184 LIGHT, VEGETATION AND CHLOROPHYLL 



CH CH 



HC C C HC C C 



HC CH +2H HC CH2 



\ // ^ \ / 



N+ < N 



I -2H I 



CH CH 



DPN and DPNH2 



We can see the significance, in the processes of photo- 

 synthesis, of everything which bears on the accumulation and 

 transport either of hydrogen or of energy and if, as we might 

 be tempted to think, the luminous phase results in the 

 accumulation of hydrogen and energy, the role of adenylic acid 

 is of primary importance in its two forms of ATP and DPN. 



DIASTASES 



Diastases take part in every chemical activity of the 

 living organism. Their action is catalytic and they are 

 necessary auxiharies which are theoretically unchanged at the 

 end of the reaction. 



They consist of a proteic support, the apodiastase, which is 

 relatively voluminous and on which depends the adaptation to 

 a particular function. Fixed to this support, the active parts, the 

 codiastases, will act only if they are placed on site by their sup- 

 port. ATP and DPN seem to be among the principal codiastases. 



The first reaction of photosynthesis, the fixation of carbon 

 dioxide in the form of carboxyl, is eff'ected, as we have seen, 

 either by the animal or vegetable organism in the Wood and 

 Werkmann reaction, or by chlorophyll in the Hill reaction. 

 Carbon of one valency is freed of its oxygen and fixed on a 

 dicarbonate or tricarbonate substance, for example, on 

 pyruvic acid, which becomes mahc acid: 



CHg-CO-COOH+COa+Ha^ 



COOH - CH2 - CHOH - COOH 



