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 12
... produced under domestication ; I believe that a small part of the difference is due to their being descended from distinct species . In the case of strongly marked races of some other domesticated species , there is presumptive or even ...
... produced under domestication ; I believe that a small part of the difference is due to their being descended from distinct species . In the case of strongly marked races of some other domesticated species , there is presumptive or even ...
Página 16
... produced by crossing two breeds unless one of the parent - stocks possessed the charac- teristic enormous crop ? The supposed aboriginal stocks must all have been rock - pigeons , that is , they did not breed or willingly perch on trees ...
... produced by crossing two breeds unless one of the parent - stocks possessed the charac- teristic enormous crop ? The supposed aboriginal stocks must all have been rock - pigeons , that is , they did not breed or willingly perch on trees ...
Página 18
... produced a bird of as beautiful a blue colour , with the white loins , double black wing - bar , and barred and white- edged tail - feathers , as any wild rock - pigeon ! We can understand these facts , on the well - known principle of ...
... produced a bird of as beautiful a blue colour , with the white loins , double black wing - bar , and barred and white- edged tail - feathers , as any wild rock - pigeon ! We can understand these facts , on the well - known principle of ...
Página 20
... produced , either from one or from several allied species . Some effect may be attributed to the direct and definite action of the external conditions of life , and some to habit ; but he would be a bold man who would account by such ...
... produced , either from one or from several allied species . Some effect may be attributed to the direct and definite action of the external conditions of life , and some to habit ; but he would be a bold man who would account by such ...
Página 21
... produced as 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 ...
... produced as 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 ...
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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