CHAPTER IX. 



FEEDS AND FEEDING. 



SECTION LX. THE COMPOSITION OF PLANTS. 



By PROF. J. E. HALLIGAN, 

 Chemist in Charge, Louisiana State Experiment Station. 



Animals live on entirely different substances from 

 plants. The latter require mineral substances and air 

 for existence, while animals use the substances which 

 are stored up by the plants for their food. The sub- 

 stances which the plant stores up in its period of 

 growth are termed dry matter and water. When the 

 water is driven off from plants the dry matter is what 

 remains. If we burn this dry matter a large propor- 

 tion of it passes off in the form of invisible gases. 

 This material which so disappears is known as or- 

 ganic matter. That which is left is the ash or mineral 

 matter. The amounts of organic matter and ash vary 

 in different kinds of plants and grains. The organic 

 matter is composed of protein, fats, nitrogen free ex- 

 tract, and fiber. The ash is made up of soda, phos- 

 phorus, sulphur, potash, lime, sand and other mineral 

 substances. 



Protein. This includes all the nitrogenous com- 

 pounds present in plants. It is represented in the 

 animal by the lean meat, muscles and ligaments which 

 connect the bones, the organic parts of bone, the nerves, 

 the brain and the internal organs. The white of egg, 

 the curd of milk, glue, gelatin, and the gluten of flour 

 approach pure protein in composition. The other 

 constituents, namely, fats, carbohydrates, water and 

 ash, do not contain any protein. 



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