_The Science of Growing Timber._ In order to better understand the many diversified problems which are being studied at the Forest Experiment Stations, it is necessary to give the reader a few ideas concerning the science of forest ecology. This science is the basis of all problems dealing with the growing of timber and is therefore a study of the utmost importance to forestry. Forest ecology is the study of the relations of trees and forests to their surroundings. By surroundings (or environment) we mean all the factors which influence their growth and reproduction, such as soil temperature, soil moisture, soil texture, rainfall, light, wind, air temperature, relative humidity, altitude, slope, exposure, and surface. Forests, we must remember, are not warehouses of standing logs; they are not merely aggregations of individual trees; but they are complex communities of living organisms, which are affected in many ways by climate and soil and which, in turn, affect in no small degree the climatic and soil conditions in their immediate vicinity. The forester cannot treat the forest as an aggregation of individuals, for forests have laws which govern their behavior which are entirely different from those that govern the individual tree. Some foresters and botanists prefer to call this science by the name of "tree sociology," and they compare it with human sociology. Individuals, as we well know, are governed by different natural laws than communities. Just so with trees and forests. In order, therefore, to grow a never-failing supply of timber intelligently and economically we must understand these complex organisms and communities, we must study their behavior under different soil and climatic conditions and ascertain the conditions under which they grow best. Only by doing this can the forester achieve all the objects of forestry, namely, to help Nature to produce more and better timber, in a shorter length of time and at the smallest possible cost. The experimental work of the Forest Experiment Stations is grouped under such categories as these: dendrological studies, forestation studies, studies in forest influences, studies relating to forest management, studies in forest protection, commercial tree studies, and grazing studies.