Qn the Vital Principle. 235 



the irritability of the mufcles, that is, the livino- 

 principle, is alfo deftroyed, and their deftrudion 

 is fimultaneous. The laft part of the experi- 

 ment proves their identity, when the irritability 

 of the mufcles is reftored, by exciting the fmall 

 remainder of nervous energy contained in the 

 fpinal marrow. 



4. Dr. Haller himfelf is obliged to make a 

 concefTion, on this fubjeft, fufficient to deftroy 

 his favourite hypothefis of the vis infita* : Mpa- 

 ret caufam motus equidem per nervos dimittiy caterum 

 quacunque ea cauja ftty aliquamdiu tamen in nervo 

 integram et efficacem Jupereffe^ " etfi nervus a cerehro 



Jeparatus earn iaujam nuper non accepit." The per- 

 manency of the caufe of motion, after the fepa- 

 ration of a mufcle from the fource of that caufe, 

 may be well illuftrated, by the duration of im- 

 preffions on our fenfes, after the exciting caufe 

 is removed ; as in the experiment always quoted 

 to this purpofe, of the circular appearance of an 

 ignited body kept in rotatory motion. 



5. When a paralytic limb is convulfed by the 

 eleftric fhock, the motion never takes place 

 without the patient's confcioufnefs. In this cafe 

 there is no diftindlion between the vital prin- 

 ciple and that exertion, which, in voluntary 

 motion, is always attributed to the mind. 



' * Phyfiolog, lom. IV. p. 338. 



In 



