Divergence, principle of, xxv, 37 _n._, 145 _n._, 208 _n._ Domestication, variation under, 57, 62; --accumulated effects of, 75, 78; --analysis of effects of, 76, 83 Ears, drooping, 236 Elevation, geological, favouring birth of new species, 32, 34 _n._, 35 _n._, 185-189; --alternating with subsidence, importance of for evolution, 33, 190; --bad for preservation of fossils, 194 Embryo, branchial arches of, 42, 220; --absence of special adaptation in, 42, 44 _n._, 220, 228; --less variable than parent, hence importance of embryology for classification, 44 _n._, 229; --alike in all vertebrates, 42, 218; --occasionally more complicated than adult, 219, 227 Embryology, 42, 218; its value in classification, 45, 200; law of inheritance at corresponding ages, 44 _n._, 224; young of very distinct breeds closely similar, 44 _n._, 225 Ephemera, selection falls on larva, 87 _n._ Epizoa, 219 Essay of 1842, question as to date of, xvi; description of MS., XX; compared with the _Origin_, xxii Essay of 1844, writing of, xvi; compared with that of 1842 and with the _Origin_, xxii Evolution, theory of, why do we tend to reject it, 248 Expression, inheritance of, 114 Extinction, 23, 147, 192; locally sudden, 145; continuous with rarity, 147, 198 Extinction and rarity, 198 Eye, 111 _n._, 128, 129, 130 Faculty, in relation to instinct, 123 Faunas, alpine, 30, 170, 188; of Galapagos, 31 _n._, 82, 159; insular-alpine very peculiar, 188; insular, 159, 160 Fauna and flora, of islands related to nearest land, 187 Fear of man, inherited, 17, 113 Fertility, interracial, 103, 104 Fish, colours of, 130, 131; eggs of carried by water-beetle, 169; flying, 128 _n._; --transported by whirlwind, 169 Floras, alpine, 162; of oceanic islands, 162; alpine, related to surrounding lowlands, 163; alpine, identity of on distant mountains, 163; alpine resembling arctic, 164; arctic relation to alpine, 164 Flower, morphology of, 39, 216; degenerate under domestication if neglected, 58; changed by selection, 66 Fly, causing extinction, 149 Flying, evolution of, 16, 131 Food, causing variations, 1, 58, 77, 78 Formation (geological) evidence from Tertiary system, 144; (geological), groups of species appear suddenly in Secondary, 26, 144; Palaeozoic, if contemporary with beginning of life, author's theory false, 138 Formations, most ancient escape denudation in conditions unfavourable to life, 25, 139 Forms, transitional, 24, 35 _n._, 136, 142, 194; on rising land, 196; indirectly intermediate, 24, 135