On several occasions I experimented with newly born pouch young, gently removing them from the teats to which they had firmly attached themselves by means of their powerful tongues.


I quote from mj^ notes in one case (no. 301, experimented upon in the presence of Dr. C. H. Heuser, of The Wistar Institute, January 20, 1917) :

Female tied do^ii and pouch opened. Young which were removed from teats crawled about, moving hands alternately, as in swimming. Were able to crawl among hairs and find teats by their own efforts. One specimen, removed three times, found teat each time and three others found teats after wandering about.

These experiments certainly argued strongly in favor of some little independence of action on the part of these 'embryos,' a term that Doctor Meigs ('47) would have us abandon when speaking of these breathing, sanguiniferous, digesting pouch young."

On February 6, 1917, on opening specimen no. 402 under anesthesia, I was surprised to find a collapsed but very vascular uterus, as if birth had just taken place. This proved to be the case, for on remo\'ing the animal from the table I found that the entire litter of foetuses had been expelled during the operation. They were mostlj' still ali\'e, entangled in foetal envelopes and immersed in the foetal fluid. To some of the foetuses the umbilicus was still attached ; others were free, but no navel could be seen in any case. None of the foetuses, even after being freed of membranes and liquids, could crawl about, as they were apparently drowned in their own embryonic fluid. It seemed likely, therefore, that the emlsryos, on emerging from the vagina, need the assistance of the mother to lick away the fluid expelled from them, and this w-as later verified by actual observation.

Embryos near term were also removed from the uterus, freed of their envelopes, and allowed to crawl about over the mother, which they did for at least fifteen minutes.

On one occasion I removed one uterus three days before term (no. 131), and about the time that birth was to be expected from the remaining uterus I injected, some pituitrin subcutaneously, hoping to witness parturition thus brought on. But owing to the fact that abortion had pre\dously taken place, as was afterward learned, onlj' mucus was extruded from the genital orifice.


It is intorpstinp; to note, however, that after the injection of pituitrin the female Uctced out the pouch at freciuent intervals, an act which probably always precedes parturition.

The birlh of the opossum

Specimen no. 443 was broupiht to the laboratory February 2, 1920, having been captured uninjured several nights before. She was a healthy female of medium size, and In' palpation of the mammary glands, after the method which I have described at another place ('19, p. 24), T recognized her as pregnant and Hkely to give birth within several days. I removed her to my home, where she was kept under observation night and day, and the success which attended the undertaking is largely due to my wife's enthusiasm and perseverance.

The animal was i)laced just outside a window in a cage illuminated within by a red electric light, which arrangement was least disturbing to the animal as she was insulated against noises from within the room; the sight of persons moving about in the room caused little response on the part of the animal, but slight noises near the cage startled her great h'.

At 10:30 P.M., February (>, 1920, the animal showed signs of restlessness and soon began cleaning out the pouch, which she did about four times. Then began a short series of spasmodic contractions of the abdominal wall, after which she came to a sitting posture with legs extended. .\t no time did she stand on her hind legs, as Doctor Michel seems to have observed, for such

t po.sition is certainly strained and unnatural. I once had an opossum give birth while she was confined in a Inulaji sack in which she was carried to the laboratory. In this case it was assuredly' impo.s-sible for her to stand on her hind legs during parturition.

After assuming the sitting i)osture, our specimen bent her body forward and licked the vulva: however, her position at this time was such that we could not see the embryos, which very likely passed into the pouch with the fust licking of the genital opening. Hence we went to the outside where we could plainly hear her lap up the chorionic fluid; then suddenly a tinj- bit of flesh appeared at the vulva and scampered up over the entanglement of hair into the pouch to join the other foetuses, which now could be seen to have made the trip without our having observed them. Unerringlj' the embryo tra^'eled by its own efforts; without any assistance on the mother's part, other than to free it of liquid on its first emergence into the world, this ten-day-old embryo, in appearance more like a worm than a mammal, is able, immediately upon release from its liquid medium, to crawl a full three inches over a difficult terrain. Indeed, it can do more: after it has arrived at the pouch it is able to find the nipple amid a forest of hair. This it must find — or perish.

Having now satisfied ourselves as to the manner in which the 3'oung opossum reaches the pouch, we etherized the female, hoping still to find some of the embryos within the genital tract. But it happened that we had witnessed the last of the litter make the journey. The pouch contained a squirming mass of eighteen red embryos of which twelve were attached, though thirteen might have been accommodated. The remainder were, of course, doomed to starvation. Even some of these unfortunates, however, held on with their mouths to a flap of skin or to the tip of a minute tail, while several continued to move about.

With the mother under the influence of ether, we now gently pulled off a number of embrj'os from the teats in order to test their reactions. The teats had ah-eady been drawn out from about a millimeter in height to double that length, doubtless bj' the traction of the embryo itself, for the bottom of the pouch certainly presented a busy scene with each member of the closepressed litter engaged in verj^ active breathing and sucking movements.

One detached young, placed near the vulva, crawled readily back into the pouch. Two or three others regained the teats after some delaj^, and one wanderer, which lost out in the first scramble, found a vacated teat and attached itself even after twenty minutes' delay, showing that the instinct to find the teat . persists for some time. If the skin be tilted, the embryos, can be made to travel upward and even away from the pouch, for they are negatively geotropic.

For locomotion the embryo employs a kind of 'overhand stroke,' as if swimming, the head swajnng as far as possible to the side opposite the hand which is taking the jiropcUing stroke. With each turn of the head the snout is touched to the mother's skin as if to test it out, and if the teat is touched, the embryo stops and at once takes hold.

It is thus ajiparent that the opossum embryo at birth possesses not only fairly well-developed respiratory and digestive systems, but that it has attained a neuromuscular development sufficient to enable it to find its place in the pouch where food and shelter await it.

The 7iu7nber of pouch young

Most female opossums possess thirteen teats, of which usualljonlj' the posterior eleven are functional. I have often found as many as eleven pouch yovmg attached, but only in two cases as many as twelve. Doctor ^leigs ('47) on one occasion found thirteen. I have seen litters consisting of fifteen, seventeen, and eighteen newlj- born j'oimg in the pouch, with as few as seven attached to teats, and have removed from pregnant uteri as many as twenty-two normal foetuses near term. Such overproduction with consequent mortality has already been pointed out for the opossum and other marsupials (Hill, '10, '11: Hartman, '19).

Folklore

In the popular mind the generation of no animal is so shrouded in mystery as that of the opossum. From New Jersey to Texas several beliefs are current which it might be well to state at this point.

There is a wide-spread notion that copulation takes place in the nostril of the female and that the 'fruit of conception' is blown into the pouch. This superstition rests upon two observed facts: first, that the opossum penis is dichotomous and, second, that the female licks out the pouch immediately prior to parturition.

Another notion is that the pouch young is organically connected with, or 'grown to,' the teat, in fact so intimatelj^ that bleeding results from the forced separation of the pouch young. Doctor Meigs ('47) already showed that this is not the case.

Doctor ]Meigs mentions and refutes the idea prevailing in his time that the pouch young produces a teat wherever it happens to take hold of the skin in the pouch.

Finalh', it is often stated that the marsupial mother pumps milk into the pouch young. Whether or not this is true the writer does not know, but certain it is that from the very beginning the young opossum engages in active sucking movements.

THE PASSAGE OF THE FOETUSES FROM THE UTERUS

As is, of course, well known, the opossum, as a member of the order Marsupalia, possesses two uteri. These do not communicate posteriorly, but open each into a separate shallow cul de sac, on either side of a median partition. Each cul de sac communicates laterallj' with a loop, the 'lateral vaginal canal' (Hill, '97), which cur^-es laterad, then caudad and mediad, until near the midline the two canals almost touch; and from this point backward they Ue parallel until they empty into the 'median vaginal canal' (Hill, '97) or urogenital passage (Owen, '68). The lateral vaginal canals thus resemble two question marks placed face to face; the curved portions lie in the body cavity, the 'stems' are imbedded in the connective tissue of the urogenital strand. The urethra forms a third parallel tube, lying in the midline ventrad to the straight portion of the lateral A-aginal canals and emptying with them into the median vaginal canal.

In two Austrahan species Hill (Parameles, Dasj-urus; Hill, '98, '00) made the surprising discovery that the embryos at birth do not pass out through the lateral vaginal canals, but break through by a cleft-like rupture, the 'pseudo vaginal canal, directly into the median vaginal canal from the culdesac into which the os uteri opens. The new passage is described as a split in the connective tissue, at no time lined with epithelium and containing fragments of foetal membranes together with leucocvtes and maternal blood clots.


I have on several occasions demonstrated in the opossum the existence of the pseudovaginal passage discovered by Hill. In sjiecinien no. 402. aheady iiiontioiiod as aborting under an abdominal operation, one could follow a bloody trail direct into the median vaginal canal exactly as Hill had described it The hemorrhage was less severe in no. 443, the birth of whose young has been described above, but the new passage was ea.sil}- demonstrable. The organs were fixed in Bouin's fluid and sectioned. The findings are quite in accord with those of Hill. The pseudovaginal canal is seen to be simply a slit in connective tissue between the bladder and urethra voiitrally and the caudal ends of the lateral vaginal canals dorsally. In formaldehyde preparations of the organs taken from non-pregnant females such a pseudovaginal passage can with great ease be pushed through; that is, the urethra maj- very readily be separated from the parts dorsal to it. It appears quite certain that the contraction of the alxlominal and the uterine walls is sufficient to force the new passage at the tune of birth.

The embryonic envelopes are partly retained within the uterus, a fact already noted by Osborn ('87) for the opossum, and partly scattered along the median vaginal canal. None were found in tiie lateral vaginal canals either by Osborn or by the writer. It is possible that an embryo may even drag parts or all of its foetal membranes to the exterior, in which case the mother may lick it free; but my only evidence on this point is the presence of the foetal membranes about many of the embryos in the case of one abortion.

The opossum should therefore lie added to the list of marsupials which force the 'pseudovaginal canal' at parturition.

One might suppose from this that the lateral vaginal canals would pos.sess a special function. The writer believes with Hill that the}' function as rcceptacula scminis, .since in the marsupials several days elapse between copulation and ovulation. In the opossum the enlargement of the canal is one of the striking features of the prooestrus period. .\t oestrus they "have attained an enormous size and are filled to turgidity with a thin, lymi)li-like fluid. Soon after ovulation thej' shrink almost to the resting stage and are filled with cheesy masses of cpithehal cells, which remind one of a similar phenomenon described bj^ Stockard and Papanicolaou ('17) for the guinea-pig at oestrus.

ADDENDUM

Several months after the foregoing paper had been received by the editor of this journal the writer received a note from Dr. H. H. Donaldson, of The Wistar Institute, in which he stated that he had learned from Dr. N. Hollister, Superintendent of the National Zoological Park, Washington, D. C, of a pubhshed account of parturition in Macropus rufus, the deer kangaroo. The article in question is in the nature of a communicatioii by the observer, Mr. A. Goerling, to the 'Western ]\Iail,' of Perth, Australia, and was published January 3, 1913. Doctor Hollister's kindness in having the article copied makes it possible to present this interesting account to the readers of The Anatomical Record and thus render it more generally available to zoologists. The accounts of the birth of Didelphys virgiiiiana, as detailed above, and of INIacropus rufus, as reported by ^Ir. Goerling, are seen to be in perfect agreement on the one essential point, namel}^ that the young reach the pouch and find the teat by their own efforts and entirely without the assistance of the mother. It would seem, therefore, that this will be found to hold universally among the numerous species of the ]Marsupialia. The following are Mr. Goerling's notes dated December 19, 1912:

THE BIRTH OF THE KANGAROO

The question of how the young kangaroo comes into the pouch has long been looked upon as answered. According to obscivations made, the young is born and placed on the pap by its mother, and this view has been accepted In" zoologists.

On the 25th of February, 1906, 1 had the good fortune to make the most interesting and astounding obseivation. I had a number of Macropus rufus and M. cervinus in my possession, caged in varioussized cages. On the morning of the above mentioned date I was attracted by the peculiar behavior of a female M. rufus. She refused the feed placed before her; and on seeing blood marks in the cage, I

'The italics are mine.


came to the cont'lusic^n tliat the nniinal liad just given birth to a young one. Shi' was sittiinj in tliat resting ]iosition in which kangaroos can often be seen. Tlie tail pas.<eii forward through the legs, thus she was sitting almost entirely on the thick part of her tail. 8hc took no notice of my presence, although not more than three weeks in captivity, and was busy licking and cleaning herself. Presently she lifted her head, when I was astonished to see a young kangaroo clinging to the long fur about four inches below the opening of the pouch.

It moved about slowly, ven- slowly, through the fur upwards, using the arms in its progress, and conlittiuiUy moving the head from side to side, thus a.ssi.sting the upward movement. Nearly 30 minutes were required by the little wanderer to reach the top of the pouch, the last end in a semicircle. During the whole of this time the mother paid no attention to her offspring, offering no ass-istance, ami leariny it entirely to its own exertions. She then became restless; and not wishing to disturb her, I moved a short distance away, when she at once started to feed. A little later I paid another visit to her cage. She was sitting upright, the young one had disajjpeared, but the fur was still bearing evidence of the struggle, a plain visible track leading to and ending on the top of the pouch.

Now I had the explanation of a previous observation, but which I misconstrued at the time. I had a female ]\Iacropus woodwardi — Woodward's kangaroo — in captivity; and noticing blood stains in the cage. I beheved the animal was hurt. I then noticed just such a young kangaroo clinging to the fur below the pouch, and thought the mother by restless movements had dislodged it.

My obser\-ation of the 25th of Februaiy, 1006, proves that the new born kangaroo has to look after its own safety and reach the pouch mthotd the mother's as.vstance.

The anns of the new born kangaroo are strongly developed, the small hands open and close hke a cat's ])aw, and by these strong little anns and hands the young one is enabled to labour its way to the pouch, the place of safety and nourishment.

The cjuestion now presents itself, how can the young, with such a hard and firmly closed mouth, attach itself to the pap? I am convinced that at the time of birth the mouth has a wider opening and is perhaps more ela.stic than such specimens po.^.sess which are found in the pouch of the mother. Once a young kangaroo is removed from the pap, it is unable to reattach it.self.

As concluding proof that all newly born marsupials must reach the pouch by their own exertions, I mention that bandicoots, native cats and those very smallest of marsupials, the i)0uched mice, have the opening of the pouch in a reversed po.sition to the kangaroos and phalangers. I had once in my pos-scssion a ver>' small specimen of pouched mouse, having ten young ones in the pouch, each one not lugger than a grain of wheat. (Jnly through the opening of the pouch being reversed are these .smallest of boi-n mammals enabled to reach it with saftitv and without much exertion.

LITERATURE CITED

Hartman, Carl G. 1919 Studies in the development of the opossum (Didelphys virginiana L.)- Parts III and IV. Jour. Morph., vol. 32, no. 1, pp". 1-UO.

Hill, J. P. 1895 Preliminary note on the occurrence of a placental connection in Parameles obesula, and on the foetal membranes of certain macropods. Proc. Linn. Soc, New South Wales, vol. 10 (2nd ser.), part 4. 1897 The placentation of parameles (Contributions to the embryology of the Marsupialia I). Quart Jour. Micr. Sci., vol. 40, pp. .385-142. 1899. 1900 Contributions to the morphology and development of the female urogenital organs in the Marsupialia, no. 1. On the female urogenital organs in Parameles, with an account of the phenomena of parturition. Proc. Linn. Soc. N. S. Wales, vol. 24, pp. 42-82. Part I, March 29; nos. 2-5, id., vol. 25, pp. 519-532.

1900 Contributions to the embryology of the Marsupialia. Quart. Jour. Micr. Sci., vol. 43, pp. 1-22.

1900 On the foetal membranes, placentation and parturition of the native cat (Dasyurus viverrinus). Anat. Anz., Bd. 18, s. 364—373.

Hill and O'Donoghue 1913 The reproductive cycle in the marsupial Dasyurus viverrinus. Quart. Jour. Micr. Sci., vol. 59.

Meigs, Dr. Charles D. 1847 Reproduction of Didelphys virginiana. Proc. Am. Philosophical Soc, Philadelphia, vol. 4, pp. 327-330.

Michel, Dr. Middleton 1850 Researches on the generation and development of the opossum. Proc. Am. Assn. Adv. Sci., vol. 3, Charleston, S. C.

OsBORN, H. F. 1888 The foetal membranes of the marsupials: the yolk sac placenta in Didelphys. Jour. ^lorph., vol. 1, pp. 373-382.

Owen, Richard 1868 Anatomy of vertebrates, vol. 1, p. 682.

Selenka, E. 1887 Studien ueber Entwioklungsgeschiehte der Thiere. IV (1 and 2), Das Opossum (Didelphys virginiana). Wiesbaden.

Stockard, Charles R., and PAPANicoLAor, George N. 1917 The existence of a typical oestrous cycle in the guinea-pig with a study of its histological and physiological changes. Am. Jour. Anat., vol. 22, pp. 225265.


Resunien por el autor, Frank Charles Mann. Clinioa Mavd, Rochester, ^linnesota.

Psincreas accesorio.

En el present e trabajo se describen dos pancreas accesorios hallados en perros. En uno de los casos la ghindula aberrante estaba situada a corta distancia distal del ligamento de Treitz, en la inserci6n nicsentcrica del yeyuno. La glandula presentaba fomia triangular, niidiendo 27 X 20 X 15 nun. Poseia un conducto definido que desembocaba en el yeyuno. Su estructura histol6gica coiTesjionde a la del tejido pancreatico normal, pero existe una cantidad relativaniente pequena de tejido insular, y los islotes son muy pequefios.

La segunda gldndula aberrante estaba situada en la pared del duodeno, a corta distancia de la entrada del conducto pancredtico menor. Presentaba forma de disco y media 5x3 mm. Su estructura histol6gica revela la presencia de acmi y conductos normales, pero hay una ausencia casi completa de tejido insular. En este ultimo caso es interesante la estrecha relaci6n entre el tejido pancreatico y la nuisculatura lisa de la pared duodenal.

TransUtioD by Joe6 F. Xonidex Comfll Mfdiml CoIIoitc. Nrw York author's abstract of THI3 PAPER ISSUED BT THE BIBLIOGRAPHIC SERVICE, SEPTEMBER 13

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