10 CLASS MAMMALIA. 



another mammary, and these two sorts of gestation 

 act differently, one supplying the deficiencies of the 

 other." With Barton, however, the meaning of the word 

 gestation is obvious. He applies the term to the simul- 

 taneous existence of the uterus and the pouch, to the 

 notion of those two domiciles, in which certain phenomena, 

 imperfectly exhibited in the one, are completed in the 

 other. But with M. de Blainville, the idea of uterine 

 and mammary gestation extends only to the different action 

 of certain modes of nutrition. In the mammalia, he says, 

 the foetus, before it can be sustained independently, is ca- 

 pable of drawing its nutriment from the mother in two 

 distinct places, and two different manners ; i. e., in the 

 uterus from the blood, by means of the vascular system, 

 and at the teats from the milk by the intestinal canal . 

 And the two modes of nutrition, as to their duration, are 

 in an inverse ratio in the various animals. M. de Blain- 

 ville applies this generalization to the pouched animals. 

 He imagines that one of these two modes of nutrition 

 might be altogether suppressed. If the uterine be done 

 away, we have the pouched animals ; if the mammary, we 

 have mammalia without mammae ; i.e., the monotremes. 

 That an animal may be born by means of a mammary nu- 

 trition, organized like a young one that has its full term 

 of uterine gestation, is a bold conjecture, and accordingly 

 M. de Blainville does not absolutely insist upon it. But 

 he gives some consistency to this idea, when he admits at 

 the end of his observations, that the foetus probably passes 

 directly from the uterus into the pouch, observing that the 

 round ligament, the use of which in the ordinary mam- 

 malia is not known, may be the means of this passage. 



M. Geoffroy, lamenting the vagueness and obscurity ex- 

 isting in the science of the Marsupiata, wrote an article 

 on the subject in 1819, with this query as title, " Are the 

 pouched animals born attached to the teats of the mo- 



