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 41
... genera ( i.e. , those including many species ) being placed on one side , and all those in the smaller genera on the other side , the former will be found to include a somewhat larger number of the very common and much diffused or ...
... genera ( i.e. , those including many species ) being placed on one side , and all those in the smaller genera on the other side , the former will be found to include a somewhat larger number of the very common and much diffused or ...
Página 42
... genera . Moreover , the species of the large genera which present any varieties , invariably present a larger average number of varieties than do the species of the small genera . Both these results follow when another division is made ...
... genera . Moreover , the species of the large genera which present any varieties , invariably present a larger average number of varieties than do the species of the small genera . Both these results follow when another division is made ...
Página 322
... genera each with the same number of species , then we may conclude that generally only one species of each of the older genera has left modified descendants , which constitute the new genera containing the several species ; the other ...
... genera each with the same number of species , then we may conclude that generally only one species of each of the older genera has left modified descendants , which constitute the new genera containing the several species ; the other ...
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