358 



B. KOK 



Under a variety of conditions we exposed algae to strong light and 

 followed the time course of the decay of the rate. 



Only with certain types of algae could results as described by 

 Myers and Burr (5) be obtained, namely, an apparent saturation at 



300 

 200 - 



-«-Ro 



3nt. =a32 



vl.O (2.3) 



-I — I 1 I 1 I I I I I ■ I 



I I 



1 I I 



10 



14 16 



18 20 22 24 



timt of axposurt minutts 



Fig. 4. Progressive decay of the photosynthetic (saturation) rate in strong light 

 of various indicated intensities and at two temperatures. Half-times of the slopes 

 are indicated in parentheses. After Kok (6). 



intermediate photosynthetic rates over a range of medium light 

 intensities before the onset of photoinhibition. Such cells show a rela- 

 tively fast (temperature-dependent) dark-recovery reaction. The 

 final level represents an equilibrium between photochemical destruc- 

 tion and dark restoration. Other algae do not clearly show recovery 

 reactions during or after the decay. In most cases the photosynthetic 

 saturation rate does not decay immediately upon illumination, but 



