SUMMARY 



This summary is an attempt by the chairman and organizer 

 to present a brief, moderately critical guide to major points 

 of experimental and theoretical interest in the 70-odd re- 

 ports collected in this volume. The reader should be aware, 

 however, that the emphases and interpretations of this survey 

 are unavoidably biased. 



At the present meeting the general focus of attention 

 was on the questions revolving around the cooperation of two 

 distinct light reactions, and in particular, the electron 

 transport pathways associated with each. Since many papers 

 in this volume already contain diagrams visualizing the 

 interaction of several light and dark steps, we will not 

 attempt to reproduce another one at this point. We will be 

 commenting on various aspects of these schemes, and the 

 reader is referred to one or more of them for clarification 

 of the over-all relationships. 



The necessity for cooperation of two "photosystems" in 

 green plant photosynthesis has been established clearly from 

 studies of the dependency of photosynthetic rates, and of 

 fluorescence yield, on illumination by different wavelengths 

 of light and combinations or alternations of these wave- 

 lengths. These "photosystems" may, according to one view, 

 utilize their own specific pigment complexes for light ab- 

 sorption, and activate different parts of the photosynthetic 

 electron transport chain. System I (terminology of ^uysens* 



Names refer to first authors of articles in this 

 volume. 



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