This volume deals with some of the fundamental problems of biology, and presents a series of views (the results of nearly thirty years of study), which the author has correlated for the first time in systematic form. 22.--+The Interpretation of Nature.+ By C. LLOYD MORGAN, LL. D., F. R. S. Crown 8vo. Net, $1.25. Dr. Morgan seeks to prove that a belief in purpose as the causal reality of which Nature is an expression is not inconsistent with a full and whole-hearted acceptance of the explanations of naturalism. 23.--+Mosquito Life.+ The Habits and Life Cycles of the Known Mosquitoes of the United States; Methods for their Control; and Keys for Easy Identification of the Species in their Various Stages. An account based on the investigation of the late James William Dupree, Surgeon-General of Louisiana, and upon the original observations by the Writer. By EVELYN GROESBEECK MITCHELL, A.B., M.S. With 64 Illustrations. Crown 8vo. Net, $2.00. This volume has been designed to meet the demand of the constantly increasing number of students for a work presenting in compact form the essential facts so far made known by scientific investigation in regard to the different phases of this, as is now conceded, important and highly interesting subject. While aiming to keep within reasonable bounds, that it may be used for work in the field and in the laboratory, no portion of the work has been slighted, or fundamental information omitted, in the endeavor to carry this plan into effect. 24.--+Thinking, Feeling, Doing.+ An Introduction to Mental Science. By E. W. SCRIPTURE, Ph.D., M.D., Assistant Neurologist Columbia University, formerly Director of the Psychological Laboratory at Yale University. 189 Illustrations. 2d Edition, Revised and Enlarged. Crown 8vo. Net, $1.75. "The chapters on Time and Action, Reaction Time, Thinking Time, Rhythmic Action, and Power and Will are most interesting. This book should be carefully read by every one who desires to be familiar with the advances made in the study of the mind, which advances, in the last twenty-five years, have been quite as striking and epoch-making as the strides made in the more material lines of knowledge."--_Jour. Amer. Med. Ass'n._, Feb. 22, 1908. 25.--+The World's Gold.+ By L. DE LAUNAY, Professor at the École Superieure des Mines. Translated by Orlando Cyprian Williams. With an Introduction by Charles A. Conant, author of "History of Modern Banks of Issue," etc. Crown 8vo. Net, $1.75. M. de Launay is a professor of considerable repute not only in France, but among scientists throughout the world. In this work he traces the various uses and phases of gold; first, its geology; secondly, its extraction; thirdly, its economic value.