548 PHILOSOPHICAL TRANSACTIONS. [aNNO 17y5. 



XI. Observations on the hiflnence which incites the Muscles of Animals to Con- 

 tract in Galvanis Experiments. By IVilliam Charles IVells, M. D., F. R. S. 

 p. 246. 



Mr. Volta, in his letters to Mr. Cavallo, which have been read to this Society, 

 not only has shown tliat the conclusions which Mr. Galvani drew from his expe- 

 riments on the application of metals to the nerves and muscles of animals, are 

 in various respects erroneous, but has also made known several important facts, 

 in addition to those which had been discovered by that author. As he appears 

 however, from these letters, to have fallen into some mistakes himself, and has 

 certainly not exhausted the subject which he has treated in them, I shall venture 

 to communicate a few observations I have made respecting it, which may con- 

 tribute both to correct his errors, and to increase our knowledge of the cause of 

 those motions, which have been attributed by Mr. Galvani and others to an 

 animal electricity. These observations will be so arranged, as to furnish an- 

 swers, more or less satisfactory, to the following questions: Does the incitement 

 of the influence which, in Galvani's experiments, occasions the muscles of ani- 

 mals to contract, either wholly, or in part, depend on any peculiar property of 

 living bodies ? What are the conditions necessary for the excitement of this 

 influence ? Is it electrical ? 



When a muscle contracts, on a connection being formed, by means of one or 

 more metals, between its external surface and the nerve which penetrates it, 

 Mr. Galvani contends that, previously to this effect, the inner and outer parts 

 of the muscle contain different quantities of the electric fluid ; that the nerve is 

 consequently in the same state, with respect to that fluid, as the internal sub- 

 stance of the muscle ; and that on the application of one or more metals be- 

 tween its outer surface and the nerve, an electrical discharge takes place, which 

 is the cause of the contraction of the muscle. In short, he supposes a complete 

 similarity to exist between a muscle, in a proper condition to exhibit this appear- 

 ance, and a charged Leyden phial ; the nerve of the former answering, as far as 

 his experiments are concerned, the same purpose as the wire, which is connected 

 with the internal surface of the latter. 



Now, if this were just, such a muscle ought to contract, whenever a com- 

 munication is formed between its internal surface and the nerve, by means of 

 any conductor of electricity; and accordingly Mr. Volta, who to a certain extent 

 adopts Mr. Galvani's theory, asserts this to be the case, as often as the experi- 

 ment is made on an animal which has been newly killed. But I am inclined to 

 believe that he rests this assertion on some general principle, which he thinks 

 established, and not on particular facts; for he gives none in proof of it, am! I have 

 often held a nerve of an animal newly killed in one hand, while with the other I 

 touched the muscle to which the nerve belonged, but never saw contractions by 



