14. From Malpighi's _Anatomy of the Silkworm_ (1669), 65 15. Swammerdam, 1637-1680, 69 16. From Swammerdam's _Biblia Naturæ_, 74 17. Anatomy of an Insect Dissected and Drawn by Swammerdam, 76 18. Leeuwenhoek, 1632-1723, 79 19. Leeuwenhoek's Microscope, 82 20_a_. Leeuwenhoek's Mechanism for Examining the Circulation of the Blood, 83 20_b_. The Capillary Circulation, after Leeuwenhoek, 84 21. Plant Cells from Leeuwenhoek's _Arcana Naturæ_, 86 22. Lyonet, 1707-1789, 90 23. Larva of the Willow Moth, from Lyonet's Monograph (1750), 92 24. Muscles of the Larva of the Willow Moth, from Lyonet's Monograph, 93 25. Central Nervous System and Nerves of the Same Animal, 93 26. Dissection of the Head of the Larva of the Willow Moth, 94 27. The Brain and Head Nerves of the Same Animal, 95 28. Roesel von Rosenhof, 1705-1759, 97 29. Réaumur, 1683-1757, 98 30. Nervous System of the Cockchafer, from Straus-Dürckheim's Monograph (1828), 101 31. Ehrenberg, 1795-1876, 108 32. Gesner, 1516-1565, 114 33. John Ray, 1628-1705, 116 34. Linnæus at Sixty (1707-1778), 124 35. Karl Th. von Siebold, 135 36. Rudolph Leuckart, 136 37. Severinus, 1580-1656, 142 38. Camper, 1722-1789, 144 39. John Hunter, 1728-1793, 145 40. Vicq d'Azyr, 1748-1794, 147 41. Cuvier as a Young Man, 1769-1829, 152 42. Cuvier at the Zenith of His Power, 153 43. H. Milne-Edwards, 1800-1885, 157 44. Lacaze-Duthiers, 1821-1901, 159 45. Lorenzo Oken, 1779-1851, 160 46. Richard Owen, 1804-1892, 161 47. J. Fr. Meckel, 1781-1833, 162 48. Karl Gegenbaur, 1826-1903, 164