The Origin of Species by Means of Natural Selection, Or, The Preservation of Favored Races in the Struggle for Life, 2권D. Appleton, 1896 |
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2 페이지
... namely , the sterility of species when first crossed , and the sterility of the hybrids produced from them . Pure species have of course their organs of reproduc- tion in a perfect condition , yet when intercrossed they produce either ...
... namely , the sterility of species when first crossed , and the sterility of the hybrids produced from them . Pure species have of course their organs of reproduc- tion in a perfect condition , yet when intercrossed they produce either ...
4 페이지
... namely Kölreuter and Gärtner , arrived at diametrically opposite conclusions in regard to some of the very same forms . It is also most instructive to compare - but I have not space here to enter on details - the evidence advanced by ...
... namely Kölreuter and Gärtner , arrived at diametrically opposite conclusions in regard to some of the very same forms . It is also most instructive to compare - but I have not space here to enter on details - the evidence advanced by ...
5 페이지
... namely , by too close inter- breeding . I have made so many experiments and collected so many facts , showing on the one hand that an occasional cross with a distinct individual or variety increases the vigour and fertility of the ...
... namely , by too close inter- breeding . I have made so many experiments and collected so many facts , showing on the one hand that an occasional cross with a distinct individual or variety increases the vigour and fertility of the ...
6 페이지
... namely , the Hon . and Rev. W. Herbert . He is as emphatic in his conclusion that some hybrids are perfectly fertile - as fertile as the pure parent - species - as are Kölreuter and Gärtner that some degree of sterility between distinct ...
... namely , the Hon . and Rev. W. Herbert . He is as emphatic in his conclusion that some hybrids are perfectly fertile - as fertile as the pure parent - species - as are Kölreuter and Gärtner that some degree of sterility between distinct ...
7 페이지
Charles Darwin. singular fact , namely , that individual plants of certain species of Lobelia , Verbascum and Passiflora , can easily be fertilised by pollen from a distinct species , but not by pollen from the same plant , though this ...
Charles Darwin. singular fact , namely , that individual plants of certain species of Lobelia , Verbascum and Passiflora , can easily be fertilised by pollen from a distinct species , but not by pollen from the same plant , though this ...
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accumulated adapted admit affinity allied species ancient animals appear Archipelago arctic areas become believe birds breeds Cambrian changes characters classification climate closely allied continent crustaceans degree deposited difficulty distant distinct species domestic doubt embryo Europe existing extinct fact faunas fertilised fertility flowers formations formerly forms fossil fresh-water Fritz Müller Gärtner genera genus geological period geological record Glacial period groups of species habits hybrids hybrids produced important individuals inhabitants inherited insects instance intermediate intervals land larvæ less living mammæ mammals manner marine Marsupials migration modified descendants mongrels mountains natural selection naturalists nearly occur oceanic islands offspring organisation palæontologists paleozoic parent parent-form peculiar perfect pistil plants pollen present probably produced quadrupeds reciprocal crosses regions remains remarked reproductive resemblance rocks rudimentary organs seeds Silurian South America species belonging stage stamens sterility structure successive suppose terrestrial tertiary tion variations varieties whilst widely different wings