82 



THE KELATIONS OF MAN 



tremely large size, and the vascular processes which are 

 developed from it and eventually give rise to the forma- 

 tion of the placenta (taking root, as it were, in the parental 



FIG. 15. A. Unman ovum (after Kolliker). a. germinal vesicle, b. ger- 

 minal spot. 



B. A very early condition of Man, with yelk-sac, allantois and am- 



nion (original). 



C. A more advanced stage (after Kolliker), compare fig. 14, C. 



organism, so as to draw nourishment therefrom, as the root 

 of a tree extracts it from the soil) are arranged in an en- 

 circling zone, while in Man, the allantois remains compar- 

 atively small, and its vascular rootlets are eventually re- 

 stricted to one disk-like spot. Hence, while the placenta 

 of the Dog is like a girdle, that of Man has the cake-like 

 form, indicated by the name of the organ. 



But, exactly in those respects in which the developing 

 Man differs from the Dog, he resembles the Ape, which, 

 like man, has a spheroidal yelk-sac and a discoidal some- 

 times partially lobed-placenta. 



So that it is only quite in the later stages of develop- 

 ment that the young human being presents marked differ- 



