462 



LIGHT AND LIFE 







c 



o 



680 700 720 



The difference curve 

 represents the absorpfion 

 specirum of the 

 pigmenf, 0^695, enhanced 

 by Cl650 absorpfion 



680 



700 



720 



Wavelength, m/j 



Fig. 13. An action spectrum for Chlorella photosynthesis with (dotted line) and 

 without (solid line) background light of 650 m^. The difference between the 

 curves is shown at the riglit. 



c 



CD 

 > 



o 

 a) 



600 



700 



650 

 Wavelength, mp 



Fig. 14. Action spectra of photosynthesis in Botiydiolysis alpina, Starr No. 29.5, 

 with two diflcrcnt background colors. This alga docs not contain chlorophyll b. 

 The enhancement appears to be caused by the simultaneous illumination of C,670 

 and C,695, indicating a different chemical function for the two forms of chloro- 

 [jliyll a. 



