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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20 페이지
... breeds several truly - inherited sub - breeds , or species , as he would call them , could be shown him . Great as are the differences between the breeds of the pigeon , I am fully convinced that the common opinion of naturalists is ...
... breeds several truly - inherited sub - breeds , or species , as he would call them , could be shown him . Great as are the differences between the breeds of the pigeon , I am fully convinced that the common opinion of naturalists is ...
23 페이지
... breeds of the pigeon are perfectly fertile , as I can state from my own observations , purposely made , on the most distinct breeds . Now , hardly any cases have been ascer- tained with certainty of hybrids from two quite distinct ...
... breeds of the pigeon are perfectly fertile , as I can state from my own observations , purposely made , on the most distinct breeds . Now , hardly any cases have been ascer- tained with certainty of hybrids from two quite distinct ...
24 페이지
... breeds . Thirdly , those characters which are mainly distinctive of each breed are in each eminently variable , for ... breeds , which method was never practiced before , has improved them astonishingly . " About this same period the ...
... breeds . Thirdly , those characters which are mainly distinctive of each breed are in each eminently variable , for ... breeds , which method was never practiced before , has improved them astonishingly . " About this same period the ...
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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 divergence domestic doubt effects eggs embryo existing extinct extremely facts favorable fertility flowers formation forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing intermediate intervals kind lamellæ larvæ less living male mammals manner marsupials migration modified descendants natural selection naturalists nearly nest occasionally 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