66 ANIMAL ELECTRICITY. LECTURE III. 



deflection is only diminished by CO^ from without, and 

 here is the same nerve o^ivinor a similar diminution as 

 the consequence of tetanisation. (Compare figs. 

 30 & 31). Indeed, if this last plate had been first 

 brought to your notice, and without reference to the 

 group of considerations just traversed, you would 

 very likely have taken the diminution to be a 

 common fatigue effect. 



Provisionally admitting as an established datum 

 that carbon dioxide is one of the products of nerve 

 activity, our next question is : what becomes of it ? 



I can venture upon no positive answer to this 

 question. For the moment it seems to me that 

 there are two possible answers open to our further 

 investigation. 



It is possible that the CO^ may be dissipated by 

 diffusion from the nerve, but it is also possible that it 

 may be reintegrated within the nerve itself. 



I have not yet found means of deciding between 

 these two alternatives, which I have nevertheless not 

 felt it unprofitable to state and briefly consider. 



Obviously the first alternative presents itself first ; 

 what more natural fate can we imaoine for CO,, if 

 produced within a nerve, than its dissipation by dif- 

 fusion into the surrounding atmosphere or into the 

 lymph and l)lo(3d, as in the case of the CO^ evolved 

 within a muscle ? I have nothing to say against this 

 obvious probability, and can only point out as a 



