286 t'HILOSOPHICAL TRANSACTIONS. [aNNO 1793. 



Galvaiii de Viribus Electricitatis in Motu Muscular! Commentarius. Bononiae, 

 1791." This subject, under the name of galvanism, has given occasion to 

 several important discoveries, having been very much cultivated by many respec- 

 table philosophers, and by none more than by those of England. 



Dr. Galvani having cut and prepared a frog, so that the legs hung on one side 

 of the spine of the back, separate from the rest of the body, solely by the crural 

 nerves laid bare, he found that there were produced very quick motions in the 

 legs, with spasmodic contractions in all the muscles, whenever a spark was taken 

 from the prime-conductor of an electric machine, not on the body of the ani- 

 mal, but on every other body, and in every other direction ; this part of the 

 animal being placed at a considerable distance from the conductor, and in certain 

 circumstances. These were, that the animal, thus dissected, should be in con- 

 tact, or very nearly so, with some metal, or other good conducting substance of 

 a sufficient extent, and still better between 2 such conductors, the one of them 

 being directed towards the extremity of the said legs of the animal, or some one 

 of the muscles, the other towards the spine, or the nerves. It is also of great 

 advantage that one of these, called the nervous and the muscular conductors, 

 but preferably the latter, should have a free communication with the floor. It 

 is in this position especially that the legs of the animal receive violent shocks, 

 leap up and down rapidly on each spark from the conductor of the machine, 

 though it may be pretty far distant, and though the discharge be not made on 

 either the nervous or muscular conductor, but on some other body, likewise 

 distant from them, and having another communication for transmitting such a 

 charge, as on some person placed in an opposite corner of the room. 



Such was the first step, which led him to the fine and grand discovery of an 

 animal electricity, properly so called, appertaining not only to frogs, and other 

 cold-blooded animals, but also to all warm-blooded ones, as quadrupeds, birds, 

 &c. ; a discovery which makes the subject of the 3d part of the work, a subject 

 quite new and interesting. 



It was chance that presented to Mr. Galvani the phenomenon just described, 

 but at which he was more astonished than he needed to have been, had he given 

 due attention to the effects of electric atmospheres. Yet who could have believed 

 that an electric current, so weak as not to be rendered sensible by the most deli- 

 cate electrometers, was capable of affecting so powerfully the organs of an ani- 

 mal, and of exciting in its members, cut off many hours before, motions as strong 

 as those of the living animal, as the vigorous springing of the legs, the leap- 

 ing, &c. not to mention the most violent tonic convulsions. 



Mr. Volta endeavoured to determine the least electric force requisite to pro- 

 duce these effects, as well in a living isolated frog, as in one dissected and pre- 

 pared as before-mentioned ; which Mr. G. had omitted to do. Mr. Y. chose 



