128 ACTION OF THE BRAIN AND NEBVES. 



bringing it near the organs or insulating the fish, covering 

 it with a metallic plate, and causing the plate to communi- 

 cate by a conducting wire with the condenser of Volta, 

 We were at great pains to vary the experiments by which 

 we sought to render the electrical tension of the torpedo 

 sensible ; but they were constantly without effect, and per- 

 fectly confirmed what M. Bonpland and myself had observed 

 respecting the gymnoti, during our abode in South America. 



Electrical fishes, when very vigorous, act with equal 

 energy under water and in the air. This observation led us 

 to examine the conducting property of water ; and we found 

 that, when several persons form the chain between the 

 superior and inferior surface of the organs of the torpedo, 

 the shock is felt only when these persons join hands. The 

 action is not intercepted if two persons, who support the 

 torpedo with their right hands, instead of taking one 

 another by the left hand, plunge each a metallic point into 

 a drop of water placed on an insulating substance. On 

 substituting flame for the drop of water, the communication 

 is interrupted, and is only re-established, as in the gym- 

 notus, when the two points immediately touch each other in 

 the interior of the flame. 



We are, doubtless, very far from having discovered all 

 the secrets of the electrical action of fishes which is modified 

 by the influence of the brain and the nerves ; but the 

 experiments we have just described are sufficient to prove 

 that these fishes act by a concealed electricity, and by elec- 

 tromotive organs of a peculiar construction, which are 

 recharged with extreme rapidity. Yolta admits that the 

 discharges of the opposite electricities in the torpedos and 

 the gymnoti are made by their own skin, and that when we 

 touch them with one hand only, or by moans of a metallic 

 point, we feel the effect of a lateral shock, the electrical 

 current not being directed solely the shortest way. When 

 a Leyden jar is placed on a wet woollen cloth (which is a 

 bad conductor), and the jar is discharged in such a manner 

 that the cloth makes part of the chain, prepared frogs, 

 placed at different distances, indicate by their contractions 

 that the current spreads itself over the whole cloth in a 

 thousand different ways. According to this analogy, the 

 most violent shock givei* by the gymnotus at a distance 



