Diphasic variation in metal, 113, 114, 115, 116, 188 in nerve, 188 in plant, 46, 188 Dose, effect on inorganic response, 89, 146, 189 plant response, 79, 189 Electrical recorder, 11 Electrical response. _See_ Response, electrical Electric tapper, 24 Exaltation, response by relative, 89 Fatigue, absence of, under certain conditions, in metal, 120 in muscle, 39 in plant, 39 apparent, with increased frequency of stimulation, in metal, 120 in muscle, 40 in plant, 40 diminution of response under strong stimulus due to, in plant, 57 in metal, 118, 119, 185 in muscle, 118, 185 in plant, 20, 185 due to overstrain, 41 rapid, under continuous stimulation in metal, 121, 130 in muscle, 42, 130 in plant, 42, 130 removal of, by rest in plant, 43 theory of, in muscle, 38, 185 Holmgren on retinal current, 149 Hysteresis, 137 Injury, current of, in nerve, 7 Inorganic response. _See_ Metal, electrical response in Kuhne on retinal current, 149 Kunkel on electrical changes by injury or flexion in plant, 14, 70 Light, after-effect of short exposure to, on photo-sensitive cell, 171 on retina, 171 decline and reversal of response under continuous, in photo-sensitive cell, 166 in retina 166 effect of temperature on response of photo-sensitive cell produced by, 158 retinal response produced by, 158 relation between intensity and response to, in photo-sensitive cell, 161, 162 in retina, 162 response to, after-oscillation in photo-sensitive cell, 159, 163 effect of increasing length of exposure in photo-sensitive cell, 159 in retina, 160 in frog's retina, 150, 151, 156, 164, 166 in photo-sensitive cell, 152, 153, 154, 155, 157, 165, 166 McKendrick on retinal response, 149 Mechanical recorder, 3 response, 1 stimulus by electric tapper, 24 by spring-tapper, 23 by vibrator, 24 conditions of maintaining uniformity of, 26 means of graduating intensity of, 22, 24, 96