200 COMPARATIVE ELECTRO-PHYSIOLOGY 



Bell, for example, thought it might be possible to explain 

 * the discharge of the electrical organ solely by the negative 

 variation of the nerve-current, concomitant with innervation. 

 In this arrangement the dorsal surface of the electrical plate 

 (of Torpedo) would, at the moment of innervation, become 

 positive, the ventral surface negative, as actually occurs.' 



As against this, it was pointed out by Du Bois-Reymond 

 that this hypothesis in the first place predicates the existence 

 of a current of rest, caused by the ' natural ' cross-sections 

 (acting like artificial sections) of the nerves in the plates, and 

 accordingly heterodromous to that of the discharge. Instead 

 of this permanent current which must correspond in E.M.F. 

 with the discharge, if the nerve-current is to disappear in the 

 negative variation there is only an inessential P.D. during 

 rest, and the resulting ' organ-current ' is always homodromous 

 with the discharge. 1 



Even had these objections not existed, however, Bell's 

 hypothesis would have failed to explain the electrical action 

 of Malepterurus. Du Bois-Reymond himself tried to explain 

 the action of the electrical organ, ' not by the negative 

 variation of the nerve current, but by a process in the 

 electrical plates transformed from muscles, comparable with 

 the negative variation of the muscle-cur rent y as set forth from 

 the standpoint of the pre-existence theory.' Here, however, 

 it is perhaps sufficient to point out that the pre-existence 

 theory, on which the hypothesis was based, is now held to be 

 invalidated. 



There remains only the Chemical, or Alteration Theory, 

 which associates all electrical changes with the corresponding 

 chemical processes of assimilation and dissimilation. But 

 it has not been made clear in what way these can bring about 

 the characteristic discharge of the electrical organ. 



There is another point, not altogether unrelated to this 

 subject, which may be dealt with on the present occasion, 

 I allude to the so called ' blaze current ' of Dr. Waller. By 

 this is meant an after-current in the same direction as the 



1 Biedermann, EUctro- Physiology (English translation), vol. II. p. 462. 



