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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... degree of sterility . Kölreuter makes the rule universal ; but then he cuts the knot , for in ten cases in which he found two forms , considered by most authors as distinct species , quite fertile together , he unhesitatingly ranks them ...
... degree of sterility . Kölreuter makes the rule universal ; but then he cuts the knot , for in ten cases in which he found two forms , considered by most authors as distinct species , quite fertile together , he unhesitatingly ranks them ...
Página 16
... degree in the first cross and in the hybrids produced from this cross ; that the fertility of hybrids is not related to the degree in which they resemble in external appearance either parent ; and lastly , that the facility of making a ...
... degree in the first cross and in the hybrids produced from this cross ; that the fertility of hybrids is not related to the degree in which they resemble in external appearance either parent ; and lastly , that the facility of making a ...
Página 21
... degree of sterility could be increased through natural selection to that high degree which is common with so many species , and which is universal with species which have been differentiated to a generic or family rank , will find the ...
... degree of sterility could be increased through natural selection to that high degree which is common with so many species , and which is universal with species which have been differentiated to a generic or family rank , will find the ...
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