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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Página 11
... look at this sterility in animals , not as an indelible characteristic , but as one capable of being removed by domestication . Finally , considering all the ascertained facts on the intercrossing of plants and animals , it may be ...
... look at this sterility in animals , not as an indelible characteristic , but as one capable of being removed by domestication . Finally , considering all the ascertained facts on the intercrossing of plants and animals , it may be ...
Página 19
... look at the curious and complex laws governing the facility with which trees can be grafted on each other as incidental on unknown differ- ences in their vegetative systems , so I believe that the still more complex laws governing the ...
... look at the curious and complex laws governing the facility with which trees can be grafted on each other as incidental on unknown differ- ences in their vegetative systems , so I believe that the still more complex laws governing the ...
Página 23
... look a little closer at the probable na- ture of the differences between species which induce sterility in first crosses and in hybrids . In the case of first crosses , the greater or less difficulty in effecting an union and in ...
... look a little closer at the probable na- ture of the differences between species which induce sterility in first crosses and in hybrids . In the case of first crosses , the greater or less difficulty in effecting an union and in ...
Página 43
... crossed species , and of crossed varieties . If we look at species as having been specially created , and at varieties as having been produced by secondary laws , this similarity would be an. CHAP . IX . ] HYBRIDS AND MONGRELS COMPARED .
... crossed species , and of crossed varieties . If we look at species as having been specially created , and at varieties as having been produced by secondary laws , this similarity would be an. CHAP . IX . ] HYBRIDS AND MONGRELS COMPARED .
Página 49
... look for forms intermediate between each species and a common but unknown progenitor ; and the progenitor will gen- erally have differed in some respects from all its modi- fied descendants . To give a simple illustration : the fantail ...
... look for forms intermediate between each species and a common but unknown progenitor ; and the progenitor will gen- erally have differed in some respects from all its modi- fied descendants . To give a simple illustration : the fantail ...
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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