693 



MARSUPIATA. 



MARSUPIATA. 



94 



noticed, indicating a commencing determination of blood to that part, 

 and at different periods during the day the female was observed to 

 put her head into the pouch and lick off the secretion. When she 

 was again examined, at six o'clock in the evening, a slight increase of the 

 secretion was the only perceptible change in the state of the pouch, but 

 there was no appearance in the nipples indicative of the event so soon 

 about to take place. The nipple in use by the young one of the previous 

 year was the right superior or anterior one ; it was nearly two inches 

 in length, and one-third of an inch in diameter, while the other three 

 were about half an inch in length, and about a line in diameter. I 

 took notes of the appearance of the marsupium on the 6th, the 10th, 

 15th, 21st, 30th, and 38th days of uterine gestation ; no material 

 alteration was however observable till after the death of the young 

 Kangaroo of the previous year, which took place on the twenty-fifth 

 day, when the brown secretion first began to appear, and the nipple 

 that had been in use to diminish. As parturition took place in the 

 night, the mode of transmission to the pouch was not observed. No 

 blood or albuminous discharge could be detected on the litter, nor 

 any trace of it on the fur between the vagina and orifice of the pouch ; 

 but these might have been removed by the mother. The appearances 

 presented by the little one thus detected within twelve hours after 

 being deposited in the pouch were as follows : It resembled an earth- 

 worm in the colour and semitransparency of its integument, adhered 

 firmly to the point of the nipple, breathed strongly but slowly, and 

 moved ito fore legs when disturbed. Its body was bent upon the 

 abdomen, its short tail tucked in between the hind legs, which were 

 d shorter than the fore legs, but with the three divisions of 

 the toes now distinct. The whole length from the nose to the end of 

 the tail, when stretched out, did not exceed one inch and two lines. 

 On the 9th of October I again examined the pouch ; the young one 

 was evidently grown and respired vigorously. I determined to detach 

 it from the nipple for the following reasons : 1st, to decide the nature 

 of the connection between the foetus and the nipple ; 2nd, to ascertain, 

 if possible the nature of the mammary secretion at this period ; 3rd, 

 to try whether so small a foetus would manifest the powers of a volun- 

 tary agent in regaining the nipple ; and lastly, to observe the actions 

 of the mother to effect the same purpose, which one might presume 

 would be instinctively analogous to those by means of which the 

 foetus was originally applied to the nipple. With respect to the first 

 point, I was aware that the Hunterian dissections, as exhibited in the 

 preparations in the museum of the college, and the observations of 

 Mr. Morgan and Mr. Collie, concurred in disproving the theory of a 

 vascular mode of connection between the mammary foetus and the 

 nipple; nevertheless as a discharge of blood had been stated by 

 Oeoffroy St. Hilaire to accompany marsupial birth, or the spontaneous 

 detachment of the foetus from the nipple, and even the anastomoses 

 and distribution of the continuous vessels in the neck of the foetus 

 had been speculated on by him, it became desirable to have ocular 

 demonstration of the facts. 



" The foetus retained a firm hold of the nipple ; when it was 

 detached, a minute drop of whitish fluid, a serous milk, appeared on 

 the point of the nipple. About half a line of the extremity of the 

 nipple had entered the mouth, which extremity was of smaller 

 diameter than the rest of the nipple, not being as yet so compressed 

 by the contracted orifice of the mouth as to form a clavate extremity, 

 guch as it afterwards presents. The young one moved its extremities 

 vigorously after being detached, but did not make any apparent effort 

 to apply its legs to the integument of the mother, so as to creep along, 

 but seemed, in regard to progressive motion, to be perfectly helpless. 

 It was deposited at the bottom of the pouch, and the mother was 

 liberated and carefully watched for an hour. She immediately showed 

 symptoms of uneasiness, stooping down to lick the orifice of the 

 vagina, and scratching the exterior of the pouch. At length she 

 grasped the sides of the orifice of the pouch with her fore paws, and 

 drawing them apart, as in the act of opening a bag, she thrust her head 

 into the cavity as far as the eyes, and could be seen moving it about 

 in different direction!). During this act she rested on the tripod 

 formed by the tarsi and tail. She never meddled with the pouch 

 while in the recumbent posture ; but when stimulated by uneasy 

 sensations, she immediately rose and repeated the process of drawing 

 open the bag and inserting her muzzle, sometimes keeping it there for 

 half a minute at a time. I never observed that she put her fore-legs 

 into the pouch ; they were invariably employed to widen the orifice. 

 When she withdrew her head, she generally concluded by licking the 

 orifice of the pouch, and swallowing the secretion. After repeating 

 the above act about a dozen times, she lay down, and seemed to be at 

 ease. 



" The freedom with which the mother reached with her mouth the 

 orifices both of the genital passage and pouch suggested at once a 

 means adequate to the removal of the young from the one to the 

 other; while at the same time her employment of the fore paws 

 indicated that their assistance in the transmission of the foetus need 

 not extend beyond the keeping open the entrance of the pouch while 

 the fcptus was being introduced by the mouth, when it is thus pro- 

 bably conducted to, and held over, a nipple, until the mother feels 

 that it has grasped the sensitive extremity of the part from which it 

 a to derive its sustenance. This mode of transmission is consistent 

 with analogy, the mouth being always employed by the ordinary 



quadrupeds, as dogs, cats, and mice, for the purpose of removing their 

 helpless offspring. It accords also with the phenomena better than 

 those which have been previously proposed ; for it is now ascertained, 

 by repeated dissections both of the Kangaroo and Opossum, that there 

 is no internal passage from the uterus to the marsupium : and if the 

 genital outlet can be brought into contact with the orifice of the 

 pouch in the dead Kangaroo by means of great stretching of the 

 relaxed parts, yet such an action has never been witnessed in the 

 living animal ;* the tender embryo would be more liable to receive 

 injury from the fore paws ; and these, from the absence of a thumb, 

 could not so effectually insure its passage as the lips, which can be 

 opposed to each other. Lastly, the young one did not by any of its 

 actions encourage the idea of its possessing the power of instinctively 

 creeping up to the nipple. When the female had rested quiet for 

 about half an hour we again examined her, and found the young one 

 not at the bottom of the pouch, but within two uiches of the nipple ; 

 it was breathing strongly, and moving its extremities irregularly as 

 before. I made an attempt to replace it on the nipple, but without 

 success, and the mother was then released. On an examination two 

 days afterwards the marsupium was found empty. Every portion of 

 the litter was carefuHy searched, in the hopes of finding the foetus, 

 but without success. The mother therefore, owing to the disturbance 

 of the young one, had probably destroyed it. This was a result I 

 had not expected, for the head keeper at the Zoological Farm had 

 twice taken a mammary fetus from the nipple and pouch of the 

 mother, soon after it had been deposited there, and when it did not 

 exceed an inch in length, and it had each time again become attached 

 to the nipple. I afterwards saw this fostus attached to the nipple; 

 and it continued to grow, without having sustained any apparent 

 injury from the separation, until the death of the mother, when it 

 was nearly ready to leave the pouch. A similar result occurred to 

 Mr. Collie." 



Outline of the Kangaroo about twelve hours after uterine birth, showing its 

 natural size and external development at this period. The elongation of the 

 jaws has reduced the mouth to a simple round anterior orifice, which subse- 

 quently becomes even more contracted before the lateral fissures begin to 

 extend backwards. The eye is concealed by the completely formed eyelids. 

 Three divisions are now seen at the posterior extremity. A longitudinal line 

 indicates the separation of the umbilical pedicle, n, the upper nipple of the 

 left side, to which the above fostus was attached ; t, the lower nipple of the 

 same side. 



The young one observed by Mr. Collie (' Zoological Journal,' vol. v.) 

 was of nearly the size of the last and half the middle joint of one's 

 little finger ; and the flesh-coloured integuments were so transparent 

 as to permit the higher coloured vessels and viscera to be seen through 

 them. The extremities seemed completely formed, and its muscular 

 power was testified by its efforts in sucking, during which it put every 

 part of its body in motion. "According to the testimony of the 

 person," continues Mr. Collie, " who preserved the mother with this 

 little one for me, the latter by no means passes the whole of its time 

 with the lacteal papilla in its mouth, but has been remarked, more 

 than once, without having hold of it. It has even been wholly removed 

 from the sac to the person's hand, and has always attached itself anew 

 to the teat. Yesterday, on again looking at it, I gently pressed with 

 the tip of my finger the head of the little one away from the teat of 

 which it had hold, and continued pressing a little more strongly for 

 the space of a minute altogether, when the teat, that had been 

 stretched to more than an inch, came out of the young one's mouth, 

 and showed a small circular enlargement at its tip, well adapting it for 

 being retained by the mouth of the sucker. The opening of the mouth 

 seemed closed in on both sides, and only sufficiently open in front to 

 admit the slender papilla. After this I placed the extremity of the 

 teat close to the mouth of the young, and held it there for a short 

 time without perceiving any decided effort to get hold of it anew ; 

 when I allowed the sac to close, and put the mother into her place of 

 security. An hour afterwards the young one was observed still unat- 

 tached, but in about two hours it had hold of the teat and was actively 

 employed in sucking." 



Professor Owen then refers to a similar experiment tried with a 

 mammary footus about the size of a Norway rat by Mr. Morgan. 

 This foatus, after two hours' separation from the nipple, regained ita 



* Professor Owen observes that this argument is not applicable to those 

 Afarmpiata which, like Pcramelca and the smaller South American Opossums, 

 have the duplicaturcs of integument forming the pouch extended close to the 

 clouca. 



