74 



PROBLEMS IN PHO lOSYNTHESIS 



quantum requirement were therefore three times higher. The values in 

 Tables 11 and 12 derived from a few experiments (48) demonstrate once 

 again the dependency of the quantum requirement on the CO2 pressure. 



TABLE 11 



Influence of CO2 partial pressure on the quantum requirement in acid medium. Temperature 



20° C. Small vessel: K'o, = 0.915 mm^, A'',n, = 1.503 mm^. Large vessel: A'o^ = 1.321 mm^, 



A'coj = 1.910 mm'''. Ceil respiration nearly compensated with white light. Intermittent 



measured light 6440 A (1 min white, 1 min white + red, etc.). 



TABLE 12 

 Influence of CO2 partial pressure on the quantum requirement in alkaline medium. Temperature 

 20° C. Vessel constant Ko^_ = 0.915 mm^ and 0.911 mm^. CeU respiration nearly compensated 

 with white light. Intermittent measured light 6440 A (1 min white, 1 min white + red, etc.). 



In more recent experiments Emerson and Chalmers (20, 21) do not make 

 any use of Warburg's results. They still obtain quantum requirements of 

 about 10 in alkaline medium. In their experiments the CO2 pressure is as 

 low as 0.5 atm %. Moreover, they insist on using very dense cell suspensions 

 (300 to 400 yul cells per 8 ml liquid) and total absorption (see § 17). 



