Copy 7

The origin of species by means of natural selection, or The preservation of favoured races in the struggle for life / by Charles Darwin.

  • Darwin, Charles, 1809-1882.
Date:
1872
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: The origin of species by means of natural selection, or The preservation of favoured races in the struggle for life / by Charles Darwin. Source: Wellcome Collection.

    10/522 (page VI)
    CHAPTER IY. Natural Selection; or the Survival of the Fittest. Natural Selection — its power compared with man’s selection — its power on characters of trifling importance — its power at all ages and on both sexes — Sexual Selection — On the generality of intercrosses between individuals of the same species — Circumstances favourable and unfa vourable to the results of Natural Selection, namely, intercrossing, isolation, number of individuals — Slow action— Extinction caused by Natural Selection—Divergence of Character, related to the diversity of inhabitants of any small area, and to naturalisation — Action of Natural Selection, through Divergence of Character and Extinction, on the descendants from a common parent — Explains the grouping of all organic beings — Advance in organisation — Low forms preserved — Convergence of character—Indefinite multiplication of species — Summary Page 62-105 CHAPTER Y. Laws of Variation. EiFeets of changed conditions — Use and disuse, combined with natural selection ; organs of flight and of vision — Acclimatisation — Correlated variation—Compensation and economy of growth — False correlations — Multiple, rudimentary, and lowly organised structures variable —• Parts developed in an unusual manner are highly variable : spécifié characters more variable than generic : secondary sexual characters variable — Species of the same genus vary in an analogous manner — Reversions 10 long-lost characters — Summary 106-132 CHAPTER VI. Difficulties of the Theory. Difficulties of the theory of descent with modification — Absence or rarity of transitional varieties — Transitions in habits of life — Diversified habits in the same species — Species with habits widely different from those of their allies — Organs of extreme perfection — Modes of transition—Cases of difficulty — Natura non facit saltum — Organs of small importance—Organs not in all cases absolutely perfect — The law of Unity of Type and of the Conditions of Existence embraced by the theory of Natural Se’-ection .. .. <t .. .. 133-167