I. GENERAL ACTIVITIES OF LIVING ORGANISMS.<br><br>The casual observer, even if he watches thoughtfully the various activities of plants and animals, would hardly believe these activities capable of classification into two general classes. He notes the germination of the plant seed and its early growth, step by step approaching a stage of maturity; it blossoms, produces seed, and if it is an annual plant, withers and dies. If it is a perennial plant its leaves only, wither and die at the approach of winter, the plant passing into a resting stage from which it awakes the following spring to repeat again its annual cycle.<br><br>If he observes an animal he finds that it similarly develops to a stage of maturity, reproduces its kind, withers and dies; but incident to these general activities he notes numerous others that seem to have no relation to the activity of the plant. He sees men tilling the fields, felling the forests, building houses, factories and railroads; …
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