On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle of LifeAppleton, 1864 - 440페이지 |
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6 페이지
... sterility of first crosses and of hybrids - Sterility various in degree , not universal , affected by close interbreeding , removed by domestication- Laws governing the sterility of hybrids - Sterility not a special endowment , but ...
... sterility of first crosses and of hybrids - Sterility various in degree , not universal , affected by close interbreeding , removed by domestication- Laws governing the sterility of hybrids - Sterility not a special endowment , but ...
16 페이지
... Sterility has been said to be the bane of horticulture ; but on this view we owe variability to the same cause which produces sterility ; and variability is the source of all the choicest productions of the garden . I may add , that as ...
... Sterility has been said to be the bane of horticulture ; but on this view we owe variability to the same cause which produces sterility ; and variability is the source of all the choicest productions of the garden . I may add , that as ...
30 페이지
... sterility : from the history of the dog I think there is some probability in this hypothesis if applied to species closely related to- gether , though it is unsupported by a single experiment . But to extend the hypothesis so far as to ...
... sterility : from the history of the dog I think there is some probability in this hypothesis if applied to species closely related to- gether , though it is unsupported by a single experiment . But to extend the hypothesis so far as to ...
45 페이지
... sterility of hybrids ; but the cases of plants not propagated by seed are of little importance to us , for their endurance is only temporary . Over all these causes of Change I am convinced that the accumulative action of Selection ...
... sterility of hybrids ; but the cases of plants not propagated by seed are of little importance to us , for their endurance is only temporary . Over all these causes of Change I am convinced that the accumulative action of Selection ...
216 페이지
... of one general law , leading to the advancement of all or- ganic beings , namely , multiply , vary , let the strongest live and the weakest die . CHAPTER VIII . HYBRIDISM . Distinction between the sterility of 216 [ CHAP . V11 . INSTINCT .
... of one general law , leading to the advancement of all or- ganic beings , namely , multiply , vary , let the strongest live and the weakest die . CHAPTER VIII . HYBRIDISM . Distinction between the sterility of 216 [ CHAP . V11 . INSTINCT .
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accumulated adapted affinities allied species America amount ancient animals appear become bees believe birds breeds cause cells characters cirripedes climate closely allied colour continuous crossed crustaceans degree difficulty distinct species disuse divergence domestic doubt embryo endemic Europe existing exterminated extinct extremely facts favourable fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hermaphrodites hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing intermediate land larvæ less living look male mammals manner migration modification modified descendants natural selection naturalists nearly nest offspring organic organisation perfect pigeons pistil plants pollen present probably produced progenitor ranked reciprocal crosses remarked resemble rudimentary seeds seems sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion trees variability variation varieties vary whole widely
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424 페이지 - In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history.
63 페이지 - There is no exception to the rule that every organic being naturally increases at so high a rate, that, if not destroyed, the earth would soon be covered by the progeny of a single pair.
79 페이지 - I may be allowed to personify the natural preservation or survival of the fittest, cares nothing for appearances, except in so far as they are useful to any being. She can act on every internal organ, on every shade of constitutional difference, on the whole machinery of life. Man selects only for his own good: Nature only for that of the being which she tends.
70 페이지 - I counted thirtytwo little trees ; and one of them, with twenty-six rings of growth, had during many years tried to raise its head above the stems of the heath, and had failed. No wonder that, as soon as the land was enclosed, it became thickly clothed with vigorously growing young firs. Yet the heath was so extremely barren and so extensive that no one would ever have imagined that cattle would have so closely and effectually searched it for food. Here we see that cattle absolutely determine the...
169 페이지 - If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.
63 페이지 - Hence as more individuals are produced than can possibly survive, there must in every case be a struggle for existence, either one individual with another of the same species, or with the individuals of distinct species, or with the physical conditions of life.
167 페이지 - To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest degree.
378 페이지 - Nothing can be more hopeless than to attempt to explain this similarity of pattern in members of the same class, by utility or by the doctrine of final causes. The hopelessness of the attempt has been expressly admitted by Owen in his most interesting work on the 'Nature of Limbs.
187 페이지 - Under changed conditions of life, it is at least possible that slight modifications of instinct might be profitable to a species; and if it can be shown that instincts do vary ever so little, then I can see no difficulty in natural selection preserving and continually accumulating variations of instinct to any extent that was profitable. It is thus, as I believe, that all the most complex and wonderful instincts have originated.
165 페이지 - I can see no difficulty in a race of bears being rendered, by natural selection, more and more aquatic in their structure and habits, with larger and larger mouths, till a creature was produced as monstrous as a whale.