68 A CHEMICAL SIGN OF LIFE 



this narcotic on the weight of the tissue shows that a 2 

 per cent concentration has but little effect for the first 

 ten minutes, though during the course of half an hour a 

 gain of 50 to 100 per cent takes place. A 3 per cent 

 concentration produces a gain of 25 per cent in ten min- 

 utes, while in a 4 per cent solution the nerve gains 50 

 per cent in the same space of time. These results, 

 together with those on the frog's nerve, indicate that, 

 whatever interpretation we put upon this change in. 

 weight, the result of such a process is temporarily, at 

 least, to increase slightly the amount of carbon dioxide 

 evolved, and that, so far as the effects of narcotics are 

 concerned in our work, its slightly increased production 

 from the narcotized nerve which gains in weight may be 

 looked upon as adventitious. The correctness of our 

 interpretation of the diminution of carbon dioxide output 

 as an effect primarily connected with narcosis is further 

 supported by a study of the effects of weak concentra- 

 tions of narcotics for different periods of time. 



Effects of weak concentrations of narcotics on carbon 

 dioxide production in the nerve fiber. It is well known 

 that the primary effect of narcotics is to increase irri- 

 tability, after which the typical depression follows. 

 This primary effect is well brought out by the use of 

 rather weak concentrations of narcotics. Although 

 we have made no quantitative determination of the 

 degree of irritability, it is evident that a nerve after ten 

 minutes' immersion in a 0.4 per cent chloral hydrate 

 solution has become abnormally irritable. After about 

 one hour's treatment, however, the nerve finally becomes 

 paralyzed. If the carbon dioxide output of a nerve 

 treated for ten minutes with a 0.4 per cent chloral 



