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 329
... migration of the more dominant forms of life from one region into another having been more or less effectually prevented , at periods more or less remote ; -on the nature and number of the former immigrants ; —and on the action of the ...
... migration of the more dominant forms of life from one region into another having been more or less effectually prevented , at periods more or less remote ; -on the nature and number of the former immigrants ; —and on the action of the ...
Página 330
... migrated from the same region ; for during the vast geographical and climatal changes which have supervened since ancient times , almost any amount of migration is possible . But in many other cases , in which we have reason to believe ...
... migrated from the same region ; for during the vast geographical and climatal changes which have supervened since ancient times , almost any amount of migration is possible . But in many other cases , in which we have reason to believe ...
Página 422
... migration by many means . A broken or interrupted range may often be accounted for by the extinction of the species in the intermediate regions . It cannot be denied that we are as yet very ignorant as to the full extent of the various ...
... migration by many means . A broken or interrupted range may often be accounted for by the extinction of the species in the intermediate regions . It cannot be denied that we are as yet very ignorant as to the full extent of the various ...
Contenido
VARIATION UNDER NATURE | 30 |
STRUGGLE FOR EXISTENCE | 45 |
NATURAL SELECTION | 59 |
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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