Excerpt from An University Text-Book of Botany Continuous change is necessary in order that the material universe may remain in its present condition. Since the amount of matter is constant, it follows that the particles Of matter must be capable Of dissociation and recombination, otherwise, sooner or later, a stable condition is reached which is incompatible with the existence of life. Living organisms, plants and animals, are the most important agents upon the earth in this redistribution of matter. The inert, inorganic substances are decomposed through the activity of living organisms, the components being united with others into the innumerable com pounds of which living substances are composed. The organic com pounds in turn undergo repeated changes Within the organism, which may itself serve as food for others. The simpler compounds result ing from the chemical changes within the organism may remain inert, like the masses of limestone developed from the skeletons of coral polyps, or the fiinty deposits left by the accumulated Shells of Diatoms; or, like carbon-dioxide, they may again be utilized as food for plants. It is the province of biology, in its broadest sense, to study the part played by plants and animals in the economy of nature - their relation to each other and to the inorganic world. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.