EVOLUTION OF CARBOHYDRATES 53 



fats. It is therefore to the plants that we should 

 look for their formation. These bodies take their 

 rise from a few simple combinations of ions dis- 

 sociated from C0 2 and water ; from which, together 

 with ions from ammonia compounds, nitrates, and 

 a few other salts, the plant builds up the complicated 

 substances of its organism. An endeavour is here 

 made to give an idea of their evolution or 

 development. 



The synthetic processes are started from the 

 dissociation of carbonic dioxide and water by the 

 energy of sunlight into CO, OH, H, and ions. 

 The equation CO 2 + H 2 = CH 2 + 2 represents in 

 gross what takes place in the leaves of the plant. 

 But the intermediate stages are not represented and 

 the knowledge of them is not quite so clear. Under 

 the influence of the sun's rays hydrogen peroxide, 

 H 2 2 , is formed, which may split into OH ions ; or 

 water may be directly split into H and OH ions. 

 Again an O ion may be split off from C0 2 , leaving 

 the CO ion or carbonyl. Now CO+OH = CO-OH 

 or carboxyl, which is an anion, and an acid radical 

 formed in the construction of the molecules of all 

 organic acids. 



CO-OH + OH = CH(OH) + 2 or CH 2 O + 2 . 



The O atom in the carbonyl ion CO may be dis- 

 placed by an OH ion, thereby forming CHO, which 

 is the aldehyde index represented by 



?0 



the oxygen being shown as a double circle. The 

 tetrad carbon joins by two of its poles or valencies 



