No. 646] THE DURATION OF LIFE 391 



The situation here is evidently quite different from 

 what obtained with the wild type flies. The Quintuples 

 lived somewhat longer in the control bottles than in the 

 ventilated. In the case of flies from stock, the difference 

 in the means amounts to 1.73 days, and is 3.5 times its 

 probable error. The numbers are, however, small, and 

 as an examination of Table III shows, the long survival 

 of 2 individuals in the control series after age 34 ac- 

 counts for a considerable part of the difference in the 

 means. With a larger experimental sample much of the 

 difference in the means would, we feel sure, disappear. 

 The influence of these same two individual flies is clearly 

 seen in the greatly increased variability of the control 

 series over the ventilated in the stock groups. 



In general we are of the opinion that in the case of 

 Quintuple flies the difference in ventilation represented 

 by a bolting cloth screen versus a cotton stopper has no 

 significant influence upon duration of life. The results 

 with extremely short-lived line 405, we regard as typical 

 of what one should expect with Quintuple flies in this 

 sort of an experiment. 



The reason for the difference between wild type and 

 Quintuple flies in their response to ventilation is founded, 

 in our opinion, upon the normal differences in behavior 

 between the two types. In Quintuples the wings do not 

 function (the wing mutation in this stock is Vestigial). 

 The consequence is that these flies are much less active, 

 and generally appear to live on a lower metabolic plane, 

 than wild type flies. Their oxygen needs are presumably 

 smaller, and it would therefore be reasonable to expect 

 that they would not show the difference in duration of 

 life with increased ventilation that the wild type flies do. 

 In this connection, it should be noted that their actual 

 behavior in this experiment was in accordance with the 

 view here suggested. They showed no such definite tend- 

 ency to congregate at the top of the bottle under the 

 bolting cloth as the wild type flies did. Their distribu- 

 tion was about the same in ventilated as in the control 



