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 123
... families . Thus it is , as I believe , that two or more genera are produced by descent with modification , from two or more species of the same genus . And the two or more parent - species are supposed to have descended from. G 2 CHAP ...
... families . Thus it is , as I believe , that two or more genera are produced by descent with modification , from two or more species of the same genus . And the two or more parent - species are supposed to have descended from. G 2 CHAP ...
Página 124
... families , or genera , with those now living , yet are often , in some degree , intermediate in character between existing groups ; and we can understand this fact , for the extinct species lived at very ancient epochs when the. 124 CHAP ...
... families , or genera , with those now living , yet are often , in some degree , intermediate in character between existing groups ; and we can understand this fact , for the extinct species lived at very ancient epochs when the. 124 CHAP ...
Página 125
... families , or even orders , according to the amount of divergent modification supposed to be represented in the diagram . And the two new families , or orders , will have descended from two species of the original genus ; and these two ...
... families , or even orders , according to the amount of divergent modification supposed to be represented in the diagram . And the two new families , or orders , will have descended from two species of the original genus ; and these two ...
Página 126
... families , orders , and classes , as at the present day . Summary of Chapter . - If during the long course of ages and under varying conditions of life , organic beings . vary at all in the several parts of their organisation. 126 CHAP ...
... families , orders , and classes , as at the present day . Summary of Chapter . - If during the long course of ages and under varying conditions of life , organic beings . vary at all in the several parts of their organisation. 126 CHAP ...
Página 128
... sections and sub - genera , spe- cies of distinct genera much less closely related , and genera related in different degrees , forming sub - fami- lies , families , orders , sub - classes ,. 128 CHAP . IV . NATURAL SELECTION .
... sections and sub - genera , spe- cies of distinct genera much less closely related , and genera related in different degrees , forming sub - fami- lies , families , orders , sub - classes ,. 128 CHAP . IV . NATURAL SELECTION .
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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