1098 



THE THORAX. 



Along this vessel it descends to supply the lower extremities and viscera of the 

 abdomen and pelvis, the chief portion being, however, conveyed by the umbilical 

 arteries to the placenta. 



From the preceding account of the circulation of the blood in the foetus it will 

 be seen 



1. That the placenta serves the double purpose of a respiratory and nutritive 



Ductus arteriosus. 



Internal iliac artery. 



FIG. 698. Plan of the foetal circulation. In this plan the figured arrows represent the kind of blood, as 



well as the direction which it takes in the vessels. Thus, arterial Wood is figured ^> > ; venous blood 1 



^yr >; mixed (arterial and venous) blood, ^^ >. 



organ, receiving the venous blood from the foetus, and returning it again re-oxy- 

 genated and charged with additional nutritive material. 



2. That nearly the whole of the blood of the umbilical vein traverses the liver 



