Some New Preillumination Experiments with 



Carbon- 14 



HIROSHI TAMIYA, SHIGETOH MIYACHI, and TOYOYASU HIRO- 



IvAWA, The Tokugawa Institute for Biological Research and Department oj 



Botany, Faculty of Science, University of Tokyo 



Using C^^ as a tracer Calvin and Benson (1,2) found that the CO2- 

 fixing capacity of green cells increased markedly when the cells were 

 illuminated immediately prior to provision of CO2 in the dark ("pre- 

 illumination"). This C02-fixing capacity gradually decreased in 



i_JO_„S..J 10 20 30 40 



TIME (IN MINUTES) OF PRE -ILLUMINATION 



Fig. 1. Induction phenomenon in the process of formation of R in the light. 

 Ordinate: cpm of C^* fixed in 30 seconds in the dark; abscissa: the time which 

 the cells spent in the light and dark, as indicated, prior to the provision of C'^02. 

 Experiments illustrated in the upper and lower parts of the figure were performed 

 with different algal samples. 



darkness, and it was inferred that during illumination the concen- 

 tration of the agent in cells responsible for the CO2 fixation is de- 

 termined by relative rates of photochemical formation and non- 

 213 



