The Origin of Species by Means of Natural Selection,: Or the Preservation of Favoured Races in the Struggle for LifeJohn Murray, Albemarle Street., 1891 - 432페이지 |
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57개의 결과 중 6 - 10개
35 페이지
... island . The local forms are moderately constant and distinct in each separate island ; but when all from the several islands are compared together , the differences are seen to be so slight and graduated , that it is impossible to ...
... island . The local forms are moderately constant and distinct in each separate island ; but when all from the several islands are compared together , the differences are seen to be so slight and graduated , that it is impossible to ...
36 페이지
... islands . When , on the other hand , an animal or plant ranges over the same continent , or inhabits many islands in the same archipelago , and presents different forms in the different areas , there is always a good chance that ...
... islands . When , on the other hand , an animal or plant ranges over the same continent , or inhabits many islands in the same archipelago , and presents different forms in the different areas , there is always a good chance that ...
47 페이지
... islands in a period of less than ten years . Several of the plants , such as the cardoon and a tall thistle , which are now the commonest over the wide plains of La Plata , clothing square leagues of surface almost to the exclusion of ...
... islands in a period of less than ten years . Several of the plants , such as the cardoon and a tall thistle , which are now the commonest over the wide plains of La Plata , clothing square leagues of surface almost to the exclusion of ...
59 페이지
... island , or of a country partly surrounded by barriers , into which new and better adapted forms could not freely enter , we should then have places in the economy of nature which would assuredly be better filled up , if some of the ...
... island , or of a country partly surrounded by barriers , into which new and better adapted forms could not freely enter , we should then have places in the economy of nature which would assuredly be better filled up , if some of the ...
67 페이지
... Islands consist of a variety so well marked , that it was formerly ranked as a distinct species under the name of Uria lacrymans . In cases of this kind , if the variation were of a beneficial nature , the original form would soon be ...
... Islands consist of a variety so well marked , that it was formerly ranked as a distinct species under the name of Uria lacrymans . In cases of this kind , if the variation were of a beneficial nature , the original form would soon be ...
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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 facts 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 occur 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