On the Origin of Species by Means of Natural Selection, Or, The Preservation of Favoured Races in the Struggle for LifeAppleton, 1898 - 432 páginas |
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Página 2
... considered . The distinction probably has been slurred over , owing to the sterility in both cases being looked on as a special en- dowment , beyond the province of our reasoning powers . The fertility of varieties , that is of the ...
... considered . The distinction probably has been slurred over , owing to the sterility in both cases being looked on as a special en- dowment , beyond the province of our reasoning powers . The fertility of varieties , that is of the ...
Página 3
... considered by most authors as distinct species , quite fertile to- gether , he unhesitatingly ranks them as varieties . ner , also , makes the rule equally universal ; and he dis- putes the entire fertility of Kölreuter's ten cases ...
... considered by most authors as distinct species , quite fertile to- gether , he unhesitatingly ranks them as varieties . ner , also , makes the rule equally universal ; and he dis- putes the entire fertility of Kölreuter's ten cases ...
Página 16
... considered as good and distinct species , are united , their fertility graduates from zero to perfect fertility , or even to fertility under certain conditions in excess ; that their fertility , besides being eminently susceptible to ...
... considered as good and distinct species , are united , their fertility graduates from zero to perfect fertility , or even to fertility under certain conditions in excess ; that their fertility , besides being eminently susceptible to ...
Página 34
... considered by most botanists as varieties , are said by Gärtner to be quite sterile when crossed , and he subsequently ranks them as undoubted species . If we thus argue in a circle , the fertility of all varieties produced under nature ...
... considered by most botanists as varieties , are said by Gärtner to be quite sterile when crossed , and he subsequently ranks them as undoubted species . If we thus argue in a circle , the fertility of all varieties produced under nature ...
Página 46
... considered as varieties , and their mongrel offspring , are very generally , but not , as is so often stated , invariably fertile . Nor is this almost universal and perfect fertility surprising , when it is remembered how liable we are ...
... considered as varieties , and their mongrel offspring , are very generally , but not , as is so often stated , invariably fertile . Nor is this almost universal and perfect fertility surprising , when it is remembered how liable we are ...
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Términos y frases comunes
admit affinity allied species ancient animals appear Archipelago arctic areas become believe birds Cambrian changes characters cies classification climate closely allied common progenitor 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 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 sediment seeds Silurian South America stage stamens sterility structure successive suppose terrestrial tertiary theory tion variations varieties whilst widely different wings