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:
1880
Catalogue details

Licence: Public Domain Mark

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.

Provider: This material has been provided by King’s College London. The original may be consulted at King’s College London.

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    CHAPTER VII. Miscellaneous Objections to the Theory of Natural Selection. Longevity — Modifications not necessarily simultaneous — Modifications apparently of no direct service—Progressive development — Characters of small functional importance, the most constant—Supposed incom- petence of natural selection to account for the incipient stages ot useful structures—Causes which interfere with the acquisition through natural selection of useful structures—Gradations of structure with changed functions—Widely different organs in members of the same class, developed from one and the same source—Reasons for disbeliev- ing in great and abrupt modifications Page 168-204 CHAPTER VIII. Instinct. Instincts comparable with habits, but different in their origin — Instincts graduated — Aphides and ants — Instincts variable — Domestic in- stincts, their origin — Natural instincts of the cuckoo, molothrus, ostrich, and parasitic bees — Slave-making ants — Iiive-bee, its cell- making instinct— Changes of instinct and structure not necessarily simultaneous—Difficulties of the theory of the Natural Selection of instincts — Neuter or sterile insects — Summary .. .. 205-234 CHAPTER IX. Hybridism. Distinction between the sterility of first crosses and of hybrids — Sterility various in degree, not universal, affected by close interbreeding, re- moved by domestication — Laws governing the sterility of hybrids — Sterility not a special endowment, but incidental on other differences, not accumulated by natural selection — Causes of the sterility of first crosses and of hybrids — Parallelism between the effects of changed conditions of life and of crossing — Dimorphism and Trimorphism — Fertility of varieties when crossed and of their mongrel offspring not universal — Hybrids and mongrels compared independently of their fertility — Summary 234-263