132 ANIMAL ELECTRICITY. LECTURE VI. 



which the effects of carbonic acid and of tetanisa- 

 tion upon anodic currents have been recorded. Car- 

 bonic acid produces either an augmentation or a 

 diminution of these currents. Tetanisation also pro- 

 duces either an augmentation or a diminution. 



On reviewing a considerable number of records, 

 we should find that In the case of carbonic acid, a 

 diminution of A. Is the rule, an augmentation of A. the 

 somewhat rare exception ; whereas in the case of 

 tetanisation, although a diminution of A. has usually 

 been produced, an augmentation of A. has occurred 

 frequently enough not to deserve the qualification 

 of exceptional. 



I think we may admit these results to rank as 

 confirmatory evidence of the conclusion that tetanisa- 

 tion gives rise to carbonic acid ; an augmented A. Is 

 a slighter effect than a diminished A., and it is not 

 surprising perhaps to find the slighter effect more 

 frequent by tetanisation than by carbonic acid freely 

 supplied. 



But whether this be admitted as evidence or not 

 — in Chapter III. the point is Indeed already based 

 on evidence which Is, In my opinion, sufficient and 

 conclusive — these experiments clearly show that 

 the electro-mobility of nerve Is modified by carbonic 

 acid and by prolonged tetanisation. 



The modifications of the Kathodic current effected 

 by carbonic acid are more regular than are those of 

 the anodic current. The former appears to be less 



