424 



R. A. OLSON, F. S. BRACKETT, R. G. CRICKARD 



3 6 9 12 



SECONDS OF DARK TIME 



Fig. 5. Plot of data from experiment recorded in Fig. 4. 



TIME IN MINUTE INTERVALS 



Fig. 6. Effect of interposed short and long dark intervals in the presence of 5% 

 CO2 (original rate record). Same conditions as Ln Fig. 5 but equilibrated with 5% 

 CO2 prior to run. Oxygen concentrations in millimeters of Hg are indicated at 

 various points along the record. 



