(;arbon-14 preillitmination experimknts 



2 1 f) 



20 



40 60 80 100 



TIME IN MINUTES 



Fig. 3. Effect of air on the course of formation of R in the light. Temperature: 

 20 °C. Curve A: algal suspension was flushed with N2 throughout the experi- 

 ment; Curve B: algal suspension was flushed first with N2 and later (at the time 

 indicated by the arrow) with air; Curve C: algal suspension was flushed with air 

 from the beginning of illumination. 



20 40 



TIME IN MINUTES 



Fig. 4. Effect (in the light) of varying concentrations of O2 on R pre-formed in 



N2 atmosphere. 



Decay of R in the dark normally was complete in some 15 minutes. 

 In the presence of oxygen R was considerably depressed. Figure 2 

 shows that the initial course of R formation (including the char- 



