ELECTRIC ORGANS. 95 



{Gymnotus). The structure and arrangement of the electric 

 organ is very different in these fishes, and will be subsequently 

 described in the special account of the several species. 



The phenomena attending the exercise of this extraordi- 

 nary faculty also closely resemble muscular action. The time 

 and strength of the discharge are entirely under the control 

 of the fish. The power is exhausted after some time, and it 

 needs repose and nourishment to restore it. If the electric 

 nerves are cut and divided from the brain the cerebral action 

 is interrupted, and no irritant to the body has any effect to 

 excite electric discharge ; but if their ends be irritated the 

 discharge takes place, just as a muscle is excited to contraction 

 under similar circumstances. And, singularly enough, the 

 application of strychnine causes simultaneously a tetanic state 

 of the muscles and a rapid succession of involuntary electric 

 discharges. The strength of the discharges depends entirely on 

 the size, health, and energy of the fish : an observation entirely 

 agreeing with that made on the efficacy of snake-poison. Like 

 this latter, the property of the electric force serves two ends 

 in the economy of the animals which are endowed with it ; 

 it is essential and necessary to them for overpowering, stun- 

 ning, or killing the creatures on which they feed, whilst 

 incidentally they use it as the means of defending themselves 

 from their enemies. 



