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 36
... observed by Mr. Walsh to present in their larval or mature state , or in both states , slight , though constant differences in colour , size , or in the nature of their secretions . In some instances the males alone , in other instances ...
... observed by Mr. Walsh to present in their larval or mature state , or in both states , slight , though constant differences in colour , size , or in the nature of their secretions . In some instances the males alone , in other instances ...
Página 153
... observed by Matteucci , an analogous organ in the tail manifests but little electricity , even when the animal is greatly irritated ; so little , that it can hardly be of any use for the above purposes . Moreover , in the Ray , besides ...
... observed by Matteucci , an analogous organ in the tail manifests but little electricity , even when the animal is greatly irritated ; so little , that it can hardly be of any use for the above purposes . Moreover , in the Ray , besides ...
Página 251
... observed the same fact with certain seaweeds or Fuci . Gärtner , moreover , found that this difference of facility in making reciprocal crosses is extremely common in a lesser degree . He has observed it even between closely related ...
... observed the same fact with certain seaweeds or Fuci . Gärtner , moreover , found that this difference of facility in making reciprocal crosses is extremely common in a lesser degree . He has observed it even between closely related ...
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