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 77
... occasional cross being indispensable ; for owing to the nature of the fertilising element there are no means , analogous ... occasionally intercross , the difference between them and unisexual species is , as far as function is concerned ...
... occasional cross being indispensable ; for owing to the nature of the fertilising element there are no means , analogous ... occasionally intercross , the difference between them and unisexual species is , as far as function is concerned ...
Página 219
... occasionally laid an egg in other birds ' nests . If the old bird profited by this occasional habit through being ... occasionally lays her eggs on the bare ground , sits on them , and feeds her young . This rare event is probably a case ...
... occasionally laid an egg in other birds ' nests . If the old bird profited by this occasional habit through being ... occasionally lays her eggs on the bare ground , sits on them , and feeds her young . This rare event is probably a case ...
Página 360
... occasionally arriving after long intervals of time in the new and isolated district , and having to compete with new associates , would be eminently liable to modification , and would often produce groups of modified descendants . But ...
... occasionally arriving after long intervals of time in the new and isolated district , and having to compete with new associates , would be eminently liable to modification , and would often produce groups of modified descendants . But ...
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