30 A CHEMICAL SIGN OF LIFE 
criticism, since there are many other evidences that the 
metabolism of the nervous system is more intense than 
that of any other tissue of the body. There is, as far 
as we know, no physiological reason for assuming a 
priori that the nerve has a lower metabolism than other 
tissues, but, on the contrary, the direct and indirect 
TABLE III 
CO: per 
Animals Kilogram a i Determined by * 
per Hour © r 
Crustacea (whole animal).........)............/...005 Bee Jolyet and Regnaut 
Crayfish (Astacus).............4 37.7 CC. 12.5 si a re 
Crab (Cancer pagurus)........... 89.9 c.c. 16 * fe * 
Lobster (Homarus vulgaris)........ 54.4 C.C. 15 a a a 
Nerve of spider crab (Labinia cana- 
PECULGLON sions, shiek geek 1a, oa to wre Sie 212 C.c. or 15-16 Tashiro 
0.402 g. 
Frog: 
(Rana esculenta) (whole animal)... 0.082 g. 17 Schultz 
(Rana temporaria) (whole animal) 0.355 g- 19-20 Pott 
(Rana pipiens) (sciatic nerve)... . 0:33: E: 15 Tashiro 
(Rana _ temporariat) (isolated 
muscle).......... een Batnccees 0.18 g. 21 Fletcher 
OB tiie die tacts Sangrguald Said dues d: Make Stn BOG) Be 12 ina pie deal Regnaut and Reiset 
Man at rest.................0055 Oi GAT: VB: bec caine deed rod aes Pettenkoffer and Voit 
ers OROT Ber isu eels ak cs Bo 
Te ee snk En dbs ater 4 arene Orn Si7e ome | |ehened. Sects ent See Speck 
* All the figures are quoted from Schiafer’s Text Book of Physiology, I, 702, 707, and 
708, except that of the isolated muscle, which I calculated from Fletcher (op. cit.). 
Fletcher fails to state the weight of a leg, but gives the value 0.2 c.c. for one-half hour. 
eres that if we take each leg as 6 g. in average, the value will not be far from the 
truth. 
t Fletcher fails to state the species of the frog, but it is inferred from Hill’s paper. 
evidence shows that it has a more intense metabolism. 
It is no doubt true, however, that an isolated nerve, such 
as we have used, respires somewhat faster than the 
same nerve intact in the body, because the effect of 
cutting the nerve is to act as a stimulant. But, even 
allowing for this effect, the metabolism still remains 
markedly higher than that of most other tissues. We 
may add here, however, that the hourly rate of output 
of carbon dioxide from the resting nerve of a frog is 
