Prof. _John M. Coulter's Plant Relations_[20] is one of two parts of a system of teaching botany proposed by the author. Each of the two books is to represent the work of half a year, but each is to be independent of the other, and they may be used in either order. The two books relate respectively, as a whole, to ecology, or the life relations of surroundings of plants, and to their morphology. The present volume concerns the ecology. While it may be to the disadvantage of presenting ecology first, that it conveys no knowledge of plant structures and plant groups, this disadvantage is compensated for, in the author's view, by the facts that the study of the most evident life relations gives a proper conception of the place of plants in Nature; that it offers a view of the plant kingdom of the most permanent value to those who can give but a half year to botany; and that it demands little or no use of the compound microscope, an instrument ill adapted to first contacts with Nature. The book is intended to present a connected, readable account of some of the fundamental facts of botany, and also to serve as a supplement to the three far more important factors of the teacher, who must amplify and suggest at every point; the laboratory, which must bring the pupil face to face with plants and their structure; and field work, which must relate the facts observed in the laboratory to their actual place in Nature, and must bring new facts to notice which can be observed nowhere else. Taking the results obtained from these three factors, the book seeks to organize them, and to suggest explanations, through a clear, untechnical, compact text and appropriate and excellent illustrations. [20] Plant Relations. A First Book of Botany. By John M. Coulter. New York: D. Appleton and Company. (Twentieth Century Text Books.) Pp. 264. Price, $1.10. The title of _The Wilderness of Worlds_[21] was suggested to the author by the contemplation of a wilderness of trees, in which those near him are very large, while in the distance they seem successively smaller, and gradually fade away till the limit of vision is reached. So of the wilderness of worlds in space, with its innumerable stars of gradually diminishing degrees of visibility--worlds "of all ages like the trees, and the great deep of space is covered with their dust, and pulsating with the potency of new births." The body of the book is a review of the history of the universe and all that is of it, in the light of the theory of evolution, beginning with the entities of space, time, matter, force, and motion, and the processes of development from the nebulæ as they are indicated by the most recent and best verified researches, and terminating with the ultimate extinction of life and the end of the planet. In the chapter entitled A Vision of Peace the author confronts religion and science. He regards the whole subject from the freethinker's point of view, with a denial of all agency of the supernatural.