METABOLISM OF INSECTS 



547 



other investigators. It consisted of a 

 closed system of chambers and tubes, 

 through which a circulation of air was 

 maintained by means of a small air pump. 

 The apparatus was run over a period of 

 five hours for each experiment, and the air 

 in the circuit was bubbled through barium 



OBSERVATIONS 



The carbon dioxide output of the 

 nymphs under ordinary laboratory condi- 

 tions was taken as representing the stand- 

 ard output, to which comparisons could 

 be made with the data secured under ex- 



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Fig. 1. Rate of CO2 Output over Period of Three Months 



Time interval 10 days. Temperature 2.2.°C. Abscissas, gram body weight per insect. Ordinates, milli- 

 grams CO2 per gram insect per hour. For further explanation see description in text. 



hydroxide, which precipitated the carbon 

 dioxide as barium carbonate. The excess 

 of barium hydroxide was titrated with 

 hydrochloric acid, using phenolphthalein 

 as indicator. At the end of each experi- 

 ment, carbon dioxide determinations in 

 milligrams per gram insect per hour were 

 made. 



perimental conditions. The determina- 

 tions were made every ten days and the 

 data taken over a period of three months. 

 The animals were still in good condition 

 at the end of this period. The results 

 (fig. 1) show a relatively smooth curve; 

 the rate of C0 2 output is higher for 

 animals lighter in weight and decreases 



