MARSUPIALIA. 



321 



them at the utmost) capable of taking refuge in 

 her pouch." * 



Besides the satisfactory evidence, thus afforded 

 by different and independent observers, respect- 

 ing the condition of the mammary foetus and its 

 true relations to the nipple, the discovery of the 

 uterine foetus was announced nearly at the 

 same time by two naturalists in two different 

 species of marsupial animals. Mr. Collie, 

 whose experiment on the young mammary 

 foetus of a Kangaroo has just been quoted, 

 states in the same letter, " I have just now 

 procured two gravid uteri, (of the Macro- 

 pus Brunii,) in which foetuses seem to be 

 arrived at, or very near to, the termination of 

 the period of gestation. One of them, which 

 is about the size of the smallest young already 

 mentioned, which was about one-half larger 

 than the body of the common wasp, as being 

 in the abdominal sac, has protruded through 

 an opening inadvertently made in the uterus, 

 and is distinctly seen through its transparent 

 membranes and the liquor amnii."-)- About the 

 same time Dr. Rengger, a naturalist who was 

 detained several years by the Dictator Francia 

 in Paraguay, gave the following account of the 

 generation of a species of Opossum ( Didelphis 

 Azara) in his work on the Mammalia of that 

 province. " The foetuses are developed in the 

 cornua uteri, and not in the lateral canals. 

 Some days after impregnation they have the 

 form of small round gelatinous corpuscles, 

 which do not appear, even when examined 

 with a lens, to have any communication with 

 the mother, but a red line indicates the first 

 commencement of development. Towards the 

 end of gestation, when the foetuses have attained 

 the length of six lines, they are seen to be en- 

 veloped in a membrane and provided with an 

 umbilical chord, which is united to the uterus 

 by the medium of many filaments. The head, 

 the four extremities, and tail are recognizable 

 with the naked eye, but those foetuses which 

 are nearest the Fallopian tubes are generally least 

 advanced. " In gestation they make the circuit of 

 the lateral canals, in which they are found to be 

 deprived of their foetal envelopes, and to have 

 no communication with the parent by means of 

 the umbilical chord ; whilst one foetus was 

 found in this situation, two others were still in 

 the body of the uterus (vaginal cul-de-sac), 

 from which the umbilical chords were not yet 

 detached. At this period a slight enlargement 

 of the cul-de-sac and lateral canals was the 

 only change perceptible in them."J 



Thus, by the various observations derived 

 from the different sources above indicated, the 

 following propositions are satisfactorily esta- 

 blished, viz. that the young of the Marsu- 

 pialia are developed, primarily, as Tyson con- 

 jectured, in the true uteri or cornua uteri ; but 

 that, contrary to Tyson's opinion, they are, as 



* Barton, ' Facts, Observations, and Conjectures 

 relative to the Generation of the Opossum.* Annals 

 of Philosophy, vol. vi. 1823, p. 349. 



t Zoological Journal, vol. v. p. 240. 



t From the Analysis of Rengger's " Saugethiere 

 von Paraguay" in the Bulletin des Sciences Nat. 

 torn. xxi. p. 469. 



VOL. Iir. 



compared with other Mammalia, prematurely 

 born; and that, nevertheless, the attachment 

 of the immature young to the nipple is essen- 

 tially the same as in ordinary mammals, the 

 young marsupial being nourished by the lac- 

 teal secretion, and its blood aerated by its own 

 independent respiratory actions. 



Such, therefore, being the condition of the 

 problem of marsupial generation in the year 

 1830, there remained to be determined by exact 

 experiment and observation the period of uterine 

 gestation, the structure of the foetal envelopes 

 and appendages, the nature of the connection, 

 if any, between the uterine foetus and the 

 womb, the manner of the uterine birth, and the 

 condition and powers of the new-born young. 



With a view to the solution of these ques- 

 tions, I applied for and obtained from the 

 Council of the Zoological Society permission to 

 perform the requisite experiments on the Kan- 

 garoos in the menagerie in Regent's Park. A 

 healthy female ( Macropus major, Shaw) was 

 separated from the rest ; she had a young one 

 which measured about one foot two inches from 

 the nose to the root of the tail, and which 

 continued to return to the pouch for the purpose 

 of sucking and for shelter. The right superior 

 nipple was the one in use ; it was nearly two 

 inches long, and one-third of an inch in dia- 

 meter ; the mammary gland formed a large 

 swelling at its base. The other three nipples 

 were everted, and about half-an-inch in length. 



A healthy full-grown male was admitted into 

 the paddock with this female for a certain 

 period each day, and watched, during that 

 time, by the keeper or myself. In the course 

 of a week the female seemed to be in a con- 

 dition to excite the sexual ardour, and after 

 a few days toying on the part of the male, she 

 received his embrace on the 27th August, at 

 1 p.m. The female stood with her fore-paws 

 off the ground, the male mounted, ' more 

 canino,' embracing her neck with his fore-paws, 

 and retained his hold during a full quarter of 

 an hour; during this period the coitus was 

 repeated three times, and on the second occa- 

 sion much fluid escaped from the vulva. The 

 male was removed from the female in the 

 evening of the same day, and was not after- 

 wards admitted to her. On September the 2d, 

 six days after the coitus, I examined the pouch 

 of the female, and this scrutiny was repeated 

 every morning and evening until the birth of 

 the young kangaroo had taken place. I select 

 the following from the notes taken on those 

 occasions : 



" Sept. 6th. 10th day of gestation. The 

 pouch is nearly free from its peculiar brown 

 musky secretion. The right superior nipple 

 retains its large size, and the young one that 

 has left the pouch returns occasionally to suck. 



" Sept. llth. 15th day of gestation. No 

 appearance of a mammary foetus ; nipples in 

 the same condition ; the young kangaroo con- 

 tinues to suck and return to the pouch for 

 shelter. 



" Sept. 30th. 34th day. The nipple in 

 use by the young kangaroo (which has died) is 

 diminished in size, and the brown secretion 



