94 ANIMAL ELECTRICITY. LECTURE IV. 



These extrapolar currents, on the side of the 

 anode in fig. 39, on the side of the kathode in 

 fig. 40, precisely imitate what are known to phy- 

 siologists as the Anelectrotonic and Katelectrotonic 

 currents of nerve. And it is highly probable that 

 the latter like the former are of electrolytic origin.^ 



But now as regards any possible future identifica- 

 tion of ionic products in nerve, we must be on our 

 guard. At the anode the current enters the fiuid, 

 then leaves it to enter the metal core ; the ions arising 

 at the interface between sheath and core are thus 

 kathodic or basic. Similarly the ions of the fiuid 

 sheath round the core under the battery kathode, are 

 not kathodic, but anodic or acidic. 



This point will come up again in the case of 

 medullated nerve-fibres, where core as well as sheath 

 is a moist non-metallic electrolyte. Meanwhile, to- 

 wards the avoidance of a confusion not seldom made 

 here between anode and kathode, way-in and way-out, 

 I give a formal experiment on a core-model, in which 



^ Similar experiments can be made on core-models without 

 any central wire, on e.g. a clay pipe soaked in salt solution and 

 filled with a solution of copper sulphate; du Bois-Reymond in- 

 deed showed long since that the surface of separation between 

 two different electrolytes traversed by a current, gives birth to 

 electrolysis (hydrogen and base in the electrolyte behind the 

 current, oxygen and acid at the electrolyte in front). Monatshev. 

 d.Beyl. Akad.,ij. ]\i\i,i^$6. Gesammelte Abhandlungen. Ueber 

 Polarisation an der Grenze ungleichartiger Elektrolyte, vol. i., 

 p. I. 



