Page:Darwinism by Alfred Wallace 1889.djvu/510

Horse tribe, pedigree of, 384
ancestral forms of, 386

Humming-birds, recognition marks of, 226

Huth, Mr., on close interbreeding, 160

Huxley, Professor on the struggle for existence, 37
on fossil crocodiles, 383
on anatomical peculiarities of the horse tribe, 384
on development of vertebrates, 448
on early man, 456
on brains of man and the gorilla, 457

Hybridity, remarks on facts of, 166
summary on, 184

Hybrids, infertility of, supposed test of distinct species, 152
fertility of, 159
fertile among animals, 162
between sheep and goat, 162
fertile between distinct species of moths, 163
fertile among plants, 163

Hymenopus bicornis, resembling flower, 212


I

Icterus Baltimore, diagram showing proportionate numbers which
vary, 63

Imitative resemblances, how produced, 205

Increase of organisms in a geometrical ratio, 25

Inedible fruits rarely coloured, 308

Insect and self-fertilisation, alternation of, in flowers, 328

Insect-fertilisation, facts relating to, 316

Insects, coloured for recognition, 226
warning colours of, 233
sexual coloration of, 269
importance of dull colours to female, 272
visiting one kind of flower at a time, 318
and flowers, the most brilliant not found together, 335

Insects, no proof of love of colour by, 336
and birds at sea, 357
in mid-ocean, 359
at great altitudes, 360
geological distribution of, 403
ancestral in Silurian, 405
fossil support evolution, 405

Instability of useless characters, 138

Instinct, the theory of, 441

Insular organisms illustrate powers of dispersal, 354

Interbreeding, close, injurious effects of, 160
supposed evil results of close, 326

Intercrossing, swamping effects of, 142
not necessarily useful, 325

Intermediate forms, why not found, 380

Islands, all oceanic are volcanic or coralline, 342

Isle of Man, small butterflies of, 106

Isolation, the importance of, 119
to prevent intercrossing, 144
by variations of habits, etc., 145
Rev. J.G. Gulick on, 147
when ineffective, 150

Ituna Ilione and Thyridia megisto, figures of wings of, 251


J

Jacobin, 93

Jenyns, Rev. L., on internal variations of mammalia, 69

Jordan, Mons. A., on varieties of Draba verna, 77

Judd, Professor, on dust fallen at Genoa, 363
on Hungarian fossil lacustrine shells, 381


K

Kerguelen Island, wingless insects of, 106

Kerivoula picta, protective colour of, 201