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 7
... genus Hippeastrum , in Cory- dalis as shown by Professor Hildebrand , in various or- chids as shown by Mr. Scott and Fritz Müller , all the individuals are in this peculiar condition . So that with some species , certain abnormal ...
... genus Hippeastrum , in Cory- dalis as shown by Professor Hildebrand , in various or- chids as shown by Mr. Scott and Fritz Müller , all the individuals are in this peculiar condition . So that with some species , certain abnormal ...
Página 12
... genus , yields a perfect gradation in the number of seeds produced , up to nearly complete or even quite complete fertility ; and , as we have seen , in certain abnormal cases , even to an excess of fertility , beyond that which the ...
... genus , yields a perfect gradation in the number of seeds produced , up to nearly complete or even quite complete fertility ; and , as we have seen , in certain abnormal cases , even to an excess of fertility , beyond that which the ...
Página 13
... genus , for instance in Dianthus , these two opposite cases occur . The fertility , both of first crosses and of hybrids , is more easily affected by unfavourable conditions , than is that of pure species . But the fertility of first ...
... genus , for instance in Dianthus , these two opposite cases occur . The fertility , both of first crosses and of hybrids , is more easily affected by unfavourable conditions , than is that of pure species . But the fertility of first ...
Página 14
... genus , we meet with this same difference ; for instance , the many species of Nicotiana have been more largely crossed than the species of almost any other genus ; but Gärtner found that N. acuminata , which is not a particularly ...
... genus , we meet with this same difference ; for instance , the many species of Nicotiana have been more largely crossed than the species of almost any other genus ; but Gärtner found that N. acuminata , which is not a particularly ...
Página 15
... genus have a remarkable power of impressing their likeness on their hybrid offspring ; but these two powers do not at all necessarily go together . There are certain hybrids which , instead of having , as is usual , an intermediate ...
... genus have a remarkable power of impressing their likeness on their hybrid offspring ; but these two powers do not at all necessarily go together . There are certain hybrids which , instead of having , as is usual , an intermediate ...
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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