274 



GENERAL SCIENCE 



from the fields, and vegetables from the garden. Indirectly plants 

 furnish him meat and milk for food, and provide food for the horse 

 that does his work and carries him to and fro on business and for 

 pleasure. 



Without plants a vast store of the oxygen of the atmosphere would in 

 time become combined with the world's supply of carbon as carbon 

 dioxide gas. 



As result of the storage by plants of solar energy in the manufacture 

 of starch, sugar, cellulose, oils, and proteins, the earth's supply of energy 

 to maintain life and to do much of its work is continuously being 

 replenished. The energy liberated in the human body and in animals 



FIG. 88. The turpentine " orchard ". 



by the process of oxidation, and in the boiler of the steam engine when 

 coal is burned, is but solar energy stored by plants. 



From land surfaces covered by vegetation there is being given back 

 into the air daily by transpiration of plants during the growing season 

 amounts of water computed as tons per acre. 



It must not be overlooked in this connection that paper, which in its 

 varied forms has become so indispensable in modern life, is essentially 

 cellulose, whether made from cotton or linen rags, from wood pulp, or 

 from straw. Making record of the days happenings in newspapers, 

 and of the affairs and thoughts of men as set forth in books, taxes the 

 world's supply of cheap paper-making material. 



