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 23
... supposed aboriginal stocks must all have been rock - pigeons , that is , not breeding or willingly perching on trees . But besides C. livia , with its geographical sub - species , only two or three other species of rock - pigeons are ...
... supposed aboriginal stocks must all have been rock - pigeons , that is , not breeding or willingly perching on trees . But besides C. livia , with its geographical sub - species , only two or three other species of rock - pigeons are ...
Página 24
... supposed ex- termination of so many species having similar habits with the rock - pigeon seems to me a very rash assump- tion . Moreover , the several above - named domesticated breeds have been transported to all parts of the world ...
... supposed ex- termination of so many species having similar habits with the rock - pigeon seems to me a very rash assump- tion . Moreover , the several above - named domesticated breeds have been transported to all parts of the world ...
Página 26
... seems to me rash in the extreme . From these several reasons , namely , the improbability of man having formerly got seven or eight supposed species of pigeons to breed freely under domestication ; these. 26 CHAP . I. DOMESTIC PIGEONS .
... seems to me rash in the extreme . From these several reasons , namely , the improbability of man having formerly got seven or eight supposed species of pigeons to breed freely under domestication ; these. 26 CHAP . I. DOMESTIC PIGEONS .
Página 27
... supposed species being quite unknown in a wild state , and their becoming nowhere feral ; these species having very abnormal characters in certain respects , as compared with all other Columbidæ , though so like in most other respects ...
... supposed species being quite unknown in a wild state , and their becoming nowhere feral ; these species having very abnormal characters in certain respects , as compared with all other Columbidæ , though so like in most other respects ...
Página 44
... supposed not to be in- herited : but who can say that the dwarfed condition of shells in the brackish waters of the Baltic , or dwarfed 7 plants on Alpine summits , or the thicker fur. 44 CHAP . II . VARIATION UNDER NATURE .
... supposed not to be in- herited : but who can say that the dwarfed condition of shells in the brackish waters of the Baltic , or dwarfed 7 plants on Alpine summits , or the thicker fur. 44 CHAP . II . VARIATION UNDER NATURE .
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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