128 



The Maximum Efficiency of Photosynthesis 



The observed assimilatory quotients, y = CO2 absorbed/O-2 produced, ranged 

 between — 0.8 and — 1.33, with an average of — 1.06. The deviation from — 1.0 



was in the opposite direction from that 

 claimed by investigators who have re- 

 ported outbursts of CO 2. in light 4 » 5 . On 

 the contrary, on the average a little more 

 CO2 was absorbed in light than O2 was 

 produced. Thus, one of the two main 

 loopholes that have been used to evade 

 the high efficiency in photosynthesis is 

 now closed. The other important loop- 

 hoole — the participation of respiration in 

 efficient photosynthesis in whatsoever a 

 manner 11 — is now closed too, since the 

 same high efficiencies have been obtained 

 at more than 6-fold compensated respi- 

 ration as at uncompensated respiration, 

 where light has also been shown directly 

 to be without notable infiuence.* 



The fact must thus be envisaged that 

 in a perfect nature photosynthesis is per- 



Table 1 fect tOO. 



1 







hv 



o 2 



4.6 



2.9* 



4.5* 



3.9* 



3.6 



4.2 



2.8 



2.5 



4.2* 



4.8* 



3.4 



4.2 



3.2 



3.0** 



3.5** 



4.8 



4.4 



Average 3.7 



V 



co 2 \ 



Oo / 



—0.80 



—1.03* 



-0.90* 



-1.04* 



-1.18 



—0.97 



-1.23 



-1.25 



-1.13 



-0.90* 



-1.28 



-1.04 



-1.33 



-1.10** 



-1.02** 



-0.82 



-1.00* 



-1.06 



References 



1 Warburg, Otto, Reprinted in Katalytische Wirkun- 

 gen der lebendigen Substanz. Julius Springer, Berlin, 

 1928. 



2 Warburg, Emil, Photochemie. Handbuch der Experi- 

 mentalphysik Vol. 18, p. 619. Leipzig, 1928. 



3 Manning, W. M., Stauffer, J. F., Duggar, B. M., 

 and Daniels, F., J. Am. Chem. Soc. 60 (1938), 266. 



4 Emerson, R., and Lewis, C M., Am. J. Botany 26 

 (1939), 808. 



5 Ibid. 28 (1941), 789. 



6 Warburg, Otto (trans.) Am. J. Botany 35 (1948), 194 

 (cf. Ref. 10, Chap. XXI). 



7 Stoffwechsel der Tumoren. Julius Springer, Berlin, 

 1926. 



8 Franck, J., and Loomis, W. E., Photosynthesis in 

 Plants. The Iowa State College Press, Arnes, Iowa 

 1949. 



9 Spoehr, H. A., and Miiner, H. A., Plant Physiol. 24 

 (1949), 120. 



10 Warburg, O., Schwermetalle als Wirkungsgruppen 

 von Fermenten, Werner Saenger, Berlin, 1948. Trans- 

 lation. Clarendon Press, Oxford, 1949. 



11 Burk, D., and Lineweaver, H., Nature 135 (1935), 

 621. 



12 Cold Spring Harbor Symposia Quant. Biol. 3 (1935), 

 165. 



13 Warburg, O., and Schocken, V., Arch. Biochem. 21 

 (1949), 363. 



14 Franck, J., Arch. Biochem. 23 (1949), 297. 



15 Noddack, W., Z. physik. Chem. 185 A (1939), 241. 



16 Noddack, W., and Eichhoff, H., Z. physik. Chem. 

 185A (1939), 222. 



17 Eichhoff, H., Biochem. Z. 303 (1939), 112. 



18 Noddack, W., and Kopp, C, Z. physik. Chem. 187A 

 (1940), 79. 



19 Kopp, C, Biochem. Z. 310 (1941), 191. 



20 Burk, D., Hendricks, S., Korzenovsky, M., Schok- 

 ken, V., and Warburg, O., Science 110 (1949), 225. 



21 Warburg, O., Burk, D., Schocken, V., Korzenovsky, 

 M., and Hendricks, S., Arch. Biochem. 23 (1949), 330. 



22 Warburg, O., Burk, D., Schocken, V., and Hen- 

 dricks, S., Biochimica et Biophysica Acta, Meyerhof 

 Festschrift Volume 4, pp. 335—346 (1950). 



* Zusatz 1961. Ein ganz anderer Zusammenhang zwischen Lichtwirkung und 

 Atmung ist 1950 entdeckt worden (vergl. Arbeit 11 dieses Buchs). 



