On the Origin of Species by Means of Natural Selection: Or The Preservation of Favoured Races in the Struggle for LifeHumphrey Milford, Oxford University Press, 1923 - 454 páginas |
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Página 21
... slight degree from each other . Altogether at least a score of pigeons might be chosen , which if shown to an ornithologist , and he were told that they were wild birds , would certainly , I think , be ranked by him as well - defined ...
... slight degree from each other . Altogether at least a score of pigeons might be chosen , which if shown to an ornithologist , and he were told that they were wild birds , would certainly , I think , be ranked by him as well - defined ...
Página 27
... slight differences , yet they ignore all general arguments , and refuse to sum up in their minds slight differences accumulated during many successive generations . May not those natural- ists who , knowing far less of the laws of ...
... slight differences , yet they ignore all general arguments , and refuse to sum up in their minds slight differences accumulated during many successive generations . May not those natural- ists who , knowing far less of the laws of ...
Página 30
... colour , shape , and hairi- ness , and yet the flowers present very slight differences . It is not that the varieties which differ largely in some one point do not differ at all in other points 30 ON THE ORIGIN OF SPECIES.
... colour , shape , and hairi- ness , and yet the flowers present very slight differences . It is not that the varieties which differ largely in some one point do not differ at all in other points 30 ON THE ORIGIN OF SPECIES.
Página 31
... slight variations , either in the leaves , the flowers , or the fruit , will produce races differing from each other chiefly in these characters . It may be objected that the principle of selection has been reduced to methodical ...
... slight variations , either in the leaves , the flowers , or the fruit , will produce races differing from each other chiefly in these characters . It may be objected that the principle of selection has been reduced to methodical ...
Página 35
... slight in internal parts or organs . Man can hardly select , or only with much difficulty , any deviation of structure excepting such as is externally visible ; and indeed he rarely cares for what is internal . He can never act by ...
... slight in internal parts or organs . Man can hardly select , or only with much difficulty , any deviation of structure excepting such as is externally visible ; and indeed he rarely cares for what is internal . He can never act by ...
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Términos y frases comunes
accumulated adapted affinities allied species America amount analogous ancient appear Archipelago become bees believe birds breeds cause cells characters cirripedes climate closely allied colour common parent continuous crossed crustaceans degree difficulty distinct species divergence 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 land larvæ less living male mammals manner Marsupials migration modification modified descendants natural selection naturalists nearly nest oceanic islands offspring organisation perfect pigeons pistil plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rock-pigeon rudimentary organs seeds sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion trees variability variation vary whole widely