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: Propuction By Lone STANDING (FROoG’s SCIATIC) 
I 2 3 4 
Minimum Cubic ot ‘ 
Centimeters Neces-| Total Amount o 
Temeeeine Time Elapsed sary to Give v CO: Produced by 
Degrees C after Isolation Calculated for ro mg. of Nerve in 
8 zo mg. for 10 1o Minutes 
Minutes 
BAe ses ovsaste ane ema aes Immediately 2.7 Cc. 5.5X10~7 g. CO: 
1 hour 7.08 C.c. 2.1X10—7 g. CO: 
2 hours 10.8 cc. 1.4X1077 g. CO; 
5.5 hours 12.8 c.c. 1.1X107~7 g. COr 
7 hours 15.3 cc. 0.9X10—7 g. COz 
ro.5 hours 21.0 C.C. 0.6X10—7 g. CO: 
26 hours 9 cc. * 1.6X10—7 g. CO: 
27.4 hours 1.8 ce. 8.1X10~7 g. CO. 
rae Char rae oe point should be noted (after 26 hours, it is clear that 
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 
