ANIMAL ELECTRICITY. LECTURE IL 5 I 



(i) The negative variation of du Bois-Reymond, 

 due to disintegrative activity at L. 



(2) The positive after- variation of Hering, due 

 to reintegrative chemical movement at L. 



(3) The positive variation to which I have alluded 

 above, present only in certain states of nerve, attri- 

 butable to integrative chemical movement during 

 augmented activity at L.^ 



In the first case zincativity at L, deoxidation of 

 inogen, rejection of CO^, acidificatory effect. 



In the second, and possibly third cases anti- 

 zincativity at L, oxidation of inogen, deacidification. 



But I cannot interpret matters at this stage with 

 any degree of assurance, and shall therefore refrain 

 from the attempt. Let me rather emphasise the bare 

 fact that nerve is an extraordinarily sensitive reagent 

 to the presence of CO^. Here is a fresh nerve, giving 

 a by no means impressive response, but I breathe 

 through the little vessel that contains it, and there will 

 be a perfectly obvious improvement of the response 

 within one or two minutes, due to the carbonic acid 

 contained in expired air. The nerve is by far the 

 most sensitive reagent I know of to carbonic acid ; left 

 for a minute or two in a tube of one cubic centimetre 



^ The conceivable changes at T are left out of count ; there 

 is, however, evidence to support the view that the negative 



variation is often the sum of two homodromous activities 



zincativity at L and anti- zincativity at T. 



