EXPERIMENT STATION BULLETINS. 



563 



TABLE IV. 



CO2 



Reipiralion, and of insects in air. 



O2 



Table IV gives tlie result of some respiration experiments carried 

 out by the method just described with a few si5ecies of insects in air. 

 Moist air at temperatures between 20° and 24° C. was used. 



The results tabulated in IV represent great variation in the amounts 

 of carbon dioxide and oxygen present at the end of the experiments. 

 It will be seen that these variations did not affect the value of the res- 

 piratory quotient very much. In record No. 1, only about 3% of oxygen 

 remained at the end of the experiment. When however, the oxygen 

 percentage became less than one, the respiratory quotient was found 

 to rise in value. This is illustrated in records No. 10 and No. 11. Note 

 that in none of the following experiments testing the effect of insecti- 

 cides was the percentage of oxygen allowed to run anything like that 

 low. 



After specimens of P. cornutus were kept in the insectary some time, 

 even under the best care, with food, their vitality lowered and the 

 value of the respiratory-quotient diminished a little. Eesults of ex- 

 periments No. 8 and No. 9 are of this kind. During an experiment, 

 insects lose in weight a small amount (see Nos. 1 and 2 Table IV) due 

 to excreta and water vapor thrown off. 



EFFECT OF GASOLINE AND KEROSENE VAPORS UPON 



CO 2 



Os 



In studying the effect of insecticide vapors upon the respiratory 

 quotient of insects, it was the aim to eliminate from consideration all 

 other factors by keeping them the same through both parts of the 

 experiment. Thus, the respiratory quotient was first found for an 



