2 CHEMISTRY OF PLANT LIFE 



in this way and to apply some such term as " intake " to the sun- 

 pie raw materials which are taken into the organism and utilized 

 by it in its synthetic processes. But the custom of using the 

 words " food," or " nutrient," to represent anything that is taken 

 into the organism and in any way. utilized by it for its nourish- 

 ment has been followed so long and the newer terms are them- 

 selves so subject to criticism that they have not yet generally 

 supplanted the loosely used word " food." 



If such use is permitted, however, it is necessary to recognize 

 that only the green parts of green plants can use this inorganic 

 " food," and that the colorless plants must have organic food. 



To avoid this confusion, the suggestion has recently been 

 made that all of the intake of plants and animals shall be con- 

 sidered as food, but that those forms which supply both materials 

 and potential energy to the organism shall be designated as 

 synergic foods, while those which contain no potential energy shall 

 be known as anergic foods. On this basis, practically all of the 

 food of animals, excepting the mineral salts and water, and all of 

 the organic compounds which are synthetized by plants and later 

 used by them for further metabolic changes, are synergic foods; 

 while practically all of the intake of green plants is anergic food. 



It is with the latter type of fopd materials that this chapter 

 is to deal; while the following and all subsequent chapters deal 

 with the organic compounds which are synthetized by plants and 

 contain potential energy and are, therefore, capable of use as syn- 

 ergic food by either the plants themselves or by animals. It will 

 be understood, therefore, that in this chapter the word " food " 

 is used to mean the anergic food materials which are taken into 

 and used by green plants as the raw materials for the synthesis 

 of organic compounds, with the aid of solar energy, or that of pre- 

 viously produced synergic foods. In all later chapters, the term 

 " food " will be used to mean the organic compounds which serve 

 as the synergic food for the green parts of green plants and as the 

 sole supply of nutrient material for the colorless parts of green plants 

 and for parasitic or saprophytic forms (see page 16). 



PLANT FOOD ELEMENTS 



The raw materials from which the food and tissue-building 

 compounds of plants are synthetized include carbon dioxide, 



