66. DIPHASIC VARIATION IN METALS 113 67. NEGATIVE, DIPHASIC, AND POSITIVE RESULTANT RESPONSE 115 IN METALS 68. CONTINUOUS TRANSFORMATION FROM NEGATIVE TO POSITIVE 116 THROUGH INTERMEDIATE DIPHASIC RESPONSE 69. FATIGUE IN MUSCLE 118 70. FATIGUE IN PLATINUM 118 71. FATIGUE IN TIN 119 72. APPEARANCE OF FATIGUE DUE TO SHORTENING THE PERIOD 120 OF RECOVERY 73. FATIGUE IN METAL UNDER CONTINUOUS STIMULATION 121 74. 'STAIRCASE' RESPONSE IN MUSCLE AND IN METAL 122 75. ABNORMAL RESPONSE IN NERVE CONVERTED INTO NORMAL 124 UNDER CONTINUED STIMULATION 76, 77. ABNORMAL RESPONSE IN TIN AND PLATINUM CONVERTED INTO 125 NORMAL UNDER CONTINUED STIMULATION 78. GRADUAL TRANSITION FROM ABNORMAL TO NORMAL RESPONSE 126 IN PLATINUM 79. INCREASE OF RESPONSE IN NERVE AFTER CONTINUOUS 127 STIMULATION 80, 81. RESPONSE IN TIN AND PLATINUM ENHANCED AFTER 127, 128 CONTINUOUS STIMULATION 82. MAGNETIC ANALOGUE 132 83, 84. RECORDS OF RESPONSES TO INCREASING STIMULI IN TIN 134, 135 85. INEFFECTIVE STIMULUS BECOMING EFFECTIVE BY 135 SUPERPOSITION 86. INCOMPLETE AND COMPLETE FUSION OF EFFECTS 136 87. CYCLIC CURVE FOR MAXIMUM EFFECTS SHOWING HYSTERESIS 137 88. ACTION OF POISON IN ABOLISHING RESPONSE IN NERVE 139 89. ACTION OF STIMULANT ON TIN 141 90. ACTION OF STIMULANT ON PLATINUM 142 91. DEPRESSING EFFECT OF KBr ON TIN 143 92. ABOLITION OF RESPONSE IN METALS BY 'POISON' 143 93. 'MOLECULAR ARREST' BY THE ACTION OF 'POISON' 145 94. OPPOSITE EFFECTS OF SMALL AND LARGE DOSES ON THE 146 RESPONSE IN METALS 95. RETINAL RESPONSE TO LIGHT 150 96. RESPONSE OF SENSITIVE CELL TO LIGHT 152 97. TYPICAL EXPERIMENT ON THE E.M. VARIATION PRODUCED BY 154 LIGHT 98. MODIFICATION OF THE PHOTO-SENSITIVE CELL 155 99. RESPONSES IN FROG'S RETINA 156 100. RESPONSES IN SENSITIVE PHOTO-CELL 157 101. EFFECT OF TEMPERATURE ON THE RESPONSE TO LIGHT 159 STIMULUS 102. EFFECT OF DURATION OF EXPOSURE ON THE RESPONSE 159 103. RESPONSES OF SENSITIVE CELL TO INCREASING 161 INTENSITIES OF LIGHT 104. RELATION BETWEEN THE INTENSITY OF LIGHT AND 162 MAGNITUDE OF RESPONSE