248 Humboldt on Electrical Eels^ and the method 
touching the body of the fish with a hand armed with metal^ 
than with the naked hand. They are stronger also, when, in- 
stead of touching the fish with one hand, naked, or armed with 
metal, we press it at once with both hands, either naked or 
armed. These differences, I repeat, become sensible only when 
you have gymnoti enough at your disposal, to be able to choose 
the weakest ; and the extreme equality of the electric dischar- 
ges admits of distinguishing between the sensations felt alter- 
nately 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 believed to be good conductors, pre- 
vent the action of the gymnoti from being transmitted to man. 
I was surprised at not feeling the least shock on pressing wet sticks 
of sealing-wax against the organs of the fish ; while the same ani- 
mal gave me the most violent strokes, when excited by means 
of a metallic rod. Mr Bonpland received shocks when carry- 
ing a gymnotus on two cords of the fibres of the palm-tree, 
which appeared to us extremely dry. A strong discharge makes 
its way through very imperfect conductors. Perhaps also the 
obstacle which the conducting arc presents, renders the dis- 
charge 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. 
When two j>ersons, insulated or not insulated, hold each 
other's hands, and one of these persons only touches the fish 
with the hand, either naked or armed with metal, the shock is 
most commonly felt by both at once. It happens, however, al- 
so, that, in the most painful shocks, the person who comes into 
immediate contact with the fish alone feels the shock. When 
the gymnotus is exhausted, or in a very weak state of excitabi- 
lity,^ nnd will no longer emit strokes on being irritated with one 
hand ; the shocks are felt, in a very vivid manner, on forming 
the chain, and employing both hands. Even then, however, 
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