66 A CHEMICAL SIGN OF LIFE 



during the experiment. With this contingency in view, 

 certain possible objections are here considered. 



The method employed for carbon dioxide determina- 

 tion is so delicate that a change in the reaction of the 

 sea-water, brought about possibly by the addition of 

 the narcotic, might be sufficient materially to alter the 

 values obtained. This, indeed, is the reason why we 

 have never been able to investigate the effects of potas- 

 sium cyanide, since the slight trace of alkalinity thus 

 introduced seriously modifies the results. This objec- 

 tion, however, we have been able to refute by direct 

 experimental means. 



If tjie solution of the narcotic differs in reaction 

 from sea-water sufficiently to influence the determina- 

 tion, a similar effect should be observed in the case of a 

 nerve which has been killed. Two freshly isolated 

 nerves of approximately the same weight were killed 

 simultaneously by means of steam and left for twenty 

 minutes, one in a 2 per cent solution of chloral hydrate 

 and the other in sea- water. A measurement of the 

 adventitious carbon dioxide production from the two 

 nerves so treated gave no evidence of any difference. 

 The diminution of carbon dioxide from nerves subjected 

 to the action of narcotics cannot, therefore, be referred 

 to any change in the reaction of the sea-water produced 

 by the narcotic. 



% Another possibility is involved in the fact that certain 

 narcotics produce phenomena other than those of nar- 

 cosis. This is probably the reason why the metabolism 

 change is never exactly the same in the case of two 

 nerves in which typical narcosis has been induced by 

 different means. One of these effects must be a change 



