XIII. ACTION SPECTRA AND ABSORPTION SPECTRA 440 



2I^. Smakula, A., Angexi\ Chcm., 47, 057-665 (1934). 



Sd. Uber, F. M., Am. J. Botany, 26, 799-807 (1939). 



26. Wald, G., Harmj Lectures, 61, 117-160 (1945-46). 



27. Riemerschmid, G., Onderstepoort J. Vet. Sd. Animal Ind., 17, 89-104 



(1941). 



28. Wald, G., Science, 101, 653-658 (1945). 



29. Wald, G., in Proceedings of the Colour Vision Conference, Cambridge, 



England, 1947; Docuvienta Ophthalmalogica, Vol. 3 (in press). 



Adtlenthini 



Since this chapter went to press there have been two important 

 developments which should be mentioned briefly: 



Reinvestigation of the quantum efficiencj^ of photosynthesis by 

 Bui'k, Hendricks, Korzenovsky, Schoken, and Warburg (Science, 110, 

 225-229 (1949)) has yielded maximum values near 4 quanta per 

 molecule of oxygen liberated, in good agreement with the values 

 reported by Warburg in 1923. This calls for some modification of 

 ^'alues cited in this chapter. 



Enhancement of recovery from effects of ultraviolet radiation by 

 exposure to light from the short end of the visible and long end of the 

 ultraviolet spectra has been demonstrated: in fungi by Kelner 

 (Proc. Natl. Acad. Sci. U. S., 35, 73 (1949)); in bacteriophage 

 (in the presence of E. coli) by Dulbecco {Nature, 163, 949 (1949)); 

 and for the sea urchin by Blum, Price, Robinson, and Loos {Biol. 

 Bull, 97, 232 (1949)), and Marshak {Biol. Bull, 97, 244 (1949)). 

 This may call for revision of our ideas on the effects of ultraviolet 

 radiation. 



