On the Origin of Species by Means of Natural Selection: Or The Preservation of Favoured Races in the Struggle for LifeHumphrey Milford, Oxford University Press, 1923 - 454 páginas |
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Página 39
... islands . Although I do not doubt that some domestic animals vary less than others , yet the rarity or absence of distinct breeds of the cat , the donkey , peacock , goose , etc. , may be attributed in main part to selection not having ...
... islands . Although I do not doubt that some domestic animals vary less than others , yet the rarity or absence of distinct breeds of the cat , the donkey , peacock , goose , etc. , may be attributed in main part to selection not having ...
Página 45
... islands of the Galapagos Archipelago , both one with another , and with those from the American mainland , I was much struck how entirely vague and arbitrary is the distinction between species and varieties . On the islets of the little ...
... islands of the Galapagos Archipelago , both one with another , and with those from the American mainland , I was much struck how entirely vague and arbitrary is the distinction between species and varieties . On the islets of the little ...
Página 60
... islands in a period of less than ten years . Several of the plants , such as the cardoon and a tall thistle , now most numerous over the wide plains of La Plata , clothing square leagues of surface almost to the exclusion of all other ...
... islands in a period of less than ten years . Several of the plants , such as the cardoon and a tall thistle , now most numerous over the wide plains of La Plata , clothing square leagues of surface almost to the exclusion of all other ...
Página 74
... island , or of a country partly surrounded by barriers , into which new and better adapted forms could not freely enter , we should then have places in the economy of nature which would assuredly be better filled up , if some of the ...
... island , or of a country partly surrounded by barriers , into which new and better adapted forms could not freely enter , we should then have places in the economy of nature which would assuredly be better filled up , if some of the ...
Página 95
... island , although the total number of the species inhabiting it , will be found to be small , as we shall see in our chapter on geographical distribution ; yet of these species a very large proportion are endemic , - that is , have been ...
... island , although the total number of the species inhabiting it , will be found to be small , as we shall see in our chapter on geographical distribution ; yet of these species a very large proportion are endemic , - that is , have been ...
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Términos y frases comunes
accumulated adapted affinities allied species America amount analogous ancient appear Archipelago become bees believe birds breeds cause cells characters cirripedes climate closely allied colour common parent continuous crossed crustaceans degree difficulty distinct species divergence doubt embryo endemic Europe existing exterminated extinct extremely facts favourable fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hermaphrodites hybrids hybrids produced important individuals inhabitants inherited insects instance instincts intercrossing land larvæ less living male mammals manner Marsupials migration modification modified descendants natural selection naturalists nearly nest oceanic islands offspring organisation perfect pigeons pistil plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rock-pigeon rudimentary organs seeds sexual selection Silurian slight South America sterility structure struggle successive suppose swimbladder tend theory tion trees variability variation vary whole widely