622 



THE PLACENTA. 



In the cow, for example, the external membrane of the egg, beside 

 being everywhere supplied with branching vessels, presents upon 



Fig. 224. 



F<ETAL Pro, with its membrane?, contained in cavity of uterus, 

 c, c. Cavity of uterus, d. Amuiou. e, e. Allautois. 



/, a, b, b. Walls of uterus. 



various points of its surface no less than from seventy to eighty oval 

 spots, at each of which the vessels of the chorion are developed into 

 abundant tufted prominences, hanging from its exterior in thick, 

 velvety, vascular masses. At each point of the uterine mucous mem- 

 brane, corresponding with one of these tufted masses, the maternal 

 bloodvessels are developed in a similar manner, projecting into the 

 uterine cavity as a flattened rounded mass or cake; which, with that 

 part of the foetal chorion which is adherent to it, is known by the 



Fig. 225. 



COTYLEDON OF Cow's UTERI'S, n, a. Surface of foetal chorion. &, b. Bloodvessels of foetal 

 chorion. d, d. Bloodvessels of uterine mucous membrane, c, c. Surface of uterine mucous nieui- 

 braue. 



name of the Cotyledon. Each cotyledon forms, therefore, a little 

 placenta. (Fig. 225.) In its substance the tufted vascular loops 

 coming from the uterine mucous membrane (d, d) are entangled 



