EXCITATION AND CONDUCTION 69 



hydrate solution is compared in the usual manner with 

 that of a normal nerve, it is easily demonstrated that the 

 carbon dioxide production of the nerve so treated is 

 greatly increased. The quantitative determinations 

 tabulated above illustrate this perhaps more con- 

 vincingly (see Table IX, horizontal column 3). 



That this change in the carbon dioxide production of 

 the nerve when treated with the lower concentration is 

 closely connected with the physiological state is further 

 demonstrated in the following experiments. Many claw 

 nerves were isolated from several spider crabs, each 

 pair chosen being approximately of the same weight, and 

 of each pair one was placed in a o. 4 per cent solution of 

 chloral hydrate and the other in sea- water. A compari- 

 son was made of the rate of carbon dioxide production 

 of the first pair in the biometer in the usual manner at 

 the end of ten minutes; at the end of half an hour a 

 second pair was compared similarly, and so on. The 

 result is giyen in Table IX. This table is of more than 

 passing interest, for it illustrates an easy source of error 

 in the study of narcosis. Evidently it is of prime 

 importance to determine the carbon dioxide output 

 during a comparatively small time interval, rather 

 than during one of long duration. If we were to deter- 

 mine the output of the gas for sixty minutes' respiration 

 of the nerve treated with a o . 4 per cent chloral hydrate 

 solution, we might be led to the conclusion that the 

 narcotic has no effect whatever on the metabolic rate. 

 For although we have shown, by taking corresponding 

 nerves at the beginning and at the end of the narcosis, 

 that the primary effect is to increase carbon dioxide 

 production and that later it is greatly diminished, the 



