A. R. MOORE 621 



tory rate, since the surface was reduced by contraction. Immedi- 

 ately upon relaxation the rate increased from 30 to 100 per cent of 

 that of the resting muscle (see figures under "sartorius muscle" 

 Table III) . The method used is therefore adequate to show changes 

 in the metabolic activity of muscle resulting from contraction. Since 

 the same method fails to reveal changes in carbon dioxide production 

 in the nerve as the result of stimulation, it is necessary to conclude 

 that the functional activity of nerve fiber does not depend upon 

 processes resulting in the production of carbon dioxide. 



SUMMARY. 



1. With the indicator method of Haas, the rates of carbon dioxide 

 production have been measured in the case of the sciatic nerve, 

 various parts of the brain, and the sartorius muscle of the frog. The 

 rate of respiration of the sciatic nerve is from 10 to 30 per cent of 

 that of the other tissues, vd,rying somewhat with the individual. 



2. Stimulation of the sciatic nerve with induction shocks sufficient 

 to induce tetanus of the muscle does not increase the output of carbon 

 dioxide from the sciatic nerve, even if continued as long as 30 minutes. 

 Sartorius muscle used as a control showed a marked increase in car- 

 bon dioxide " production upon relaxation after contraction resulting 

 from such stimulation. 



3. These facts indicate that the nerve impulse does not depend 

 upon processes leading to the production of carbon dioxide. 



