EXPERIMENTS ON LONGEVITY 



399 



mental approach. Experiments were car- 

 ried out, with the most painstaking atten- 

 tion to details of technique, in order to 

 secure reliability of results, in which flies 

 were hatched under such conditions that, 



fed flies. Two general results of sig- 

 nificance emerged from these experiments. 

 The first is shown in figure 6, and the 

 second in figure 7. 

 In making this diagram, shown in 



Vestigial 

 (100) 



Wild 

 (100) 



Vestigial 

 (50) 



3 9 15 PJ 



27 33 39 45 51 



Age in Hours 



57 63 69 75 81 



Fig. 7. Survivorship Distribution for Normal Wild Type and Vestigial Drosophila, under Complete 

 Starvation at Three Densities of Population 



as fully developed flies, they could never 

 obtain any food. Under the conditions of 

 complete starvation the durations of life 

 of large numbers of individuals were ob- 

 served. These durations were a matter of 

 hours, instead of days as in the normally 



figure 6, it was necessary, in order to com- 

 pare the forms of the life curves of fed and 

 starved flies, to measure age in relative 

 terms, instead of absolutely in hours or 

 days. This was done by taking the total 

 life span as 100 per cent of life duration, 



