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II. TAMIYA, S. MIYACHl, T. HIROKAWA 



Gaffron et at. (5), that the initial rate of dark CO2 incorporation was 

 cyanide-sensitive. Upon reducing the C"02 fixation time in the dark to 

 10 seconds (instead of 30 seconds) the initial rate of CO2 fixation 

 was determined in the presence of varying amounts of cyanide and 

 at various times after the end of illumination. During the course of 



1 







I 2 3 4- s 



TIME IN MINUTES IN THE DARK 

 Fig. 8. Effect of cyanide on the decay of R in the dark. Algae were first illumi- 

 nated for 50 minutes in the absence of cyanide; and simultaneously with turning 

 off the light, cyanide was added and the subsequent fate of R was followed by 

 measuring C* fixed in 10 seconds in the dark. 



this 10-second exposure to C^^02 it was determined by other experi- 

 ments that fixation was linear with time. Figure 8 shows that the 

 decay of COj-fixing capacity was an increasing function of cyanide 

 concentration. The upper part of Fig. 8 is a semilogarithmic plot of 

 these data indicating approximately first-order decay. 



It can be shown from kinetic considerations that, irrespective 

 of the difference in the rate of reaction between R and C^'^Oo in the 



