HISTORY Of GALVANISM. 297 



HISTORIC SKETCH OF GALVANISM. 



THE firft publication * upon the fubject is the work of Firft publication 

 Galvani himfelf, which appeared in 1791 . It begins by giv- ° n ga vanifm b ^ 

 zng an account of the following accidental difcovery. A frog Legs of a frog, 

 had its hinder legs feparated from its body, except that tin. { 'plated from 

 1 if i- 'J j 1 1 1 1 -J the body, were 



crural nerves were left undivided, and was by chance laid upon con vulfed by ex- 



a table on which ftood an electrical machine. It was obferved tremeiy minute 



1 1 1 1 1 1 ■ o • 1 r n~ ' portions of elec- 



that when the animal was placed in contact with, or luflici- tricity. 

 ently near to, an extent! ve furface of a conductor of the elec- 

 tric fluid, if a fpark were taken from the machine in any di- 

 rection, the legs of the animal were fpafmodically contracted. 

 When the frog formed part of the electric circle, fo that the 

 fluid palled immediately through it, a quantity almoft imper- 

 ceptible was found to excite contractions of the mufcles. A 

 much fmaller quantity of the electric fluid produced the effect, 

 when the animal was prepared in the manner defcribed above, 

 than when the body was left intire, becaufe in the former cafe 

 the fluid was confined to the r-yow track of the nerves in its. 

 paflage along the circuit. A prepared frog appears therefore 

 to be a moll delicate electrometer, as it exhibited contractions 

 where no marks of electricity could be difcovered by the in- 

 struments either of Bennet or Cavallo. Galvani afterwards 

 found that contractions could be produced in the limbs of pre- 

 pared frogs by the electricity of the atmofphere, and it was in 

 confequence of fome arrangements which he made for this 

 purpofe, that he was led to his great difcovery of animal elec- 

 tricity. He found that he was able to produce contractions Proper galva- 



in the limbs of frogs without the aid of any foreign or artificial $*' or ." ntrac f 

 , . . / ft . °" 0ons without 



excitement, merely by the application of a conducting fub- excited eleftri- 

 ftance from the nerve to the mufele. Thefe contractions were*"*' 

 capable of being produced, of whatever fubfiances the circuit 

 of communication was compofed, provided only they were all 

 conductors of the electric fluid. The effects were found to be 

 much increafed by applying a metallic coating to the nerve. 

 He found this peculiar fpecies of electricity to exift in a great 

 variety of animals, and that the contractions may be excited 



* Sultzer in his Theorie des Plaifirs, quoted by Fabbroni, Philof. 

 Journal, quarto JV. 120, mentioned the tafte by contaft of two 

 metals.-- ~N, 



either 



