BESSEL KOK AXD C.EORCE HOCH 



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ANACYSTIS 

 1^ . 700 mfl 



lr^ ■■ 3% 



400 



500 



600 



700 



m fi 



WAVELENGTH OF DETECTING LIGHT 



Fig. 4. Changes of absorption induced in a suspension of the blue-green alga 

 Atiacystis uidulaus by far-red flashing light (fir.O-TOO m/j.). Dark-lime between 

 flashes 0.01 sec (from 17). 



Most of the remainder of this discussion will be restricted to a 

 number of observations of a pigment ("P 700") which is presumably 

 responsible for the 700 m^u. shift. Table 1 summarizes the characteris- 

 tics of the fast absorption decrease at 700 ny. 



An often observed asymmetry of the band (13) could be due to 

 screening by chlorophyll a, i)ut might also indicate that we are dealing 

 with a band shift (in addition to a decreased extinction coefficient) . 



The fact that with even the shortest flashes we could obtain (3 X 



