The Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for Life, Volumen2D. Appleton, 1898 |
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Página 13
... resemblance between species in structure and constitu- tion . Now the fertility of first crosses , and of the hybrids produced from them , is largely governed by their systematic affinity . This is clearly shown by hy- brids never ...
... resemblance between species in structure and constitu- tion . Now the fertility of first crosses , and of the hybrids produced from them , is largely governed by their systematic affinity . This is clearly shown by hy- brids never ...
Página 15
... resemble one of them ; and such hybrids , though externally so like one of their pure parent- species , are with rare exceptions extremely sterile . So again amongst hybrids which are usually intermediate in structure between. CHAP . IX ...
... resemble one of them ; and such hybrids , though externally so like one of their pure parent- species , are with rare exceptions extremely sterile . So again amongst hybrids which are usually intermediate in structure between. CHAP . IX ...
Página 16
... resemble in external appearance either parent ; and lastly , that the facility of making a first cross between any two species is not always governed by their syste- matic affinity or degree of resemblance to each other . This latter ...
... resemble in external appearance either parent ; and lastly , that the facility of making a first cross between any two species is not always governed by their syste- matic affinity or degree of resemblance to each other . This latter ...
Página 27
... resemble closely either pure parent . Nor do I pretend that the fore- going remarks go to the root of the matter ; no explana- tion is offered why an organism , when placed under un- natural conditions , is rendered sterile . All that I ...
... resemble closely either pure parent . Nor do I pretend that the fore- going remarks go to the root of the matter ; no explana- tion is offered why an organism , when placed under un- natural conditions , is rendered sterile . All that I ...
Página 42
... resemblance in mongrels and in hybrids to their respective parents , more especially in hybrids pro- duced from ... resemble each other closely ; and so it is with mongrel plants from a reciprocal cross . Both hybrids and mongrels can be ...
... resemblance in mongrels and in hybrids to their respective parents , more especially in hybrids pro- duced from ... resemble each other closely ; and so it is with mongrel plants from a reciprocal cross . Both hybrids and mongrels can be ...
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Términos y frases comunes
admit affinity allied species ancient animals appear Archipelago arctic areas become believe belonging birds Cambrian changes characters cies classification climate closely allied continent crustaceans degree deposited difficulty distant distinct species domestic doubt embryo eral 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 inhabitants inherited insects instance intermediate intervals land larvæ less living mammals manner marine Marsupials migration modified descendants mongrels mountains natural selection naturalists nearly occur oceanic islands offspring organisation palæontologists Palæozoic 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 stage stamens sterility structure successive suppose terrestrial tertiary theory tion variations varieties whilst whole widely different wings