Intelligence lapsed, 107; influence of, on instinct, 169; of ants, Lord Avebury on, 218; biological importance of, 310 Intelligent behaviour, 117; evolution of, 155 Intelligent process distinguished from rational, 59, 138 Intercommunication, 193, 336 Interest, 243 Internal factors in instinctive behaviour, 102 Irritability, fundamental, property of protoplasm, 240, 296 J JAMES, Prof. Wm., theory of emotions, 246, 292 Jays, bathing of, 89; mode of taking food, 94 JENNER on cuckoo, 92 JENNINGS, Dr. H. S., on behaviour of Paramecia, 5 K KERNER, Dr., on sun-dew, 26; on sensitive Oxalis, 27; on Valisneria, 29 King-crab, reflex action in, 298 KNIGHT, Andrew, on Norwegian ponies, 110 KROPOTKINE, Prince, on mutual aid among animals, 227 L Lamarckian hypothesis, 169, 171, 177 Language, nature of, 195 LANKESTER, Prof. E. Ray, on small-brained mammal, 168 Lapwing, instinctive behaviour of, 113 Law of battle, 313 Leech, observation on, 159 _Leucopsis_, instincts of, 79 LEWES, G. H., on lapsed intelligence, 107 Limpets, observations on, 156 LINDLEY, Dr., on children, 141 Locality, studies by wasps, 128 LOCKE, John, limitations of animals, 167 M MACKENZIE, Prof. J. S., on ethics, 278; on conscience, 281; on ambiguity of word “pleasure,” 285 Make-believe, 280 Mammals, early small-brained, 168 Manipulation (Stout), 251 MARCHAL, Prof., on instincts of _Cerceris_, 74 MARSHALL, Mr. H. R., on instinct, 66 Martin, nest-building of, 113 MARTINEAU, James, on pleasure and pain, 284 MAUPAS, M., observations on infusoria, 4 MAYER, Dr. A. G., on mating instinct of moths, 83 MCCOOK, Dr., on ants, 214 Meaning, Dr. Stout’s use of term, 46, 243, 268 MEDLICOTT, Mr. H. B., on behaviour of wild pigs, 196 Megapodes, instinctive flight of, 87 _Meloë_, instincts of, 81 Mental development, stages of, 48, 56 MERCIER, Dr. Charles, on criteria of intelligence, 120 Metaphysical explanations, 19; aspect of instinct, 64; of impulse, 237; of purpose, 294; of will, 307; of life, 325 MILLS, Prof. Wesley, on social influence on puppy, 220 _Miltogramma_, parasitic fly, 134 Mimicry, Batesian and Müllerian, 165; intelligent aspect of, 311 Modifiability, 171 Modification, defined, 36; relation of, to hereditary characters, 170 MÖLLER, Herr, on fungus garden of ants, 216 Monistic hypothesis, 309, 315 Monkey, capuchin, imitation in, 188 _Monodontomerus_, instincts of, 79 Moor-hen, diving of, 89 Moths mating, instinct of, 83 Motive in rational conduct, 60 Movement plays, 251 MÜLLER, Prof. Max, on barrier between brute and man, 204 Müllerian mimicry, 165, 166 Mystery of life, 18 N Natural selection, shielding of chicks from, 111; under uniform and variable circumstances, 175; in playtime of life, 319