302 



INDEX OF SUBJECTS 



Ddmmerungssehen (see Scotopia), 17 

 Deuteranopic vision, 159, 232, 287 

 Deviation, standard, 149 

 Dichromatic vision, 158, 162, 216, 232, 267 



adaptation in, 174 

 Dichromatism, approximate, 235 

 Dichromic, 294 



Differential threshold or liminal discrimina- 

 tion value, 19, 30, 230, 233, 294 

 Diffraction spectrum, 3 

 Discrimination of hue, 30, 230, 233, 294 

 Dispersion spectrum, 3 

 Double-room, Hering's, 58, 74, 126 

 Duplicity theory, 198, 203 



Electrical changes due to light, 15, 139, 206, 



219 



Energy of spectrum.; 28 

 Episcotister, 5, 92 

 Epithelium, pigment, 11, 145, 197, 211, 



212 



Equal-area curves, 228 

 Equality of brightness method, 44, 98, 107 

 Evolution of colour vision, 130, 282, 288, 



294, 298 



Extinction of colour, 61, 121 

 of light, 62, 121 



Fading, complete, 261, 275 



of after-images, 110 

 Fatigue, 112, 219, 231, 281 

 Fechner-Helmholtz law, 107 

 Fechner's law, 20 

 Field of vision, 66 

 Fishes, anatomy, 11, 13 



colour vision of, 143 

 Flicker method, 45, 55, 173, 191 

 Form sense, 204 

 Fovea centralls, 9, 16, 81, 105, 117, 208 



night blindness of, 50, 83, 208 

 Fraunhofer lines, 3, 29, 47 

 Fundamental colours, 214, 220, 230, 258 



Gauging the spectrum, 39, 164, 215 

 General threshold or liminal value, 19, 60, 



80, 117 



Grassmann's laws, 33 

 Grey, 271, 282 

 mean, 251, 260 



" Hemeralopia " (night-blindness), 49, 197. 



209 



Heptachromic, 294 

 Heredity, 159, 186 

 Hering's "double-room," 58, 74, 126 

 Hering's theory, 200, 251 

 Heterochromatic photometry, 43. 0(1 

 Hexachromic, 294 

 Hue, 27 



discrimination of, 30, 230, 233, 294 



Inadequate stimuli, 19 

 Induction, 17, 49, 101, 125, 218, 254, 279 

 temporal, 17, 49, 203, 255 



Induction, simultaneous (Hering), 125, 127. 



219, 255, 279 



spatial, 17, 125, 219, 255, 264 

 successive, 101, 219, 254, 279 



Infant vision, 131, 152 



Inhibition, 93, 259, 275 



Intensity, 28, 57, 78, 91, 95 



Interference spectrum, 3 



Intrinsic light, 104, 251, 276 



Invariable colours, 70 



Law, Fechner-Helmholtz, 107 



Fechner's, 20 



Grassmann's, 33 



Miiller's, 18 



Porter's, 96, 208 



Talbot-Plateau, 92 



Weber's, 19 



of Coefficients, 107 



of Specific energies of the senses, 18 

 Least perceptible differences, method of, 



19 



Lenticular pigmentation, 8, 41. 181 

 Light area, 119 



chaos, 104, 251 



extinction of, 62, 121 



intrinsic, 104, 251, 276 



sense, 204 

 Luminosity, 28, 42, 96, 100, 223, 236, 



294 " 



Luminosity contrast, 127 

 Luminosity curves of dichromats, 172, 240 



of monochromats, 189 



of trichromats, 42, 223 



Macula lutea, 9, 81 



Macular pigmentation, 41, 169, 181, 183. 



241, 259 

 Mammals, anatomy, 11, 14 



colour vision of, 132 

 Mean error, method of, 19 

 Mean grey, 251, 260 

 Mean variation, 149 

 Memory colours, 22 

 Method, constant, 19 



critical frequency, 96 



equality of brightness, 44, 98, 107 



flicker, 45, 55, 173, 191 



of least perceptible differences, 19 



limiting, 19 



of near error, 19 



preference, 132, 137 



of production, 19 



of right and wrong answers, 19 



visual acuity, 44, 99 

 Minimal field luminosity curve, 72 

 Minimal time luminosity curve, 74 

 Mixture of pure-colour stimuli, 33, 162 

 Monochromatic vision, 159, 186, 209, 2\7, 



267, 288 

 Mtiller's law, 18 



Negative after-image, 101 

 Neutral point, 163, 169, 207, 233 



