EXCITATION AND CONDUCTION 



79 



of carbon dioxide of two equal weights of proximal and 

 distal portions of the same nerve were compared in the 

 biometer under identical conditions. The portion of 

 the nerve which gave off sufficient carbon dioxide to 

 produce the precipitate of barium carbonate in the 

 shortest time and the greatest abundance evidently 

 produced the most carbon dioxide. 



TABLE xm 



COMPARATIVE STUDIES ON RATE OF CARBON DIOXIDE PRODUCTION FROM Two 



PORTIONS OF VARIOUS NERVES 



While we have not by any means exhausted the 

 various kinds of nerve fibers available for the study 

 of this gradient, the results obtained in those nerves 

 already examined have been very uniform and the 

 nerves themselves have had varied functions and have 

 come from several different classes of animals, namely, 



