28 



A CHEMICAL SIGN OF LIFE 



ments were tried to discover how the carbon dioxide 

 production behaved at successive time intervals after 

 the nerve was removed from the body. A number of 

 sciatic nerves were isolated from several frogs of the same 

 size and sex and were left for varying periods of time in 

 Ringer's salt solution, in which they live well. The 

 rate of the gas production was then determined in the 

 nerves when removed from the Ringer solution after 

 one hour, two hours, and at other intervals up to 

 twenty-five hours. The interesting results given in 

 Table II make it clear that the fresh nerve produces the 



TABLE II 

 SHOWING DECREASED CO* PRODUCTION BY LONG STANDING (FROG'S SCIATIC) 



* The gradual increase at this point should be noted (after 26 hours, it is clear that 

 bacterial decomposition sets in). 



most carbon dioxide and that the amount produced per 

 unit of time interval decreases rapidly up to about 

 twenty-three hours and from then on suffers a very 

 rapid increase. These facts show that the carbon dioxide 

 output diminishes as the vitality of the nerve diminishes, 

 and that as bacterial decomposition sets in there is a 

 sudden and rapid increase. There is, therefore, a 



