454 



E 

 O 

 O 



3 

 c 

 .9 



1 



I 



cf 



Fig. 3. Effect of O2 concentration in 

 air upon the compensation point in 

 light. 



. 2 % Oxygen 

 + 21 % Oxygen 



Both after 600ft -c 



100 



200 300 



Time (sec) after Light off 



400 



Fig. 4. Effect of O^ concentration in air upon the evolution of carbon 

 dioxide in dark. 



