There has been a widespread request that a book containing the most recent developments in and contributions to science be included in the Modern Library. In this book Professor Harrow, the author of "From Newton to Einstein" and "Vitamines" includes the important articles that have been written on science in the last decade. In the volume are included "The Physiology of the Aviator," "Conceptions and Misconceptions in Psychoanalysis," "Natural Death and Duration of Life," "Einstein's Law of Gravitation" etc. Each article is written by a scientist who is an authority in his own particular field, and the text is so live and important that we feel this volume is an eminent addition to the Modern Library.