The Great War has caused a vast destruction of the sounder portion of the belligerent peoples and it is certain that in the next generation the progeny of their weaker members will constitute a much larger proportion of the whole than would have been the case if the War had not occurred. Owing to this immeasurable calamity that has befallen the white race, the question of eugenics has ceased to be merely academic. It looms large whenever we consider the means of avoiding a stagnation or even decline of our civilization in consequence of the losses the War has inflicted upon the more valuable stocks. Eugenics is by no means tender with established customs and institutions, and once it seemed likely that its teachings would be left for our grandchildren to act on. But the plowshare of war has turned up the tough sod of custom, and now every sound new idea has a chance. Rooted prejudices have been leveled like the forests of Picardy under gun fire. The fear of racial decline provides the eugenist with a far stronger leverage than did the hope of accelerating racial progress. It may be, then, that owing to the War eugenic policies will gain as much ground by the middle of this century as without it they would have gained by the end of the century. This book could not have been written ten years ago because many of the data it relies on were not then in existence. In view of inquiries now going on, we may reasonably hope that ten years hence it will be possible to make a much better book on the subject. But I am sure that this book is as good a presentation as can be made of eugenics at its present stage of development. The results of all the trustworthy observations and experiments have been taken into account, and the testing of human customs and institutions in the light of biological principles tallies well with the sociology of our times. I cannot understand how any conscientious person, dealing in a large way with human life, should have the hardihood to ignore eugenics. This book should command the attention not only of students of sociology, but, as well, of philanthropists, social workers, settlement wardens, doctors, clergymen, educators, editors, publicists, Y. M. C. A. secretaries and industrial engineers. It ought to lie at the elbow of law-makers, statesmen, poor relief officials, immigration inspectors, judges of juvenile courts, probation officers, members of state boards of control and heads of charitable and correctional institutions. Finally, the thoughtful ought to find in it guidance in their problem of mating. It will inspire the superior to rise above certain worldly ideals of life and to aim at a family success rather than an individual success. EDWARD ALSWORTH ROSS. The University of Wisconsin Madison, Wisconsin July 1918. APPLIED EUGENICS CHAPTER I NATURE OR NURTURE?