ANIMAL ELECTRICITY. LECTURE III. 59 



evidence of any chemical or physical change in 

 tetanised nerve, it seems to me not worth while 

 pausing to deal with the criticism that it is not CO^ 

 but ''something else" that has given the result. 



Moreover, the evidence is corroborated in a very 

 remarkable manner under a considerable variety of 

 conditions. 



Fig. 21 (675). — Verification. 



But before we are in a position to properly 

 appreciate this further evidence, it will be necessary to 

 enter into a digression, speculative from one point of 

 view, empirical, however, as regards our experimental 

 survey of the effects of carbonic acid acting from 

 without and presumably acting from within. 



The typical electrical effect of excitation of a 

 freshly excised nerve is the negative variation of du 



