The Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeJ. Murray, 1920 - 432페이지 |
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52개의 결과 중 1 - 5개
vii 페이지
... 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 incidental on other differences , not ...
... 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 incidental on other differences , not ...
xii 페이지
... hybrid moths . The discussion on the fertility of hybrids not having been acquired through natural selection condensed and modified . On the causes of sterility of hybrids , added to and corrected . 267 Pyrgoma found in the chalk . 326 ...
... hybrid moths . The discussion on the fertility of hybrids not having been acquired through natural selection condensed and modified . On the causes of sterility of hybrids , added to and corrected . 267 Pyrgoma found in the chalk . 326 ...
7 페이지
... 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 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 state of nature ...
18 페이지
... hybrids or mongrels from between all the breeds of the pigeon are perfectly fertile , as I can state from my own observa- tions , 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 observa- tions , purposely made , on the most distinct breeds . Now , hardly any cases have been ascertained with certainty ...
30 페이지
... 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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accumulated adapted admit affinities allied species America analogous ancient appear beak become bees believe belonging birds breeds cause cells characters climate closely allied colour continued crossed crustaceans degree developed difficulty distinct species domestic animals doubt effects eggs embryo existing extinct extremely fact favourable female fertilised fertility flowers formation formerly forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number habits Hence hybrids important increase 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 oceanic islands offspring organisation organs parent peculiar perfect pigeon pistil pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive supposed tend theory tion variability variations varieties vary whilst whole wings young