NORTHWESTERN UNIVERSITY, Evanston, Ill., April, 1908. CONTENTS PART I The Sources of Biological Ideas Except Those of Organic Evolution CHAPTER I PAGE An Outline of the Rise of Biology and of the Epochs in its History, 3 Notable advances in natural science during the nineteenth century, 3. Biology the central subject in the history of opinion regarding life, 4. It is of commanding importance in the world of science, 5. Difficulties in making its progress clear, 5. Notwithstanding its numerous details, there has been a relatively simple and orderly progress in biology, 6. Many books about the facts of biology, many excellent laboratory manuals, but scarcely any attempt to trace the growth of biological ideas, 6. The growth of knowledge regarding organic nature a long story full of human interest, 7. The men of science, 7. The story of their aspirations and struggles an inspiring history, 8. The conditions under which science developed, 8. The ancient Greeks studied nature by observation and experiment, but this method underwent eclipse, 9. Aristotle the founder of natural history, 9. Science before his day, 9, 10. Aristotle's position in the development of science, 11. His extensive knowledge of animals, 12. His scientific writings, 13. Personal appearance, 13. His influence, 15. Pliny: his writings mark a decline in scientific method, 16. The arrest of inquiry and its effects, 17. A complete change in the mental interests of mankind, 17. Men cease to observe and indulge in metaphysical speculation, 18. Authority declared the source of knowledge, 18. The revolt of the intellect against these conditions, 19. The renewal of observation, 19. The beneficent results of this movement, 20. Enumeration of the chief epochs in biological history: renewal of observation, 20; the overthrow of authority in science, 20. Harvey and experimental investigation, 20; introduction of microscopes, 20; Linnæus, 20; Cuvier, 20; Bichat, 21; Von Baer, 21; the rise of physiology, 21; the beginnings of evolutionary thought, 21; the cell-theory, 21; the discovery of protoplasm, 21. CHAPTER II Vesalius and the Overthrow of Authority in Science, 22