On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeMurray, 1860 - 502 páginas |
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Página vii
... hybrids - Sterility various in degree , not universal , affected by close inter- breeding , removed by domestication - Laws governing the sterility of hybrids — Sterility not a special endowment , but incidental on other differences ...
... hybrids - Sterility various in degree , not universal , affected by close inter- breeding , removed by domestication - Laws governing the sterility of hybrids — Sterility not a special endowment , but incidental on other differences ...
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 26
... 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 ...
... 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 ...
Página 43
... 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 50
... hybrids ; and there is , as it seems to me , an overwhelming amount of experimental evidence , show- ing that they descend from common parents , and con- sequently 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 , show- ing that they descend from common parents , and con- sequently 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 animals appear become bees believe birds breeds cause cells characters cirripedes climate closely allied colour common parent 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 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 male mammals manner Marsupials migration modification modified descendants natural selection naturalists nearly nest oceanic islands offspring organisation perfect pigeons plants pollen present probably produced progenitor racters ranked reciprocal crosses remarked resemble rock-pigeon rudimentary organs seeds sexual selection Silurian slight South America sterility structure struggle successive supposed tend theory tion variability variations varieties vary whole widely