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 ( Mucropus 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. 11th.-15th day of gestation. No appearance of a mammary fcetus ; 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 has begun to be formed. (IF-Will the fetus seize the larger nipple as the readiest, or be directed to another more proportionate to the size of its mouth ? " Oct. 4th.-38th day. The keeper has observed the female putting her nose into the pouch, and licking the entry. She was exa mined at six in the evening ; there was a slight increase of the brown secretion; the nipple formerly in use has diminished one-third in size ; the other nipples indicate no appearance of approaching parturition.
" Oct. 5th.-39th day. The keeper exa mined the pouch at seven this morning, and found there the young one attached to a nipple. On being made acquainted with this fact I re paired to the Zoological Gardens, and examined the pouch. The new-born kangaroo (fig.140) was attached to the left superior nipple (fig. 140, a), to the point of which it adhered pretty firmly. It measured one inch from the mouth to the root of the tail, was quite naked, and co vered by a thin semitransparent vascular integu ment ; the place of attachment of the umbilical chord was obscurely indicated by a longitudinal linear cicatrix. The fore-legs were longer and stronger than the hind ones, and the digits were provided with claws • the toes were developed on the hind legs; the body was bent forward and the short tail tucked in between the hind legs. This little animal breathed strongly, but slowly ; no direct act of sucking could be perceived. Such, after a gestation of thirty eight days, is the condition of the new-born young of a species of Kangaroo, of which the adult, when standing erect on his hind feet and tail, can reach to the height of seven feet. The birth having taken place in the night, the mode of transference of the young to the pouch and nipple was not observed.