68 Galvanism, from Galvani to Ohm. 



assistants touched the inner crural nerve of the frog with the 

 point of a scalpel ; whereupon at once the muscles of the limbs 

 were violently convulsed. 



" Another of those who used to help me in electrical experi- 

 ments thought he had noticed that at this instant a spark was 

 drawn from the conductor of the machine. I myself was at the 

 time occupied with a totally different matter; but when he 

 drew my attention to this, I greatly desired to try it for myself,. 

 and discover its hidden principle. So I, too, touched one or 

 other of the crural nerves with the point of the scalpel, at the 

 same time that one of those present drew a spark ; and the same 

 phenomenon was repeated exactly as before."* 



After this, Galvani conceived the idea of trying whether the 

 electricity of thunderstorms would induce muscular contractions 

 equally well with the electricity of the machine. Having 

 successfully experimented with lightning, he " wished," as he 

 writes,! " to try the effect of atmospheric electricity in calm 

 weather. My reason for this was an observation I had made,, 

 that frogs which had been suitably prepared for these experi- 

 ments and fastened, by brass hooks in the spinal marrow, to 

 the iron lattice round a certain hanging-garden at my house,, 

 exhibited convulsions not only during thunderstorms, but 

 sometimes even when the sky was quite serene. I suspected 

 these effects to be due to the changes which take place during 

 the day in the electric state of the atmosphere ; and so, with 

 some degree of confidence, I performed experiments to test the 

 point; and at different hours for many days I watched frogs 

 which I had disposed for the purpose ; but could not detect any 

 motion in their muscles. At length, weary of waiting in vain, 

 I pressed the brass hooks, which were driven into the spinal 

 marrow, against the iron lattice, in order to see whether 

 contractions could be excited by varying the incidental circum- 



* According to a story which has often been repeated, but which rests on no 

 sufficient evidence, the frog was one of a number which had been procured for th& 

 Signora Galvani, who, being in poor health, had been recommended to take a soup, 

 made of these animals as a restorative. f Loc. cit., p. 377. 



