It remains only to state that the present volume contains nothing new, either in fact or in principle; the particular form and mode of presenting the evolutionary history of nature may be considered as the author's personal contribution to the subject. Nothing has been stated that has not the sanction of high authority as well as of the writer's own conviction; but it will be clear that the believers in the truth of the analysis as made in the later chapters may become progressively fewer, as the various aspects of human life and of human nature are severally treated. Nevertheless, I believe that this volume presents a consistent reasonable view that will not be essentially different from the conceptions of all men of science who believe in evolution. CONTENTS CHAPTER PAGE I. EVOLUTION. THE LIVING ORGANISM AND ITS NATURAL HISTORY 1 II. THE STRUCTURE AND DEVELOPMENT OF ANIMALS AS EVIDENCE OF EVOLUTION 35 III. THE EVIDENCE OF FOSSIL REMAINS 73 IV. EVOLUTION AS A NATURAL PROCESS 106 V. THE PHYSICAL EVOLUTION OF THE HUMAN SPECIES AND OF HUMAN RACES 150 VI. THE MENTAL EVOLUTION OF MAN 197 VII. SOCIAL EVOLUTION AS A BIOLOGICAL PROCESS 241 VIII. EVOLUTION AND THE HIGHER HUMAN LIFE 278 INDEX 313 I EVOLUTION. THE LIVING ORGANISM AND ITS NATURAL HISTORY The Doctrine of Evolution is a body of principles and facts concerning the present condition and past history of the living and lifeless things that make up the universe. It teaches that natural processes have gone on in the earlier ages of the world as they do to-day, and that natural forces have ordered the production of all things about which we know.