PART III. 



THE NUTRITION OF THE TISSUES. 



SECTION I. 



The Supply of Energy and Material to the Body. 



THE FOOD. 



CONSTITUENTS OF THE FOOD. 



The nature of the requirements of the energy and material 

 have been considered. The supply of these in the food 

 must now be studied. 



The different constituents of food-stuffs may be classified 

 as : — A. Those supplying energy. 



(1) Nitrogenous compounds. 



(2) Fats. 



(3) Carbohydrates. 



B. Those supplying no energy. 



(4) Ash (inorganic elements). 



(5) Water. 



(6) Accessory factors. 



A. Food-Stuffs yielding Energy. 



1. Nitrogenous Compounds. 



Nitrogenous compounds are divided into two classes, 

 viz. (rt) proteins, and (6) soluble nitrogenous compounds. 



(a) Proteins. — The chemistry and nature of these have 

 been already discussed (p. 14). 



Occurrence. — Proteins form the chief and characteristic 



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