Part 25

Cœlogynes, 51

Coloration of tropical birds, 110

Colour, cause of change of, in humming-birds, 144

Colour in nature, problems of, 159 how far constant, 161 as affected by heat and light, 161 of tropical birds, 163 of tropical butterflies, 164 of temperate and tropical flowers, 165 changes of, in animals produced by coloured light, 167 voluntary change of, in animals, 170 not usually influenced by coloured light, 171

Colour, the nature of, 180 how produced, 183 changed by heat, 183 a normal product of organization, 185 as a means of recognition, 196 proportionate to integumentary development, 198 not caused by female selection, 198

Colour absent in wind-fertilized flowers, 233 same theory of, in animals and plants, 234 of flowers and their distribution, 235

Colour, nomenclature of, formerly imperfect, 247

Colour-development as illustrated by humming-birds, 212 local causes of, 216 in animals, summary, 216

Colour-perception, supposed recent growth of, 244

Colour-sense, origin of the, 241 need for, 243 not of recent origin, 246 not wholly explicable, 248

Colours, classification of organic, 172 protective, 172 warning, 174 sexual, 177 typical, 179 of animals, how produced, 184 theory of protective, 187 theory of warning, 189 theory of sexual, 192 theory of typical, 215

Colours and ornaments of humming-birds, 127

Colours of fruits, attractive, 224 protective, 225

Colours, which first perceived, 243

Cometes sparganurus, very pugnacious, 214

Compositæ, arborescent in oceanic islands, 276

Continent, past changes of the great Eastern, 321

Continents of Tertiary period, probable aspect of, 343

Copridæ, 95 probable use of horns of, 202

Crematogaster, genus of ants, 83

Cross-fertilization of flowers, use of, 228 complex arrangements for, 229

Cuckoos, 104

Danaidæ, warning colours of, 174

Danainæ, Acræinæ and Heliconiinæ, local resemblances of, 256

Daphne pontica, 230

Darwin, Mr., on mode of cross-fertilization and its use, 228 not too highly rated, 252 on vegetation of Galapagos, 272 on use of scented leaves, 277 on former union of West Indian islands and S. America, 306 on oceanic islands, 307 revolution in thought effected by, 284

Deserts on line of tropics, 28

Desmoncus, 41