Chapter I: Preface

This little book has been written chiefly for the use of students in the Medical Department of the Columbian University. It is designed to serve only as an _introduction_ to the study of the Development Theory, and the subject has been presented, it is hoped, in a manner that will render it interesting and easily intelligible to the general reader.

The doctrine of Evolution itself enters so largely into all those departments of knowledge that especially concern the human race, and it has so profoundly modified our ideas with regard to the origin and destiny of man, that it has attained a commanding interest and become an almost necessary ingredient in what is called a liberal education.

An overwhelming majority of Anthropologists, Zoölogists, and Botanists, and a goodly number—constantly increasing—of Christian clergymen and laymen, have been almost compelled to believe in the truth of the Evolution Theory, whether they would or not, and they cannot but realize how very widely the theory extends into almost every department of human knowledge. No one, therefore, who aspires even to a moderate degree of intellectual culture, can well afford to exclude a clear understanding of what this Doctrine of Evolution really is. It is hoped this little work will render such a conception easily attainable.

The author makes no claim for originality, unless it be in the _manner_ of presenting the subject. He has utilized the facts collated by other observers, and sometimes quoted the exact language and expressions of well-known writers on Evolution, and has endeavored to put them together in a way that may be helpful to those who are beginning the study of the Evolution Theory.

No attempt has been made to prove the truth of the theory: this is assumed. The arguments in support of it are coextensive with our knowledge of Comparative Anatomy, Embryology, Physiology, Psychology, and many other sciences.

In the preparation of the book the author is especially indebted to his friend Prof. Theodore Gill, the eminent ichthyologist, for many valuable suggestions, and more particularly for his aid in constructing the Diagram of Development. He also desires to thank his friend Dr. A. F. A. King for his kindly assistance in preparing the manuscript for the press; and also his friend Dr. L. O. Howard, Chief of the U. S. Bureau of Entomology, for much valuable information and assistance.

D. K. SHUTE.

August 1, 1899, 1318 L Street, N. W., Washington, D. C.

CONTENTS.

PAGE

INTRODUCTION xiii
System of Classification xiv
Definition of Evolution xv

SECTION I.

ORGANIC CELLS: THE VISIBLE UNITS OF LIFE 3
Structure and Composition of Cells 4
Activities of Cells 7
Examples of Unicellular Animals and Plants 10
Mitosis 25
Maturation of the Human Ovum 29
Fertilization of the Human Ovum 29, 42
Segmentation of the Oösperm 31
Gastrulation 32

SECTION II.

HEREDITY WITH VARIATION 39
Examples of Variations 39
Illustrations of Heredity 40
Nucleus in Heredity 41
Heritages 47
Pseudo-Heredity 53
Environment and Variations 55
Acquired Characters 65
Pangenesis 66
Continuity of Germ-Cells 67
Modified Pangenesis 68
Heredity Stronger than Environment 75

SECTION III.

UNSTABLE ENVIRONMENT 81
Development of North America 85
Archæan Era 85
Palæozoic Era 86
Silurian Period 87
Devonian Period 87
Carboniferous Period 87
Jurassic Period 88
Cretaceous Period 88
Tertiary Period 89
Quaternary Period 89

SECTION IV.

TRANSMUTATIONS OF LIVING FORMS 93
Archæan Era 94
Table of Stratified Rocks and the Successive
Appearance of Typical Life-Forms 95
Cambrian Period 96
Lower Silurian Period 96
Upper Silurian Period 98
Devonian Period 100
Carboniferous Period 102
Permian Period 104
Triassic Period 105
Jurassic Period 106
Cretaceous Period 108
Tertiary Period 110
Quaternary Period 113

SECTION V.

NATURAL SELECTION 119
Artificial Selection 120
Multiplication of Animals 122
Elimination of the Unfit 125
The Coloration of Animals and Environment 127
Protective Coloration 128
Protective Resemblance 138
Alluring Coloration 141
Warning Coloration 144
Mimicry 147
Recognition Marks 150
Sexual Selection 152
Insect Selection 160
Isolation of Varieties 166

SECTION VI.

EVOLUTION OF MAN 173
Development of the Frog 173
Development of Man 180
Useless Scaffolding in Man 191
Development of the Brain 199
The Brain and Psychic Phenomena 206
Evolution and Social Problems 222