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 5
... ranges widely and is very numerous , and why another allied species has a narrow range and is rare ? Yet these relations are of the highest importance , for they determine the present welfare , and , as I believe , the future success ...
... ranges widely and is very numerous , and why another allied species has a narrow range and is rare ? Yet these relations are of the highest importance , for they determine the present welfare , and , as I believe , the future success ...
Página 41
... ranges . BEFORE applying the principles arrived at in the last chapter to organic beings in a state of nature , we must briefly discuss whether these latter are subject to any variation . To treat this subject at all properly , a long ...
... ranges . BEFORE applying the principles arrived at in the last chapter to organic beings in a state of nature , we must briefly discuss whether these latter are subject to any variation . To treat this subject at all properly , a long ...
Página 46
... ranges ; and lastly , according to very numerous experiments made during several years by that most careful observer Gärtner , they can be crossed only with much difficulty . We could hardly wish for better evidence of the two forms ...
... ranges ; and lastly , according to very numerous experiments made during several years by that most careful observer Gärtner , they can be crossed only with much difficulty . We could hardly wish for better evidence of the two forms ...
Página 47
... range of his observations , he will meet with more cases of difficulty ; for he will encounter a greater number of closely - allied forms . But if his observations be widely extended , he will in the end generally be enabled to make up ...
... range of his observations , he will meet with more cases of difficulty ; for he will encounter a greater number of closely - allied forms . But if his observations be widely extended , he will in the end generally be enabled to make up ...
Página 49
... ranges generally present varieties ; and this might have been expected , as they become exposed to diverse physical ... range , and to a certain extent from commonness ) , E L often give rise to varieties sufficiently well marked to ...
... ranges generally present varieties ; and this might have been expected , as they become exposed to diverse physical ... range , and to a certain extent from commonness ) , E L often give rise to varieties sufficiently well marked to ...
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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