198 ELECTRIC FISHES. LiECT. X. 



If we carefully and rapidly remove, from a very lively 

 torpedo, one of its electric organs, by separating it from the 

 cartilages and integuments which cover and encompass it, 

 but leaving uninjured the great nervous trunks which are 

 distributed to it, we readily perceive that all its different 

 parts, the integuments, cartilages, &c., have no influence 

 upon the discharge. 



Fig. 14. 



Electric organ of the Torpedo. 



Indeed, if we cover the separated organ with prepared 

 frogs, and then apply the conductors of the galvanometer 

 upon the two surfaces, and irritate the nerves, we observe 

 that the frogs contract, and the needle deviates, thus indi- 

 cating a current which circulates, as usual, in the galvano- 

 meter from the dorsal to the abdominal surface of the organ. 



By proceeding in this way, we observe another very 

 curious phenomenon, namely, that the discharge is obtained 

 sometimes in one portion of the electric organ, and some- 

 times in another. For this purpose it is sufficient to irritate 

 separately each of the nerves of the same organ ; and we 

 find that all the frogs arranged thereon do not contract, but 

 only some of them, viz. those which occupy the point 

 where the irritated nerve ramifies. We can obtain these 

 discharges for a short period only. Nevertheless, if we 

 irritate the nerves by passing an electric current through 

 them, the separated organ retains the faculty of giving a 

 discharge for a greater length of time. The current which 

 traverses the nerve of the electric organ of the torpedo, 

 obeys the same laws as those which regulate its action upon 



