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 6
... fact of an increase of fertility in the successive genera- tions of artificially fertilised hybrids , in contrast with those spontaneously self - fertilised , may , as I believe , be accounted for by too close interbreeding having been ...
... fact of an increase of fertility in the successive genera- tions of artificially fertilised hybrids , in contrast with those spontaneously self - fertilised , may , as I believe , be accounted for by too close interbreeding having been ...
Página 7
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 ...
Página 8
... fact would have been notorious to nursery- Horticulturists raise large beds of the same hy- brid , and such alone are fairly treated , for by insect agency the several individuals are allowed to cross freely with each other , and the ...
... fact would have been notorious to nursery- Horticulturists raise large beds of the same hy- brid , and such alone are fairly treated , for by insect agency the several individuals are allowed to cross freely with each other , and the ...
Página 10
... fact we must conclude either that the abo- riginal parent - species at first produced perfectly fertile hybrids , or that the hybrids subsequently reared under domestication became quite fertile . This latter alter- native , which was ...
... fact we must conclude either that the abo- riginal parent - species at first produced perfectly fertile hybrids , or that the hybrids subsequently reared under domestication became quite fertile . This latter alter- native , which was ...
Página 12
... facts can here be given . When pollen from a plant of one family is placed on the stigma of a plant of a distinct family , it exerts no more influence than so much inorganic dust . From this absolute zero of fertility , the pollen of ...
... facts can here be given . When pollen from a plant of one family is placed on the stigma of a plant of a distinct family , it exerts no more influence than so much inorganic dust . From this absolute zero of fertility , the pollen of ...
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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