The Origin of Species by Means of Natural Selection,: Or the Preservation of Favoured Races in the Struggle for LifeAppleton, 1898 - 432페이지 |
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36개의 결과 중 1 - 5개
v 페이지
... offspring not uni- versal - Hybrids and mongrels compared independently of their fertility - Summary Page 1 CHAPTER X. ON THE IMPERFECTION OF THE GEOLOGICAL RECORD . On the absence of intermediate varieties at the present day - On the ...
... offspring not uni- versal - Hybrids and mongrels compared independently of their fertility - Summary Page 1 CHAPTER X. ON THE IMPERFECTION OF THE GEOLOGICAL RECORD . On the absence of intermediate varieties at the present day - On the ...
ix 페이지
... offspring not uni- versal - Hybrids and mongrels compared independently of their fertility - Summary . THE view commonly entertained by naturalists is that species , when intercrossed , have been specially en- dowed with sterility , in ...
... offspring not uni- versal - Hybrids and mongrels compared independently of their fertility - Summary . THE view commonly entertained by naturalists is that species , when intercrossed , have been specially en- dowed with sterility , in ...
2 페이지
... offspring . Hybrids , on the other hand , have their reproductive organs functionally impotent , as may be clearly seen in the state of the male element in both plants and animals ; though the formative organs themselves are perfect in ...
... offspring . Hybrids , on the other hand , have their reproductive organs functionally impotent , as may be clearly seen in the state of the male element in both plants and animals ; though the formative organs themselves are perfect in ...
3 페이지
... offspring , with the average number produced by both pure parent - species in a state of nature . But causes of serious error here intervene : a plant , to be hybridised , must be castrated , and , what is often more important , must be ...
... offspring , with the average number produced by both pure parent - species in a state of nature . But causes of serious error here intervene : a plant , to be hybridised , must be castrated , and , what is often more important , must be ...
5 페이지
... offspring ; and both sexual elements in hybrid plants are already affected in some degree . But I believe that their fertility has been di- minished in nearly all these cases by an independent cause , namely , by too close interbreeding ...
... offspring ; and both sexual elements in hybrid plants are already affected in some degree . But I believe that their fertility has been di- minished in nearly all these cases by an independent cause , namely , by too close interbreeding ...
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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