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 5
... hand that an occasional cross with a distinct individual or variety increases the vigour and fertility of the offspring , and on the other hand that very close interbreeding lessens their vigour and fertility , that I cannot doubt the ...
... hand that an occasional cross with a distinct individual or variety increases the vigour and fertility of the offspring , and on the other hand that very close interbreeding lessens their vigour and fertility , that I cannot doubt the ...
Página 13
... hand , there are species which can be crossed very rarely , or with extreme difficulty , but the hybrids , when at last produced , are very fertile . Even within the limits of the same genus , for instance in Dianthus , these two ...
... hand , there are species which can be crossed very rarely , or with extreme difficulty , but the hybrids , when at last produced , are very fertile . Even within the limits of the same genus , for instance in Dianthus , these two ...
Página 108
... hand , by the ostrich and extinct Archeo- pteryx , and on the other hand , by the Compsognathus , one of the Dinosaurians - that group which includes the most gigantic of all terrestrial reptiles . Turning to the Invertebrata , Barraude ...
... hand , by the ostrich and extinct Archeo- pteryx , and on the other hand , by the Compsognathus , one of the Dinosaurians - that group which includes the most gigantic of all terrestrial reptiles . Turning to the Invertebrata , Barraude ...
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