482 



RHYTHMS IN PLANTS AND ANIMALS 



27-rX-57 



2a-a-57 



19-IXS7 



MIX-57 



Fig. 2. The eclosion of Diosophila in light-dark cycles of varying photo- 

 period is illustrated here. The phase of the eclosion rhythm remains fixed 

 relative to the dark-light transition for all photoperiods greater than 4 hr. 

 The light intensity was 75-100 ft-c. 



