Vesalius, in a broad sense, one of the founders of biology, 22. A picture of the condition of anatomy before he took it up, 23. Galen: his great influence as a scientific writer, 24. Anatomy in the Middle Ages, 24. Predecessors of Vesalius: Mundinus, Berangarius, Sylvius, 26. Vesalius gifted and forceful, 27. His impetuous nature, 27. His reform in the teaching of anatomy, 28. His physiognomy, 30. His great book (1543), 30. A description of its illustrations, 30, 31. Curious conceits of the artist, 32. Opposition to Vesalius: curved thigh bones due to wearing tight trousers, the resurrection bone, 34, 35. The court physician, 35. Close of his life, 36. Some of his successors: Eustachius and Fallopius, 36. The especial service of Vesalius: he overthrew dependence on authority and reëstablished the scientific method of ascertaining truth, 37, 38. CHAPTER III William Harvey and Experimental Observation, 39 Harvey's work complemental to that of Vesalius, 39. Their combined labors laid the foundations of the modern method of investigating nature, 39. Harvey introduces experiments on living organisms, 40. Harvey's education, 40. At Padua, comes under the influence of Fabricius, 41. Return to England, 42. His personal qualities, 42-45. Harvey's writings, 45. His great classic on movement of the heart and blood (1628), 46. His demonstration of circulation of the blood based on cogent reasoning; he did not have ocular proof of its passage through capillaries, 47. Views of his predecessors on the movement of the blood, 48. Servetus, 50. Realdus Columbus, 50. Cæsalpinus, 51. The originality of Harvey's views, 51. Harvey's argument, 51. Harvey's influence, 52. A versatile student; work in other directions, 52. His discovery of the circulation created modern physiology, 52. His method of inquiry became a permanent part of biological science, 53. CHAPTER IV The Introduction of the Microscope and the Progress of Independent Observation, 54