On the Origin of Species by Means of Natural Selection: Or, The Preservation of Favoured Races in the Struggle for LifeD. Appleton, 1909 - 430 páginas |
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Página 46
... occasionally , the chance of their appearance will be much increased by a large number of individuals being kept ; and hence this comes to be of the highest importance to success . On this principle Marshall has remarked , with respect ...
... occasionally , the chance of their appearance will be much increased by a large number of individuals being kept ; and hence this comes to be of the highest importance to success . On this principle Marshall has remarked , with respect ...
Página 47
... played an important part in the origin of our domestic breeds . When in any country several domestic breeds have once been established , their occasional intercrossing , with the aid of selection , has , no doubt SUMMARY OF VARIATION 47.
... played an important part in the origin of our domestic breeds . When in any country several domestic breeds have once been established , their occasional intercrossing , with the aid of selection , has , no doubt SUMMARY OF VARIATION 47.
Página 49
... be doubted whether monstrosities , or such sudden and great deviations of structure as we occasionally see in our domestic productions , more especially with plants , are ever permanently propagated in a VARIATION UNDER NATURE 49.
... be doubted whether monstrosities , or such sudden and great deviations of structure as we occasionally see in our domestic productions , more especially with plants , are ever permanently propagated in a VARIATION UNDER NATURE 49.
Página 65
... occasional - year , otherwise , on the principle of geometrical increase , .. its numbers would quickly become so inordinately great that no country could support the product . Hence , as more individuals are produced than can possibly ...
... occasional - year , otherwise , on the principle of geometrical increase , .. its numbers would quickly become so inordinately great that no country could support the product . Hence , as more individuals are produced than can possibly ...
Página 82
... occasionally arise , few will deny ; but that the process of variation should be thus indefinitely prolonged is an assumption , the truth of which must be judged of by how far the hypothesis accords with and explains the general ...
... occasionally arise , few will deny ; but that the process of variation should be thus indefinitely prolonged is an assumption , the truth of which must be judged of by how far the hypothesis accords with and explains the general ...
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Términos y frases comunes
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