HOME ECONOMICS AND EDUCATION 549 



necessary to the body, but it is usually supplied in abundance by 

 beverages. Water forms from 40 to 50 per cent of the ordinary 

 cuts of meat, 10 to 12 per cent of dried seeds, grains and foods pre- 

 pared from them, and 80 to 90 per cent of vegetables and fruits. 

 Many cooked foods contain more water than the raw material due 

 to the manner of cooking them. Compare flour and bread in the 

 above table. In baked, roasted or fried meat the amount of water is 

 diminished in cooking. 



The most important of the actual nutrients has been seen to be 

 protein. This occurs most abundantly in animal foods meat, fish, 

 eggs, and dairy products, and in the dried legumes, as beans and 

 peas. Protein forms 14 to 26 per cent of meats, 28 to 38 per cent 

 of cheese, 18 to 25 per cent of dried legumes and from 7 to 15 per 

 cent of the cereals. Fruits contain only from less than 1 to 5 per 

 cent of protein. Wheat flour has 11 per cent and bread 9 per cent, 

 the decrease being due to the water added in bread making. Fat 

 forms from 10 to 40 per cent of meat, over 80 per cent of salt pork, 

 85 per cent of butter, 25 to 40 per cent of cheese and 10 to 50 per 

 cent of nuts. Carbohydrates form 5 per cent of milk, 70 to 80 per 

 cent of cereals, 60 to 70 per cent of dried legumes and the bulk of 

 the nutrients of vegetables. Mineral matters occur in all the ordi- 

 nary foods one per cent or less in meats, from 0.3 to over 2 per cent 

 in cereals and from 3 to 4 per cent in dried legumes. 



In brief, then, it may be said that meats, fish, eggs, milk, fresh 

 vegetables, and fruits contain the most refuse and water; that pro- 

 tein is most abundant in the animal foods and in the legumes and 

 occurs in considerable quantities in the cereals; that fats occur 

 principally in the animal foods; that carbohydrates are found al- 

 most exclusively in the vegetable product and milk; and that small 

 quantities of mineral matters are found in all food materials. The 

 fuel value varies within wide limits, being greatest in those materials 

 which contain the most fat and the least water. 



DIGESTION, ASSIMILATION, AND EXCRETION. 



We live not upon what we eat, but upon what we digest. Food 

 as we buy it in the market, or even as we eat it, is not usually in 

 condition to be made into body structure or used as body fuel. It 

 must first go through a series of chemical changes by what is called 

 digestion, which prepare it to be absorbed, taken into the blood and 

 lymph, and carried to the parts of the body where it is needed. 

 Digestion takes place in the alimentary canal, partly in the stom- 

 ach, but more in the intestine. As the result, the useless portions 

 are separated and rejected, while the parts which can serve for nutri- 

 ment are changed into forms in which' they can be absorbed, taken 

 into the circulation, and utilized. 



Digestion. The alterations which the food undergoes in di- 

 gestion are brought about by substances called ferments, which are 

 secreted by the digestive organs. The saliva in the mouth has the 

 power of changing insoluble starches into soluble sugar, and helps 

 to fit the food to be more easily worked on by the stomach. The 

 gastric juice of the stomach acts upon protein, and the pancreatic 



