268 



RELATION OF FOOD TO NUTRIMENT. 



Elements of Food The body requires, for the mainten- 

 ance of its existence, for its growth and for the performance of its 

 functions, a variety of kinds and a variety of forms of food ; but as 

 its constituent elements are limited in number, the chemical com- 

 position of the food need not include a great variety of factors. 

 Carbon, hydrogen, oxygen and nitrogen exist in far larger quantity 

 than any other elements ; sulphur and phosphorus are also pres- 

 ent; but other constituents exist in only exceedingly small quanti- 

 ties. Food should, therefore, supply all these requirements in dif- 

 ferent combinations, if the body is to be maintained in health. It 

 is not, however, necessary that one kind of food should yield every 

 kind of material required in the structure of the body, for then that 

 one would be sufficient; but it is essential that it contain some of 

 the material required, and it is also essential that by the combina- 

 tion of different foods all the material required is supplied. Some 

 foods are undoubtedly more valuable than others, either because 

 they supply a large quantity of nutriment in a small compass or 

 because it is in such a state that it can be easily assimilated. These 

 are, of course, to be preferred when the functions of the body are 

 deranged by disease. 



Food is required by the body for two chief purposes, viz. : To 

 produce and maintain the various tissues while they are fulfilling 

 their divers vital functions, and to generate heat, without which life 

 would cease. That the maintenance of the tissues is of great im- 

 portance is evident from the decay of life which is invariably as- 

 sociated with the wasting of the tissues. That the generation of 

 heat is essential is evident from the fact that, while waste of tissues 

 may go on for a long period before death occurs, the removal or 

 lessening of heat is soon followed by the termination of life. When 

 the body is in a state of disease we nave therefore to meet these two 

 principal requirements the maintenance of tissue and the main- 

 tenance of heat. Now, in accordance with these requirements, there 

 are foods which are assimilated by particular tissues and go to 

 maintain them, called in general terms "flesh-formers;" others 

 sustain the vital heat and are known as "heat-formers;-" others 

 again both nourish tissue and supply heat. 



Animal and Vegetable Products Food is derived from 

 all natural sources from earth, water and air; from solids, liquids 

 and gases ; from substances living and organic, or inanimate and 

 inorganic. The food thus variously derived is converted, by the 

 action of vital forces, into those compounds which the body can 

 assimilate and change into a part of itself. But before it can be so 

 assimilated in the human body, the greater part of it must become 

 organic. Chemical elements uncombined are of no service as food. 

 They must be built up into some living organism to be of service. 

 Hence our food generally consists of animal and vegetable pro- 

 ducts, the animal having been also previously derived from the veg- 

 etable. Indeed, all our foods are primarily derived from the veget- 



