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274 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.

Mr. Wilbur S. Jackman has sought in preparing his manual of Nature Study for Grammar Grades, 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.

In the preparation of his book on Fertilizers 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.

We have received, with only a short interval between them, the first volume of a third edition and the fourth or last volume of the second edition of Alfred H. Allen's Commercial Organic Analysis. The former volume is first to reach us. It is a high testimony to the value of the work in itself that the publication of a rival issue of the edition of 1885 had been begun by another house, although its age, as suggested by the date, would indicate that it had much need of revision. During the thirteen years since the publication of this edition later research has thrown new light on many features of the science and processes, and has corrected many of the old conceptions, and the author's views on some points have changed in the light of the more recent results, so that the preparation of a new edition had become necessary. Mr. Allen has found it now impossible for him to undertake the continuous labor which would be imposed by such a task, and the work of revision has been undertaken by Henry Leffmann, of Philadelphia. For this new edition Mr. Allen