430 



INDEX 



Coat of insects, development of the, 



205-7 

 Cock, spurs of the, 84 

 Cockchafer, the, 84 

 Cold, efifect of, on butterflies, 341 

 Cold-blooded animals, 119 

 Colour as protection, 53-5 

 Colours, animal, origin of, 91 



„ of animals and selection, 166 



„ of insects, 185 

 Combinations, chemical, 230 

 Common features expressed in ideas, 



393 

 Concepts, 378 



„ of animals, 392 

 Conscience, evolution of, 408 

 „ variations of, 410 



Consciousness, 386 



„ not evolved, 404 



„ unimaginable, 404 



Coecum, the, 159 

 Co-operation in the body, 165 

 Copepoda, 252 

 Copper butterfly, the, 195 

 Coquetting, 86 

 Correlation, law of, 164 

 Cosmic process, the, 425 

 Cosmozoic theory, 314 

 Courtship of animals, 82-8 

 Coyness, 86 

 Crab, legs of the, 245 



„ pincers of the, 204-5 

 Craw-fish, the, 240, 245 

 Creation, theory of, 155 

 Cretaceous period, 119 

 Cricket, pairing of the, 196 

 Cries of birds, 94 

 Crocodile, age of the, 149 

 Cross-bill, the, 98 

 Crustacea, 184 

 Cuckoo, as destroyer of insects, 45 



„ cry of the, 95 

 Curiosity in animals, 76 

 Cyanic theory, the, 316 

 Ciliated infusoria, 293 

 Circulation of blood in the bird, 156 

 „ „ » frog, 155 



Civilisation, effect of, on animals, 



42,47 . , , 



Civilisation, evolution of, 406 



Dachshund, the, 210 

 Daphnidae, 252 



Darwin and over-production, 26 

 Darwinian ethic, the, 417, 420 

 Darwinism, definition of, 38 

 Death, nature of, 307-11 

 „ utility of, 312 



Definite variations in animals, 258, 



332 

 Degeneration of organs, 156-8 

 Descartes on instinct, 64 

 Descent, theory of, 37 

 Descriptive science, 399 

 Design on butterflies' wings, igi 

 Determinants, 333 

 De Vries, Hugo, 344 

 Differentiation of life-forms, 318 

 Dinosauri, the, 120, 129 

 Direction, sense of, in birds, 1 10-12 

 Distomum hepaticum, 274, 283 

 Distomum macrostomum, 283 

 Divisibility of bodies, 362 

 Division of labour in organisms, 290 

 Dochtnius duodenalis, 278 

 Dragon-fly, the, 19, 22, 194, 196 

 Dreams and art, 72 

 Dualism, 427 

 Duty, idea of, 422, 427 



Ear-bones, the, 154 

 Earth, end of the, 312, 323 

 Earth's history, periods of the, 122 

 Earthworm, the, 238 



„ use of the, 266 



„ regeneration in the, 267 



„ summer store of the, 56 



Earwig, the, 202 

 Echinoderms, 263 

 Echinorhyncus, 272 

 Economy of nourishment, 168-70 

 Eel, reproduction of the, 178-80 

 Eel-pout, the, 172 

 Efficient causes, 367 

 Eggs, colours of, 92 



„ number in certain animals, 26 



„ of reptiles, 138 



„ poisonous, 176 



„ provision for development of, 59 

 Egoism, 417 

 Egyptian plants, 34 

 Egyptian seeds do not grow, 233 

 Elastic types, 132 

 Elements, chemical, 229 

 Elephant, trunk of the, 241, 332 

 Embryo, development of the human, 



171 

 Embryonic adaptations, 249-51 



„ development, evolution- 

 ary aspect of, 170, 248-51 

 Empirical science, 396 

 End in organisms, 364 

 Eris talis, 193 

 Eternity of matter, 314 

 Ether, 381 



„ invisibility of, 382 



