OF ELECTRICITY IN ANIMALS. 



53 



between the wire and the file. The production of the spark 

 is probably effected when the circuit is broken at the precise 

 moment of the passage of the torpedo's current. 



The use of the file is clearly seen, since the friction 

 causing the circuit to be closed and broken at very short 

 intervals, some of them will necessarily coincide with the dis- 

 charge, as it has but a short duration. Let us observe, in 

 passing, that the production of two sparks during the discharge 

 of the torpedo, shows very clearly that it has an appreciable 

 duration, measured at least by the time which has elapsed 

 during the passage of the wire across two successive teeth of 

 the file. 



A. Moreau succeeded in collecting this electricity on a con- 

 denser which allowed him to measure the variation of the 

 intensity of the discharge by the indications of a gold leaf 

 electroscope. We have seen how our acquaintance with the 

 electrical phenomena of the torpedo has passed through many 

 successive stages, and how the progress of physical inquiry 

 has, on this subject, invaded the domains of physiology. 



Nevertheless, the discharge of the torpedo, as the above- 

 mentioned experiments have shown, seems like a kind of 

 hybrid phenomenon, in which the effects of tension machines 

 appear to be confounded with those of a galvanic battery. 

 We must, by new researches, endeavour to assign the place 

 in the series of well-known manifestations of electricity, which 

 the discharge of electric fishes ought to occupy. 



Considered in a physiological point of view, this pheno- 

 menon possesses another kind of interest. The most recent 

 discoveries tend to assimilate the function of this electrical 

 apparatus with that of a muscle. If, for example, we com- 

 pare the action of the nervous system on the electrical organs 

 of certain fishes, with that which the nerve exercises over the 

 muscle, we are struck with the following analogies : — 



The electrical discharges, like muscular shocks, can be 

 produced under the influence of the will of the animal ; they 

 may also be considered as reflex phenomena; excitation of 

 the electric nerve produces the discharge, as that of the motor 

 nerve produces, the shock of a muscle ; an entire paralysis of 

 the electrical apparatus takes place when the nerve is cut, as 



