94 



B. L. STKP^HLER AND V. H. LYNCH 



lels both the 520- and 648-mM bands in its time course, but appears 

 closer to the G48-iniu band in its i-esponse to Hght intensity variations. 

 It is also clear from these measurements that these two peaks are due 

 to different chemical compounds, since the changes do not parallel 

 each other as a function of the external variables. 



8. It was established that the 520-m/i absorption band could not 

 be due to a modulated red fluorescence artifact because there was no 



HIATTREATED CHlOREllA 



250 



LIGHT INTENSITY Foot C o n d I e s 



Fig. (). Light intensity dependence of Chlorella transnaission changes at 525 m/i 

 following partial inactivation by heat. The deflection equals about 3 to 4 O.D.U. 

 X 10 -^ at saturation. 



difference signal when a red filter was inserted in front of the photo- 

 multiplier and the cells were illuminated in a flow system. The changes 

 could not be due to a modulating green fluorescence because there is 

 little if any green fluorescence in Chlorella. 



9. When the cells were subjected to heat treatment and then 

 illuminated an interesting effect was noted. After 4 minutes at 51 °C. 

 only an increase in absorption was noted; and, surprisingly, this 

 increase encompassed the entire spectral region measured. Figure 6 

 shows the intensity dependence of the process, and Fig. 7 illustrates 

 the wavelength dependence of this phenomenon. Treatment at 60°C. 

 for 4 minutes completely destroyed any reversible changes in absorp- 

 tion. The luminescence was reduced to about 5% of the normal value 

 by the former treatment and completely ol)literated l)y the latter. 



