On the Origin of Species by Means of Natural Selection, Or, The Preservation of Favoured Races in the Struggle for LifeAppleton, 1898 - 432 páginas |
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Página 15
... , 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 . ] OF FIRST CROSSES AND OF HYBRIDS . 15.
... , 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 . ] OF FIRST CROSSES AND OF HYBRIDS . 15.
Página 16
Charles Darwin. again amongst hybrids which are usually intermediate in structure between their parents , exceptional and abnormal individuals sometimes are born , which closely resemble one of their pure parents ; and these hybrids are ...
Charles Darwin. again amongst hybrids which are usually intermediate in structure between their parents , exceptional and abnormal individuals sometimes are born , which closely resemble one of their pure parents ; and these hybrids are ...
Página 22
... structure and fertility have been slowly accumulated by natural selection , from an advantage having been thus indirectly given to the community to which they belonged over other communities of the same species ; but an individual ...
... structure and fertility have been slowly accumulated by natural selection , from an advantage having been thus indirectly given to the community to which they belonged over other communities of the same species ; but an individual ...
Página 26
... structures and constitutions , including of course the reproductive systems , having been blended into one . For it is scarcely possible that two organisations should be compounded into one , without some disturbance occurring in the ...
... structures and constitutions , including of course the reproductive systems , having been blended into one . For it is scarcely possible that two organisations should be compounded into one , without some disturbance occurring in the ...
Página 33
... structure or in constitution , relatively to external conditions , and yet be sterile when united in certain ways . For we must remember that it is the union of the sexual elements of individuals of the same form , for instance , of two ...
... structure or in constitution , relatively to external conditions , and yet be sterile when united in certain ways . For we must remember that it is the union of the sexual elements of individuals of the same form , for instance , of two ...
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admit affinity allied species ancient animals appear Archipelago arctic areas become believe birds Cambrian changes characters cies classification climate closely allied common progenitor 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 individuals 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 parent parent-form peculiar perfect pistil plants pollen present probably produced quadrupeds reciprocal crosses regions remains remarked reproductive resemblance rocks rudimentary organs sediment seeds Silurian South America stage stamens sterility structure successive suppose terrestrial tertiary theory tion variations varieties whilst widely different wings