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 146
... rarely go near the water ; and no one except Audubon has seen the frigate - bird , which has all its four toes webbed , alight on the surface of the ocean . On the other hand , grebes and coots are eminently aquatic , although their ...
... rarely go near the water ; and no one except Audubon has seen the frigate - bird , which has all its four toes webbed , alight on the surface of the ocean . On the other hand , grebes and coots are eminently aquatic , although their ...
Página 217
... rarely or never become " broody , " that is , never wish to sit on their eggs . Familiarity alone prevents our seeing how largely and how permanently the minds of our domestic animals have been modified . It is scarcely possible to ...
... rarely or never become " broody , " that is , never wish to sit on their eggs . Familiarity alone prevents our seeing how largely and how permanently the minds of our domestic animals have been modified . It is scarcely possible to ...
Página 249
... rarely produce any offspring , are generally very sterile ; but the parallelism between the difficulty of making a first cross , and the sterility of the hybrids thus produced - two classes of facts which are generally confounded ...
... rarely produce any offspring , are generally very sterile ; but the parallelism between the difficulty of making a first cross , and the sterility of the hybrids thus produced - two classes of facts which are generally confounded ...
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