MEMOIR ON THE REPRODUCTION OF THE OPOSSIM. 163 



means of oxydating its blood as the most active and powerful dolphin or sturgeon — and I 

 cannot imagine that even the profuse supply of trachea; in the annelides can exceed in 

 liberality the oxygen endowments of the young opossum of three and a half grains' 

 weight. 



Many have doubted whether the young is not attached by a vascular union to the teat 

 — an idea that has been put forth by high authority. Mr. Owen, however, has set that 

 matter in a clear light. 



Nevertheless, I resolved to ascertain whether any milk was in the stomach, and there- 

 fore removed that organ, and putting it under a compressor to squeeze out the contents, 

 examined them with one of Oberhaueser's instruments, under a high power. The vesi- 

 cles of the milk were innumerable. Dr. Barton, page 8, in a note, says, " In an opossum 

 weighing only forty-one grains, I have seen the stomach very considerably extended with 

 a white matter, or milk. But the milk that is afforded to the embryons for a few days 

 after their first reception into the marsupium is nearly pellucid or transparent." — Letter 

 to Bourne. So that the animal sucks and swallows milk, and fills its intestines, and 

 makes chyle, and has a powerful hrcmatosis, and a vast aeration, with muscular and 

 organic innervations, at the end, or sooner, of one day's marsupial life ! the weight being 

 thnc and a half grains. 



It is quite apparent that M. Milne Edwards and M. Pouchct arc wrong in their 

 opinions as to the forwardness of the vital organs in this early stage; and all my asto- 

 nishment and doubt as to the state of the development and the means of living in the 

 marsupial didelph are quite at an end — as I find there is nothing in it different from what 

 occurs in the young child at its mother's breast. 



Monday, March 8th. — Upon opening the pouch to-day, I observed the young moving 

 their arms and bodies freely, each one busy at its needful work; pulling and even tugging 

 at the nipples. They occasionally slowly extend the body, and then, by a sudden start, 

 or jerk, flex it again, after the manner of a shrimp or cray-fish. 



Wednesday, March 10th. — The young considerably larger — all at work. 



Saturday. March 13th. — The pouch opened at 5, p.m. Young arc much grown and 

 very frisky. I counted twelve of them at the nipples. 



Sunday, March 14th, 4 p.m. — I removed a young didelph, which adhered so strongly 

 that the nipple was drawn quite forth of the sac before it let go. On the nipple, again, 

 was no bulb, but it resembled the figure. 



The animal now weighs twelve grains in Mr. Bringhurst's scale. Seven days ago it 

 weighed three and a half grains; an increase of about two hundred and fifty per cent. 



Its whole length, one and one-tenth inches; when flexed, six-tenths. 



\" haire on the rose-coloured skin, which is more wrinkled than before. 

 \t twentj minutes past 7, p.h., which is three and a half hours since I took it oil', it 

 breathes thirty-two per minute, by the watch — very regularly — the counts repeated 

 several times. 



Sleepsfand wakes by turns on the lock of cotton where it lies. External organs and 

 scrotum lame. 



