The concluding chapter, while cautious in the discussion of current problems, attempts, assisted by the lessons of the past, to indicate the probable future movement of thought, springing out of present economic conditions. [Footnote X: The Development of English Thought. A Study in the Economic Interpretation of History. By Simon N. Patten, Ph. D. New York: The Macmillan Company. 1899. $3.] Mr. _Wilbur S. Jackman_ has sought in preparing his manual of _Nature Study for Grammar Grades_,[Y] to propose a few of such problems arising in a thoughtful study of Nature as are within the comprehension of grammar-school pupils, and to offer suggestions designed to lead to their solution. Directions may perhaps be given by the teacher--that is, by some teachers, but very few--but even if he knows how, it is hardly possible for him to make them as systematic to so large an extent as would be required by a school of inquiring pupils; and such a plan as the author offers may be accepted as a valuable help. Take, for instance, the first lesson on the mutual relations of plants and insects--as to plants. The student is told what equipment to take, what places to visit; is reminded of seven kinds of evidence in the shape of galls, stings, eaten leaves, etc., to be considered; and is given a list of queries to be recollected in studying the phenomena, in their general aspect, as to the benefit or injury received by the plant from insects, the attractions it offers, and the defenses it possesses, with "number work" relating to the extent of the depredations, and methods of representing the results of the study in picture. The book contains forty-five such lessons on different aspects of Nature. [Footnote Y: Nature Study for Grammar Grades. A Manual for the Guidance of Pupils below the High School in the Study of Nature. By Wilbur S. Jackman. Danville, Ill.: The Illinois Printing Company. Pp. 407.] In the preparation of his book on _Fertilizers_[Z] it has been the aim of Mr. _Voorhees_ to point out the underlying principles and to discuss, in the light of our present knowledge of the subject, some of the important problems connected with the use of fertilizing materials. While the author recognizes the lack of definite knowledge on many vital points, he considers it desirable, when the investigations of the experiment stations are becoming so important and they are so well prepared to study the fundamental principles of plant nutrition, for the practical man to have a clear understanding of what is now known. The book treats of the natural fertility of the soil and the sources of the loss of the elements of fertility, the functions of manure and fertilizers and the need of artificial ones, the different classes of fertilizers, the chemical analysis of them, and the methods of using them with their special application to various crops.