DAILY RHYTHMS 



497 



12 A 



12 B 



Fig. 12. As in Fig. 11 the result of conflicting light and temperature 

 cycles on the eclosion rhythm in Drosophila is illustrated. The top four 

 histograms (12) are results of experiments similar to those shown in 

 cultures 5, 6, 7, and 8 of Fig. 11 except that the temperature cycle had a 

 mean of 18°C and an amplitude of ±6°C. The next four histograms 

 (12A) show what happens if cultures on these conflicting cycles of light 

 and temperature are put into DD and constant temperature (21°C). The 

 eclosion rhythm settles down to a phase determined primarily by the 

 previous light-dark cycle. The bottom set of histograms (12B) show 

 what happens if cultures on these conflicting cycles of light and tempera- 

 ture are put into DD. The eclosion rhythm becomes entrained by the 

 temperature cycle. 



