The Origin of Species by Means of Natural Selection,: Or the Preservation of Favoured Races in the Struggle for LifeJohn Murray, Albemarle Street., 1891 - 432 páginas |
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Página 27
... occasionally appear , but these are rejected as faults or deviations from the standard of perfection in each breed . The common goose has not given rise to any marked varieties ; hence the Toulouse and the common breed , which differ ...
... occasionally appear , but these are rejected as faults or deviations from the standard of perfection in each breed . The common goose has not given rise to any marked varieties ; hence the Toulouse and the common breed , which differ ...
Página 30
... occasional intercrossing , with the aid of selection , has , no doubt , largely aided in the formation of new sub - breeds ; but the importance of crossing has been much exaggerated , both in regard to animals and to those plants which ...
... occasional intercrossing , with the aid of selection , has , no doubt , largely aided in the formation of new sub - breeds ; but the importance of crossing has been much exaggerated , both in regard to animals and to those plants which ...
Página 31
... occasionally see in our domestic produc- tions , more especially with plants , are ever permanently propagated in a state of nature . Almost every part of every organic being is so beautifully related to its complex conditions of life ...
... occasionally see in our domestic produc- tions , more especially with plants , are ever permanently propagated in a state of nature . Almost every part of every organic being is so beautifully related to its complex conditions of life ...
Página 46
... its natural lifetime produces several eggs or seeds , must suffer destruction during some period of its life , and during some season or occasional year , otherwise , on the principle. 46 [ CHAP . III . STRUGGLE FOR EXISTENCE .
... its natural lifetime produces several eggs or seeds , must suffer destruction during some period of its life , and during some season or occasional year , otherwise , on the principle. 46 [ CHAP . III . STRUGGLE FOR EXISTENCE .
Página 47
... occasional year , otherwise , on the principle of geometrical increase , its numbers would quickly become so inordinately great that no country could support the product . Hence , as more indi- viduals are produced than can possibly ...
... occasional year , otherwise , on the principle of geometrical increase , its numbers would quickly become so inordinately great that no country could support the product . Hence , as more indi- viduals are produced than can possibly ...
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Términos y frases comunes
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