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Yes, the changing of water, air and earthy substances 

 into vegetable material is useful, and in growth the 

 vegetable matter is again wrought into many beautiful 

 forms. 



The one great service which plants render the ani- 

 mal kingdom is the purification of the air: this is the 

 effect above referred to. When animals are breathing 

 they take in oxygen which they need to keep the blood 

 pure, and cast off carbonic acid: this is not fit to be 

 taken again into the system, and were it to accumulate 

 in the air to any extent animals could not live. This 

 is where plants perform their great service: they need 

 the carbon and absorb it, and it goes to their various 

 parts and nourishes them, while the oxygen formed by 

 the combination is given out fresh and pure, thus 

 making a complete and thorough change in the atmos- 

 phere and keeping it in a state of purity by the con- 

 stant circulation. 



This is not the only way in which plants are and 

 may be used. When large, like trees, they are made 

 into lumber, which is absolutely necessary in the con- 

 struction of buildings and furniture. Our best walnut 

 articles, and also mahogany and rosewood, are all made 

 from what was once a small weak plant. They also 

 furnish us with tools and utensils, and an infinite num- 

 ber of other articles. 



The greater portion of the food of man and the low- 

 er animals is furnished by plants. Considerable of 

 the material used in the manufacture of clothing is 

 obtained from plants, such as cotton and silk: the silk 

 although made by the silkworm in reality comes from 

 the fibers of the mulberry leaf upon which they feed. 



