ENDOGENOUS DIURNAL PERIODICITY 



500 



509 



Fig. 3. Pilobolus spliaerosporus. Periodic discharge of sporangia in con- 

 tinuous darkness (after 12: 12-hr light-dark cycles). Abscissas = begin- 

 ning of continuous darkness. (After Schmidle, 1951.) 



12 3 



DAYS 



Fig. 4. Periplaneta americana. Rhythm of activity in continuous dim 

 light. 



ii.^u$k-M'~-^4^ 



DAYS 



Fig. 5. Mesocricetus auratiis. Rhythm of activity in continuous dim 

 light. 



