Theories of Willstattef. 165 



the carbon dioxide of the air to a greater concentration, on account 

 of its property to taUe up more carbon dioxide at lower temperature 

 suited to increase of assimilation under natural conditions. The 

 carbon dioxide wanders on to the place of smallest carbon dioxide 

 pressure. 



The real assimilation process we can differentiate into several 

 sub-processes. Chlorophyll takes up carbon dioxide and at the 

 same time forms a dissociable compound. One must suppose 

 that this compound takes up light energy, and thereby undergoes 

 rearrangement into an isomer of greater energy content, which is 

 suited for its own disintegration. A transformation product of 

 carbonic acid which can be split off enzymatically with loss of 

 energy, must be imagined as intermediate product, as the obser- 

 vation recorded in the first chapter makes it very probable that a 

 part of the assimilation process is of enzymatic nature. 



There is only known one isomer of carbonic acid of peroxide 

 nature to which could be ascribed the role of intermediate product, 

 performic acid, obtained in solution by J. d'Ans and W. Prey, which 

 easily dissociates into carbon dioxide and water. In the assimilation 

 process one must of course imagine another way of dissociation of 

 the intermediate product, namely, its disintegration with evolution 

 of oxygen. 



As for performic acid, various structural formulae can be 

 considered 



0— OH H O 



C and C 



/- ^ y \ 



HO HO O 



Formylhydroperoxide. Formaldehydeperoxide. 



so it is quite possible that the intermediate product of photo- 

 synthesis bound to chlorophyll is a peroxide other than the known 

 substance, performic acid." 



In our opinion this latter part of Willstatter's theory, which is 

 based on his experiments with chlorophyll sols and carbon dioxide, 

 is due to premature and incorrect interpretation of his experimental 

 results. These, briefly, are as follows. In a system consisting of a 

 chlorophyll sol and carbon dioxide, a certain amount of carbon 

 dioxide will be absorbed by the water constituting the dispersion 

 medium, and a further quantity will be used in the production of 

 phaeophytin according to the equation 



