CHAPTER VIL 



THE CHEMICAL PROCESSES TAKING PLACE IN PLANTS. 



A LARGE variety of chemical products has been isolated 

 from plants which include, in addition to fats, carbo- 

 hydrates, and proteins, such substances as the tannins, 

 essential oils (such as turpentine oil, to which camphor 

 and certain resins are chemically allied), basic substances 

 (alkaloids), and the various pigments. Although many of 

 these products have been investigated in detail, arid their 

 constitution has been determined, practically nothing is 

 known with regard to their method of formation in the 

 plant and to their function. In fact, the study of the bio- 

 chemistry of plants is still in a very rudimentary stage. 

 Nevertheless, there are certain fundamental facts which 

 have been discovered which throw considerable light on 

 the part played by plants in the general economy of 

 nature. 



It has already been stated that the chief foodstuffs of 

 animals are the fats, carbohydrates, and proteins, substances 

 of considerable chemical complexity, which in the organism 

 undergo processes of degradation and oxidation, yielding 

 thereby a source of energy for the maintenance of animal heat 

 and for locomotion. The necessary foodstuffs are elaborated 

 by the plants, or at any rate by the higher phanerogamous 

 plants, from comparatively simple materials. Plants, 

 therefore, act as the synthetic agents which manufacture 



