=112. The value of soil surveys.= The full appreciation of the preeminent value of water-content, particularly of the chresard, greatly simplifies the ecological study of soils. The ecologist is primarily concerned with soil water only in its relation to the plant, and while a fair knowledge of soil structure is essential to a proper understanding of this, he has little concern with the detailed study of the problems of soil physics. For the sake of a proper balance of values, he must avoid the tendency noted elsewhere of ignoring the claims of the plant, and of studying the soil simply as the seat of certain physical phenomena. Accordingly, it is felt that mechanical and chemical analyses, determinations of soluble salt-content, etc., have much less value than has been commonly supposed. The usual methods of soil survey, which pay little or no attention to water-content, and none at all to available water, are practically valueless for ecological research. This statement does not indicate a failure to appreciate the importance of the usual soil methods for many agricultural problems, such as the use of fertilizers, conservation of moisture, etc., though even here to focus the work upon water-content would give much more fundamental and serviceable results. For these reasons, slight attention will be paid to methods of mechanical and chemical analysis. In their stead is given a brief statement of the origin, structure, and character of soils with especial reference to water-content.