194 



B. CHANCE, M. BALTSCHEFFSKY, L. SMITH 



Duysens reports that distilled water treatment of the whole cells 

 gives a similar light effect (2) . 



After incubation with the inhibitor, the kinetics of the fast light 

 reaction is recorded without interference from the slow reaction as 



e 



Z +0.005 



e 



Q. 

 O 



-0.005- 



Opticol density at 

 430 m^ increases 

 as light IS turned 

 on 



430 m>j 



370 



400 430 



460 



Fig. 2. The difference spectra corresponding to the rapid phase of the reaction 

 caused by infrared illumination in Fig. 1. 



shown in Fig. 3. The records show clearly (1) that no "instan- 

 taneous" processes are involved; (2) that the kinetics of the light 

 reaction differ from those of the dark reaction, the light reaction being 



^^/A^^-s-^-^*^ 



430-470m;j 

 log Io/I=0.005- 



Increase of O.D. at 430m>ii 

 10 sec *i 



Temp = 7''C -"'^sc^ ^ Tennp. = ~22°C 



Fig. 3. The kinetics of the effect of infrared illumination upon R. rubrum cells 

 inhibited by 0.1 mM phenyl mercuric acetate. 



considerably more rapid than the dark reaction, as would be ex- 

 pected if the effect of light is to displace a chemical equilibrium; 

 (5) that temperature affects both the light and dark reactions, al- 



