LATER DEVELOPMENT OF VASCULAR SYSTEM 371 



C. V.sc.d. 



V3C.S. 



V.c.i. 



A.OM 



V.c.fi.d. 



Vscd. 



Fig. 213. — Reconstruction of the venous system of 

 a chick of 5 days. Ventral view. (After Miller.) 

 a., Mesonephric veins. Ao., Aorta. A. sc. s., Left 

 sciatic vein. Other abbreviations as before. 



the right and left postcardinal veins passes through the vas- 

 cular network of the mesonephros, and empties into the sub- 

 cardinal veins, from which it flows into the vena cava inferior, 

 and so through the meatus venosus to the heart. Prior to the 

 sixth day, however, the greater portion of the blood in tlie pos- 



FiG. 212. — Reconstruction of the venous system of a chick of 90 hours, 

 ventral view. (After Miller.) 

 A. o. m., Omphalomesenteric artery, a. sc. s.. Left sciatic artery. A. 

 u. s., Left umbilical artery, b., Vessels enclosed within ventral side of meso- 

 nephros. V. c. p. d., s., Ri^ht and left posterior cardinal veins. V. c. i., 

 Vena cava inferior. V. sc. d., s., Right and left subcardinal veins. 



