THE ENERGETICS OF PHOTOSYNTHESIS 



101 



36 



28 

 Q 



X 



E 

 E 



c 

 01 



m 



03 



^ 16 



Q. 



24 



20 



10 20 30 40 50 60 70 80 90 

 < min light x min dark 



100 110 



Fig. 41. Oxygen evolulion in the light and oxygen uptake in the dark as a lunctiun of 

 oxygen pressure. In both experiments 100 ^1 cells are suspended in 7 ml. 0.2 molar car- 

 bonate buffer, pH 8.8 (95% bicarbonate + 5% carbonate). Gas phase: 2 vol % CO. + 

 argon. Curve I: F,,, = 9.759 ml, /f^., = 0.931 mm-'. Curve II: F,^. = 14.544 ml, K,-,^ = 

 X.'ill mm-. Incident light intensity (green): 30 ^1 quanta min (Warburg et. al.. Zschr, 

 Naturj.). 



Fig. 42. Respiration and photosynthesis 

 at low oxygen pressures (Warburg et al., 

 Zschr. Xaturf.). 



O, pressure m mm H^O 



equal conditions in two vessels of different volume. The curves in Figure 

 41 were obtained in this way. By drawing the tangents at points of equal 

 O2 pressure, it can be established, for instance, that photosynthesis at point A 

 on curve I for the small vessel is the same as at point B of the curve II for the 



larger vessel. 



dp\/dt X A'^,^ = dp^'/dt X A'^^^ 



(43) 



The points of equal pressure and equal photosynthesis on the two curves are, 

 however, not attained at the same time. At equal chemical turnover the 

 Oo pressure in the small vessel (curve I) will of course increase more rapidly 

 than the O2 pressure in the larger vessel (curve II). 



