122 SIMILARITY or TI1E ELECTRIC ACTION. 
received some very violent shocks. Had we placed a very 
delicate electroscope in the contiguous strata of water, it 
might possibly have deen influenced at the moment when 
the gymnotus" seemed to direct its stroke elsewhere, Pre- 
pared frogs, placed immediately on the body of a torpedo, 
experience, according to (Talvani, a strong contraction at 
every discharge of the fish. 
The electrical organ of the gymnoti acts only under the 
immediate influence of the brain and the heart. On cutting 
a very vigorous fish through the middle of the body, the 
fore part alone gave shocks. These are equally strong in 
whatever part of the body the fish is touched; it is most 
disposed, however, to emit them when the pectoral fin, the 
electrical organ, the lips, the eyes, or the gills, are pinched. 
Sometimes the animal struggles violently with a person 
holding it by the tail, without communicating the least 
shock. Nor did I feel any when I made a slight incision 
near the pectoral fin of the fish, and galvanized the wound 
by the contact of two pieces of zinc and silver. The gym- 
notus bent itself convulsively, and raised its head out of the 
water, as if terrified by a sensation altogether new ; but I 
felt no vibration in the hands which held the two metals. 
The most violent muscular movements are not always ac- 
companied by electric discharges. 
The action of the fish on the human organs is transmitted 
and intercepted by the same bodies that transmit and inter- 
cept the electrical current of a conductor charged by a 
Leyden jar, or Voltaic battery. Some anomalies, which we 
thought we observed, are easily explained, when we recollect 
that even metals (as is proved from their ignition when 
exposed to the action of the battery) present a slight 
obstacle to tire passage of electricity ; and that a had con- 
ductor annihilates the effect, on our organs, of a feeble 
electric charge, whilst it transmits to us the effect of a 
very strong one. The repulsive force which zinc and silver 
exercise together being far superior to that of gold and 
silver, I have found that when a frog, prepared and armed 
with silver, is galvanized under water, the conducting arc 
of zinc produces contraction as soon as one of its extre- 
mities approaches the muscles within three lines distance ; 
while an arc ef gold does not excite the organs, when the 
