Part 23

Camouflage, 210 terrestrial, 210 detection of, 215 marine, 222 airplane, 234

Carr, observations on distance illusions, 108

Chromatic aberration, 19, 135

Chlorophyl, 214

Circle, 11 arcs of, illusion, 86 contracting and expanding illusion, 98

Clouds, 235

Color, 124 after-images, 128 blending in camouflage, 216 contrasts and brightness, 114 growth and decay of sensation, 131 illusions of, 156 retiring and advancing, 138 saturation, 154 sensibility of retina, 138 warm and cold, 158

Confusability, 226

Confusion theory of angular illusions, 100

Contour, illusions of, 52 and angles, illusions, 87

Contracting and expanding circles, illusion of, 98

Contrasts, illusions of, 53 simultaneous, 124, 154 apparatus for, 115, 125 color, 114, 154, 188 brightness, 114

Convergence, illusions of, 108, 191

Cord, twisted, illusion, 88

Daylight, artificial, 189

Decoration, painting and, 179

Decorator, 188

Dember, 167

Depth and distance, illusions, 102

Direction, illusions of Zöllner's, 76 Wundt's, 79 Hering's, 80

Disk, Mason, 132

Distance and depth, illusions, 102 and size, 35, 104, 166

Distance illusions, Carr's observations, 108

Double images, 37

Dynamic theory of angular illusions, 99

Enlargement of sun and moon at horizon, apparent, 169

Equivocal figures, 64

Euclid, 8