INDEX 



435 



Species, characters of^ 93-5 

 Spencer, H., on play, 6a 

 Spermatozoa, 255, 303 

 Spider, the, 217 



„ pairing of the, 197 

 Spiracles, 185 

 Spiritual world, the, 388 

 Spontaneous generation, 315, 317 

 Spring as the love-season, 57 

 Squirrel, winter store of the, 56 

 Stag, antlers of the, 84, 89, 207-13 

 Stag-beetle, the, 89 



„ larva of the, 219 



State, Nietzsche's idea of the, 417 

 Stegocephala, the, 121 

 Steinheim snails, the, 125 

 Stickleback, the, 174 

 Stigma, the, 197 

 Sting of the bee, 221 



„ of insects, 193 

 Stimer, Max, 416 

 Stork, the, 46 



„ noise made by, 96 

 Strepsitera, 202 

 Struggle for life, the, 25, 27 

 Styloid bones, 157 

 Stylops meliitce, 202 

 Subjectivity of knowledge, 405 

 Sudden changes in nature, 131 

 Survival of the fittest, 28 

 Swimming-bladder of fishes, 1 50- 1 

 Symbiosis, 284 



Tadpole, the, 21 

 Tania echinococcus, 281 

 Tania saginata, 279, 280 

 Tcenia solium, 279, 280 

 Tape-worm, the, 279-82 



„ development of the, 26-7 



,, eggs of the, 26 



Teleological principles, 352 

 Teleology, 364 



Temperature of ancient Europe, 1 19 

 Thing in itself, the, 387 

 "Thus spoke Zarathustra," 421 

 Tibia, the, 168 

 Tiger-moth, the, 190 

 Toad, age of the, 149 



,, secretion of the, 146 

 Tortoise, the, 143 

 Tortoise-shell butterfly, the, 189, 191, 



193 

 Tracheae, 184 

 Tradition, 41 1 

 Trance, 233 

 Transformism, 37 

 Transitional forms, 264 

 Tree of life, the, 37 



Tree-frog, the, 148 

 Tree-locust, the, 185 

 Trichina, the, 276 

 Tropical frogs, 1 19 

 Trout, eggs of the, 26 

 Trunk-fish, the, 177 

 Truth, the will to attain, 427 

 Turkey, the, 88, 89 

 Types of animals, 132 



Ultimate concepts, 394 



„ elements, 379, 381 

 Universal concepts, 380 

 Unnucleated organisms, 308 

 Uric acid, 351 

 Use and disuse, effects of, 223, 225 



Value, idea of, 413 



„ no standard of, in science, 375 



Variations are in all directions, 368 

 , , not definitely directed, 369 

 ,, in organisms, 40 

 ,, plus and minus, 162 



„ roots of, 334 



Variety, nature of a, 33 



Vermiform appendage, 1 58 



Vertebrates, similarity of, 153 



Viper, the, 140 



Vital force, 355 



Vitalism, 350 



Voluntary action, 214 



Volvox, the, 297 



Vorticellae, 293 



Wallace, Dr. A. R., on sexual 



selection, 81 

 War-dance of animals, 89 

 War, evils of, 415 

 Wart-hog, the, 89 

 Wasmann, Father, 38 

 Wasps, predatory, 218 

 Water-beetle, the, 218 

 Water-flea, the, 20, 22, 229, 236, 252 

 Water-ousel, the, 97 

 Water-polyp, 284 

 Wasmann on co-adaptations, 213 



„ on heredity, 299 



„ on instinct, 64 



,, on the extinction of 

 species, 127 

 Whale, rudimentary organs of the, 



1 59 

 Wild cocks, 91 

 Will to live, the, 356 

 Willow, fertilisation of the, 198 

 Willow-wren, song of the, 96 

 Winged horses, possibility of, 369 

 Wings, 100 



