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 1
... seems at first highly probable , for species living together could hardly have been kept dis- tinct had they been capable of freely crossing . subject is in many ways important for us , more especial- ly as the sterility of species when ...
... seems at first highly probable , for species living together could hardly have been kept dis- tinct had they been capable of freely crossing . subject is in many ways important for us , more especial- ly as the sterility of species when ...
Página 2
... of species ; for it seems to make a broad and clear distinction between varieties and species . Degrees of Sterility . - First , for the sterility of spe- cies when crossed and of their hybrid offspring . It. 2 [ CHAP . IX . HYBRIDISM .
... of species ; for it seems to make a broad and clear distinction between varieties and species . Degrees of Sterility . - First , for the sterility of spe- cies when crossed and of their hybrid offspring . It. 2 [ CHAP . IX . HYBRIDISM .
Página 10
... seems by far the most probable , and can , indeed , hardly be doubted . It is , for instance , almost certain that our dogs are descended from several wild stocks ; yet , with perhaps the exception of certain indigenous domestic dogs of ...
... seems by far the most probable , and can , indeed , hardly be doubted . It is , for instance , almost certain that our dogs are descended from several wild stocks ; yet , with perhaps the exception of certain indigenous domestic dogs of ...
Página 17
... seems a strange arrangement . The foregoing rules and facts , on the other hand , appear to me clearly to indicate that the sterility both of first crosses and of hybrids is simply incidental or dependent on unknown differences in their ...
... seems a strange arrangement . The foregoing rules and facts , on the other hand , appear to me clearly to indicate that the sterility both of first crosses and of hybrids is simply incidental or dependent on unknown differences in their ...
Página 20
... seem to indicate that the greater or lesser difficulty of either grafting or crossing various species has been a special endowment ; although in the case of crossing , the diffi- culty is as important for the endurance and stability of ...
... seem to indicate that the greater or lesser difficulty of either grafting or crossing various species has been a special endowment ; although in the case of crossing , the diffi- culty is as important for the endurance and stability of ...
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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