I distinctly stated that great weight must be attributed to the inherited effects of use and disuse, with respect both to the body and mind. I also attributed some amount of modification to the direct and prolonged action of changed conditions of life. Some allowance, too, must be made for occasional reversions of structure; nor must we forget what I have called " correlated" growth, meaning, thereby, that various parts of the organisation are in some unknown manner so connected, that when one part varies, so do others; and if variations in the one are accumulated by selection, other parts will be modified. Again, it has been said by. several critics, that when I found that many details of structure in man could not be explained through natural selection, I invented sexual selection; I gave, however, a tolerably clear sketch of this principle in the first edition of the 'Origin of Species,' and I there stated that it was applicable to man. This subject of sexual selection has been treated at full length in the present work, simply because an opportunity was here first afforded me. I have been struck with the likeness of many of the half-favourable criticisms on sexual selection, with those which appeared at first on natural selection; such as, that it would explain some few details, but certainly was not applicable to the extent to which I have. employed it. My conviction of the power of sexual selection remains unshaken; but it is probable, or almost certain, that several of my conclusions will hereafter be found erroneous; this can hardly fail to be the case in the first treatment of a subject. When naturalists have become familiar with the idea of sexual selection, it will, as I believe, be much more largely accepted; and it has already been fully and favourably received by several capable judges. DOWN, BECKENHAM, KENT, September, 1874. First Edition Feb. 24, 1871. Second Edition Sept., 1874. 125, note 36-38, note 54-56, note 87,88 Supernumerary mammæ and digits. Disappearance of the tail in man and 207, 208 Injurious forms of selection in civi 220 Vol. I. 128, 129 41, 42 62, 63 82, note 86 234 lised nations. Indolence of man, when free from a struggle for existence. Gorilla protecting himself from rain with his hands. Hermaphroditism in fish. Rudimentary mamma in male mammals. Changed conditions lessen fertility and cause ill-health amongst savages. Darkness of skin a protection against the sun. Note by Professor Huxley on the development of the brain in man and apes. Special organs of male parasitic worms for holding the female. Greater variability of male than female; direct action of the environment in causing differences between the sexes. Period of development of protuberances on birds' heads determines their transmission to one or both sexes. Causes of excess of male births. Proportion of the sexes in the bee family. Excess of males perhaps sometimes determined by selection. Bright colours of lowly organised Sexual selection amongst spiders. worm. The humming noises of flies. Use of bright colours to Hemiptera (bugs). 174 265 266 277 Vol. II. 2 15-17 Musical apparatus of Homoptera. Development of stridulating apparatus in Orthoptera. Hermann Müller on sexual differ- Sounds produced by moths. Further cases of mimicry in butter- Cause of bright and diversified colours of caterpillars. Brush-like scales of male Mallotus. Further facts on courtship of fishes, and the spawning of Macropus. Dufossé on the sounds made by fishes. Belt on a frog protected by bright colouring. Further facts on mental powers of snakes. Sounds produced by snakes; the rattlesnake. Combats of Chameleons. Marshall on protuberances on birds' heads. Further facts on display by the Attachment between paired birds. Albino birds not finding partners, in a state of nature. Direct action of climate on birds' Further facts on the ocelli in the Cases with pigeons of colour transmitted to one sex alone. 249, 250 Taste for the beautiful permanent enough to allow of sexual selection with the lower animals. Horns of sheep originally a masculine character. Castration affecting horns of animals. Prong-horned variety of Cervus virginianus. Display by humming-birds in courtship. Page Page Page 260 516 281 266 521 288 286 534 309 299 542, 543 322, 323 316 556 341 337 Relative sizes of male and female whales and seals. Absence of tusks in male miocene pigs. Dobson on sexual differences of bats. Reeks on advantage from peculiar colouring. Difference of complexion in men and women of an African tribe. Speech subsequent to singing. Schopenhauer on importance of courtship to mankind. 359 et seq. 588 et seq. 391 et seq. Revision of discussion on communal |