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 65
... structure of the adult . So , conversely , modifications in the adult may affect the structure of the larva ; but in all cases natural selection will ensure that they shall not be injurious : for if they were so , the species would ...
... structure of the adult . So , conversely , modifications in the adult may affect the structure of the larva ; but in all cases natural selection will ensure that they shall not be injurious : for if they were so , the species would ...
Página 142
... structure of each squirrel is the best that it is possible to conceive under all possible conditions . Let the climate and vegetation change , let other competing rodents or new beasts of prey immigrate , or old ones become modified ...
... structure of each squirrel is the best that it is possible to conceive under all possible conditions . Let the climate and vegetation change , let other competing rodents or new beasts of prey immigrate , or old ones become modified ...
Página 143
... structure here alluded to , which perhaps may all be the result of disuse , indicate the steps by which birds ... structure highly perfected for any particular habit , as the wings of a bird for flight , we should bear in mind that ...
... structure here alluded to , which perhaps may all be the result of disuse , indicate the steps by which birds ... structure highly perfected for any particular habit , as the wings of a bird for flight , we should bear in mind that ...
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