SUMMARY 451 



found invariably and that none of the data at hand force the use of the 

 nomenclature championed by adherents of the cyclic and noncyclic 

 schemes. The majority opinion at our discussion last night was that 

 there was no definitive experiment now, or in prospect, that would 

 force adoption or abandonment of either the hypotheses of a unidirec- 

 tional electron flow, on the one hand, or of a coupled backward flow on 

 the other. At the moment, neither hypothesis can be dignified by the 

 term "mechanism," Of course, all those who find it convenient or 

 comfortable to use the terminology of cyclic and noncyclic should by 

 all means be allowed to do so. 



Now we come to a very important phase— the presentation of data 

 bearing on the primary photochemical act. Here we have a great bur- 

 geoning of activity. 



Nowadays, symposia on photosynthesis are dominated by characters 

 who show us difference spectra, flash photometer traces, and so on, 

 and we have to learn their language, I suppose. Elsewhere I have 

 mentioned that photosynthesis falls into a number of categories, each 

 of which is dominated by a certain discipline, and between which com- 

 munications do not exist. The first discipline is radiation physics, 

 which would include people like James Franck, and the next discipline 

 is photochemistry, of which there are few representatives here, 

 actually few card-carrying photochemists, because most such will 

 never be seen dead with a thing as complicated as chlorophyll. K they 

 do have it, they have it in a form which hardly has anything to do at 

 all with biologically interacting photochemical systems— and for a 

 good reason! Then there are the biochemists, who exist in a world by 

 themselves, and whose researches begin about the time the primary 

 act has been over for several decades, so to speak. Then there come 

 the botanists and plant physiologists, who have seen with regret their 

 field disappear from under their hands. Then we have the ecologists— 

 and occasionally phenomena like Billy Sol Estes. 



Some of us have spent time in a number of these disciplines and 

 carry over certain rigid attitudes about the use of terms which have 

 well-defined meanings in one area of research and appear to be mis- 

 applied in another. There are also divergences about what areas are 

 critically in need of development. For myself, I feel that enzymology 

 is not a critical phase of photosynthesis research at this time. There 

 are lots of good enzymes around and it seems that hard work, rather 

 than fresh ideas, is needed. The trouble comes, I think, in that shadowy 

 region between photochemistry and biochemistry. I won't mention the 

 trouble between the physicist and the photochemist, between whom 

 communication is minimal. But there is lots of trouble at the point 

 where we have people like Witt talking to people like Warburg, to take 

 two extreme examples. 



Now let me try to summarize the situation with regard to the photo- 

 chemical act. The primary photochemistry is electron chemistry; it is 



