8 



JOSEPH HALL BODINE AND PAUL RUDBERT ORR. 



tures for the production of a certain number of pupae on a partic- 

 ular day than in the case of the wild where the same culture can 

 usually be used for several days. One gets a much larger number 

 of body weights for one day old vestigial pupae of different cul- 



.oon 



WEIGHT IN CMS 



Time-days. 



3 5 X 



FIG. 3. Shows body weight of wild and vestigial pupae from day of forma- 

 tion to emergence. Ordinate represents body weight per pupa in grams, 

 abscissa, time in days indicated. X = fly just after emerging; a = vestigial; 

 b wild. 



tures than for the wild pupae where larger numbers of body 

 weights for one day old pupae are obtained from the same cul- 

 ture. In calculating average body weights, therefore, this fact 

 plays an important part and should be kept in mind especially be- 

 cause of its significance in the determining of the rates of carbon 

 dioxide output and oxygen intake per body weights of the animals. 

 To control adequately such a factor it would doubtless be neces- 

 sary to change the flies to new culture bottles every day so that the 

 pup:e from the eggs laid in any one day could be obtained. If 

 this factor is taken into consideration and a more extensive study 

 made, we feel certain that a much smaller difference in the average 

 body weights of the two stocks would be noted. It is also of in- 

 terest to note from Fig. 3 that during the life of the pupae there is 

 steady decrease in weight. At the emergence of the fly, however, 

 a rather marked increase in weight seems to occur and as a mat- 

 ter of fact the fly just after emerging weighs somewhat more than 

 the pupa from which it came. This increased weight is doubtless 

 due to absorption of water. 



OXYGEN CONSUMPTION. 



Inasmuch as the present paper deals only with a comparison of 

 respiratory metabolism in the two stocks of flies, the data pre- 



