On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeEaston Press, 1976 - 470 páginas |
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Página 43
... varieties or incipient species greater than the average are now manufacturing , many of the species already manufactured still to a certain extent resemble varieties , for they differ from each other by less than the usual amount of ...
... varieties or incipient species greater than the average are now manufacturing , many of the species already manufactured still to a certain extent resemble varieties , for they differ from each other by less than the usual amount of ...
Página 56
... varieties of the same species , the struggle will generally be almost equally severe , and we sometimes see the contest soon decided : for instance , if several varieties of wheat be sown together , and the mixed seed be resown , some ...
... varieties of the same species , the struggle will generally be almost equally severe , and we sometimes see the contest soon decided : for instance , if several varieties of wheat be sown together , and the mixed seed be resown , some ...
Página 266
... varieties , and Naudin has come to the same conclusion . The following case is far more remarkable , and seems at ... varieties when crossed produce less seed than the similarly coloured varieties of the same species . Moreover , he ...
... varieties , and Naudin has come to the same conclusion . The following case is far more remarkable , and seems at ... varieties when crossed produce less seed than the similarly coloured varieties of the same species . Moreover , he ...
Contenido
VARIATION UNDER NATURE | 30 |
STRUGGLE FOR EXISTENCE | 45 |
NATURAL SELECTION | 59 |
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Términos y frases comunes
accumulated adapted admit affinities allied species America ancient appear beak become bees believe belonging birds breeds cause cells characters climate closely allied colour common progenitor continuous crossed crustaceans degree developed difficulty distinct species divergence doubt effects eggs embryo existing exterminated extinct extremely facts favourable fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological geological period gradations greater number groups of species habits Hence hybrids hybrids produced important increase 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 plants pollen present preserved principle probably produced quadrupeds ranked reciprocal crosses remarked resemblance rudimentary seeds slight South America stamens sterility structure struggle successive supposed swimbladder theory variability variations varieties vary whilst whole wings young