CHAPTER XVII 

 THE COMPOSITION OF PLANTS AND ANIMALS 



The plant as a source of food is of great interest to feeders 

 of live stock. All our farm animals eat green plants with 

 relish, just as a man enjoys celery. When plants are properly 

 dried and cured as hay, their value for feed is not thereby 

 affected. All of our grains are products of plants; and from 

 these directly, or indirectly by milling, do we obtain some of 

 our most valuable feeds for farm animals. So the facts are 

 that the plant, in one form or another, really furnishes our 

 horses, cattle, sheep, swine, and poultry with about all of 

 their food. 



The material of which plants are made is taken from both 

 soil and air, but largely from the soil. Like animals, plants 

 must have food. The chemist tells us that all matter is 

 composed of elements, about 13 of which provide food for 

 the plants. The names of some of these are common, such 

 as iron, sulphur, and phosphorus. There are four others: 

 Carbon Oxygen 



Hydrogen Nitrogen 



that are also important. Besides these, the plant needs 

 potassium, calcium, sodium, magnesia, chlorin, and silica. 

 Most of these elements are found in different combinations in 

 the soil, more or less dissolved in the water. By means of its 

 roots, the plant takes up the water and so carries this food 

 through all its various parts. As this water or sap 

 moves through the structure of the plant cells, the food in 

 solution is used to promote growth. Carbon, oxygen, 

 nydrogen, and nitrogen are gases in the air. The first two 



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