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the establishment of the cell theory by Schieden and Schwann in 1838-'40, it has been recognized that a clear understanding of the processes which go on in the body, both physiological and pathological, and of their relations to parent and offspring, can only be obtained through a study of the cell. This study has thrown new light on many obscure points in heredity, and has revolutionized our theories of the "vital process." Such books as the one before us are the cause as well as the result of such investigations—through their attractiveness stimulating the student to renewed effort. This one is a series of micro-photographs taken from sections of the eggs of the sea urchin and so arranged as to illustrate the principal phenomena in the fertilization and early development of the animal egg. The photographic reproductions are accompanied by a critical description and drawings illustrating every stage, and are preceded by a simple introductory account of the recent history and growth of the science. The refined histological technique and the manual skill necessary for original work of this quality are rarely at the command of the student. He has to get his knowledge from text-books, hence an accurate reproduction of the various specimens is quite essential. The photographs in this work were taken with especial care, not retouched, and reproduced in the prints as closely as possible. The book is unique in containing the first satisfactory series of photographic representations of the early history of the ovum. Prof. Wilson is to be congratulated both as to his own work and in having so skillful a collaborator as Dr. Learning.

The author of this book, who is the instructor in physics in the English High School of Boston, has been before the public as an author of text-books on physics for the past thirteen years. His latest production is characterized by a fullness which he intends to be a protest against "smaller books," "cheaper books," and "primers of science." "Education in physics," he affirms, "implies the presentation of the great truths of that science in their unmutilated form, the indication of their relations to one another, and the furnishing the student an opportunity of observing and exercising the logical processes that have led to the discovery of those truths. Any text-book that aims to introduce the student to a study of such importance and such inexhaustible possibilities should not lose sight of this truth and encourage mere dilettanteism." Accordingly, he supplements his statement of physical laws by a store of concrete applications and other illustrative matter. The book contains a "high-school" course and an "advanced" course, the latter comprising the former and additional matter distinguished by indenting. Some illustrative experiments are given, but the work is not intended to serve as a laboratory manual. A considerable number of problems and exercises have been inserted, a key to which is furnished to instructors. There are nearly five hundred illustrations, and a colored chart showing spectra and combinations of colors.

An experimental laboratory has, with the growth of modern methods of teaching, become almost a necessity in the study of botany. The book before us is designed to aid and direct experimental study. As to the scope of his book the author says: "With the rapid advance of investigation it is next to impossible that an elementary laboratory manual should include the latest results, especially when the essential points of many of them may yet be in controversy, and need the critical treatment which is certainly not within the province of a work of this character. In the hands of an instructor in touch with current botanical thought such deficiencies are easily supplied. The present work consists of a series of