On 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 36
... , on the other hand , which , as shown by the mere fact of their domesti- ' cation , were not originally highly sensitive to changes in their conditions of life , and which can now 36 [ CHAP . IX . FERTILITY OF VARIETIES.
... , on the other hand , which , as shown by the mere fact of their domesti- ' cation , were not originally highly sensitive to changes in their conditions of life , and which can now 36 [ CHAP . IX . FERTILITY OF VARIETIES.
Página 37
... changes of conditions , might be expected to produce varieties , which would be little liable to have their reproductive powers injuriously affected by the act of crossing with other varieties which had originated in a like manner . I ...
... changes of conditions , might be expected to produce varieties , which would be little liable to have their reproductive powers injuriously affected by the act of crossing with other varieties which had originated in a like manner . I ...
Página 39
... changes of an unknown nature in their sex- ual elements . Hybrids and Mongrels compared , independently of their fertility . Independently of the question of fertility , the off- spring of species and of varieties when crossed may be ...
... changes of an unknown nature in their sex- ual elements . Hybrids and Mongrels compared , independently of their fertility . Independently of the question of fertility , the off- spring of species and of varieties when crossed may be ...
Página 45
... changes in the conditions of life add to the vigour and fertility of all organic beings ; and secondly , that the crossing of forms , which have been exposed to slightly different conditions of life . or which have varied , favours the ...
... changes in the conditions of life add to the vigour and fertility of all organic beings ; and secondly , that the crossing of forms , which have been exposed to slightly different conditions of life . or which have varied , favours the ...
Página 50
... that one form had re- mained for a very long period unaltered , whilst its de- scendants had undergone a vast amount of change ; and the principle of competition between organism and organism , 50 [ CHAP . X. IMPERFECTION OF THE.
... that one form had re- mained for a very long period unaltered , whilst its de- scendants had undergone a vast amount of change ; and the principle of competition between organism and organism , 50 [ CHAP . X. IMPERFECTION OF THE.
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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