FOOD 



233 



Bread, meat, and potatoes are organic substances, while 

 air, water, and salt are inorganic substances. So, if we are 

 to regard the latter group as food, we evidently should 

 recognize a great and fundamental distinction that exists 

 between organic and inorganic foods; it is only the organic 

 foods that can supply energy to living things or contribute 

 to their living substance; "inorganic foods" are necessary 

 to life, and yet they have an entirely different relationship 

 to it from that of the organic foods; they provide the 

 physical conditions under which life operates rather than 

 providing anything which becomes a part of life itself. 



To some writers this distinction seems so important that 

 they use the word food as applied to organic substances only. 

 Such usage makes the elementary study of food much 

 clearer. Thus when you consider photosynthesis, you find 

 that in this process green plants transform certain inorganic 

 substances (water and carbon dioxide) into a certain class 

 of organic substances (carbohydrates). Now shall we call 

 both the product of this process and the raw materials it 

 uses by the same name, i. e., food? If we do so, we shall 

 be saying that plants manufacture food, and at the same 

 time be saying that they get their food from the air (car- 

 bon dioxide) and from the soil (water) . This is so confusing 

 and inconsistent that it is evidently better to call only 

 the finished product food, and to call the raw materials 

 food-substance or food-material. Thus we not only make 

 our meaning more clear, but we emphasize one of the two 

 most fundamental changes which occur in what we call 

 the cycle of life, namely, the transformation of inorganic 

 substances into organic ones. The other great change is 

 the transformation of organic substances back to inorganic, 

 thus completing the cycle. 



