266 COMPARATIVE ELECTRO- PHYSIOLOGY 



I give below (fig. 167) photographic records of the 

 responsive after-effects actually obtained on carrying out 

 this experiment on the lead strip prepared as described. It 

 is here seen that whatever had been the direction of the 

 shock, homodromous t or heterodromous j, the responsive 

 current was always one-directioned : that is to say, from the 

 more negatively-excitable lower to the positively-excitable 

 upper surface. If the test of the 'blaze-current' is to be 

 accepted, then we shall be compelled to refer this metallic 

 strip to the category of organic matter in a living condition ! 



FIG. 167. Photographic Records of After-effect of Homodromous f and 

 Heterodroraous 4- Induction-shocks in Prepared Strip of Lead 



Note uni-directioned response, whatever be direction of induction-shock. 



Since it is admitted that the electrical response of living 

 tissues is due to molecular excitation, and since we obtain 

 similar electrical effects, as just seen, from the inorganic, it 

 is clear that excitability is the property, not of the organic 

 alone, but of all matter. It is also clearly seen that the one 

 directioned response of an anisotropic structure so charac- 

 teristic, among other things, of the electrical organ of 

 certain fishes depends on its differential molecular excit- 

 ability. The phenomenon is thus reduced to what are almost 

 its last terms namely, the molecular. It is therefore un- 

 necessary to call in the aid of such indeterminate factors as 

 vitalism, or assimilation and dissimilation. 





