ORDER CARNASSIER. 7 



These observations occasioned Professor Reimanus, of 

 Hamburgh, to address himself on the subject to Dr. Barton 

 in America. Roume de St. Laurent, who had already com- 

 municated to Buffon, that the nipples of the female Di- 

 delphis appeared at a certain time, in the form of little 

 clear bulbs, in which the embryo was commenced, had also 

 excited the zeal and stimulated the researches of Dr. Barton. 

 This learned physician answered the appeals of his corre- 

 spondents, and in two letters (one addressed to the Professor, 

 the other to M. Roume) states his facts, observations, 

 and conjectures, touching the generation of the Opossum. 

 His observations are of great importance, and the more so, 

 as while he professes never to depart from what he deemed 

 sound physiological views, the facts he brings forward de- 

 cidedly militate against the theory he proposes to establish : 

 part of his remarks we shall give in substance to the reader. 



The Didelphes put forth not fetuses, but gelatinous 

 bodies, embryos without eyes or ears. The mouth of these 

 embryos is not cut : sprung from parents about the size of 

 a Cat, they weigh at their first appearance generally about 

 a grain, some a little more, and seven of them together 

 weighed ten grains. Barton detached one of these em- 

 bryos, weighing about nine grains, without producing any 

 wound. In this he contradicts what Pennant and other 

 English naturalists have asserted. Fifteen days of develop- 

 ment in their new domicile (an expression of Barton's, in- 

 tended to give what he thinks the true character of the 

 pouch) are sufficient to bring the little ones to the size of 

 a mouse ; they do not quit the teats until they are as large 

 as rats. After this they resume suckling, at pleasure, being 

 then equally sustained by the mother's milk, and whatever 

 substances they can eat at that period. It is necessary to 

 the perfect development of these embryos, that the organs 

 of digestion and respiration should be in perfect harmony. 

 Accordingly, we find the nostrils considerably widened from 



