340 ELECTRO-PHYSIOLOGY. 



It is now proved that the organ of tlie torpedo, and probably that of other 

 electric fishes, is not an electro-naotor instantaneously called into action, but au 

 electro-motor which is constantly active. I take, therefore, from a torpedo, dead 

 for several hours, a piece of the organ, which I reduce to a ciibic form and render 

 as small as conveniently may be, without forgetting the position of the bases of 

 the prisms with reference to the back and belly, of the fish. This piece, place's 

 on the gutta-percha support, is brought into contact with the cushions of the 

 most sensitive galvanometer. If I touch the bases corresponding to the belly 

 and the back, 1 obtain a deviation equivalent to the entire quadrant, and which 

 indicates a current directed in the galvanometer from the back to the belly, as 

 in the discharge of the fish. The needle settles at 70 or SO degrees, and the 

 deviation endures for several hours, decreasing very slowly. By touching the 

 longitudinal wall of the prisms, and now one, now the other of the bases, a de- 

 viation is obtained which is slighter, but still in the direction of the discharge. 

 There is no deviation in the single case in which I touch at the same time any 

 of the two lateral faces. 



This constant electro-motor power of the organ of the torpedo persists long 

 after the excitability of the nerve is completely extinct. I have left a torpedo for 

 twenty-four hours in a tin vessel surrounded with a Irigorific mixture, and after 

 that lapse of time a portion of its organ and a portion of that of another torpedo 

 left in the air have presented no diiference. I have found the same result in a 

 torpedo which had been for five days in ice. Even in a torpedo poisoned with 

 curare the proper electro-motor power of the organ persists as in a torpedo un- 

 touched. I have also verified, by resorting to the so-called differential method, 

 that this electro-motor power of the organ is independent of the size of the piece 

 on which we operate — that is, of the number of prisms of Avhich it is composed, 

 and that, on the other hanfl, it is proportional to the length of the prisms. Nor 

 does the power in question vary through the nature of the gas in which the 

 portion of the organ is kept. This was verified by keeping it in air more or 

 less rarified, in oxygen, carbonic acid and hydrogen. On the contrary, if the 

 organ is kept immersed in any liquid for ten or twelve hours, the power is much 

 weakened. Saline solutions act feebly, but acid or alkaline solutions even very 

 much diluted, and in Vv^hich the organ is immersed but a few hours, entirely de- 

 stroy the electro-motor power. On comparing a piece of the organ taken from a 

 living torpedo with the gastrocnemian of a frog of the same length, the electro- 

 motor power of the organ is found to prevail over the muscle; but two of the 

 latter united overcome the organ. 



The result which I consider most interesting as regards the theory of the 

 electric function of the fish is the influence which the excitation of the nervous 

 system of the organ exercises in permanently increasing its electro-motor power. 

 The experiment is decisive and easily performed, I take from the same torpedo 

 two equal pieces of organ, with the precaution that each of them shall have 

 united with it a portion of the nervous trunk. I oppose these pieces to one 

 another by bringing into contact either the two faces of the back or those of 

 the belly, and assure myself that there is no differential current. Then, the 

 double battery being decomposed, I irritate with the electric current or with an 

 instrument the nerve of one of the pieces, which yields several successive dis- 

 charges, as is indicated by the galvanoscopic frog. I now recompose the battery, 

 and find a strong difiereutial current in the piece of organ which has given the 

 discharges and which has been in action. The differential current continues 

 diminishing, till after a certain time it becomes null. The phenomenon may be 

 tl^en reproduced in the same piece several times in succession, a diminution, 

 however, in the differential current being always observed, which is, of course, 

 owing to the cessation of the discharges of the organ. The conclusion is, that 

 the excitation of the nervous system increases the electro-motor power of the 

 organ J in the living animal it is exalted to the point of yielding strong dis- 



