The Origin of Species by Means of Natural Selection: Or, The Preservation of Favored Races in the Struggle for LifeP.F. Collier & son, 1902 - 356페이지 |
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14 페이지
... color of this vigorous race I take for granted , from what has been already said , would be dark . But the same dis- position to form varieties still existing , a darker and a darker race would in the course of time occur : and as the ...
... color of this vigorous race I take for granted , from what has been already said , would be dark . But the same dis- position to form varieties still existing , a darker and a darker race would in the course of time occur : and as the ...
32 페이지
... - such as size from the amount of food , color from the nature of the food , thickness of the skin and hair from Grath Sni 1 / cture of Conditions climate , etc. Each of the endless variations which we 32 THE ORIGIN OF SPECIES.
... - such as size from the amount of food , color from the nature of the food , thickness of the skin and hair from Grath Sni 1 / cture of Conditions climate , etc. Each of the endless variations which we 32 THE ORIGIN OF SPECIES.
37 페이지
... Color and constitutional peculiarities go together , of which many remarkable cases could be given among animals and plants . From facts collected by Heusinger , it appears that white sheep and pigs are injured by cer tain plants ...
... Color and constitutional peculiarities go together , of which many remarkable cases could be given among animals and plants . From facts collected by Heusinger , it appears that white sheep and pigs are injured by cer tain plants ...
52 페이지
... of as beautiful a blue color , with the white loins , double black wing - bar , and barred and white - edged tail - feathers , as any wild rock- pigeon ! We can understand these facts , on the 52 THE ORIGIN OF SPECIES.
... of as beautiful a blue color , with the white loins , double black wing - bar , and barred and white - edged tail - feathers , as any wild rock- pigeon ! We can understand these facts , on the 52 THE ORIGIN OF SPECIES.
53 페이지
... colors and markings . Or , secondly , that each breed , even the purest , has within a dozen , or at most within a score , of generations , been crossed by the rock - pigeon ; I say within a dozen or twenty genera- tions , for no ...
... colors and markings . Or , secondly , that each breed , even the purest , has within a dozen , or at most within a score , of generations , been crossed by the rock - pigeon ; I say within a dozen or twenty genera- tions , for no ...
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adapted admit affinities allied species America analogous ancient animals appear beak become bees believe belonging birds breeds cause cells characters climate closely allied color common continent crossed crustaceans degree developed difficulty distinct species domestic doubt eggs embryo existing extinct extremely facts favorable fertility flowers formation forms fossil Fritz Müller genera genus geological Glacial period gradations greater number groups of species habits Hence hybrids important individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living male mammals manner marsupial migration modification modified descendants natural selection naturalists nearly nest offspring organs ORIGIN OF SPECIES paleozoic parent peculiar perfect pigeon pistil plants pollen present principle probably produced progenitor quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive supposed swimbladder theory tion trees variability variations varieties vary whole wings young