(Figure 29 , Caption) 



10. A representation of the vascular system of birds: 

 ab — the heart, from which five pairs of arterial 

 arches go? c — the cephalic artery; d — the vertebral 

 artery, for the formation of which a part of the 

 arterial root (e) is used; f — division into branches 

 in the umbilical artery; g — the anterior vertebral 

 vein; hi — the posterior vertebral vein; h — the caudal 

 vein; k — the transverse venous system; 11 — the 

 umbilical vein (the lower vein of the stomach) ; 

 m — the hollow vein; n — the vein of the yolk sac; 

 o — the common venous stem; p — the yolk artery. 



14. The conversion of the branchiate vascular system into 

 constant arteries in mammals: a — arterial stem; 

 b — the aortic roots; c — the aortic arch; d, c — the 

 carotid arteries. 



19. A section of the chicken egg: a — the embryo; 



b — the amnion; c — the yolk duct; d — the yolk sac; 

 h — the serous membrane; i — the condensed albumen; 

 k — the shell membrane. 



20. Ovum of a rabbit. 



21. Ovum of a bitch. 



22. Ovum of swine. 



2 3 . Human ovum . 



24 . Scheme of the formation of the amnion and the serous 

 membrane in mammals. 



402 



