The Origin of Species by Means of Natural Selection,: Or the Preservation of Favoured Races in the Struggle for LifeJohn Murray, Albemarle Street., 1891 - 432 páginas |
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Página 16
... perfect plumage is acquired varies , as does the state of the down with which the nestling birds are clothed when hatched . The shape and size of the eggs vary . The manner of flight , and in some breeds the voice and disposition ...
... perfect plumage is acquired varies , as does the state of the down with which the nestling birds are clothed when hatched . The shape and size of the eggs vary . The manner of flight , and in some breeds the voice and disposition ...
Página 19
... perfect series ; so we can in some other cases , but not with all the breeds . Thirdly , those characters which are mainly distinctive of each breed are in each eminently variable , for instance the wattle and length of beak of the ...
... perfect series ; so we can in some other cases , but not with all the breeds . Thirdly , those characters which are mainly distinctive of each breed are in each eminently variable , for instance the wattle and length of beak of the ...
Página 21
... perfect and as useful as we now see them ; indeed , in many cases , we know that this has not been their history . The key is man's power of accumulative selection : nature gives successive variations ; man adds them up in certain direc ...
... perfect and as useful as we now see them ; indeed , in many cases , we know that this has not been their history . The key is man's power of accumulative selection : nature gives successive variations ; man adds them up in certain direc ...
Página 31
... perfect , as that a complex machine should have been invented by man in a perfect state . Under domestication monstrosities some- times occur which resemble normal structures in widely different animals . Thus pigs have occasionally ...
... perfect , as that a complex machine should have been invented by man in a perfect state . Under domestication monstrosities some- times occur which resemble normal structures in widely different animals . Thus pigs have occasionally ...
Página 70
... perfect manner , by the continued pre- servation of all the individuals which presented slight deviations of structure mutually favourable to each other . I am well aware that this doctrine of natural selection , exemplied in the above ...
... perfect manner , by the continued pre- servation of all the individuals which presented slight deviations of structure mutually favourable to each other . I am well aware that this doctrine of natural selection , exemplied in the above ...
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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 continued crossed crustaceans degree developed difficulty distinct species domestic animals doubt effects eggs embryo existing extinct extremely facts favourable female fertilised fertility flowers formation formerly forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number habits Hence hybrids 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 occur oceanic islands offspring organisation organs parent peculiar perfect pigeon pistil pollen present preserved principle probably produced 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