EMBRYOLOGY. 



-I- 



for it. But in the interest of a more precise definition it is advisable 



to use the name 

 only in the re- 

 stricted sense 

 in which it has. 

 been employed 

 in this chapter, 

 and in other 

 cases to speak 

 of a villous 

 membrane or 

 chorion only. 

 The forma- 

 tion of the pla- 

 centa presents 

 in its details 

 important mo- 

 difications. 



Fig. 135a. Uterus of a Cow laid open, in the middle of the period of The Tfo^tt'fc- 



gestation. From BALFOUR, after COLIN. 



T', Vagina ; 7, uterus ; C'k, chorion ; C\ cotyledons of the uterus ; C", festal nants, in which 



cotyledons. , -, i i 



the blastoder- 



mic vesicle is drawn out into two tips, as in the Pig, present a 

 special type 

 (fig. 135a). On 

 their chorion 

 (CK) have been 

 developed very 

 many small 

 placentse 

 2 }, which here 

 are also called 

 cotyledons. The 

 number of the 

 latter is ex- 

 ceedingly vari- 

 able in the 



TJL 



different 



spe- 



Fig. 135b. Cotyledon of a Cow, the fostal and maternal parts half 

 detached from each other. After COLIN, from BALFOUR. 



C'ies, from sixty u, Uterus; C\ maternal part of the cotyledon (placenta uterina) ; 

 f^ . 1-v, ^v-L/1 c ^. chorion of the embryo; C", fcetal part of the cotyledon 



to one iiuiKiiecL ,, , ,. x 



(chorion frondosnm or placenta roetalis). 



in the Sheep 



and Cow, and only from five to six in the Doe. They are united with 



