295 



ANIMAL PHYSIOLOGY. 



monary artery is called the truncus arteriosus; and it may 

 be mentioned that fibrous vestiges of this, as well as of the 

 ductus venosus, umbilical vein, and hypogastric arteries, 

 remain in the body permanently. 



The oxygenated blood, returning to the foetus by the 

 umbilical vein, passes partly into the vena cava inferior 



Fig. 158. FCETAL CIRCULATION. The course of ihe blood is indicated 

 by arrows, and its quality by shading, a, Umbilical vein bring- 

 ing back aerated blood from the placenta; &, ductus venosns; 

 c, ductus arteriosus; d, hypogastric arteries; e, mesenteric 

 vessels ; /, portal vein, and above it the hepatic vein. 



