Saltatory Evolution, 29-32 (see also Mutations) Sanders, experiments on Vanessa by, 65 Savigny, 249 Schelling, 4, 5, 200, 201 Schleiden and Schwann, Cell-theory of, 147 Schoetensack, on _Homo heidelbergensis_, Foot Note 118 Schütt, 23 SCHWALBE, G., on _The Descent of Man_, 111-145 Seeck, O., Foot Note 240 Segregation, 97, 98 Selection, artificial, 24, 25, 26, 41, 45, 120, 269-272 --germinal, 35, 36, 46-52, 64 Selection, natural (see Natural Selection) --organic, 53, 171, 172 --sexual, 55-64, 117, 118 --social and natural, 271 --23-86, 103, 129, 130 Selenka, 131 Semnopithecus, 132 Semon, R., 28, 153 Sergi, 138, 143 Sex, recent investigations on, 99, 100 Sibbern, 201 _Smerinthus ocellata_, 38 _Smerinthus populi_, 38 _S. tiliae_, 38 Smith, A., 200 Sociology, Darwinism and, 264-280 --History and, 255 Sollas, W. J., 134 Sorley, W. R., 217 Species and varieties, 100 Spencer, H., on evolution, 204-209 --on the theory of Selection, 41 Spencer, H., on Sociology, 268 --on the transmission of acquired characters, 149 --on Weismann, 41, 150 --2, 17, 217, 231, 268 Sphingidae, variation in, 37 Spinoza, 153, 206 Standfuss, 82 Stephen, L., 217 Sterility in hybrids, 104-106 Sterne, C, Foot Note 10 Struggle for existence, 25, 26, 272-274 Sutton, A. W., Foot Note 73 Synapta, calcareous bodies in skin of, 38-41 Syrphus, 75 Tarde, G., 279 Tennant, F. R., Foot Note 218 Tetraprothomo, 138, 144 THOMSON, J. A., on _Darwin's Predecessors_, 1-22 --150 --and P. Geddes, 276 Treschow, 201 Treviranus, 8, 14, 15 Turgot, 249 Turner, Sir W., 150 Tylor, 267 Tyndall, W., 267 Tyrrell, G, Foot Note 222 Uhlenhuth, on blood reactions, 135 Use and disuse, 28, 41-43, 48-54, 94, 95, 119, 149 Vanessa, 63 _V. levana_, 31 _V. polychloros_, 82 _V. urticae_, 65, 82 Variability, Darwin's attention directed to, 24 --W. Bateson on, 87-110 --causes of, 200 Variation, Darwin's views as an evolutionist, and as a systematist, on, 212 --and heredity, 87-110 --minute, 28-32 --in relation to species, 100, 101 Varigny, H. de, 6, 19 Verworn, 136 _Vestiges of Creation_, Darwin on _The_, 15 Virchow, his opposition to Darwin, 157, 158 --on the transmission of acquired characters, 149 Vogt, 137 Voltaire, 248 VRIES, H. de, the Mutation theory of, 31, 101, 151, 213 WAGGETT, Rev. P. N., on _The Influence of Darwin upon Religious Thought_, 223-245 Wallace, A. R., on Colour, 63, 71 --and Darwin, Foot Note 7, 23, 183 --on the Descent of Man, 116 --on Malthus, 17 --on Natural Selection, 2, 16, 163, 232 Wallace, A. R., on social reforms, 275, 276 --on Sexual Selection, 183, 184 Walton, 237 Watt, J., and Natural Selection, 21 WEISMANN, A., on _The Selection Theory_, 23-86 --his germ-plasm theory, 46-51, 149, 150 --and Prichard, 20 --and Spencer, 42 Weismann, A., on the transmission of acquired characters, 93-95 --156