872 Rural School Leaflet 



FOOD 

 Layton S. Hawkins 



(State Education Department) 



We all know that food is necessary for the life 

 of plants and animals. Plants make their own 

 food from the materials that they get from the 

 air and the soil. Animals cannot do this, but 

 must use the food manufactured by plants. Some 

 ani:nals obtain this food directly from the plants, 

 others from animals that have in turn lived on 

 plants. Thus we see that all food really comes from the same source. 



(i) Name all the animals that you know use only plants for food; all 

 that use only animals; all that use some of each. 



(2) Name two common domestic animals that now use both vegetable 

 and meat food, but whose ancestors were exclusively flesh eaters. 



All foods are a mixture or combination of several substances, called 

 nutrients. These nutrients are three in number: (i) proteins, or proteids; 

 (2) carbohydrates; (3) fats, or oils. In addition to these nutrients nearly 

 all foods contain some mineral matter, as salt, lime, and the like. You 

 will remember Professor Rice told you last year that nearly nine tenths 

 of the white of the egg is protein. * Carbohydrate is a term applied to 

 starches and sugars. Starch in nearly pure form is found in the potato 

 and in cornstarch. Unfortunately for our understanding of all these nutri- 

 ents, they are not always found in so separate a form as is the protein in 

 the egg or the starch in the potato. In some cases they are combined in 

 such a way that only the chemist can separate them. 



Our diet or the ration of a cow means the total amount of food eaten 

 in twenty-four hours. A balanced diet or ration is one in which the 

 proper proportion of the above nutrients is maintained. (A well-balanced 

 diet contains 10 to 15 per cent of the nutrients as protein, 25 to 40 per 

 cent as fat, 40 to 60 per cent as carbohydrates. A well-balanced ration 

 contains 12 to 20 per cent as protein, 3 to 5 per cent as fat, 80 to go per 

 cent as carbohydrates [see page 75].) Many of our common foods are 

 also fed to animals. Look up tables that show the relative amount of 

 the various nutrients in our common foods, f 



Protein foods build up the muscular tissues. They form new tissues 

 in young, growing, and developing animals and replace the torn-down and 



♦Rural School Leaflet, September, 1911, page 139. 

 t In almost any physiology. 



