Circulation of the Blood 129 



in such a way that they seem to have a common 

 ending, so that where they terminate on the upper 

 portion of the testis, on that cone-shaped process called 

 the corpus varicosum et pampiniforme, it is altogether 

 uncertain whether we are to regard their terminations 

 as veins, or as arteries, or as both. In the same way 

 are the ultimate ramifications of the arteries which 

 run to the umbilical vein, lost in the tunics of this 

 vessel. 



What doubt can there be, if by such channels the 

 great arteries, distended by the stream of blood sent 

 into them, are relieved of so great and obvious a torrent, 

 but that nature would not have denied distinct and 

 visible passages, vortices, and estuaries, had she in- 

 tended to divert the whole current of the blood, and 

 had wished in this way to deprive the lesser branches 

 and the solid parts of all the benefit of the influx of 

 that fluid ? 



Finally, I shall quote this single experiment, which 

 appears to me sufficient to clear up all doubts about 

 the anastomoses, and their uses, if any exist, and to set 

 at rest the question of a passage of the blood from 

 the veins to the arteries, by any special channels, or by 

 regurgitation. 



Having laid open the thorax of an animal, and tied 

 the vena cava near the heart, so that nothing shall pass 

 from that vessel into its cavities, and immediately after- 

 wards, having divided the carotid arteries on both sides, 

 the jugular veins being left untouched ; if the arteries 

 be now perceived to become empty but not the veins, 

 I think it will be manifest that the blood does nowhere 

 pass from the veins into the arteries except through the 

 ventricles of the heart. Were it not so, as observed by 

 Galen, we should see the veins as well as the arteries 

 emptied in a very short time, by the efflux from their 

 corresponding arteries. 



For what further remains, oh Riolanus ! I congratu- 

 late both myself and you : myself, for the opinion with 



K 



