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
... 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 avoided . Now let us turn to the results arrived at ...
... 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 avoided . Now let us turn to the results arrived at ...
Página 8
... genera of animals are as distinct from each other as are the genera of plants , then we may infer that animals more widely distinct in the scale of nature can be crossed more easily than in the case of plants ; but the hybrids ...
... genera of animals are as distinct from each other as are the genera of plants , then we may infer that animals more widely distinct in the scale of nature can be crossed more easily than in the case of plants ; but the hybrids ...
Página 9
... are generally ranked in distinct genera , have often bred in this country with either pure parent , and in one single instance they have bred inter se . This was effected by Mr. Eyton , who 27 CHAP . IX . ] DEGREES OF STERILITY .
... are generally ranked in distinct genera , have often bred in this country with either pure parent , and in one single instance they have bred inter se . This was effected by Mr. Eyton , who 27 CHAP . IX . ] DEGREES OF STERILITY .
Página 18
... genera within the same family have been grafted together , in other cases species of the same genus will not take on each other . The pear can be grafted far more readily on the quince , which is ranked as a distinct genus , than on the ...
... genera within the same family have been grafted together , in other cases species of the same genus will not take on each other . The pear can be grafted far more readily on the quince , which is ranked as a distinct genus , than on the ...
Página 22
... genera in- cluding numerous species , a series can be formed from species which when crossed yield fewer and fewer seeds , to species which never produce a single seed , but yet are affected by the pollen of certain other species , for ...
... genera in- cluding numerous species , a series can be formed from species which when crossed yield fewer and fewer seeds , to species which never produce a single seed , but yet are affected by the pollen of certain other species , for ...
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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