54 8 



THE QUARTERLY REVIEW OF BIOLOGY 



progressively as the animals increase 

 in body weight. Differences in body 



is led to assume that younger individuals 

 have the higher rate of respiratory output. 

































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Sec 



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170 



.190 



.Zio 



.230 



Fig. i. Rate of CO2 Output in Darkness 



Time interval 7 days. Temperature iz°C. Abscissas, gram body weight per insect. Ordinates, milli- 

 grams C0 2 per gram insect per hour. For further explanation see description in text. 



weight, especially in nymphs, are closely Smaller animals are generally more active 

 correlated with differences in age, and one and are immature and growing. 



