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 5
... flowering season : hence hybrids , if left to themselves , will generally be fertilised during each generation by pollen from the same flower ; and this would probably be injurious to their fertility , already lessened by their hybrid ...
... flowering season : hence hybrids , if left to themselves , will generally be fertilised during each generation by pollen from the same flower ; and this would probably be injurious to their fertility , already lessened by their hybrid ...
Página 6
Charles Darwin. as from the anthers of the flower itself which is to be fer- tilised ; so that a cross between two flowers , though probably often on the same plant , would be thus effected . Moreover , whenever complicated experiments ...
Charles Darwin. as from the anthers of the flower itself which is to be fer- tilised ; so that a cross between two flowers , though probably often on the same plant , would be thus effected . Moreover , whenever complicated experiments ...
Página 7
... flowers ; three were fertilised by Herbert with their own pollen , and the fourth was subsequently fertilised by the pollen of a compound hybrid descended from three distinct species : the result was that the ovaries of the three first ...
... flowers ; three were fertilised by Herbert with their own pollen , and the fourth was subsequently fertilised by the pollen of a compound hybrid descended from three distinct species : the result was that the ovaries of the three first ...
Página 8
... flowers of the more sterile kinds of hy- brid Rhododendrons , which produce no pollen , for he will find on their stigmas plenty of pollen brought from other flowers . men . In regard to animals , much fewer experiments have been ...
... flowers of the more sterile kinds of hy- brid Rhododendrons , which produce no pollen , for he will find on their stigmas plenty of pollen brought from other flowers . men . In regard to animals , much fewer experiments have been ...
Página 12
... flower of the hybrid to wither earlier than it otherwise would have done ; and the early with- ering of the flower is well known to be a sign of in- cipient fertilisation . From this extreme degree of sterility we have self - fertilised ...
... flower of the hybrid to wither earlier than it otherwise would have done ; and the early with- ering of the flower is well known to be a sign of in- cipient fertilisation . From this extreme degree of sterility we have self - fertilised ...
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Términos y frases comunes
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