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 14
... breeds by the crossing of any lesser number : how , for instance , could a pouter be produced by crossing two breeds unless one of the parent - stocks possessed the characteristic enormous crop ? The supposed aboriginal stocks must all ...
... breeds by the crossing of any lesser number : how , for instance , could a pouter be produced by crossing two breeds unless one of the parent - stocks possessed the characteristic enormous crop ? The supposed aboriginal stocks must all ...
Página 15
... breeds , and some truly wild breeds , have , besides the two black bars , the wings chequered with black . These several marks do not occur together in any other species of the whole family . Now , in every one of the domestic breeds ...
... breeds , and some truly wild breeds , have , besides the two black bars , the wings chequered with black . These several marks do not occur together in any other species of the whole family . Now , in every one of the domestic breeds ...
Página 17
... breeds . Thirdly , those characters which are mainly distinctive of each breed are in each eminently variable , for ... breeds , which method was never practised before , has improved them astonishingly . " About this same period the ...
... breeds . Thirdly , those characters which are mainly distinctive of each breed are in each eminently variable , for ... breeds , which method was never practised before , has improved them astonishingly . " About this same period the ...
Contenido
VARIATION UNDER NATURE | 30 |
STRUGGLE FOR EXISTENCE | 45 |
NATURAL SELECTION | 59 |
Derechos de autor | |
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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