“I am much pleased with it and congratulate you upon securing so excellent a treatment. It is one of the most readable scientific books I have, and goes unerringly to the fundamentals of our most recent advances in the experimental study of heredity as well as those of the older studies.”--PROFESSOR GEORGE H. SHULL, Cold Spring Harbor, Long Island, N. Y. “There was a decided need for just such a work. The book strikes me as most excellently done.”--PROFESSOR H. S. JENNINGS, Johns Hopkins University. THE MACMILLAN COMPANY =Publishers= =64-66 Fifth Avenue= =New York= The Fitness of the Environment BY LAWRENCE J. HENDERSON Assistant Professor of Biological Chemistry in Harvard University _Cloth, 12mo, $1.50 net_ “Darwinian fitness is compounded of a mutual relationship between the organism and the environment. Of this, fitness of environment is quite as essential a component as the fitness which arises in the process of organic evolution; and in fundamental characteristics the actual environment is the fittest possible abode of life.” Such is the thesis which this work seeks to establish through discussions of the physical and chemical characteristics of life and cosmogony, and through critical study of the properties of matter in their biological relations. Water and carbonic acid are shown to be the primary constituents of the environment. Analysis shows their properties, together with those of the component elements, hydrogen, oxygen, and carbon, to make up a series of maxima, among all known compounds and elements, so numerous, so varied, and so highly favorable, to the organic mechanism that the fitness of the world for life assumes an importance not less than the fitness which has been won by adaptation in the course of organic evolution. A final chapter discusses the bearing of these conclusions upon theories of organic evolution, modern vitalism, including the views of M. Bergson, and the old natural theology, and seeks to harmonize implications of design with the mechanistic view of nature. THE MACMILLAN COMPANY =Publishers= =64-66 Fifth Avenue= =New York= COLLEGE ZOÖLOGY By ROBERT W. HEGNER, Ph.D. Assistant Professor of Zoölogy in the University of Michigan _Illustrated, Cloth, 12mo, xxiv + 733 pp., $2.60 net_