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 xv
... animals tend to vary in some degree , and , secondly , that agriculturists improve their domesticated animals by selection ; and then , he adds , but what is done in this latter case " by art , seems to be done with equal efficacy ...
... animals tend to vary in some degree , and , secondly , that agriculturists improve their domesticated animals by selection ; and then , he adds , but what is done in this latter case " by art , seems to be done with equal efficacy ...
Página 5
... animals , one of the first points which strikes us is , that they generally differ more from each other than do the individuals of any one species or variety in a state of nature . And if we reflect on the vast diversity of the plants ...
... animals , one of the first points which strikes us is , that they generally differ more from each other than do the individuals of any one species or variety in a state of nature . And if we reflect on the vast diversity of the plants ...
Página 7
... animals when reared under new or unnatural conditions Many facts clearly show how eminently susceptible the reproduc tive system is to very slight changes in the surrounding conditions . Nothing is more easy than to tame an animal , and ...
... animals when reared under new or unnatural conditions Many facts clearly show how eminently susceptible the reproduc tive system is to very slight changes in the surrounding conditions . Nothing is more easy than to tame an animal , and ...
Página 8
... animals the increased use or disuse of parts has had a more marked influence ; thus I find in the domestic duck that ... animals can be named which has not in some country drooping ears ; and the view which has been suggested that the ...
... animals the increased use or disuse of parts has had a more marked influence ; thus I find in the domestic duck that ... animals can be named which has not in some country drooping ears ; and the view which has been suggested that the ...
Página 9
... animals and plants . From facts collected by Heusinger , it appears that white sheep and pigs are injured by certain plants , whilst dark- coloured individuals escape : Professor Wyman has recently com- municated to me a good ...
... animals and plants . From facts collected by Heusinger , it appears that white sheep and pigs are injured by certain plants , whilst dark- coloured individuals escape : Professor Wyman has recently com- municated to me a good ...
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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