422 Note 29: electrical Jishes 



There seems to be no electric displacement in the organ till the electric nerve 

 acts on it. The energy of the electric discharge which then takes place is not 

 supplied to the organ by the nerve; the nerve only sets up an action which is 

 carried on by the expenditure of energy previously supplied to the organ by 

 the materials which nourish it. 



During the discharge certain chemical changes take place in the organ. 

 These changes involve a loss of intrinsic energy, and the chemical products 

 found in the organ after repeated electric discharges are similar to the products 

 found in muscles after they have performed mechanical work. 



The organ, by repeated discharges, becomes incapable of responding to 

 stimulation, and can only recover its power by the gradual process by which 

 it is nourished. 



Faraday proposed to try whether sending an artificial current through the 

 Gymnotus would exhaust the organ, if sent in the direction of the natural 

 discharge, or would restore it more rapidly to vigour if sent in the opposite 

 direction. The only experiments on the effect of electricity on electric fishes 

 seem to be those of Dr Davy, who found that an artificial current did not excite 

 the electric organs of the Torpedo, though it had an effect on the muscles, but 

 less than on those of other fishes, and of Du Bois Reymond, who found that 

 Malapterurus was very slightly affected by induction currents passing through 

 the water of his tub, though they were strong enough to stun and even to kill 

 other fishes. When the induction currents were made very strong, the fish 

 swam about till he had placed his body transverse to the lines of discharge, but 

 did not appear to be much annoyed by them*. 



The most valuable experiments hitherto made are probably those of Dr Carl 

 Sachs, who went out to Venezuela in 1876 for the express purpose of studying 

 the Gymnotus in its native rivers, with all the resources of Du Bois Reymond's 

 methods. Dr Sachs lost his life in an Alpine accident in 1878, and as he did 

 not himself publish his researches, it is to be feared that their results are lost 

 to science. 



* A somewhat extensive account of the subject is given in a dissertation, 

 De' Pesci elettrici e pseudoelettrici, per Stefano St. Sihleanu (di Bucuresti, Romania), 

 Napoli, 1876. 



[Much attention has more recently been given to the subject by physiologists. 

 It appears from microscopic observations (cf. Bayliss' I'hysiology, 1917, p. 661) 

 that in Malapterurus the electric organ consists of a large number of parallel plates 

 arranged along the fish, all innervated from a single neurone on each side: it gives a 

 discharge at about 450 volts, lasting about -005 sec. The manipulations of polari- 

 zation and arrangement of cells by which discharges of high tension were obtained 

 by Plant6 from his secondary batteries about thirty years ago may perhaps be 

 regarded as in analogy with the organic activities that go on in mutual correlation in 

 the electric organ of the fish.] 



