Natural Selection, a ‘superseded formula,’ 7 _note_; meaning of, 72; originates nothing, 75; a pillar of Weismann’s theory, 103; effect, not cause, of evolution, 104; a real though not the main force, 105, 109; in relation to mimetic markings, 106 _sqq._; and to mutual aid among species, 138 Neuter insects. See Ants _Noctiluca_, 47 Nucleus, of cell, 30, 39. Ojetti, Fr., 210 _note_ Oken, L., 110, 137 Oldfield, J., 213 _note_ Osborn, H. F., 149 _note_ ‘Ought,’ Bentham on the word, 201; contents of the word, 209 Oysters, bisexuality in, 101 Paley, W., his analogy of the watch, 1 _sqq._; on the annular ligament, 8; his conception of an ‘Esperanto’ universe, 136 _Pandorina_, 49, 61, 156 _Papilio meriones_, 107 Parthenogenesis, 55 Penrose, F. C., 257 _note_ Perrier, E., 72 _note_, 91 Personality, 157, 166, 207, 211, _Appendix A_ Pianola, analogy of, 183 ‘Pig-philosophy,’ 221 Plato, 6, 170, 182 _note_, 185, 195, 227, 244, 246 Poetry, 158. See Literature Porto Santo rabbit, 126 Potato, response to mutilation, 117 Poulton, E. B., 107 Proteid, 23, 28 Protoplasm, the substance of life, 27; structure of, 30; distinguished from minerals, 37; response in, 61, 112, 113, 117, 119 _note_, 144; a synthesis of molecules, 147 Reinke, J., on the _X_ factor in life, 1, 63, 117; his theory of dominants, 120, 175 Religion, 159, 212, 277 Reproduction, 39, 46; in multicellular organisms, 48; sexual, 51 Response, 61, 112, 115. See, Life, Protoplasm Rhythm, 254, 262 Right-handedness, 81 Rolleston, Geo., 54 Ruskin, J., 258 _note_ Saleeby, C. W., 288 Sanction, ethical, 214, 220, 226 _sqq._, 234 Santayana, G., 181, 204 Schopenhauer, A., 110, 196, 265 Selection. See Natural Selection, Germinal Selection Sex, determination of, 57; ethical problems connected with, _Appendix E_ Sigerson, G., 81 _note_ Sins, mortal and venial, 210 _note_ Slater, Fr., 210 _note_ Sloth, green fur of, 24 _note_ Snails, bisexuality in, 101 Species, fixity of, 43, 66; mutability of, 67; origin of, not modification of structure by use, ch. IV.; not chance variations, ch. V.; due to directive or psychic factor, ch. VI.; species an organic whole, 49, 138, 147. See Adaptation, Evolution Spencer, H., controversy with Weismann, 87, 149 _note_; on social institutions, 131; on Free-will, 166 _note_; his ethical system, 202, _App. C & E_ Spinoza, B., 196 Spirit, the human, how accounted for, 151, 175; relations to Matter, 178; death not a disintegration of, 190 Socrates, 227, 230 Stoicism, ethical formula of, 194; conception of Asceticism, 217; what Stoicism lacked, 227 Strasburger, E., 11, 54, 109 Synthesis, principle of, in nature, 119 _note_, 137, 142, 146, 157 Tennyson, A., 170, 219 Thomson, W. H., 184