ORGANIC CHEMISTRY 



rapidly expanding. It has been found that this 

 agent can not only effect the synthesis of complex 

 substances, but also may break these up into 

 simpler materials. Thus formaldehyde may be 

 converted into sugars, and the latter may be partly 

 broken up by light into formaldehyde and other 

 products. At present, then, it appears that light 

 may be used by the plant to effect syntheses through 

 the medium of the primary product formaldehyde, 

 but also partially to break up the complex products 

 into others, which in turn may undergo renewed 

 reaction. 



Research carried out by biochemists has shown 

 that another type of reagent or group of reagents 

 takes part in the chemical reactions of the plant. 

 These substances are also catalytic in their action ; 

 they are termed enzymes. At present very little 

 is known of the chemical nature of the enzymes ; 

 they are very unstable substances, and this property, 

 together with their physical nature, renders their 

 examination very difficult. The majority of those 

 which are known appear to act solely as degrading 

 agents, and have a specific action with definite types 

 of compounds. The investigation of the enzymes 

 is hardly beyond a preliminary stage, but sufficient 

 is known of them to enable a classification to be 

 made according to the type of substance which 

 they decompose and the nature of the decomposi- 

 tion which is effected. 



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