3 2 



A CHEMICAL SIGN OF LIFE 



It appears from these determinations that the heart 

 ganglion gives off about the same amount of carbon 

 dioxide per gram of its substance as the nerve fibers of 

 the same animal. Certainly there is no marked superi- 

 ority of carbon dioxide output by the ganglion. If 

 anything, its rate is a little lower. This is very in- 

 teresting because, as already stated, this ganglion is 



TABLE IV 



SUMMARY OF CARBON DIOXIDE PRODUCTION FROM VARIOUS NERVE TISSUES 



automatically active all the time and is constantly dis- 

 charging nerve impulses. Of course this result may 

 be due either to an equality of the metabolism in cells 

 and fibers, or the injury may have raised the rate more 

 in the nerve than in the ganglion, or in the ganglion the 

 amount of non-nervous tissue may be somewhat greater 

 than in the nerve trunk, so that the carbon dioxide pro- 



