044 SUPPLEMENT ON 



in the animal, however powerful, which may attempt to destroy 

 it ; and thus does the torpedo neutralize the efforts of its prey 

 and of its enemies. 



Like the gymnotus already spoken of, when the torpedo is 

 weakened, and near expiring, it ceases to communicate the 

 electric shock ; it often happens, indeed, that it gives no signs 

 of its invisible faculty, although in the enjoyment of all its 

 strength. It will sometimes allow itself to be touched with 

 impunity, and even then it appears that the non-employment 

 of its powers is a voluntary act, inasmuch as the irritation of 

 repeated touches will be sure at last to rouse the animal, and 

 its electric strokes are then observed to be much more violent 

 and painful than those produced in the more ordinary manner 

 by a simple contact without irritation. 



Reaumur confined a duck in a vase partly filled with 

 water, in which was a live torpedo, and in a few hours the 

 duck was killed by the repeated strokes of its enemy. 



Our countryman Walsh was the first to draw considerable 

 attention to this interesting subject, in the Philosophical 

 Transactions of 1773 and 1774. He made various experi- 

 ments on these fish at Rochelle, before it was even publicly 

 known that they visited our own coast ; and the celebrated 

 John Hunter investigated the anatomy of it about the same 

 period. Mr. Walsh was never able however to detect any 

 spark on the giving out of the fluid by the animal ; but the 

 celebrated Galvani, in 1797, by means of the microscope, 

 was more successful : so that if farther proof were wanting of 

 the identity of this fluid with the ordinary matter of elec- 

 tricity, it was then obtained. 



Having extracted largely from Humboldt on the electric 

 apparatus of the gymnotus, we shall here, for the sake of 

 parallel, give the substance of the celebrated John Hunter's 

 observations on the apparatus of the torpedo. 



Mr. Hunter informs us, that the electric organs are placed 



