The Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for Life, Volumen2D. Appleton, 1898 |
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... animals ; though the formative organs themselves are perfect in structure , as far as the microscope reveals . In the first case the two sexual elements which go to form the embryo are per- fect ; in the second case they are either not ...
... animals ; though the formative organs themselves are perfect in structure , as far as the microscope reveals . In the first case the two sexual elements which go to form the embryo are per- fect ; in the second case they are either not ...
Página 8
... animals , much fewer experiments have been carefully tried than with plants . If our systematic arrangements can be trusted , that is , if the genera of animals are as distinct from each other as are the genera of plants , then we may ...
... animals , much fewer experiments have been carefully tried than with plants . If our systematic arrangements can be trusted , that is , if the genera of animals are as distinct from each other as are the genera of plants , then we may ...
Página 9
... animals , I hardly know of an in- stance in which two families of the same hybrid have been raised at the same time from different parents , so as to avoid the ill effects of close interbreeding . On the contrary , brothers and sisters ...
... animals , I hardly know of an in- stance in which two families of the same hybrid have been raised at the same time from different parents , so as to avoid the ill effects of close interbreeding . On the contrary , brothers and sisters ...
Página 10
... animals , the various races when crossed together are quite fertile ; yet in many cases they are descended from two or more wild species . From this fact we must conclude either that the abo- riginal parent - species at first produced ...
... animals , the various races when crossed together are quite fertile ; yet in many cases they are descended from two or more wild species . From this fact we must conclude either that the abo- riginal parent - species at first produced ...
Página 11
... animals , and , considering how scanty our knowledge is in regard to hybrid animals , I have been surprised to find how generally the same rules apply to both king- doms . It has been already remarked , that the degree of fertility ...
... animals , and , considering how scanty our knowledge is in regard to hybrid animals , I have been surprised to find how generally the same rules apply to both king- doms . It has been already remarked , that the degree of fertility ...
Otras ediciones - Ver todas
The Origin of Species by Means of Natural Selection: Or the ..., Volumen2 Darwin Vista completa - 1889 |
On the Origin of Species by Means of Natural Selection Charles Darwin Sin vista previa disponible - 2016 |
Términos y frases comunes
admit affinity allied species ancient animals appear Archipelago arctic areas become believe belonging birds Cambrian changes characters cies classification climate closely allied continent crustaceans degree deposited difficulty distant distinct species domestic doubt embryo eral 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 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 palæontologists Palæozoic parent parent-form peculiar perfect pistil plants pollen present probably produced quadrupeds reciprocal crosses regions remains remarked reproductive resemblance rocks rudimentary organs seeds Silurian South America stage stamens sterility structure successive suppose terrestrial tertiary theory tion variations varieties whilst whole widely different wings