METACHEMOGENESIS IN INSECTS — ROCKSTEIN 



277 



(fig. 11) ; finally, the flight ability (as measured by wing-beat fre- 

 quency) increases sharply to a maximum at 6 to 7 days (fig. 12). 

 Those maximal values all clearly remain unchanged at this mature 

 maximal level for at least 7 days more. In Drosophila funebris 

 (Fabricius), Watanabe and Williams (1953) found a similar increase 



6 7 8 1 



AGE IN DAYS 



Fig. II. 



-Cytochrome c titer of isolated Phormia sarcosomes as a function of 

 fiy age. (After Levenbook and Williams, 1956.) 



AGE IN DAYS 



Drosophila (unabrls 



Phormio r«9>na 



6 7 6 1 



AGE IN DAYS 



Fig. 12. — Wing-beat frequency of Drosophila funebris (from unpublished data 

 of Chadwick and Williams) and of Phormia as a function of fly age. (After 

 Levenbook and Williams, 1956.) 



