| FIG. | PAGE | |
| 1. | Diagram of a Cell. (Drawn by Mr. E. P. Copeland from a sketch by the Author.) | 5 |
| 2. | Stylonychia. (Drawn by Mr. E. P. Copeland.) | 9 |
| 3. | Amœba. (Drawn by Mr. E. P. Copeland.) | 11 |
| 4. | Rotalia. (Drawn by Dr. A. L. Lawrence.) | 12 |
| 5. | Difflugia. (Drawn by Dr. A. L. Lawrence.) | 17 |
| 6. | Noctiluca. (Drawn by Dr. A. L. Lawrence.) | 18 |
| 7. | Gromia. (Drawn by Dr. A. L. Lawrence.) | 21 |
| 8. | Diagram Illustrating Mitosis. (Drawn by Mr. E. P. Copeland from a sketch by the Author.) | 26 |
| 9. | Diagram Illustrating the Maturation and Fertilization of the Ovum. (Drawn by Mr. E. P. Copeland from a sketch by the Author.) | 30 |
| 10. | Diagram Illustrating Segmentation and Gastrulation. (Drawn by Mr. E. P. Copeland from a sketch by the Author.) | 34 |
| 11. | Archæan North America. (From a drawing in Shaler’s “First Book in Geology.”) | 84 |
| 12. | Cretaceous North America. (From a drawing in Shaler’s “First Book in Geology.”) | 86 |
| 13. | Tertiary North America. (From a drawing in Shaler’s “First Book in Geology.”) | 89 |
| 14. | Genesis of Horse’s Feet. (Drawn by Mr. E. P. Copeland.) | 112 |
| 15. | Bipes, Cheirotes, and Snake. (From a drawing in Shaler’s “First Book in Geology.”) | 114 |
| 16. | Domesticated Pig and Wild Boar. (From Romanes’ “Darwin and After Darwin.”) | 121 |
| 17. | Tadpoles and Frog. (Drawn by Dr. A. L. Lawrence.) | 175 |
| 18. | Diagram of Development. (Drawn by Mr. B. H. Esterly from a sketch by the Author.) | 183 |
| 19. | Brain of Fish. (Drawn by Mr. B. H. Esterly from specimens of the Author.) | 198 |
| 20. | Brain of Reptile. (Drawn by Mr. B. H. Esterly from specimens of the Author.) | 199 |
| 21. | Brain of a Marsupial. (Drawn by Mr. B. H. Esterly from specimens of the Author.) | 200 |
| 22. | Brain of a Lemur. (Modified by Mr. B. H. Esterly from Flower.) | 201 |
| 23. | Ideal Sections of Brains. (Modified from Le Conte. Drawn by Dr. A. L. Lawrence from a sketch by the Author.) | 202 |
| 24. | Brain of Human Fœtus—Fish Phase. (Drawn by Mr. B. H. Esterly from specimens of the Author.) | 204 |
| 25. | Brain of Human Fœtus—Reptile Phase. (Drawn by Mr. B. H. Esterly from specimens of the Author.) | 204 |
| 26. | Brain of Human Fœtus—Marsupial Phase. Side View. (Drawn by Mr. B. H. Esterly from specimens of the Author.) | 204 |
| 27. | Brain of Human Fœtus—Marsupial Phase. Dorsal View. (Drawn by Mr. B. H. Esterly from specimens of the Author.) | 205 |
| COLORED PLATES | ||
| PLATE | FACING PAGE | |
| I. | Wild Rock Pigeon and Pouter. (Drawn by Mr. J. L. Ridgway from specimens in the Smithsonian Institution.) | Frontispiece |
| II. | Butterflies. (Drawn by Miss L. Sullivan from specimens in the United States Bureau of Entomology.) | 138 |
| III. | Caterpillar of Geometer Moth. (Drawn by Miss L. Sullivan from specimens in the United States Bureau of Entomology.) | 142 |
| V. | Spider on Flower. (Drawn by Miss L. Sullivan from a plate in McCook’s “American Spiders.”) | 144 |
| VI. | Elaps and Erythrolamprus. (Modified by Mr. J. L. Ridgway from a figure in Romanes’ “Darwin and After Darwin.”) | 146 |
| VII. | Salamandra maculosa. (Drawn by Mr. J. L. Ridgway from specimens in the United States National Museum.) | 148 |
| VIII. | Paradise Birds. (Drawn by Mr. J. L. Ridgway from specimens in the Smithsonian Institution.) | 152 |
| IX. | Primrose Flowers. (Drawn by Miss L. Sullivan from specimens.) | 162 |
| X. | Bee Fertilizing Flower. (Drawn by Miss L. Sullivan from specimens in the United States Bureau of Entomology.) | 164 |
| PLATES ENGRAVED IN BLACK AND WHITE | ||
| IV. | Leaf-hoppers. (Drawn by Miss L. Sullivan from drawings collected by Dr. L. O. Howard.) | 140 |
| XI. | Babies’ Grasping Power. (From a Photograph taken by Dr. Louis Robinson.) | 192 |
| XII. | Brain of Man. (From Carus’ “The Soul of Man.”) | 202 |
About This Book
An accessible introduction to evolutionary theory and allied biological disciplines aimed at students and general readers. It begins with cellular structure and activities, describing mitosis, gamete maturation, fertilization, segmentation, and gastrulation as foundations of development. It then treats heredity with variation, discussing nuclear inheritance, germ-cell continuity, pangenesis theories, acquired characters, and environmental influences. A geological survey and the fossil record are used to outline transmutations and successive life‑forms. The work explains natural and artificial selection, mechanisms of adaptation such as protective and warning coloration, mimicry, sexual selection, and isolation. It examines human development and brain evolution, considers social implications, and closes with classification, references, and a glossary.