Effect of light of short duration--After-oscillation--Positive and negative after-images--Binocular alternation of vision--Period of alternation modified by physical condition--After-images and their revival--Unconscious visual impression. 170 CHAPTER XX GENERAL SURVEY AND CONCLUSION 181 INDEX 193 ILLUSTRATIONS FIG. PAGE 1. MECHANICAL LEVER RECORDER 3 2. ELECTRIC METHOD OF DETECTING NERVE RESPONSE 6 3. DIAGRAM SHOWING INJURED END OF NERVE CORRESPONDS TO 8 COPPER IN A VOLTAIC ELEMENT 4. ELECTRIC RECORDER 11 5. SIMULTANEOUS RECORD OF MECHANICAL AND ELECTRICAL 13 RESPONSES 6. NEGATIVE VARIATION IN PLANTS 19 7. PHOTOGRAPHIC RECORD OF NEGATIVE VARIATION IN PLANTS 20 8. RESPONSE RECORDER 21 9. THE COMPENSATOR 22 10. THE SPRING-TAPPER 23 11. THE TORSIONAL VIBRATOR 24 12. RESPONSE IN PLANT TO MECHANICAL TAP OR VIBRATION 25 13. INFLUENCE OF SUDDENNESS ON THE EFFICIENCY OF 26 STIMULUS 14. THE METHOD OF BLOCK 28 15. RESPONSE IN PLANT COMPLETELY IMMERSED UNDER WATER 29 16. UNIFORM RESPONSES IN PLANT 36 17. FUSION OF EFFECT UNDER RAPIDLY SUCCEEDING STIMULI IN 36 MUSCLE AND IN PLANT 18. ADDITIVE EFFECT OF SINGLY INEFFECTIVE STIMULI ON 37 PLANT 19. 'STAIRCASE EFFECT' IN PLANT 37 20. APPEARANCE OF FATIGUE IN PLANT UNDER SHORTENED 39 PERIOD OF REST 21. FATIGUE IN CELERY 40 22. FATIGUE IN CAULIFLOWER-STALK 41 23. FATIGUE FROM PREVIOUS OVERSTRAIN 41 24. FATIGUE UNDER CONTINUOUS STIMULATION IN CELERY 42 25. EFFECT OF REST IN REMOVAL OF FATIGUE IN PLANT 43 26. DIPHASIC VARIATION IN PLANT 46 27, 28. ABNORMAL POSITIVE RESPONSES IN STALE PLANT 48, 49 TRANSFORMED INTO NORMAL NEGATIVE UNDER STRONG STIMULATION 29. RADIAL E.M. VARIATION 50 30. CURVES SHOWING THE RELATION BETWEEN INTENSITY OF 52 STIMULUS AND RESPONSE IN MUSCLE AND NERVE