324 JOSEPH HALL BODINE 



handling, and manipulation of the animal, be practically elimi- 

 nated. In these experiments nymphs or adults of the following 

 species were used: Chortophaga australior, Chortophaga viridi- 

 fasciata, Hesperotettix pratensis, and Melanoplus differentialis. 



All animals were kept in the laboratory under the same con- 

 ditions as regards food, temperature, etc., as those used for 

 other work in this laboratory. 



Carbon-dioxide determinations were made by the indicator 

 method described by Jacobs (8). This method has been ex- 

 tensively used in respiration experiments carried out in this 

 laboratory, and has been found to be accurate, rapid, and con- 

 venient. With it the normal rate of respiration of an animal is 

 ascertained by determining the time necessary to produce a 

 definite amount of CO2. The reagents used in experiments are 

 added to both control and experimental tubes and measurements 

 then made in the same manner as for the normal animals. By 

 using a series of experimental tubes, each containing the same 

 amount of indicator solution and reagent, the transfer from a 

 tube in which the required amount of CO2 has been produced to 

 a new or fresh one can be quickly made, so that the animal is 

 practically exposed continuously to the same amount of re- 

 agent during any experiment. Pyrex or nonsol tubes, 25 cc. in 

 capacity, were used throughout experiments. 



The method of expressing results is similar to that used by 

 Osterhout (1) and his students. According to it, the rate of 

 respiration after the addition of the reagent is expressed in each 

 case as per cent of the normal rate (which is always taken as 

 100 per cent). 



For further explanation of these above-mentioned methods 

 the reader is referred to the works of the authors cited. 



The chemicals — ether, chloroform, acetone, xylol, and for- 

 maldehyde — were chosen because of their ready volatility, since 

 the animals were exposed only to the vapors of the reagent. 

 Inasmuch as reagents were added to both control and experi- 

 mental tubes, any buffer or other effects due to them were the 

 same in both cases. These chemicals, too, as pointed out by 

 McClung (9), produce different effects upon the cellular struc- 



