1380 PHYSIOLOGY 



thickness of the left ventricular walls, which is so characteristic of 

 the adult, does not become evident until shortly before birth. 



FIG. 563. Diagrammatic outline of the organs of circulation in the 



foetus of six months. (After ALLEN THOMSON.) 



RA, [right auricle of the heart ; RV, right ventricle ; LA, left auricle ; 

 EV, Eustachian valve ; LV, left ventricle ; L, liver ; K, left kidney ; I, portion 

 of small intestine ; a, arch of the aorta ; of , its dorsal part ; a", lower end ; 

 vcs, superior vena cava ; vci, inferior vena where it joins the right auricle ; 

 vci, its lower end ; 8, subclavian vessels ; j, right jugular vein ; c, common 

 carotid arteries ; four curved dotted arrow lines are carried through the 

 aortic and pulmonary opening and the auriculo-ventricular orifices ; da 

 opposite to the one passing through the pulmonary artery marks the place 

 of the ductus arteriosus ; a similar arrow-line is shown passing from the 

 inferior vena cava through the fossa ovalis of the right auricle and the 

 foramen ovale into the left auricle ; hv, the hepatic veins ; vp, vena portse ; 

 x to vci, the ductus venosus ; uv, the umbilical vein ; ua, umbilical arteries ; 

 uc, umbilical cord cut short ; '', iliac vessels. 



