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 11
... extremely general result ; but that it cannot , under our present state of knowledge , be con- sidered as absolutely universal . Laws governing the Sterility of first Crosses and of Hybrids . We will now consider a little more in detail ...
... extremely general result ; but that it cannot , under our present state of knowledge , be con- sidered as absolutely universal . Laws governing the Sterility of first Crosses and of Hybrids . We will now consider a little more in detail ...
Página 15
... extremely common in a lesser degree . He has observed it even between closely related forms ( as Matthiola annua and glabra ) which many botanists rank only as varieties . It is also a remarkable fact , that hybrids raised from ...
... extremely common in a lesser degree . He has observed it even between closely related forms ( as Matthiola annua and glabra ) which many botanists rank only as varieties . It is also a remarkable fact , that hybrids raised from ...
Página 268
... extremely difficult even to conjecture by what gradations many structures have been perfected , more especially amongst broken and failing groups of organic beings , which have suffered much extinction ; but we see so many strange ...
... extremely difficult even to conjecture by what gradations many structures have been perfected , more especially amongst broken and failing groups of organic beings , which have suffered much extinction ; but we see so many strange ...
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