Selection, functional, 163; natural, shielding of chicks from, 111; under uniform and variable circumstances, 175; in playtime of life, 319; sexual, 261 ff., 313 Self, as ideal construction, 239 Sentience, 62; origin of, 330 Sexual selection, 261 ff., 313 SHARP, Dr. D., on birch-weevil, 121; on _Œcophylla_, 210 SHELLARD, Mr. E. J., observations on staghound, 144 SHERRINGTON, Prof., on emotion, 292; on spinal animal, 298 ff. Shock, effects of physiological, 302 SIMCOX, Miss Edith, quoted, 320 _Sitaris_, instincts of, 82 Slave ants, 215 Snails, observations on, 157 Social behaviour, 179; evolution of, 225 Solitary wasps, instincts of, 72 ff.; intelligence of, 126 ff. Solomon Islands, rats of, 222 Sounds emitted by young birds, 92 SPALDING, Douglas, on newly hatched turkeys, 49; on instinct, 99 Special creation, 297 Speech, connection of, with rational process, 58, 233; so-called, of monkeys, 198; of children, 203; aids passage from perceptual to ideational process, 337 SPENCE, on instinct, 63 SPENCER, Mr. Herbert, on instinct and reflex action, 70; on play due to surplus vigour, 248; on pleasure and pain, 284, 287; on survival, 288 _Sphex_, mode of carrying prey to nest, 77, 172 Spiders placed in crotch by wasps, 133 Stereotyped behaviour, 172 Sticklebacks, observations on, 130 STOUT, Dr. G. F., on “meaning” for consciousness, 46, 243, 268; on ideational and perceptual stages of mental development, 59, 271; on octopus, 158; on conative process, 235; on the self, 239; on manipulation, 251; on emotion, 293 STRANGE, Mr., on bower-bird, 261 Subject and object, 245, 276 Sun-dew leaf, behaviour of, 25 Swimming, instinctive, 85 T TAIT, Lawson, on begging-cat, 110 TARDE, M., on imitation as a social factor, 179 Tendencies, congenital, 176 THOMAS, Mr. Oldfield, on rats of Solomon Islands, 222 THORNDIKE, Dr., on swimming of chick, 85; experiments on intelligence, 147 ff.; experiments on imitation, 179, 183 ff. Tradition, animal, 220 Trial and error, method of, 139 U Unity of perceptual process, 240; of biological purpose, 297 Use, super-normal, 170; relation of, to heredity, 171, 177 V VALISNERIA, fertilization of, 28 Variation defined, 36; origin of, 327 Venus’s fly-trap, behaviour of, 26 Vigour, play due to surplus, 248 Volition as conative, 238 W WALLACE, Dr. A. R., on sexual selection, 264 WALLASCHEK, Mr., on play as surplus vigour, 248 Wapiti, antlers of, 16 WASMANN, Dr., on insects associated with ants, 213 Wasps, solitary, instincts of, 72 ff.; intelligence of, 126 ff. WEIR, Mr. Jenner, on canaries, 135 WEISMANN, Prof., on origin of instinct, 109 WHITMAN, Prof., on _Clepsine_, 159 WHITMEE, Rev. S. J., on tooth-billed pigeon, 221 Will, metaphysics of, 307