FIG. PAGE 1. PHOTOMICROGRAPHS OF BRAIN-TISSUE _Frontispiece_ 2. THE ORGANS OF THE CHEST AND ABDOMEN xi 3. MUCOUS GLAND, CAPILLARIES, AND CONNECTIVE-TISSUE SPACES 38 4. BLOOD-CORPUSCLES 60 5. SPLEEN-PULP, WITH PHAGOCYTES 81 6. DUODENUM AND NEIGHBOURING ORGANS 99 7. A LOBULE OF THE LIVER AND LIVER-CELLS 160 8. THE DIAPHRAGM DURING INSPIRATION AND EXPIRATION 172 9. THE KIDNEY 197 10. THE HEART IN LONGITUDINAL SECTION 218 11. HORIZONTAL SECTION OF THE HEART, SHOWING ITS VALVES 225 12. SECTION OF THE WALL OF A SMALL ARTERY 233 13. KYMOGRAPH 238 14. SPHYGMOGRAPH 244 15. BLOOD-PRESSURE TRACINGS 245 16. MINUTE STRUCTURE OF MUSCLE-FIBRES 262 17. THE BICEPS MUSCLE IN ACTION 286 18. ELECTRIC ORGAN OF SKATE 289 19. MINUTE STRUCTURE OF A NERVE-FIBRE 296 20. GANGLION-CELLS WITH NEURO-FIBRILLÆ OF THE LEECH 298 21. THE DEVELOPMENT OF THE GRANULES OF THE CEREBELLUM 304 22. TIGROIDS AND NEURO-FIBRILLÆ 321 23. MINUTE STRUCTURE OF THE CORTEX OF THE CEREBELLUM 339 24. MINUTE STRUCTURE OF THE CORTEX OF THE CEREBRUM 347 25. FUNCTIONAL AREAS OF THE CORTEX OF THE CEREBRUM 352 26. TASTE-BULBS 368 27. HORIZONTAL SECTION OF THE EYE 373 28. DEVELOPMENT OF THE CRYSTALLINE LENS 374 29. PURKINJE’S SHADOWS OF THE VESSELS OF THE RETINA 375 30. RETINA ADAPTED FOR OBSCURITY AND FOR BRIGHT LIGHT 377 31. SIMULTANEOUS CONTRAST 383 32. FORMATION OF AN IMAGE ON THE RETINA 391 33. THE FORM OF THE EYEBALL IN SHORT SIGHT, NORMAL SIGHT, AND LONG SIGHT 392 34. THE BLIND SPOT 394 35. AN OPTICAL ILLUSION 398 36. AN OPTICAL ILLUSION 401 37. AN OPTICAL ILLUSION 402 38. EXTERNAL, MIDDLE, AND INNER EAR 411 39. THE COCHLEA 414 40. THE ORGAN OF CORTI 415 41. NERVES OF THE CORNEAL EPITHELIUM 424 42.