180 LIGHT, VEGETATION AND CHLOROPHYLL 



the carbon dioxide, but from the water. The 2 atoms of 

 oxygen of the carbon dioxide enter into the first substances 

 synthesized and we are forced to the conslusion that the first 

 reaction of photosynthesis consists in capturing the hydrogen 

 of the water to use it for different reductions, particularly for 

 the reduction of the carbon dioxide the valencies of which 

 are progressively freed of oxygen during its progress towards 

 glucosides. 



A first step is therefore accomplished; we have succeeded 

 experimentally in making chlorophyll capture luminous energy 

 and use it to decompose water and fix carbon dioxide. 



The Dark Phase 



This phase brings us up against the chemical problem of 

 photosynthesis, which can be considered in three aspects, 

 namely, the necessary energy which accumulates through 

 phosphoric acid, the diastases which catalyse the reaction, and 

 the course followed by carbon in its transformation from 

 carbon dioxide to glucosides. 



THE ROLE OF PHOSPHORIC ACID 



When Lundegaard observed the progressive disappearance 

 of certain phosphorated compounds in the course of muscular 

 activity, new horizons opened up to the biochemists and, 

 through the work of Lippmann in particular, an increasingly 

 important role in the functioning of life was attributed to 

 phosphoric acid. 



Phosphoric acid combines with other substances through a 

 bond capable of liberating a quantity of energy by hydrolysis. 

 When it is fixed on an alcohol radical (ester bond), as it is in 

 fructose-phosphate, this bond contains 2,000 to 3,000 calories 

 and nearly double — 4,800 calories — in glucose- 1 -phosphate, 

 perhaps because the carbon, on which it is fixed, has two 

 valencies saturated with oxygen. When it is fixed on an 

 organic acid (carboxyl-phosphate) and consequently linked 

 with an atom of carbon three bonds of which are oxidized, 



