26 Trans. Acad. Sci. of St. Louis. 



perature of which varied from 9° to 12° C. Here we 

 found that they attained the surprising maximum age of 

 32 days, while their contemporaries in ordinary condi- 

 tions reached only 13 days. 



Again this year we attempted similar experiments, but 

 not in so rigorous a form. The material (two lots of 

 Cecropias and one of Polyphemus) was placed in a ce- 

 mented basement where the temperature was somewhat 

 lower than the out-of-doors, and also considerably lower 

 than the room where the other live material was kept. 

 The three tables following give the details of the work. 

 (See Table 15.) 



By comparing these 42 insects with their contempo- 

 raries, the River des Peres Cecropias, we find the mean 

 duration of life considerably greater for those kept in 

 the basement, and especially the males of the lot. The 

 mean for the entire basement lot is greater than that for 

 those kept in the ordinary living-room by 2.66 days. 



From the South St. Louis lot of Cecropias, 38 were 

 selected at random and placed in the cool basement. 

 (See Table 16.) 



In this lot the mean for the males and also for the 

 whole population is somewhat lower than that for the 

 River des Peres basement material — a condition parallel 

 with the parent stock. But here too we have a higher 

 mean duration of life than for their contemporaries in 

 the living-room. We find the cellar conditions prolong- 

 ing the life of these 2.84 days over that of their fellows. 



Sixty-six Polyphemus moths, selected at random from 

 the Atlanta, Ga., material were subjected to the same 

 treatment. (See Table 17.) 



When we compare these with their contemporaries in 

 the living-room (Table 6), we are again reminded of "not 

 how long but how well one lives ' ' ; again the laws of com- 

 pensation are revealed. These lethargic animals in the 

 cellar lived longer than did those in the living-room by 

 differences far greater than those recorded for the Ce- 

 cropias, — viz., the unmated Polyphemus males lived 3.64 



