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 9
... hybrids . When , on the one hand , we see domesticated animals and plants , though often weak and sickly , yet breeding quite freely under confinement ; and when , on the other hand , we see individuals , though taken young from a state ...
... hybrids . When , on the one hand , we see domesticated animals and plants , though often weak and sickly , yet breeding quite freely under confinement ; and when , on the other hand , we see individuals , though taken young from a state ...
Página 24
... hybrids or mongrels from between all the domestic breeds of pigeons are perfectly fertile . I can state this from my ... hybrid offspring of two animals clearly distinct being themselves perfectly fertile . Some authors believe that long ...
... hybrids or mongrels from between all the domestic breeds of pigeons are perfectly fertile . I can state this from my ... hybrid offspring of two animals clearly distinct being themselves perfectly fertile . Some authors believe that long ...
Página 40
... hybrids and mongrels , and the frequent 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 ...
... hybrids and mongrels , and the frequent 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 ...
Página 44
... hybrid nature of the intermediate links always remove the difficulty . In very many cases , however , one form is ranked as a variety of another , not because the intermediate links have actually been found , but because analogy leads ...
... hybrid nature of the intermediate links always remove the difficulty . In very many cases , however , one form is ranked as a variety of another , not because the intermediate links have actually been found , but because analogy leads ...
Página 46
... hybrids ; and there is , as it seems to me , an overwhelming amount of experimental evidence , showing that they descend from common parents , and consequently must be ranked as varieties . Close investigation , in most cases , will ...
... hybrids ; and there is , as it seems to me , an overwhelming amount of experimental evidence , showing that they descend from common parents , and consequently must be ranked as varieties . Close investigation , in most cases , will ...
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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