ANESTHETICS AND COo OUTPUT 331 



the initial increase is much more marked and to a degree much 

 below normal. Recovery from these doses is only partial. Res- 

 piratory movements continue for some time after the animal is 

 removed to the air, but otherwise the animal does not recover. 



A point of some interest noted in these and in previous experi- 

 ments is the effect of various chemicals on the muscles of the 

 jumping-legs. With some reagents marked extension of the 

 jumping-leg results, while with others no such phenomena occur. 

 With a small dose of ether (reversible) no extension is noted 

 during the course of an hour to an hour and a half. With larger 

 doses (irreversible) a marked extension occurs after a very short 

 exposure to the anesthetic. Chloroform in the smallest dose 

 invariably produces a marked extension, which after an exposure 

 of about a minute is irreversible. After an exposure to a small 

 dose of acetone for fifteen to twenty minutes the jumping-legs 

 become extended and the effect is irreversible. Xylol in the 

 smallest doses always produces a marked extension (irreversible) 

 of the jumping-legs. With formaldehyde the jumping-legs 

 become extended and do not recover after a short exposure to a 

 small dose. Experiments on the effects of chemicals on the 

 leg muscles are being continued. 



DISCUSSION 



The effect of anesthetics on respiration, as is well known, is a 

 problem in which physiologists have long been interested. The 

 various theories and results obtained have been repeatedly dis- 

 cussed and need no further mention in this paper. It is evident 

 from the experiments herein reported, however, that in grass- 

 hoppers anesthetics and other substances produce results which 

 are of some interest, especially when compared with those found 

 for other forms. Miss Irwin (6), investigating the effects of 

 ether on the CO2 output of tadpoles, frogs' eggs, fish embrj^os, 

 and aquatic insects, found that an increase in the CO2 output 

 was accompanied by irreversible changes leading to death. With 

 grasshopppers this was not found to be the case. An increase 

 followed by a decrease with reversible doses and an increase 



