On the Origin of Species by Means of Natural Selection: Or The Preservation of Favored Races in the Struggle for Life, Volumen2D. Appleton, 1888 - 458 páginas |
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Página vii
... hybrids — Sterility various in degree , not universal , affected by close interbreeding , re- moved 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 interbreeding , re- moved by domestication - Laws governing the sterility of hybrids — Sterility not a special endowment , but incidental on other differences ...
Página xii
... hybrid moths . The discussion on the fertility of hybrids not having been ac- quired through natural selection condensed and modified . On the causes of sterility of hybrids , added to and corrected . Pyrgoma found in the chalk ...
... hybrid moths . The discussion on the fertility of hybrids not having been ac- quired through natural selection condensed and modified . On the causes of sterility of hybrids , added to and corrected . Pyrgoma found in the chalk ...
Página 7
... hybrids . When , on the one hand , we see domesticated animals and plants , though often weak and sickly , breeding freely under confinement ; and when , on the other hand , we see individuals , though taken young from a state of nature ...
... hybrids . When , on the one hand , we see domesticated animals and plants , though often weak and sickly , breeding freely under confinement ; and when , on the other hand , we see individuals , though taken young from a state of nature ...
Página 19
... hybrids or mongrels from between all the breeds of the pigeon are perfectly fertile , as I can state from my own obser- vations , purposely made , on the most distinct breeds . Now , hardly any cases have been ascertained with certainty ...
... hybrids or mongrels from between all the breeds of the pigeon are perfectly fertile , as I can state from my own obser- vations , purposely made , on the most distinct breeds . Now , hardly any cases have been ascertained with certainty ...
Página 32
... hybrids and of mongrels , and the sterility of hybrids ; but plants not propagated by seed are of little importance to us , for their endurance is only temporary . Over all these causes of Change , the accumulative action of Selection ...
... hybrids and of mongrels , and the sterility of hybrids ; but plants not propagated by seed are of little importance to us , for their endurance is only temporary . Over all these causes of Change , the accumulative action of Selection ...
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Términos y frases comunes
adapted admit affinities allied species America analogous ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied colour continued crossed crustaceans degree developed difficulty distinct species doubt effects eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formation formerly forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number habits Hence hybrids important individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living male mammals manner Marsupials migration modified descendants natural selection naturalists nearly nest occasionally occur oceanic islands offspring organisation organs parent peculiar perfect pigeon pistil pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked reproductive resemblance rudimentary seeds sexual selection slight South America stamens sterility structure struggle successive supposed tend theory tion variability variations varieties vary whilst whole wings young