THE VESSELS. 295 



becomes changed into the dark red blood in the capillary rete of the body (in 

 opposition to the lungs), passes through the veins (with the exception of the 

 pulmonary) and returns through the vv. cava and coronaria cordis (see before) 

 to the right auricle. 



533. II. Circulation of the mature foetus. 



1. From the right auricle the blood passes out, a. of v. cava inf. through 

 the foram. ovale (partly) into the left auricle (partly into the right ventricle), 

 hence into the left ventricle, aorta ascendens, truncus anonymus, carotis and 

 subclavia; b. the blood of v. cava superior into the right ventricle, art. pul- 

 monalis and through the ductus arteriosus Botalli into the aorta descend, (in 

 great part) into two artt. umbilicales and in these through the umbilical cord 

 into the placenta. 



2. From the Placenta the blood passes back through the vena umbilicalis 

 into the belly of the foetus ; goes along through a branch of v. umbilicalis to 

 the ven. porta, through another, ductus venosus Arantii, to the v. cava infer. 

 into which also the blood of the liver and of the inferior half of the body empties 

 itself. 



534. A. The vessels of the small circulation, 



namely, Art. pulmonalis, which carries the blood from the right 

 half of the heart (venous blood) into the lungs ; and 



Vence pulmonales, which carry back into the left half of the 

 heart the blood which having passed through the Art. pulmonalis 

 to the lungs has been changed into arterial blood by the influence 

 of the inspired air. 



535. 1. The pulmonary artery, arteria pulmonalis s. venosa, 



arises above and before from the right ventricle (thirty-one and a half to 

 twenty-nine and one third lines wide), is situated at the commencement be* 

 fore, then to the left of the aorta, since it inclines to the posterior and right 

 concave side of this, between the auricles of the heart, afterwards before the 

 left auricle, it finally divides after a course of one and a half to two inches into 

 two branches which embrace the arch of the aorta, enter into the lungs, and 

 after fine ramifications, anastomosing with the Artt. bronchiales, they form a 

 capillary rete round about the vesicles of the lungs, from which the pulmo- 

 nary veins arise. 



a. The right branch, sixteen to eighteen lines long, and larger than the left, 

 passes away towards the right and behind aorta ascendens and V. cava supe- 

 rior, before the bronchus dexter, above the superior right pulmonary vein, and 

 enters with three branches into the three lobes of the right lung. 



b. The left branch, one inch long and narrower, passes away to the left and 

 backwards, before the aorta descendens and bronchus sinister (separated from 

 the last, sometimes by art . branch.) ; above the left superior pulmonary vein 

 and enters with two branches into the two lobes of the left lung, where the 

 pulmonary veins are situated before it. 



