386 PHOTOMECHANICAL CONSIDERATIONS 



0.1 2 r ''- 



0.08 



0.04 



CO 



400 



600 800 



WAVE LENGTH, m/x 



1000 



Fig. 3. Absorption spectra of chromatophores from blue-green mutant 

 Rhodopseudomonas spheroides: (a) before treatment, (b) after photo- 

 oxidation in the presence of 1% Triton X-100. The difference between 

 the dashed curve and the solid curve shows the reversible light- 

 induced absorbancy change. 



When cells of blue-green mutant R. spheroides are incubated 

 anaerobically in the light, their BChl is gradually converted in situ to 

 BPh. This conversion is nearly complete after two weeks of incubation. 

 Most of the BPh is retained in the chromatopho re fraction in an aggre- 

 gated state, while some (also aggregated) appears in the culture medi- 

 um. This aggregated BPh has absorption maxima at 365, 535, and 



