ANIMAL ELECTRICITY. LECTURE V. [ 03 



left, from e' to e, or from the polarised region p' p. 

 This is a Katelectrotonic current, so called because 

 it is <_)n the Kathodic side of p' p. 



\ OLi have now seen — and I will repeat the two 

 trials in rapid succession — that in each case the 

 extrapolar or electrotonic current, whether A. or K., 

 passes in the nerve in the same direction as the polar- 

 ising current by which it is aroused. 



Your first thought, perhaps — as was mine when 

 I first repeated the experiment — is one of disappoint- 

 ment. Is that all ? Yes, that is the gist of the whole 

 story, which you will find set forth at great length in 

 a long series of memoirs extending over the last 

 fifty years — at such length indeed that without some 

 definite assurance of the simplicity of the facts, even 

 a careful reader might pass it by, either missing the 

 point altogether, or as was the case in every English 

 text-book a few years ago, confusing it quite unneces- 

 sarily with the current of injury. Indeed, this con- 

 fusion was made by du Bois himself at the very out- 

 set of his work, but the confusion that remained in 

 his mind for at most a few months, was scrupulously 

 preserved in the text-books for upwards of fifty 

 years. 



Your next thought is one of suspicion. Why this 

 is mere current-diffusion along a conductor, just like 

 what would happen along a hank of wet wool. That 

 is a perfectly reasonable thought ; ordinary current- 

 diffusion might well take place ; it is indeed a common 



