ike the facts of the lower organic world.

It may seem that the biologist is straying beyond his subject when he
undertakes to extend the principles of organic evolution to those
possessions of mankind that seem to be unique. The task was undertaken in
the Hewitt Lectures because the writer holds the deeply grounded
conviction that evolution has been continuous throughout, and that the
study of lower organic forms where laws reveal themselves in more
fundamental simplicity must lead the investigator to employ and apply
those laws in the study of the highest natural phenomena that can be
found. Another motive was equally strong. Too frequently men of science
are accused of restricting the application of their results to their own
particular fields of inquiry. As individuals they use their knowledge for
the development of world conceptions, which they are usually reluctant to
display before the world. It is because I believe that the accusation is
often only too well merited that I have endeavored to show as well as
circumstances permit how universal is the scope of the doctrine based upon
the facts of biology, and how supreme are its practical and dynamic
values.

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