VOL. 4 (1950) 



QUANTUM EFFICIENXY OF PHOTOSYNTHESIS 



343 



X02 

 XC02 



+ 41.^ mm 1 

 ' 'i J 1 y = — 1.04 



— 43-0 ., j ^ 



30-5-4 



162 

 41-3 



3-9 



(p 41-3 



III. Vessel No. 7, with same cells as before but without white light (below compensation-point). 



PH9-2 



10 dark — 33.5 mm 

 10' red light — 23.5 

 10' dark — 30.5 

 10' red light — 22.5 

 10' dark — 30.0 

 20' dark — 60.5 



Light action 20' 



20' dark — 62.7 mm, 20' red light —46.0 mm 

 62.7 — 46 = + 16.7 mm = II ^1 

 j_ _ 20-5.4 

 "P 



= 9.8 



IV. Again Nos. 3 and 5, but no white light (under conpensation point) pn 4-9 



No. 5 

 10' red light ^ 5.0 mm 

 10' dark — 12 ,, 

 10' red light — 4.5 ,, 

 10' dark — 13 ,, 



No. 3 

 10' dark — 4.0 mm 



10' red light — 1.5 „ 

 10' dark — 5.0 ,, 



10' red light — 1.5 ,, 



10' dark 



-5-0 



10' red light — 4.0 



30' dark — 14.0 mm 

 30' red light — 4.5 ,, 



Light action H 

 30' 



+ 9.5 mm 



X02 

 XCO2 



45-6 



V. Again No. 7, but with half Ught intensity (Actinometer, 2.75 /il Oj per minute), pn 9-2. 



10' red light — 24 

 10' dark — 28 

 10' red light — 24.5 ,, 

 10' dark — 27.0 ,, 

 10' red light — 23 



Light action 10' 27.5 

 I 10-2.75 



23.8 = + 3.7 mm = 2.42 [x\ 



2.42 



II-3 



The total duration of these experiments was 8 hours. 



IX. SUMMARY AND CONCLUSION 



Since development of the new methods and procedures described, in a sequence 



of thirty experimental days, almost without exception quantum efficiencies of 3 to 5 



quanta per molecule of O., produced by the action of red light have been obtained. The 



CO., 

 simultaneously observed quotients of — -^ for light action lay between — 0.8 and 



— 1.3, which means that the quantum efficiencies for CO.^ consumption in red light were 

 essentially the same as those for Og production. 



These results were obtained not only with low light intensities below the compen- 



References p. 346. 



