350 



REPRODUCTION 



mother. Finally they are distributed only to a certain part 

 (placenta) of the chorion ; and as the allantoic vessels anas- 



FIG. 107. 



e, embryo; a, amnion; a', alimentary canal; vt, vitelline membrane; af, amniotic 

 fold; ac, amniotic cavity; y, yolk; al, allantois. 



tomose more and more freely with those of the chorion, the 

 umbilical vesicle shrivels, as it is no longer needed. The 

 vessels of the allantois are the two allantoic arteries and the 



