456 



M. R. CLARE. 



been gone over most carefully with the unqualified result that 

 sexual differences in metabolism are impossible to detect. If 

 such exist they must be so small that they are obscured by 

 irregularities induced by other agencies. 



30 , 



20 . 



10 . 







i. 



ta 

 D. 



N 







e 

 u 



1st Day 

 i 1 



CQ in 



in 

 i 

 in 



n 



i 



01 Ol 



i i 

 i- - 



1 - 1 - 1 - 1 - 1 - 1 



. 15 



. 13 



. 11 ~ 



op 

 "5 



. 9 



ra 



9- 



CL 



Vial Nos. 



6 11 13 H 17 18 21 22 



6 11 13 14 17 18 21 22 



FIG. 5. Oxygen rates, pupal weights and sex-ratios for lots of pupae of mating 

 Fi, of the second experimental period. Curves for the second and third days of 

 pupal life are omitted. Sex-ratios shown in brackets, the first figure for males, 

 the second for females. Upper curve = C>2 per pupa; middle curve = Oj per 

 gram; lower curve = pupal weights. Ordinates at left are C>2 values in cu. mm., 

 at right are pupal weight values in mg. per 10 pupae. Abscissae refer to the vials 

 from which experimental pupae were obtained. 



FURTHER CONSIDERATIONS ON IRREGULARITY IN 

 RESPIRATORY RATES. 



The most significant result which this study has revealed is 

 the peculiar irregularity in rates of metabolism exhibited espe- 

 cially by pupae formed under conditions of constant temperature. 

 It might be remarked that there is no ground for believing that 

 the causes underlying this irregularity are genetic in character. 

 On the contrary, the usual tendency of the rates for lots of pupae 

 derived on consecutive days from a common source to exhibit a 

 graduated character either in the direction of elevation or of 

 depression strongly suggests the effect of graduated environ- 

 mental influences. We have already eliminated pupal weight 

 and sex as important agencies responsible for irregularity in 

 rates and we may now refer to several remaining possibilities. 



