The Origin of Species by Means of Natural Selection: Or the Preservation of Favored Races in the Struggle for LifeD. Appleton, 1904 - 435 páginas |
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Página 57
... intermediate links ; nor will the commonly- assumed hybrid nature of the intermediate forms always remove the difficulty . In very many cases , however , one form is ranked as a variety of another , not because the intermediate links ...
... intermediate links ; nor will the commonly- assumed hybrid nature of the intermediate forms always remove the difficulty . In very many cases , however , one form is ranked as a variety of another , not because the intermediate links ...
Página 61
... intermediate forms will be discovered which will link together the extreme states , and these are then degraded to the rank of varie- ties . Some few naturalists maintain that animals never present varieties ; but then these same ...
... intermediate forms will be discovered which will link together the extreme states , and these are then degraded to the rank of varie- ties . Some few naturalists maintain that animals never present varieties ; but then these same ...
Página 62
... intermediate states . After this discussion , the result of so much labour , he emphatically remarks : " They are are mistaken , who repeat that the greater part of our species are clearly limited , and that the doubtful species are in ...
... intermediate states . After this discussion , the result of so much labour , he emphatically remarks : " They are are mistaken , who repeat that the greater part of our species are clearly limited , and that the doubtful species are in ...
Página 63
... intermediate forms flow in , and doubts as to specific limits augment . " He also adds that it is the best known species which present the greatest number of spontaneous varieties and sub - varieties . Thus Quercus robur has twenty ...
... intermediate forms flow in , and doubts as to specific limits augment . " He also adds that it is the best known species which present the greatest number of spontaneous varieties and sub - varieties . Thus Quercus robur has twenty ...
Página 64
... intermediate links , he will be compelled to trust almost en- tirely to analogy , and his difficulties will rise to a climax . Certainly no clear line of demarcation has as yet been drawn between species and sub - species - that is ...
... intermediate links , he will be compelled to trust almost en- tirely to analogy , and his difficulties will rise to a climax . Certainly no clear line of demarcation has as yet been drawn between species and sub - species - that is ...
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Términos y frases comunes
adapted affinities allied species America ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied colour common continent crossed crustaceans degree developed difficulty distinct species domestic doubt effects eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological geological period 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 males mammals manner marsupials migration modified descendants natural selection naturalists nearly nest occasionally offspring organisation organs parent peculiar perfect pigeon pistil pollen present principle probably produced progenitor quadrupeds ranked remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive supposed swimbladder tend theory tion trees variability variations varieties vary whilst whole wings young