350 



K. DAMASCHKE, F, TODT, D. BURK, O. WARBURG 



VOL. 12 (1953) 



minutes later, after bringing the pO^ back to ca. 0.15% by shutting off the compensating 

 illumination for somewhat less than a minute, an equivalent amount of oxygen was 

 added to the Chlorella suspension by means of extra red light, and now the respiration 

 increased (compensation decreased) during, and due to, the course of the back reaction 

 in the photosynthetic cycle (Curve 2). 



Or, as in Fig. 2, the respiration of a Chlorella suspension was first measured as an 

 initial oxygen pressure P^ (here 0.445%) fell to a pressure P (here 0.235%) over a 

 virtually linear time course. Illumination was then given until the pressure was returned, 

 by oxygen production in photosynthesis, to Pg. Now, upon darkening, much more 

 oxygen was consumed per minute (4.5 times) than previously at the same pressure P^, 

 clearly indicating a light-induced reaction of increased oxygen consumption not as- 

 cribable to low oxygen pressure alone. 



THE PHOTOSYNTHETIC ENERGY CYCLE 



Fig. 2 and 5, 3, and 4 present typical galvanometric results, respectively obtained 

 visually, photographically, and by pen-recording, that show various time courses of the 



aus 



an 



aus 



1' 

 (hompensiert) 



20" 

 Rotes 

 Ucht 



0.5 %0^ 



■Wieder kompensiert 



0A%Og 



Konsfant - welsses Ucht 



Fig. 3. Photographic record of galvanometric observations on the photosynthetic cycle, with respi- 

 ration compensated. 



References p. 355. 



