Galvanism, from Galvani to Ohm. 69 



stances of the experiment. I observed contractions tolerably 

 often, but they did not seem to bear any relation to the changes 

 in the electrical state of the atmosphere. 



" However, at this time, when as yet I had not tried the 

 experiment except in the open air, I came very near to adopt- 

 ing a theory that the contractions are due to atmospheric 

 electricity, which, having slowly entered the animal and accu- 

 mulated in it, is suddenly discharged when the hook comes in 

 contact with the iron lattice. For it is easy in experimenting 

 to deceive ourselves, and to imagine we see the things we wish 

 to see. 



" But I took the animal into a closed room, and placed it on 

 an iron- plate ; and when I pressed the hook which was fixed 

 in the spinal marrow against the plate, behold ! the same 

 spasmodic contractions as before. I tried other metals at 

 different hours on various days, in several places, and always 

 with the same result, except that the contractions were more 

 violent with some metals than with others. After this I tried 

 various bodies which are not conductors of electricity, such as 

 glass, gums, resins, stones, and dry wood ; but nothing happened. 

 This was somewhat surprising, and led me to suspect that 

 electricity is inherent in the animal itself. This suspicion was 

 strengthened by the observation that a kind of circuit of subtle 

 nervous fluid (resembling the electric circuit which is manifested 

 in the Leyclen jar experiment) is completed from the nerves to 

 the muscles when the contractions are produced. 



" For, while I with one hand held the prepared frog by the 

 hook fixed in its spinal marrow, so that it stood with its feet 

 on a silver box, and with the other hand touched the lid of 

 the box, or its sides, with any metallic body, I was surprised 

 to see the frog become strongly convulsed every time that I 

 applied this artifice."* 



Galvani thus ascertained that the limbs of the frog are con- 

 vulsed whenever a connexion is made between the nerves and 

 muscles by a metallic arc, generally formed of more than one 



*This observation was made in 1786. 



