Species, not created more than once, 168, 171, 191; evolution of, compared to birth of individuals, 150, 198, 253; small number in New Zealand as compared to the Cape, 171, 191; persistence of, unchanged, 192, 199 Sports, 1, 58, 59, 64, 74, 95, 129, 186, 206, 224 Sterility, due to captivity, 12, 77 _n._, 100; of various plants, 13, 101; of species when crossed, 11, 23, 96, 99, 103; produced by conditions, compared to sterility due to crossing, 101, 102 Struggle for life, 7, 91, 92, 148, 241 Subsidence, importance of, in relation to fossils, 25, 35 _n._, 195; of continent leading to isolation of organisms, 190; not favourable to birth of new species, 196 Swimming bladder, 16, 129 System, natural, is genealogical, 36, 208 Telegony, 108 Tibia and fibula, 48, 137 Time, enormous lapse of, in geological epochs, 25, 140 Tortoise, 146 Transitional forms, _see_ Forms Trigonia, 147 _n._, 199 Tree-frogs in treeless regions, 131 Type, unity of, 38, 214; uniformity of, lost in Plesiosaurus, 217; persistence of, in continents, 158, 178 Uniformitarian views of Lyell, bearing on evolution, 249 Use, inherited effects of, _see_ Characters, acquired Variability, as specific character, 83; produced by change and also by crossing, 105 Variation, by Sports, _see_ Sports; under domestication, 1, 57, 63, 78; due to causes acting on reproductive system, _see_ Variation, germinal; --germinal, 2, 43, 62, 222; individual, 57 _n._; causes of, 1, 4, 57, 61; due to crossing, 68, 69; limits of, 74, 75, 82, 109; small in state of nature, 4, 59 _n._, 81, 83; results of _without_ selection, 84; --minute, value of, 91; analogous in species of same genus, 107; of mental attributes, 17, 112; in mature life, 59, 224, 225 Varieties, minute, in birds, 82; resemblance of to species, 81 _n._, 82, 105 Vertebrate skull, morphology of, 215 Wildness, hereditary, 113, 119 CAMBRIDGE: PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS