CIRCULATION OF THE BLOOD. 141 



So much for the circulation ; any impediment, or perversion, 

 or excessive excitement of which, is followed by a host of dan- 

 gerous diseases and remarkable symptoms : in connexion with 

 the veins varices, abscesses, pains, hemorrhoids, hemerrhages ; 

 in connexion with the arteries enlargements, phlegmons, se- 

 vere and lancinating pains, aneurisms, sarcoses, fluxions, sudden 

 attacks of suffocation, asthmas, stupors, apoplexies, and innu- 

 merable other affections. But this is not the place to enter 

 on the consideration of these ; neither may I say under what 

 circumstances and how speedily some of these diseases, that are 

 even reputed incurable, are remedied and dispelled, as if by en- 

 chantment. I shall have much to put forth in my Medical 

 Observations and Pathology, which, so far as I know, has as 

 yet been observed by no one. 



That I may afford you still more ample satisfaction, most 

 learned Riolanus, as you do not think there is a circulation in 

 the vessels of the mesentery, I shall conclude by proposing the 

 following experiment : throw a ligature around the porta close 

 to the liver, in a living animal, which is easily done. You will 

 forthwith perceive the veins below the ligature swelling in the 

 same way as those of the arm when the bleeding fillet is bound 

 above the elbow ; a circumstance which will proclaim the course 

 of the blood there. And as you still seem to think that the blood 

 can regurgitate from the veins into the arteries by open anasto- 

 moses, let the vena cava be tied in a living animal near the divari- 

 cation of the crural veins, and immediately afterwards let an 

 artery be opened to give issue to the blood : you will soon 

 observe the whole of the blood discharged from all the veins, 

 that of the ascending cava among the number, with the single 

 exception of the crural veins, which will continue full ; and this 

 certainly could not happen were there any retrograde passage 

 for the blood from the veins to the arteries by open anastomoses. 



