298 



ELECTRO-PHYSIOLOGY 



CHAP. 



of Griinhagen and Hermann relate essentially to the consequences 

 of physical anelectrotouus, the development of which, at different 

 points of the nerve, is governed by quite a different law. Wundt's 

 communications may possibly find an explanation from the same 

 point of view. Under any circumstances, however, further 

 investigation is required, in order to make a decisive judgment 

 possible. Above all, it is legitimate to ask whether the katelectro- 

 tonus of medullated fibres (which appears to fail altogether in 

 non-medullated nerve) may not also mask a " physiological com- 

 ponent," as is certainly implied by Bernstein's experiments. 



4. In PolarisaUe Schemata 



We must now enter more particularly into the nature of 

 "physical electrotonus" as exhibited in medullated nerve, during 



FIG. 213. 



ether narcosis. Du Bois-Reymond attempted, from the stand- 

 point of his molecular theory, to explain the whole of the galvanic 

 manifestations of electrotonus by a directive influence of the 

 polarising current upon the electromotive molecules of the nerve, 

 which is not confined to the tract directly traversed, but extends 

 more or less widely beyond it. If the nerve is conceived as con- 

 structed of peripolar molecules, each consisting of two dipolar 

 halves (Fig. 213), the exciting (polarising) current, which is passed 

 through one portion of the nerve, induces a homodromous incre- 

 mental current in the entire nerve, the electrically heterogeneous 

 particles being arranged after the pattern of Volta's pile, the 

 positive zones directed to the side towards which the current 

 is flowing in the nerve, the negative zones, on the contrary, 



