364 



disposal, to be able to choose the weakest ; and 

 the extreme equality of the electric discharges 

 admits of distinguishing between the sensations 

 felt alternately by the hand naked or armed 

 with a metal, by one or both hands naked, and 

 by one or both hands armed with metal. It is 

 also in the case only of small shocks, weak and 

 uniform, that the shocks are more sensible on 

 touching the gymnotus with one hand (without 

 forming a chain) with zinc, than with copper or 

 iron. 



Resinous substances, glass, very dry wood, 

 horn, and even bones, which are generally be- 

 lieved to be good conductors, prevent the action 

 of the gymnoti from being transmitted to man. 

 I was surprised at not feeling the least shock on 

 pressing wet sticks of sealingwax against the 

 organs of the fish ; while the same animal gave 

 me the most violent strokes, when excited by 

 means of a metallic rod. Mr. Bonpland received 

 shocks, when carrying a gymnotus on two cords 

 of the fibres of the palm-tree, which appeared to 

 us extremely dry. A strong discharge makes 

 it's way through very imperfect conductors. 

 Perhaps also the obstacle, which the conducting 

 arc presents, renders the discharge more painful. 

 I touched the gymnotus with a wet pot of brown 

 clay, without effect; yet I received violent 

 shocks, when I carried the gymnotus in the same 

 pot, because the contact was greater. 



