DEYEUH'.MEXT. 



295 



a 



M 



KK.. 079. Diagramatic figures illustrating the formation of the fatal membranes 01 a 

 Mammal (;ifter Kolliker). a, Ovum with first rudiments of embryo; b, Ovum wirh 

 yolk-sac a.ud developing amnion ; c, Ovum with amniou closing and developing allautois ; 

 <l, Ovum with villous serous envelope, embryo with mouth and anus ; r, Ovum in which 

 the vascular layer of the allantois is applied to the serous envelope and has grown into 

 the villi of the latter, yolk-sac reduced, the amniotic cavity is increasing; D, Zoiia 

 radiatii; D', Villi of zoua ; Sh, subzonal membrane (serous envelope) ; &, Villi of sub- 

 zonal membrane ; Ch, Chorion (vascular layer of Allantois) ; C/iz, Choriouic villi (con- 

 sisting of choriou and subzonal membrane); Am, Amnion; Ah, Amniotic cavity; 

 E, Embryo ; A, Embryonic thickening of the external layer ; 31, of the middle layer ; J, 

 of the inner layer; Dx, cavity of the embryonic (blastodermic) vesicle, later of the yolk- 

 sac (umbilical vesicle) ; Dh, Intestinal cavity ; Dff, Umbilical stalk : Al, Alia. 



