The Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for Life, Volumen2AMS Press, 1972 |
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Página 49
... intermediate varieties , from existing in lesser numbers than the forms which they connect , will generally be beaten out and exterminated during the course of further modification and improvement . The main cause , however , of ...
... intermediate varieties , from existing in lesser numbers than the forms which they connect , will generally be beaten out and exterminated during the course of further modification and improvement . The main cause , however , of ...
Página 70
... intermediate gradations which must on our theory have existed , but abrupt , though perhaps slight , changes of form . It is all - important to remember that naturalists have no golden rule by which to distinguish species and varieties ...
... intermediate gradations which must on our theory have existed , but abrupt , though perhaps slight , changes of form . It is all - important to remember that naturalists have no golden rule by which to distinguish species and varieties ...
Página 272
... intermediate varieties in the intermediate zones . For we have reason to believe that only a few species of a genus ever undergo change ; the other species becoming utterly extinct and leaving no modified progeny . Of the species which ...
... intermediate varieties in the intermediate zones . For we have reason to believe that only a few species of a genus ever undergo change ; the other species becoming utterly extinct and leaving no modified progeny . Of the species which ...
Contenido
CONTENTS OF VOL | 1 |
CHAPTER X | 48 |
CHAPTER XII | 129 |
Derechos de autor | |
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Términos y frases comunes
accumulated adapted admit adult affinity allied species ancient animals appear Archipelago arctic areas become beds believe birds breeds Cambrian changes characters classification climate closely allied continent crustaceans degree deposited difficulty distant distinct species domestic doubt embryo 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 seeds Silurian slight South America species belonging stage stamens sterility structure successive suppose terrestrial tertiary tion variations varieties whilst widely different wings