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 iiitrht and left anterior vitelline veins. 5, Heart. 6, Anterior intes- 

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



