104 CIRCULATION OF THE BLOOD. 



process called the corpus varicosum et pampiniforme, it is alto- 

 gether 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 umbili- 

 cal 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 intended 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 afterwards, having divided 

 the carotid arteries on both sides, the jugular veins being left un- 

 touched ; if the arteries be now perceived to become empty but 

 not the veins, I think it will be manifest that the blood does no- 

 where 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 Biolanus ! I congratulate both 

 myself and you : myself, for the opinion with which you have 

 graced my circulation ; and you, for your learned, polished, and 

 terse production, than which nothing more elegant can be 

 imagined. For the favour you have done me in sending me 

 this work, I feel most grateful, and I would gladly, as in duty 

 bound, proclaim my sense of its merits, but I confess myself 

 unequal to the task ; for I know that the Enchiridion bearing 

 the name of Riolanus inscribed upon it, has thereby more of 

 honour conferred upon it than it can derive from any praise of 

 mine, which nevertheless I would yield without reserve. The 



