64 PROBLEMS IN PHOTOSYNTHESIS 



15. Lautsch, VV. and Schroeder, E. : Zschr. Xatiirf., 9b:277, 1954. 



16. Sheppard, S. E.: Phot. ./., 6,5:380, 1925. 



17. SoROKiN, C. and Myers, .1.: Science, // 7:330, 1953. 



18. Warburg, E. : Sitzungsher . Preuss. Akad. Wiss., 34:712, 1900. 



19. W ARBURG , O . : Biochem . Zschr . , / 00 : 2 30 , 1 9 1 9 . 



20. Warburg, O.: Nalurw., W-Ml, 1922. 



21. Warburg, O.: Ueber die katalytische Wirkimg der lebendigen Substanz. Springer, 



Berlin, 1928. 



22. Warburg, O.: The Metabolism of Tumours. Constable, London, 1930. 



23. Warburg, O.: Heavy Metal Prosthetic Groups. Clarendon Press, Oxford, 1949. 



24. Warburg, O.: Science, 128:68, 1958. 



25. Warburg, O. and Burk, D. : Arch. Biochem., 25:410, 1950. 



26. Warburg, O., Burk, D., Schocken, V. and Hendricks, S.: Biochim. Biophys. 



Acta, 4:335, 1950. 



27. Warburg, O. and Krippahl, G. : Zschr. Naturf., ,9^:181, 1954. 



28. Warburg, O., Klotzsch, H. and Krippahl, G. : Zschr. Naturf., J2b :622, 1957. 



29. Warburg, O., Krippahl, G., Buchholz, W. and Schroder, W. : Zschr. Naturf., 



8b:615, 1953. 



30. Warburg, O. and Negelein, E. : Zschr. phys. Chem., 702:235, 1922. 



31. Warburg, O. and Negelein, E. : Zschr. phys. Chem., 70(5:191, 1923. 



32. W^ ARBURG, O. and Negelein, E. : Biochem. Zschr., 200:414, 1928; 20-^:495, 1929. 



33. Warburg, O. and Negelein, E. : Biochem. Zschr., 274:64, 1929. 



34. Warburg, O. and Schocken, V.: Atch. Biochem., 27:363, 1949. 



35. Warburg, O. and Schroder, W. : Zschr. Naturf., /2b:7\6, 1957. 



36. Warburg, O., Schroder, W. and Gattung, H.-W.: Zschr. Naturf., 7 7b :6b4, 



1956. 



37. WiLLSTATTER, R. and Stole, A.: Untersuchungen liber die Assimilation der Kohlen- 



sdure. Springer, Berlin 1918. 



B. THE QUANTUM REQUIREMENT 



§ 26 Quantum Requirement and Efficiency 



The experiments with red and yellow light discussed in § 22 show that the 

 quantum requirement in photosynthesis is not dependent on the wave-length 

 of the light used. Thus, it is the number of quanta and not the energy content 

 which is of importance. This follows from equation 26 



moleO., ,, energy mole O. 



if - rf ?^ . w gj^gj,gy n-ioie quanta mole quanta 



However, the quantum requirement has been found to be higher in blue than 

 in red or yellow. This discrepancy can be explained by the fact that red and 

 yellow radiation is absorbed only by chlorophyll, whereas blue light is ab- 

 sorbed by chlorophyll and by yellow pigments. Many years ago Warburg 

 and Negelein (61) found that chlorophyll absorbs only 70% of the total ab- 



