280 CIRCULATORY SYSTEM. 



auricle, and transmitted, either wholly or in a great degree, into 

 the right ventricle. It would then be passed from the latter 

 through the pulmonary artery and ductus arteriosus into the de- 

 scending aorta, so that no part of the system, above the junction 

 of the duct with the aorta, could receive the benefit of it: this 

 would leave the head and upper extremities unsupplied with 

 fresh blood. Moreover, much of the latter would be fruitlessly 

 introduced, for it would depart almost immediately through the 

 umbilical arteries. But the Eustaehian valve determining the 

 flow of blood of the ascending cava into the left auricle, its pas- 

 sage into the left ventricle is a matter of course: thence it be- 

 gins the aortic circulation fairly, so that every part of the sys- 

 tem participates in its benefits. 



The celebrated Wistar* has also happily suggested, that 

 without this arrangement the blood of the coronary arteries of 

 the heart itself, the purity of which is so essential to the vigour 

 of circulation, would otherwise have been effete, and, conse- 

 quently, unfit for its object of refreshing the heart. 



The umbilical arteries become the round ligaments of the 

 bladder, after the circulation through them has ceased, with 

 the exception of their pelvic extremities, which subsequently 

 constitute the trunks of the Internal Iliac Arteries. 



CHAPTER V. 



OF THE GENERAL ANATOMY OF THE ABSORBENT SYSTEM. 



THE absorbent system is one of the most interesting of those 

 which compose the human body, both on account of its very 

 general diffusion, and of the office of interstitial absorption that 

 it incessantly carries on, thereby removing the effete parts of 

 the body and making room for the deposite of new ones. It is 



* System of Anat. vol. ii. p. 76, 3d edition. 



