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
... namely , by too close inter- breeding . I have made so many experiments and collected so many facts , showing on the one hand that an occasional cross with a distinct individual or variety increases the vigour and fertility of the ...
... namely , by too close inter- breeding . I have made so many experiments and collected so many facts , showing on the one hand that an occasional cross with a distinct individual or variety increases the vigour and fertility of the ...
Página 6
... namely , the Hon . and Rev. W. Herbert . He is as emphatic in his conclusion that some hybrids are perfectly fertile - as fertile as the pure parent - species - as are Kölreuter and Gärtner that some degree of sterility between distinct ...
... namely , the Hon . and Rev. W. Herbert . He is as emphatic in his conclusion that some hybrids are perfectly fertile - as fertile as the pure parent - species - as are Kölreuter and Gärtner that some degree of sterility between distinct ...
Página 196
... namely , that the lower any group of organisms stands the more widely it ranges . The relations just discussed , namely , lower organ- isms ranging more widely than the higher , some of the species of widely - ranging genera themselves ...
... namely , that the lower any group of organisms stands the more widely it ranges . The relations just discussed , namely , lower organ- isms ranging more widely than the higher , some of the species of widely - ranging genera themselves ...
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