388 THE HUMAN BODY 



the traces of flavoring matters which cause certain things to be 

 especially sought after and so raise their market value. We can- 

 not, however, conclude that the possession of flavor by foods is 

 wholly unnecessary. We shall see that the accessories play a very 

 real and very important role in our use of foods in general. 



Occurrence of Inorganic Materials in Food. Two inorganic sub- 

 stances, water and sodium chlorid (common salt), are taken 

 separately and consciously as constituents of the diet. We re- 

 quire such large amounts of these substances that they have to be 

 taken thus purposely to insure that enough be gotten. The other 

 inorganic materials, the chlorids, phosphates, and sulphates of 

 potassium, magnesium, and calcium, occur in most ordinary arti- 

 cles of diet, so that we do not swallow them in a separate form. 

 Phosphates, for example, exist in nearly all animal and vegetable 

 foods; while other foods, as casein, contain phosphorus in com- 

 binations which in the Body yield it up to be oxidized to form 

 phosphoric acid. The same is true of sulphates, which are partially 

 swallowed as such in various articles of diet, and are partly formed 

 in the Body by the oxidation of the sulphur of various proteins. 

 Calcium salts are abundant in bread and milk, and are also found 

 in many drinking-waters. It has been maintained that salt, as 

 such, is an unnecessary luxury; and there seems some evidence 

 that certain savage tribes live without more than they get in 

 the meat and vegetables they eat. Such tribes are, however, 

 said to suffer especially from intestinal parasites; and there is 

 no doubt that to civilized man the absence of salt is a great 

 privation. 



Occurrence of Accessories in Food. Variety in the diet depends 

 practically altogether upon the accessories, for the primary food- 

 stuffs are few in number and for the most part without very pro- 

 nounced tastes or flavors, with the single exception of sugar, whose 

 sweet taste makes it, to the eyes of most children at least, the 

 most desirable of all foods. To civilized man variety of diet is a 

 virtual necessity ; the accessories, therefore, are to him of great im- 

 portance. Both meats and vegetables owe their characteristic 

 flavors, in the main, to organic substances present in them. We 

 do not, however, depend wholly on these substances for securing 

 the needed variety in our food. Condiments, pepper and mustard 

 for example, and spices are used very largely in all civilized coun- 



