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 14
... 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 distinct species , obstinately failed to fertilise ...
... 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 distinct species , obstinately failed to fertilise ...
Página 15
... instance : Mirabilis jalapa can easily be fertilised by the pollen of M. longiflora , and the hybrids thus produced are suffi- ciently fertile ; but Kölreuter tried more than two hun- dred times , during eight following years , to ...
... instance : Mirabilis jalapa can easily be fertilised by the pollen of M. longiflora , and the hybrids thus produced are suffi- ciently fertile ; but Kölreuter tried more than two hun- dred times , during eight following years , to ...
Página 19
... instance , cannot be grafted on the current , whereas the current will take , though with difficulty , on the gooseberry . We have seen that the sterility of hybrids , which have their reproductive organs in an imperfect con- dition ...
... instance , cannot be grafted on the current , whereas the current will take , though with difficulty , on the gooseberry . We have seen that the sterility of hybrids , which have their reproductive organs in an imperfect con- dition ...
Página 30
... instance , the mid- styled form of Lythrum salicaria was illegitimately fer- tilised with the greatest ease by pollen from the longer stamens of the short - styled form , and yielded many seeds ; but the latter form did not yield a ...
... instance , the mid- styled form of Lythrum salicaria was illegitimately fer- tilised with the greatest ease by pollen from the longer stamens of the short - styled form , and yielded many seeds ; but the latter form did not yield a ...
Página 33
... instance , of two long- styled forms , which results in sterility ; whilst it is the union of the sexual elements proper to two distinct forms which is fertile . Hence the case appears at first sight exactly the reverse of what occurs ...
... instance , of two long- styled forms , which results in sterility ; whilst it is the union of the sexual elements proper to two distinct forms which is fertile . Hence the case appears at first sight exactly the reverse of what occurs ...
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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