40 FARM ANIMALS 
found in all parts of the body and is as essential for the development 
of solid tissue as any of the other ingredients. Young and grow- 
ing animals, like young and growing plants, contain the highest per- 
centage of water. As the animal matures the proportion of water 
diminishes until it reaches about one-half of the total weight. 
9. Crude fiber serves as a framework of the plant. It 
is to the plant what bones and skeleton are to the animal. 
It is made of carbon, hydrogen and oxygen. These ele- 
ments are the same that form starch. Immature and 
young plants are tender because the crude fiber is tender; 
as the plant matures, the fiber hardens and toughens—as 
found in hay and corn stover and trees. 
10. Groups of plant constituents.—Plants consist of 
many compounds. While there are physical differences, 
the chemical elements are invariably united in definite 
combinations producing definite compounds. For the 
sake of convenience these may be grouped as follows: 
I. Ash. 
Il. Water 
III. Protein or compounds containing nitrogen. 
IV. Nitrogen-free compounds,* or compounds containing no nitro- 
gen, such as starch, crude fiber, sugar, gums, etc. 
V. Ether extract, or oil, or fat. 
11. Plants and animals compared.—From the stand- 
point of composition one difference between a plant and 
an animal is in the fact that the former contains carbo- 
hydrates and the latter does not. When the soil ele- 
ments are taken into the plant they lose their individual 
identity, and, united in various ways, decome organized 
compounds. They are no longer carbon, hydrogen and 
oxygen, but starch or sugar or oil; or, if nitrogen and sul- 
phur are added, they become protein compounds. The 
plant has now fulfilled its destiny and is ready to be used 
as food for the support of animal life. 
*These being derived from the same elements, and having the same fuel value 
when assimilated by an animal, are usually termed carbohydrates. The carbohydrates 
are formed of carbon, hydrogen and oxygen; the last in proportion to form water, 
hence the name. 
