FIG. 134. Circulation in the embryo and the yolk-sac at the stage of about 

 22 s, drawn from below. Note differentiation of branches of the vitelline 

 arteries. Injected. (After Popoff.) 



1, Marginal vein. 2, Region of venous network. 3, Carotid loop. 4 r, 

 4 1, Right and left anterior vitelline veins. 5, Heart. 6, Anterior intes- 

 tinal portal. 7, Dorsal aorta. 8, Branches of vitelline arteries. 



