462 ELECTRO-PHYSIOLOGY CHAP. 



In 1873 Boll discussed the possibility of "explaining the 

 discharge of the electrical organ solely by the negative variation 

 of the nerve current, concomitant with inuervation. 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." The free ending of the 

 nerve-fibres within the plates suggests the question, " What, under 

 these conditions, must finally become of the negative variation of 

 the nerve current, since it accompanies the excitatory process 

 within the nerve-fibre in every case to the extreme periphery : 

 and whether the more than million-fold multiplication of this 

 variation of the current as engendered in the electrical plates of 

 Torpedo (not Malapterurus) by the anatomical relations of the 

 nervous ramification may not be a sufficient explanation of the 

 discharge of the Torpedo ? " 



But, as du Bois-Eeymond pointed out (4 e, p. 276), this 

 hypothesis in the first place predicates the existence of a current 

 of rest, caused by the " natural " cross-sections (acting like arti- 

 ficial sections) of the nerves in the plates, and accordingly hetero- 

 dromous 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, as 

 the after-effect of which we have learned to characterise it. Du 

 Bois-Eeymond declared it to be " no bad hypothesis " which, in 

 order to explain this, assumes " the cross-section of the nerve to 

 be covered over by a parelectronomic layer, the electromotive 

 activity of which does not merely neutralise that of the former, 

 but even to some extent outweighs it, and which has no part in 

 the negative variation. At the moment of the discharge, the 

 E.M.F. of the nerve current disappears in the negative variation, 

 and the discharge is brought about through the release of E.M.F. 

 in the parelectronomic layer." 



In the meantime, however, such an assumption became 

 illegitimate, even from the standpoint of the molecular theory, 

 owing to the indubitably powerful E.M.F. of the Torpedo dis- 

 charge, apart from the fact that Boll's hypothesis does not apply 

 to Malapterurus. As we are about to show, there are even in 

 Torpedo, not to mention the other more powerful electrical 



