The Origin of Species by Means of Natural Selection; Or, the Preservation of Favored Races in the Struggle for Life ...A.L. Burt, 1890 - 538페이지 |
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283 페이지
... hybrids should have gone on increasing . Although I know of hardly any thoroughly well - authen- ticated cases of perfectly fertile hybrid animals , I have reason to believe that the hybrids from Cervulus vaginalis and Reevesii , and ...
... hybrids should have gone on increasing . Although I know of hardly any thoroughly well - authen- ticated cases of perfectly fertile hybrid animals , I have reason to believe that the hybrids from Cervulus vaginalis and Reevesii , and ...
285 페이지
Charles Darwin. knowledge is in regard to hybrid animals , I have been sur- prised to find how generally the same rules apply to both kingdoms . It has been already remarked , that the degree of fertility , both of first crosses and of ...
Charles Darwin. knowledge is in regard to hybrid animals , I have been sur- prised to find how generally the same rules apply to both kingdoms . It has been already remarked , that the degree of fertility , both of first crosses and of ...
307 페이지
... hybrids from long cultivated plants are more subject to reversion than hybrids from species in their natural state ; and this prob- ably explains the singular difference in the results arrived at by different observers . Thus Max ...
... hybrids from long cultivated plants are more subject to reversion than hybrids from species in their natural state ; and this prob- ably explains the singular difference in the results arrived at by different observers . Thus Max ...
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adapted admit affinities allied species America ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied color continued crossed crustaceans degree developed difficulty distinct species domestic doubt effects eggs embryo existing extinct extremely facts favorable females fertility flowers formation forms fossil Fritz Müller genera genus geological geological period gilt top Glacial period gradations greater number groups of species habits Hence hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living male mammals manner marsupials migration modified descendants natural selection naturalists nearly nest oceanic islands offspring organs parent peculiar perfect pigeons pistil pollen present principle probably produced quadrupeds ranked remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive suppose tend theory tion variability variations varieties vary whole widely different wings young