Circulation of the Blood 171 



both charged and distended by the contraction of the 

 auricles, and more or less increased in size according 

 to the charge ; and farther, we can see that the dis- 

 tension of the heart is rather a violent motion, the effect 

 of an impulsion, and not performed by any kind of 

 attraction. 



Some are of opinion that, as no kind of impulse of 

 the nutritive juices is required in vegetables, but that 

 these are attracted by the parts which require them, 

 and flow in to take the place of what has been lost ; so 

 neither is there any necessity for an impulse in animals, 

 the vegetative faculty in both working alike. But there 

 is a difference between plants and animals. In animals, 

 a constant supply of warmth is required to cherish the 

 members, to maintain them in life by the vivifying heat, 

 and to restore parts injured from without. It is not 

 merely nutrition that has to be provided for. 



So much for the circulation ; any impediment, or 

 perversion, or excessive excitement of which, is followed 

 by a host of dangerous diseases and remarkable 

 symptoms : in connexion with the veins varices, 

 abcesses, pains, hemorrhoids, hemorrhages ; in con- 

 nexion with the arteries enlargements, phlegmons,, 

 severe and lancinating pains, aneurisms, sarcoses, 

 fluxions, sudden attacks of suffocation, asthmas, stupors, 

 apoplexies, and innumerable 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 round the porta close to the 



