On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeD. Appleton, 1909 - 430페이지 |
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7 페이지
... ranges CHAPTER III STRUGGLE FOR EXISTENCE 49 Its bearing on natural selection - The term used in a wide sense- Geometrical ratio of increase - Rapid increase of naturalised animals and plants - Nature of the checks to increase - Com ...
... ranges CHAPTER III STRUGGLE FOR EXISTENCE 49 Its bearing on natural selection - The term used in a wide sense- Geometrical ratio of increase - Rapid increase of naturalised animals and plants - Nature of the checks to increase - Com ...
16 페이지
... 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 ...
49 페이지
... ranges . 66 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 ...
... ranges . 66 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 ...
54 페이지
... 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 ...
55 페이지
... 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 ...
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accumulated adapted affinities allied species America analogous ancient animals appear archipelago become bees believe birds breeds cause cells characters cirripedes climate closely allied colour continuous crossed crustaceans degree difficulty distinct species divergence domestic doubt embryo endemic existing exterminated extinct extremely facts favourable fertilised fertility flowers formations forms fossil Gärtner genera genus geological geological period Glacial period gradations greater number groups of species habits Hence hybrids hybrids produced important increase individuals inhabitants inherited insects instance instincts intercrossing intermediate larvæ laws less living males mammals manner migration modification modified descendants natural selection naturalists nearly nest occasionally offspring organic organisation origin of species perfect pigeons plants pollen present principle probably produced progenitor ranked reciprocal crosses remarked resemble rock-pigeon rudimentary seeds sexual sexual selection Silurian slight sometimes South America sterility structure struggle successive supposed swimbladder tend theory variability variations varieties vary whole widely