98 



B. L. STUEIILEI! AND V. IT. LYNCH 



cause the rediictant i.s presuma])l.v being consumed ])y othei- hydrogen 

 acceptors in the photosynthetic clieniical chain while the oxidant 

 disappears mainly in a reaction producing molecular oxygen. If the 

 rates for disappearance of YOH are such that the steady-state concen- 

 tration of oxidant in prolonged light is higher than that of the re- 

 ductant the changes observed would occur. 



4. There should always be an increase in reductant during the 

 initial phase of illumination because the reductant and oxidant are 

 approximately equal in concentration at the onset of photochemistry. 



These assumptions can explain all the observed results with normal 

 algae. Schematically the relationships postulated are as follows: 



X(475) + Y(660) + HoO + hv Ch 520 + 648 



XH YOH 



P.S. 



Luminescence ^ 

 O2 Production ^ 

 Photosynthesis 



X + Y 



+ H2O 



+ energy 



4XH] [YOH] 



-'[YOH]" 



-[Z] [XH] [A?] 



/4O2 



Acknowledgment. This work was performed while the senior author was a 

 visiting investigator at the Carnegie Institution of Washington, Department 

 of Plant Biology, Stanford, California, during the summer of 1955 and was 

 supported in part by a Grant from the U.S. Atomic Energy Commission. 



The authors wish gratefully to acknowledge the helpful assistance of Mr. 

 L. R. Kruger in the building and modification of apparatuses and the per- 

 tinent and useful guidance and comments of Drs. C. S. French and James 

 H. C. Smith. 



Discussion 



Brown : Does this hot bath cause any precipitation? 



Strehler: Yes, I think so because we got occasional noninstrumental noise 

 pulses, probably due to the interruption of the measuring beam by agglomerates 

 of cells after heating. 



Frenkel : I don't quite understand how Dr. Strehler's theory can account for 

 emission. Of course, you assume that the light that is reemitted comes from a 

 substance closely related to chlorophyll. 



