The Origin of Species by Means of Natural Selection: Or the Preservation of Favored Races in the Struggle for LifeD. Appleton, 1904 - 435 páginas |
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Página 81
... 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 ex- traordinarily rapid increase 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 ex- traordinarily rapid increase and wide diffusion in ...
Página 82
... young , a small number may be produced , and yet the average stock be fully kept up ; but if many eggs or young are destroyed , many must be produced , or the species will become extinct . It would suffice to keep up the full number of ...
... young , a small number may be produced , and yet the average stock be fully kept up ; but if many eggs or young are destroyed , many must be produced , or the species will become extinct . It would suffice to keep up the full number of ...
Página 83
... young animals seem generally to suffer most , but this is not invariably the case . With plants there is a vast destruction of seeds , but , from some observations which I have made it appears that the seedlings suffer most from germi ...
... young animals seem generally to suffer most , but this is not invariably the case . With plants there is a vast destruction of seeds , but , from some observations which I have made it appears that the seedlings suffer most from germi ...
Página 84
... young elephant protected by its dam . Climate plays an important part in determining the average number of a species , and periodical seasons of extreme cold or drought seem to be the most effective of all checks . I estimated ( chiefly ...
... young elephant protected by its dam . Climate plays an important part in determining the average number of a species , and periodical seasons of extreme cold or drought seem to be the most effective of all checks . I estimated ( chiefly ...
Página 88
... 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 ...
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Términos y frases comunes
adapted affinities allied species America ancient appear Asa Gray beak become bees believe belonging birds breeds cause cells characters climate closely allied colour common continent crossed crustaceans degree developed difficulty distinct species domestic doubt effects eggs embryo existing extinct extremely facts favourable fertilised fertility flowers formation forms fossil Fritz Müller genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hybrids important individuals inhabitants inherited insects instance instincts intercrossing intermediate kind lamellæ larvæ less living males mammals manner marsupials migration modified descendants natural selection naturalists nearly nest occasionally offspring organisation organs parent peculiar perfect pigeon pistil pollen present principle probably produced progenitor quadrupeds ranked remarked resemblance rudimentary seeds sexual selection Silurian slight South America stamens sterility structure successive supposed swimbladder tend theory tion trees variability variations varieties vary whilst whole wings young