The Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeCollier Books, 1962 - 512 páginas |
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Página 171
... intermediate varie- ties should not endure for very long periods : -why , as a gen- eral rule , they should be exterminated and disappear , sooner than the forms which they originally linked together . For any form existing in lesser ...
... intermediate varie- ties should not endure for very long periods : -why , as a gen- eral rule , they should be exterminated and disappear , sooner than the forms which they originally linked together . For any form existing in lesser ...
Página 172
... intermediate links ; first , be- cause new varieties are very slowly formed , for variation is a slow process , and natural selection can do nothing until favour- able individual differences or variations occur , and until a place in ...
... intermediate links ; first , be- cause new varieties are very slowly formed , for variation is a slow process , and natural selection can do nothing until favour- able individual differences or variations occur , and until a place in ...
Página 308
... intermediate varieties , which have formerly existed , be truly enormous . Why then is not every geological formation and every stratum full of such intermediate links ? Geology assuredly does not reveal any such finely - graduated ...
... intermediate varieties , which have formerly existed , be truly enormous . Why then is not every geological formation and every stratum full of such intermediate links ? Geology assuredly does not reveal any such finely - graduated ...
Contenido
An Historical Sketch | 15 |
Introduction | 25 |
Variation Under Nature | 58 |
Derechos de autor | |
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Términos y frases comunes
accumulated adapted admit affinities allied species America analogous ancient appear 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 eggs embryo existing extinct extremely facts favourable fertilised 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 Marsupials migration modified descendants natural selection naturalists nearly nest occasionally offspring organisation organs Origin of Species parent peculiar perfect pigeons pistil 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 tend theory tion variability variations varieties vary whilst whole wings young