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 80
... improved at a slow rate ; and this may sometimes be of much importance . If , however , an isolated area be very ... improved , others will have to be improved in a corresponding degree , or they will be exterminated . Each new form ...
... improved at a slow rate ; and this may sometimes be of much importance . If , however , an isolated area be very ... improved , others will have to be improved in a corresponding degree , or they will be exterminated . Each new form ...
Página 93
... improved states of the same species , as well as the original parent - species itself , will generally tend to become extinct . So it probably will be with many whole collateral lines of descent , which will be conquered by later and ...
... improved states of the same species , as well as the original parent - species itself , will generally tend to become extinct . So it probably will be with many whole collateral lines of descent , which will be conquered by later and ...
Página 139
... improving their breeds more quickly than the small holders on the intermediate narrow , hilly tract ; and consequently the improved mountain or plain breed will soon take the place of the less improved hill breed ; and thus the two ...
... improving their breeds more quickly than the small holders on the intermediate narrow , hilly tract ; and consequently the improved mountain or plain breed will soon take the place of the less improved hill breed ; and thus the two ...
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