him say, < That all the veins communicate one with 

 the other, and run into one another ; that the veins 

 -which spread themselves over the whole body, filling 

 it with spirit, juice, and motion, are al) of them but 

 branches of one original vein. I protest, I know not," 

 says he, u where it begins or where it ends, for in a 

 circle there is neither beginning nor ending.". A little 

 further he says, u that the heart is the source of the 

 arteries, which carry blood into all parts of the body, 

 communicating to them life ani heat ;" he adds, u that 

 they are the rivulets which cherish the human body, 

 and convey life to every part of man." In another 

 part, he says, u that the heart and veins arc always 

 in motion." He compares the course of rivers, which 

 return to their sources in an unaccountable and ex- 

 traordinary manner, to the circulation of the blood* 

 In apoplexies and such like disorders, which he as- 

 cribes to obstructions in the veins, he prescribes bleetU 

 ing, in order to procure a free motion to the blood 

 and spirits. He says al>o, '* that when the bile en- 

 tors into the blood, it breaks its consistence, and dis- 

 orders Us regular course : he compares its admirable 

 mechanism to clows of thread, whose filaments overlap 

 each other ;" and says, u that in the body it performs 

 just such a circ -it, alvvays terminating where it began."; 



5. The next to Hippocrates is Plato, who speaks 

 with clearness of the circulation of the blood; u for 

 from the heart,'* he says, u spring the veins and. 

 blood, which with rapid ty carries itself into ail parts) 1 ' 

 adding, that when the blood thickens, it flows with 

 more difficulty through the veins. Aristotle too re. 

 gards the heart as the origin and fountain of the veins 

 and blood. He says, u that from the heart there arise 

 two veins, one on the right and the other on the left 

 side; and lu> was the first who called this aorla.'* He 

 held that the arteries had a, communication with the 

 veins, and that they were intimately connected tc- 

 gether. 



a 3 



