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 10
... remarked , have apparently been exposed to exactly the same conditions of life ; and this shows how unim- portant the direct effects of the conditions of life are in comparison with the laws of reproduction , of growth , and of ...
... remarked , have apparently been exposed to exactly the same conditions of life ; and this shows how unim- portant the direct effects of the conditions of life are in comparison with the laws of reproduction , of growth , and of ...
Página 15
... remarked , less uniformity of character than in true species . Domestic races of the same species , also , often have a somewhat monstrous character ; by which I mean , that , although differing from each other , and from other species ...
... remarked , less uniformity of character than in true species . Domestic races of the same species , also , often have a somewhat monstrous character ; by which I mean , that , although differing from each other , and from other species ...
Página 38
... remarked by some authors , namely , that the varieties kept by savages have more of the character of species than the varieties kept in civilised countries . On the view here given of the all - important part which selection by man has ...
... remarked by some authors , namely , that the varieties kept by savages have more of the character of species than the varieties kept in civilised countries . On the view here given of the all - important part which selection by man has ...
Página 41
... remarked , with respect to the sheep of parts of Yorkshire , that " as they generally belong to poor people , and are mostly in small lots , they never can be improved . " On the other hand , nurserymen , from raising large stocks of ...
... remarked , with respect to the sheep of parts of Yorkshire , that " as they generally belong to poor people , and are mostly in small lots , they never can be improved . " On the other hand , nurserymen , from raising large stocks of ...
Página 57
... remarked in regard to plants , and Westwood in regard to insects , that in large genera the amount of difference between the species is often exceedingly small . I have endeavoured to test this numerically by averages , and , as far as ...
... remarked in regard to plants , and Westwood in regard to insects , that in large genera the amount of difference between the species is often exceedingly small . I have endeavoured to test this numerically by averages , and , as far as ...
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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