Tubipora musica, structure and mode of reproduction of, ii. 130 Tubipora purpurea, habitat of, ii. 130 Tubularia, form and structure of the family, ii. 91 mode of propagation of, ii. 91 Tulip, structure and mode of reproduction of, i. 388 Tunicata, or Ascidians, characters of, ii. 222 groups of, ii. 222, _et seq._ Turbellariæ, structure of the, ii. 148 Turkey red, from what obtained, i. 124 Turpentine, oil of, takes fire in chlorine gas, i. 19 Turritopsis nutricula, larvæ of the Cunina octonaria, parasites of, ii. 100 U Ulva, structure and reproduction of, i. 171, 225 Ulva bullosa, reproduction of, i. 227 Ulva lactuca, structure and mode of reproduction of, i. 226 Ulva latissima, structure and mode of reproduction of, i. 225-227 Ulva Linza, structure and mode of reproduction of, i. 226 Umbilicaria, structure and habitat of, i. 308 Upas-tree of Java, causes of the virulence of, i. 426 fruit of, innocuous, i. 426 Uranium, i. 4, 5 nitrate of, phosphorescence of, i. 67 Uranite, yellow, fluorescent property of, i. 66 Uredines, structure and habitat of the, i. 277 Uredo, structure and mode of reproduction of, i. 277 Uredo candida, or Cystopus candidus, structure, habitat, and mode of reproduction of, i. 278 Uredo linearis, the rust on the leaves and chaff scales of wheat, i. 281 Uromyces appendiculatus, or fungus of the common bean, i. 280 Usnea, structure of, i. 302 Usnea melaxantha, splendour of, i. 304 Usnea Taylori, splendour of, i. 304 Usneæ, brilliancy and wide diffusion of the, i. 304 Usnic acid, produced by lichens, i. 303 Uva di mare, fruit of, i. 257 V Vacuum tubes, i. 78, _note_ electric discharges in, i. 78, 79 Valvulina, structure of, ii. 37 Vanilla, reproduction of, i. 402 Vapours, absorption of radiant heat by gases and vapours, i. 38 radiation of, equal to absorption, i. 46 Variolaria dealbata, litmus or orchil obtained from, i. 124 Vaucheria, character of the genus, i. 218, 224 structure, habitat, and modes of reproduction of, i. 218 Vaucheria marina, structure and habitat of, i. 224 Vaucheria sessilis, mode of reproduction of, i. 219 Vaucheria velutina, habitat of, i. 224 Vegetable world, microscopic structure of the, i. 167