68 THE PHYSIOLOGY OF DIGESTION AND ABSORPTION 



Protein 12.2 per cent. 



Sugar 0.5 per cent. 



Fats -} 



Lecithin t Traces. 



Choiesterin | 



Inorganic salts 0.6 per cent. 



Meats: 



Ox. Calf. Pig. Fowl. Pike. 



Water 76.7 75.6 72.6 70.8 79.3 



Solids 23.3 24.4 27.4 29.2 20.7 



Proteins 20.0 19.4 19.9 22.7 18.3 



Fats ... s 1.5 2.9 6.2 4.1 0.7 



Carbohydrates . . 0.6 0.8 0.6 1.3 0.9 



Salts 1.2 1.3 i.i i.i 0.8 



Vegetable Foods: 



Wheat. Barley. Oats. Rice. Peas. Potatoes. 



Water 13.6 13.8 12.4 13.1 14.8 76.0 



Protein 12.4 n.i 10.4 7.9 23.7 2.0 



Fat 1.4 2.2 5.2 0.9 1.6 0.2 



Starch 67.9 64.9 57.8 76.5 49.3 20.6 



Cellulose ... 25 5.3 11.2 0.6 7.5 0.7 



Mineral salts 1.8 2.7 3.0 i.o 3.1 i.o 



DIGESTION. 



Object. Digestion is largely a chemical process. Certain 

 physical phenomena are auxiliary. The foods not yielding 

 energy are not affected in a chemical way by digestion. They 

 are simply dissolved, if not already in solution, and are dis- 

 charged from the body in the same condition in which they 

 entered. But the other classes of food must either be separ- 

 ated from innutritions substances with which they enter, or 

 undergo certain changes themselves, or both, before they 

 can be absorbed and assimilated. This necessitates a com- 

 plicated digestive apparatus and the subjecting of different 

 classes of food to different digestive fluids and other gastro- 

 intestinal influences. The object of digestion is therefore 

 twofold, first, to convert the foods into soluble materials and, 



