Tortoises, conversion of turtles into land-.
Tortugas, A. Agassiz on reefs of.
Toryism, defence of.
Toucans, colour of beaks in breeding season.
Trachyte, separation of basalt and.
Tragopan.
Traill, experiments on grafting.
Transfusion experiments, by Galton.
Translations of Darwin's books.
Transplanting, effect on Alpine plants.
Transport, occasional means of.
Travels, Bates' book of. -Humboldt's. -Wallace's.
Travers, H.H., on Chatham Islands.
Trecul, on Drosera.
Trees, herbaceous orders and. -occurrence in islands. -older forms more likely to develop into. -Asa Gray on. -conditions in New Zealand favourable to development of. -crossing in. -separate sexes in.
Treub, M., on Chalazogamy.
Treviranus, Prof., on Primula longiflora.
Trifolium resupinatum, Darwin's observations on bloom on leaflets.
Trigonecephalus.
Trilobites, change of genera and species of.
Trimen, on painting butterflies.
Trimorphism, in plants.
Trinidad, Catasetum of. -Cruger on caprification in.
Triphaena (Triphoea) pronuba, robin attracted by colour of.
Tristan d'Acunha, Carmichael on. -vegetation of.
Triticum repens var. littorum, bloom-experiments on.
Trollope, A., quotation by Darwin from.
Tropaeolum, Darwin's experiments on. -peloric variety of. -waxy secretion on leaves.
Tropical climate, in relation to colouring of insects.
Tropical plants, possible existence during cooler period. -retreat of.
Tropics, climatic changes in. -description of forests in. -similarity of orders in.
Tubocytisus, Kerner on.
Tuckwell, on the Oxford British Association meeting (1860).
Tucotuco.
Tuke, D.H., on influence of mind on body. -letter to.
Tulips.
Turkey, colour of wings, and courtship. -muscles of tail of.
Turner, Sir W., Darwin receives assistance from. -on Darwin's methods of correspondence. -letters to.
Turratella.
Turtles, conversion into land-tortoises.
Tussilago, Darwin on seeds of groundsel and.
Twins, Galton's article on.
Tylor, article in "Journal of the Royal Institution" by. -on "Early History of Mankind."
Tyndall, lack of caution. -lecture by. -on the Alps. -review in the "Athenaeum" of. -on valleys due to glaciers. -work of. -dogmatism of. -on glaciers. -on Sorby's work on cleavage. -mentioned.
Typhlops.
Typical forms, difficult to select. -vagueness of phrase.
Typotherium, Falconer on.
Tyrol, Mojsisovics on the Dolomites of the.
Umbelliferae, morphological characters of. -difference in seeds from the same flower.
Undulation of light, comparison between Darwin's views and the theory of.
Ungulates, development in N. America during Tertiary period.
United States, flora of. -spread of Darwin's views in.
Unity of coloration, Walsh on.
Uredo, on Haematoxylon.
Ursus arctos, Lamont on. -U. maritimus, Lamont on.
Urticaceae.
Uruguay.
D'Urville, on Canary Islands.
Use and disuse. -in plants.
Uses, Natural Selection and.
Uspallata.
Utilitarianism, Darwin on.
Utility and inheritance.
Utopian "Flora," Darwin's idea of.
Utricularia, Darwin's work on. -U. stellaris, Sir E. Tennent on.
Vaginulus, Darwin finds new species of.
Valeriana, two forms of.
Valleys, action of ice in formation of. -Dana on Australian. -Darwin on origin of.
Valparaiso.
Van Diemen's Land, flora of, in relation to New Zealand.
Vanda.
Vandeae, structure of ovary.
Vanessa, two sexual forms of. -breeding in confinement. -colour of.
Vanilla.
Variability, backward tendency of. -Bentham on. -causes of. -De Candolle on. -dependent more on nature of organism than on environment. -Huxley and Scott on. -importance of subject of cause of. -Natural Selection and. -in oaks. -greater in bisexual than in unisexual plants. -of ferns "passes all bounds." -greater in male than female. -in ovaries of flowers. -tendency of genera at different periods towards.
Variation. -an innate principle. -Bates on. -in blackbirds. -causes of. -centrifugal nature of. -checked by Natural Selection. -climate and. -Darwin attaches importance to useless. -Darwin on favourable. -divergence of. -and external conditions. -in elephants. -in Fucus. -of large genera. -laws of. -of monotypic and polytypic genera. -and monstrosities. -and Natural Selection. -ordination and. -in peaches. -in plants. -produced by crossing. -rate of action of. -of small genera. -sterility advantageous to. -Weismann on. -galls as cause of. -and loss of dimorphism in Primula and Auricula. -Sexual Selection and minute. -transmission to sexes. -Verlot on. -Wallace on.