64 A CHEMICAL SIGN OF LIFE 



appear first on the barium hydroxide in the right cham- 

 ber, containing the normal nerve, but the amount of 

 precipitate later is seen to be much greater in this 

 chamber than in the other. The narcotized nerve is 

 giving off less carbon dioxide than the normal one. 



That the narcotized nerve produces less carbon dioxide 

 than the normal is shown more strikingly by quantita- 

 tive determinations. The average carbon dioxide output 

 for the nerve when treated for ten minutes with a 4 

 per cent ethyl urethane solution is less than 50 per cent 

 of that of the normal nerve. At 20 to 22 C. the narcot- 

 ized nerve gives 3 . 3X io~ 7 g. per centigram of tissue for 

 ten minutes' respiration, while the normal nerve, calcu- 

 lated for the same units, produces y.gXio" 7 g. One 

 exception may be noted here an experiment in which 

 the respiration of the narcotized nerve was4-9Xio~ 7 g. 

 -but this is partly explained by the fact that the 

 particular determination was effected at 25 C. Even 

 in this case the decrease of carbon dioxide was marked. 

 Qualitative experiments with a 2 per cent ethyl urethane 

 solution show that even this concentration produces 

 a diminution of carbon dioxide output. 



CHLORAL HYDRATE 



As indicated in Table VIII, a 2 per cent solution of 

 chloral hydrate in sea -water partially or wholly para- 

 lyzes the nerve in ten minutes and recovery is appar- 

 ently perfect. A 3 per cent concentration produces 

 complete paralysis and the return of excitability is 

 good. Treatment with a 4 per cent chloral hydrate 

 solution for the same period of time also produces 

 paralysis, but recovery is not always good. In each 



