The Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for Life, 2권D. Appleton, 1898 |
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13 페이지
... closely allied species generally uniting with facility . But the correspondence between syste- matic affinity and the facility of crossing is by no means strict . A multitude of cases could be given of very closely allied species which ...
... closely allied species generally uniting with facility . But the correspondence between syste- matic affinity and the facility of crossing is by no means strict . A multitude of cases could be given of very closely allied species which ...
15 페이지
... closely related forms ( as Matthiola annua and gilabra ) which many botanists rank only as varieties . It is also a remarkable fact , that hybrids raised from reciprocal crosses , though of course compounded of the very same two species ...
... closely related forms ( as Matthiola annua and gilabra ) which many botanists rank only as varieties . It is also a remarkable fact , that hybrids raised from reciprocal crosses , though of course compounded of the very same two species ...
16 페이지
... closely resemble one of their pure parents ; and these hybrids are almost always utterly sterile , even when the other hybrids raised from seed from the same capsule have a considerable degree of fertility . These facts show how ...
... closely resemble one of their pure parents ; and these hybrids are almost always utterly sterile , even when the other hybrids raised from seed from the same capsule have a considerable degree of fertility . These facts show how ...
18 페이지
... closely allied species , and varieties of the same species , can usually , but not invariably , be grafted with ease . But this capacity , as in hybridisation , is by no means absolutely means absolutely governed by systematic affinity ...
... closely allied species , and varieties of the same species , can usually , but not invariably , be grafted with ease . But this capacity , as in hybridisation , is by no means absolutely means absolutely governed by systematic affinity ...
27 페이지
... 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 have ...
... 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 have ...
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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