Ceylon and Malaya, resemblances of fauna of, 327 Chameleons, 113 Chameleon, cause of changes of its colour, 170 Chemical action changes colours, 183 Chili, humming-birds of, 141 Chiroptera, 119 _Chrysobactron Rossii_, 238 Clark, Rev. Hamlet on leaf-cutting ants, 86 Climate of Equator, general features of, 17 Climates of Timor, Angola, and Scotland compared, 14 Climbing plants of tropical forests, 37 uses of, 39 Cockatoos, 100 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 D. 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 De Vry, Mr., on the sugar-palm, 43