X.] 



THE HUMAN EMBRYO. 

 Fig. 110. 



337 



am 



c7i- 



uin 



Three Early Human Embryos. (Copied from His.) 

 A. Side view of an early embryo described by His. 



B. Embryo of about 1214 days described by Allen Thom- 



son. 



C. Young embryo described by His. 



am. amnion ; ind. medullary groove ; um. umbilical vesicle ; 

 ch. chorion, to which the embryo is attached by a stalk. 



and yolk-sac filled up but a very small part of the 

 whole cavity of the vesicle. 



The embryo, which was probably not quite normal 

 (Fig. 110 A), was very imperfectly developed; a me- 

 dullary plate was hardly indicated, and, though tbe 

 mesoblast was unsegmented, the head fold, separating 

 the embryo from the yolk-sac (wm), was already in- 

 F. &B. 22 



