CHLOROPHYLL FORMATION 



411 



When part of the protochlorophyll was transformed to chlorophyll and 

 the leaves were illuminated with light absorbed predominantly by chloro- 

 phyll (wave length 680 myu), the hght absorbed by chlorophyll was ineffec- 

 tive in the transformation (ibid.). 



-0---0-— o- ABSORPTION; IN METHANOL 

 ACTION SPECTRUM 



I 50 



I 00 



z 

 o 

 t- 

 a 

 (r 

 o 



< 



a 



50 



400 



500 



600 



WAVE LENGTH, m W, 



Fig. 7-11. Action spectra for the transformation of protochlorophyll to chlorophyll 

 in dark-grown normal and albino corn seedlings (solid line), compared with the absorp- 

 tion spectrum of protochlorophyll in methanol (broken line). The effectiveness 

 values for the normal and albino seedlings are equal in the long-wave-length band of 

 the action spectra. (Koski et al., 1951.) 



These results leave little room for doubt that protochlorophyll holo- 

 chrome is the active light absorber for its own transformation. 



After considerable amounts of chlorophyll have been formed, it is 

 hardly feasible to obtain a significant action spectrum for the partici- 



