cess of the preservation of plants as fossils is explained, the difficulties and sources of error in the determination of fossil plants are pointed out, and the rules for nomenclature and of priority in it are explained. The systematic part follows these introductory chapters, giving as full descriptions as the condition of the fossils admit, with illustrations—one hundred and eleven in all—of those belonging to the orders Thallophyta, Bryophyta, and Pterodophyta, carrying the subject as far as the Sphenophyllales. Technical as the subject necessarily is, the treatment is clear and, where the matter admits, fluent, so that no student need complain of difficulties in that line.
Dr. W. Detmer's Practical Plant Physiology is a book of experiments for the use of teachers as well as of students in higher grade schools, and supplies an aid to the study of the whole of that branch of the science by experimental processes. While the arrangement of the material in the second German edition is essentially the same as in the first, nearly every section has been enlarged or remodeled, and the book is essentially a new one; new experiments have been included for lecture demonstration or private work, and pains have been taken to render the book increasingly useful to serious students of plant physiology, especially to those who desire to familiarize themselves with methods of research. Great care has been taken in the selection of research material recommended for the experiments; and material suitable for winter work has received attention as well as summer material. This second German edition is presented by the publishers in the translation in its entirety, without addition or alteration. The two great divisions of the book are into the Physiology of Nutrition and the Physiology of Growth and Movements resulting from Irritability. In the first division the experiments bear upon the food of plants (assimilation, production of proteids, constituents of the ash, and organic compounds as food for plants); the molecular forces and processes (including movements of gases, absorption and movements of water, and absorption of mineral substances in plants); and metabolic processes in the plant. In the second division the characteristics of growing plant structures, the conditions necessary for growth, the influence of internal causes and external conditions; geotropic, heliotropic, and hydrotropic mutations, and other phenomena of irritability; the winding of tendrils and twining plants; dorsicentrality, polarity, and anisotropy and phenomena of correlation; and movements of variation, are presented.
- Practical Plant Physiology. An Introduction to Original Research for Students and Teachers of Natural Science, Medicine, Agriculture, and Forestry. By Dr. W. Detmer. Translated from the second German edition by S. A. Moor. London: Swan, Sonnenschein & Co. New York: The Macmillan Company. Pp. 555. Price, $3.
- The Sphere of Science. By Frank Sargent Hoffman, Ph. D. New York: G. P. Putnam's Sons. Pp. 268. Price, $1.50.