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 93
... Silurian stratum to the present day . We have seen in the last chapter that whole groups of species sometimes falsely appear to have been abrupt- ly developed ; and I have attempted to give an explana- tion of this fact , which if true ...
... Silurian stratum to the present day . We have seen in the last chapter that whole groups of species sometimes falsely appear to have been abrupt- ly developed ; and I have attempted to give an explana- tion of this fact , which if true ...
Página 106
... Silurian deposits of Bohemia and Scandinavia ; never- theless he finds a surprising amount of difference in the species . If the several formations in these regions have not been deposited during the same exact periods , -a formation in ...
... Silurian deposits of Bohemia and Scandinavia ; never- theless he finds a surprising amount of difference in the species . If the several formations in these regions have not been deposited during the same exact periods , -a formation in ...
Página 110
... Silurian forms , that a species might go on being slightly modified in relation to its slightly altered conditions of life , and yet retain throughout a vast period the same general characteristics . This is represented in the diagram ...
... Silurian forms , that a species might go on being slightly modified in relation to its slightly altered conditions of life , and yet retain throughout a vast period the same general characteristics . This is represented in the diagram ...
Página 113
... Silurian systems . But each fauna is not necessarily exactly intermediate , as unequal intervals of time have elapsed between conse- cutive formations . It is no real objection to the truth of the statement that the fauna of each period ...
... Silurian systems . But each fauna is not necessarily exactly intermediate , as unequal intervals of time have elapsed between conse- cutive formations . It is no real objection to the truth of the statement that the fauna of each period ...
Página 212
... We will suppose the letters A to L to represent allied genera existing during the Silurian epoch , and descended from some still earlier form . In F14 three of these genera ( A , F , 212 [ CHAP . XIV . CLASSIFICATION .
... We will suppose the letters A to L to represent allied genera existing during the Silurian epoch , and descended from some still earlier form . In F14 three of these genera ( A , F , 212 [ CHAP . XIV . CLASSIFICATION .
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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