158 PROBLEMS OF PHOTOSYNTHESIS 



reason that investigations of this kind, which, lacking physical significance, 

 contributed so much to the stoichiometric relationship between chlorophyll 

 and O2 not having been discovered much earlier. 



The photosynthetic carbon cycle as proposed by Calvin and his group is 

 based upon a series of hypotheses. Like many other contributions to the 

 chemistry of photosynthesis, it is based upon the photolysis of water, a hy- 

 pothesis which seems to be improbable today. The participation of primary 

 hydrogen acceptors such as lipoic acid or vitamin Ki lacks support. Further, 

 there is not sufficient evidence to assume a chlorophyll aggregate and its semi- 

 conductive properties. There is no doubt that the work done with '^C02 

 has opened new and interesting perspectives in the field of photosynthesis. 

 However, too hasty conclusions and too much combination of experimental 

 results with unproven theoretical considerations are extremely dangerous. 

 They may certainly lead to intriguing schemes which suggest the whole prob- 

 lem is solved, but as long as no definite evidence is provided, there is no rea- 

 son whatever to accept them as true and irrefutable. 



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