444 



M. R. CLARE. 



During the course of pupal development certain readjustments 

 are in progress which are reflected in rates of metabolism. In 

 Fig. i the changes in metabolism are shown in the form of curves. 

 Those for 4-day pupae are derived from a single mating of the 

 second experimental period while those for 5-day pupse pertain 

 to the first period. Each curve shows an initial fall after the 

 first day of pupal life succeeded by an abrupt or gradual rise. 

 The most instructive are the curves for 5-day pupse in which the 

 period of depression of metabolic rate is seen to continue from 

 the second to the third day. The curves for 4-day pupse are 

 obviously abbreviations of these. 



26 . 



22 j 



fc 



a. 



> 



& 

 a. 



14. 



6 , 



Mating Ba - 1st Period 















Hating Be - 2nd Period 



\J 



Days 12345 



12345 



1234 



1234 



FIG. i. Metabolism curves based on Oz consumption per minute per gram of 

 body weight. Ordinates = Oz values in cubic millimeters; abscissae = time in 

 days. 



This type of curve appears to be characteristic of pupae in 

 general, the modifications presented in the several species that 

 have been investigated being due chiefly to the varying extensions 

 of the period of depression. The significance of this type of 

 pupal curve has been discussed at length by several workers 

 among whom may be mentioned Tangl (1909, i and 2), Weinland 

 (1906), and quite recently Fink (1925). The researches of 

 Weismann, Perez, and others have demonstrated that early in 

 pupal life the persisting larval tissues undergo a series of histolyses 



