Human Nutrition. 751 



body, and it must also provide all the materials which are needed for the 

 growth, development and repair of the different kinds of cells. When 

 any of these is constantly lacking in the daily food the body soon gets 

 out of repair. 



If the human engine is to be kept in good running order it is important 

 to know what materials are necessary to it and the form in which they 

 best serve the body's purposes. Perhaps the simplest way to establish 

 an understanding of what food must consist is to go to the very founda- 

 tion of things and learn something of nature's marvelous power of 

 uniting very simple substances known as elements, with many of which 

 most of us are famiUar, as iron, sulfur, oxygen, carbon, etc., to form 

 complex substances called compounds. The compounds usually differ so 

 completely from the simple elements which form them that the results 

 may indeed be said to be miraculous. For example, who on tasting 

 sugar would believe that one of the elements combined to form it is 

 known to us as charcoal? Oxygen and hydrogen are the two other 

 elements which are united with carbon to produce this wonderful result. 

 Nature has the power of combining three such simple substances as these 

 in various ways to produce not only sugar but such dissimilar substances 

 as sugar, starch and fat. 



The things which we know as matter are either the simple substances 

 known as elements or are compounds formed by the combination of 

 two or more elements. Water, the liquid, is formed by the union of the 

 two elements, hydrogen and oxygen, which in their natural condition 

 are gases. Such miracles are all around us. 



The question before us is. therefore, what elements are found in that 

 matter which we know as the bndy, since it is with these we must deal 

 to keep it in repair. We must know not only what elements compose it. 

 but in what combination these elements must appear in the foods in 

 order to be useful to the body. 



Qiemistry has informed us that the following elements are always 

 found in the body in measurable quantities and that they are therefore 

 probably essential to it: 



These twelve elements are constantly needed in the fo<xl in measurable 

 quantities. A few other are apparently always present and therefore 

 probably also essential but in very minute amouots. 



