

PECULIARITIES IN THE VASCULAR SYSTEM OF THE FETUS 541 



to the lower extremities and the viscera of the abdomen and pelvis, but the greater 

 amount is conveyed by the umbilical arteries to the placenta. 



From the preceding account of the circulation of the blood in the fetus the fol- 

 lowing facts will be evident: (1) The placenta serves the purposes of nutrition 



Hypogastric arteries 



FIG. 502. Plan of the fetal circulation. In this plan the figured arrows represent the kind of blood, as well as the 



direction which it takes in the vessles. Thus arterial blood is figured > > ; venous blood, > > ; mixed 



(arterial and venous) blood, > >. 



and excretion, receiving the impure blood from the fetus, and returning it purified 

 and charged with additional nutritive material. (2) Nearly the whole of the blood 

 of the umbilical vein traverses the liver before entering the inferior vena cava; 

 hence the large size of the liver, especially at an early period of fetal life. (3) The 

 right atrium is the point of meeting of a double current, the blood in the inferior 



ngnt atnu 



