4 CLASS MAMMALIA. 



The re-production of living beings, as is well known, 

 takes place in various modes: attention, however, has 

 never perhaps been given to this subject in the degree 

 which it merits. These very various modes, these unusual 

 combinations have been observed only in animals of a lower 

 order. They were considered as something inherent in the 

 gradation of organic constitutions, a necessary consequence 

 of the scale of animal life ; but so assured did naturalists 

 feel of the uniformity existing in this respect among all 

 animals conformed like Man, that in the case of the Mar- 

 supiata, they were inclined to reject as inaccurate all that 

 did not square with received opinions on this point, and 

 agree with known analogies. Such a principle is, doubt- 

 less, essential to all just philosophizing, but some reserva- 

 tion must be observed in its application. 



Thus from the origin of our acquaintance with the Di- 

 delphes, an opinion arose that their young were actually 

 produced in the abdominal pouch beside the mammas of the 

 mother. It is nearly two centuries since Marcgrave has 

 said, " The pouch is properly the matrix of the Carigueya, 

 (Didelphis Opossum.) I have been unable to find any other ; 

 this is a point which I have ascertained by dissection. The 

 semen is produced there, and there the young are formed." 

 Pison confirms the same facts, having, as he observes, dis- 

 sected many oF these carigueyas. Valentyn, occupied in ec- 

 clesiastical functions in the East Indies, and who never was 

 aware of the existence of pouched animals in America, 

 makes the same assertion, in his account of the Molucca 

 Islands : " The pouch of the Philanders is a matrix, in 

 which the young are conceived. This pouch is not what is 

 usually supposed. The mammae are, with regard to the 

 young, what stalks are to their fruits." The young remain 

 attached to the mammae, until they have attained maturity, 

 and then separate from them as the fruit drops from the 

 stalk. 



