On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeJ. Murray, 1860 - 502 páginas "In considering the Origin of Species, it is quite conceivable that a naturalist, reflecting on the mutual affinities of organic beings, on their embryological relations, their geographical distribution, geological succession, and other such facts, might come to the conclusion that each species had not been independently created, but had descended, like varieties, from other species. Nevertheless, such a conclusion, even if well founded, would be unsatisfactory, until it could be shown how the innumerable species inhabiting this world have been modified, so as to acquire that perfection of structure and coadaptation which most justly excites our admiration. Naturalists continually refer to external conditions, such as climate, food, & c, as the only possible cause of variation. In one very limited sense, as we shall hereafter see, this may be true; but it is preposterous to attribute to mere external conditions, the structure, for instance, of the woodpecker, with its feet, tail, beak, and tongue, so admirably adapted to catch insects under the bark of trees. In the case of the misseltoe, which draws its nourishment from certain trees, which has seeds that must be transported by certain birds, and which has flowers with separate sexes absolutely requiring the agency of certain insects to bring pollen from one flower to the other, it is equally preposterous to account for the structure of this parasite, with its relations to several distinct organic beings, by the effects of external conditions, or of habit, or of the volition of the plant itself"--Introduction. (PsycINFO Database Record (c) 2012 APA, all rights reserved) |
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Página 8
... breed freely under confinement , even in the many cases when the male and female unite . How many animals there are which will not breed , though living long under not very close con- finement in their native country ! This is generally ...
... breed freely under confinement , even in the many cases when the male and female unite . How many animals there are which will not breed , though living long under not very close con- finement in their native country ! This is generally ...
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... breed in this country pretty freely under confinement , with the exception of the plantigrades or bear family ; whereas carnivorous birds , with the rarest exceptions , hardly ever lay fertile eggs . Many exotic plants have pollen ...
... breed in this country pretty freely under confinement , with the exception of the plantigrades or bear family ; whereas carnivorous birds , with the rarest exceptions , hardly ever lay fertile eggs . Many exotic plants have pollen ...
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... Breeders believe that long limbs are almost always accompanied by an elongated head . Some instances of correlation are quite whimsical : thus cats with blue eyes are invariably deaf ; colour and. CHAP . I. 11 UNDER DOMESTICATION .
... Breeders believe that long limbs are almost always accompanied by an elongated head . Some instances of correlation are quite whimsical : thus cats with blue eyes are invariably deaf ; colour and. CHAP . I. 11 UNDER DOMESTICATION .
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... breeds are often transmitted either exclusively , or in a much greater degree , to males alone . A much more important rule , which I think may be trusted , is that , at whatever period of life a peculiarity first appears , it tends to ...
... breeds are often transmitted either exclusively , or in a much greater degree , to males alone . A much more important rule , which I think may be trusted , is that , at whatever period of life a peculiarity first appears , it tends to ...
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... breed our cart and race - horses , long and short - horned cattle , and poultry of various breeds , and esculent vegetables , for an almost infinite number of generations , would be opposed to all experience . I may add , that when ...
... breed our cart and race - horses , long and short - horned cattle , and poultry of various breeds , and esculent vegetables , for an almost infinite number of generations , would be opposed to all experience . I may add , that when ...
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Términos y frases comunes
adapted affinities allied species America analogous ancient animals become bees believe birds breeds cause cells chapter characters cirripedes climate closely allied colour continuous crossed crustaceans degree difficulty distinct species divergence domestic doubt embryo Europe existing exterminated extinct extremely facts favourable Fcap fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period greater number groups of species habits Hence hermaphrodites History hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing intermediate land larvæ less living male mammals manner migration modification modified descendants natural selection naturalists nearly nest offspring perfect pigeons plants pollen Portrait Post 8vo present principle probably produced progenitor racter ranked reciprocal crosses remarked resemble rudimentary organs Second Edition seeds sexual selection Silurian slight South America sterility structure struggle successive supposed theory Third Edition tion variability variations varieties vary Vols widely Woodcuts