PHOTOREACTION AND ASSOCIATED CHANGES 



435 



20 



o 



c 

 o 



15 



O 



c 

 o 



"S. 10 

 o 



< 



3 



o 



5600 



6000 



_l_ 



6400 



6800 



7200 



7600 



Wave Length in A 



Fig. 6. Molecular absorption coefficients of the red- and far-red-absorb- 

 ing forms of the photomorphogenic pigment. 



chromophoric grouping. We have traced down several indications of 

 blue pigments but without any success. 



The positions so far out in the visible spectrum of the absorption 

 maxima, their high values of e, and the low values of e in the region be- 

 tween 4000 and 5200 A indicate that the pigments are largely conju- 

 gated systems. Porphyrins and close-ring tetrapyrroles are eliminated 

 by the low absorptions in the blue. The most lilcely probabiHties are 



