g HISTORY OF GALVANISM. 



muscles ; and points out an error into which Valli 

 had fallen in his experiment's, where he thought 

 that the contact of the nerve only is sufficient to 

 cause the contractions : he shows that, in this 

 case, the moisture on the surface of the nerve 

 acted as a conductor of the influence of one of the 

 metals to the fibres of the muscle. 



Supposed Fowler concludes that the galvanic influence is 

 ferent. not referable to electricity, because for the produc- 

 tion of the former the presence of two different 

 metals appears to be necessary, while electricity, as 

 proceeding from the electrical machine, is excited 

 by the action of an electric upon a conductor ; an 

 inference which was correct, according to the state 

 of the science at the time when he wrote. He 

 also endeavours to show that electricity and gal- 

 vanism are not, in all cases, conducted by the same 

 substances, and particularly adduces charcoal, 

 which, although a conductor of electricity, is im- 

 pervious to the galvanic influence. He afterwards 

 made some curious observations upon the effect 

 of galvanism on animals not furnished with dis- 

 tinct limbSj such as worms of various kinds. 

 These animals could not be made to contract ; yet 

 by the nature of their motions, they seemed to be 

 sensible to the impression of the two metals, when 

 they were placed, partly on one, and partly on the 

 other. From these experiments he inferred that 

 animals of this description were furnished with a 

 nervous system, and that the peculiar effect of the 

 metals upon them depended upon the mechanism 

 of their organs of motion. 



