122 SIMILAEITT OF THE ELECTRIC ACTIOW. 



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 Galvani, 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 the passage of electricity ; and that a bad con- 

 ductor annihilates the eifect, 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 :? gold does not excite the organs, when the 



