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 48
... young , and that nearly all the young have been enabled to breed . Their geometrical ratio of increase , the result of which never fails to be surprising , simply explains their extraordinarily rapid in- crease and wide diffusion in ...
... young , and that nearly all the young have been enabled to breed . Their geometrical ratio of increase , the result of which never fails to be surprising , simply explains their extraordinarily rapid in- crease and wide diffusion in ...
Página 49
... young or old , during each generation or at recurrent intervals . Lighten any check , mitigate the destruction ever so little , and the number of the species will almost instantaneously increase to any amount . Nature of the Checks to ...
... young or old , during each generation or at recurrent intervals . Lighten any check , mitigate the destruction ever so little , and the number of the species will almost instantaneously increase to any amount . Nature of the Checks to ...
Página 50
... young elephant protected by its dam . Climate plays an important part in determining the average numbers of a species , and periodical seasons of extreme cold or drought seem to be the most effective of all checks . I estimated ...
... young elephant protected by its dam . Climate plays an important part in determining the average numbers of a species , and periodical seasons of extreme cold or drought seem to be the most effective of all checks . I estimated ...
Página 52
... young trees had not been sown or planted , I was so much surprised at their numbers that I went to several points of view , whence I could examine hundreds of acres of the unenclosed heath , and literally I could not see a single Scotch ...
... young trees had not been sown or planted , I was so much surprised at their numbers that I went to several points of view , whence I could examine hundreds of acres of the unenclosed heath , and literally I could not see a single Scotch ...
Página 55
... young were not annually preserved in due proportion . Struggle for Life most severe between Individuals and Varieties of the same Species . As the species of the same genus usually have , though by no means invariably , much similarity ...
... young were not annually preserved in due proportion . Struggle for Life most severe between Individuals and Varieties of the same Species . As the species of the same genus usually have , though by no means invariably , much similarity ...
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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