210 



S. MIYACHI, T. HIROKAWA, H. TAMIYA 



during the preceding period was removed by the effect of brief il- 

 lumination. Conceivably, there occurred a decarboxylation of some 

 carboxylated compound formed by the preceding background C^^02 

 fixation. The fact that the breaking effect became more and more 



5 10 15 20 25 30 



TIME ( IN MINUTES) OF CONTACT OF 



CELLS WITH C'*02 IN THE DARK 



'IN 02 ATMOSPHERE) 



Fig. 4. Effect of light flash upon the background of C'^Oz fixation occurring in 

 O2 atmosphere. C'''0- was supplied in the dark after the cells were dark-adapted 

 for 25 minutes in O2 atmosphere. Flashing light of indicated din-ation was applied 

 at the point shown by the arrow. 



obscure with the increase of flash duration may be due to the can- 

 celing of the effect by the formation of light-induced C'*02-fixing 

 power, which became stronger at longer flash duration. 



In the experiment described above, C'^02 was supplied to the algal 

 suspension in the absence of oxygen. When similar experiments were 

 performed in O2 atmosphere, the results obtained were entirely dif- 

 ferent. As may be seen from the results shown in Fig. 4, there was no 



