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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217 페이지
... beak of a duck ? Ducks , like whales , subsist by sift- ing the mud and water ; and the family has sometimes been called Criblatores , or sifters . I hope that I may not be misconstrued into saying that the progenitors of whales did ...
... beak of a duck ? Ducks , like whales , subsist by sift- ing the mud and water ; and the family has sometimes been called Criblatores , or sifters . I hope that I may not be misconstrued into saying that the progenitors of whales did ...
218 페이지
... beak of this bird resembles in this respect the mouth of a whale . From the highly developed structure of the shoveller's beak we may proceed ( as I have learned from information and specimens sent to me by Mr. Salvin ) , without any ...
... beak of this bird resembles in this respect the mouth of a whale . From the highly developed structure of the shoveller's beak we may proceed ( as I have learned from information and specimens sent to me by Mr. Salvin ) , without any ...
219 페이지
... beak constructed like that of a common goose and adapted solely for grazing , or even a member with a beak having less well - developed lamellæ , might be converted by small changes into a species like the Egyptian goose - this into one ...
... beak constructed like that of a common goose and adapted solely for grazing , or even a member with a beak having less well - developed lamellæ , might be converted by small changes into a species like the Egyptian goose - this into one ...
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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