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 54
... considered necessary to give to two forms the rank of species is quite indefinite . In genera having more than the average number of species in any country , the species of these genera have more than the average number of varieties ...
... considered necessary to give to two forms the rank of species is quite indefinite . In genera having more than the average number of species in any country , the species of these genera have more than the average number of varieties ...
Página 77
... considered by botanists as characters of the most trifling importance : yet we hear from an excellent horticulturist , Downing , that in the United States smooth - skinned fruits suffer far more from a beetle , a curculio , than those ...
... considered by botanists as characters of the most trifling importance : yet we hear from an excellent horticulturist , Downing , that in the United States smooth - skinned fruits suffer far more from a beetle , a curculio , than those ...
Página 90
... considered as distinct individuals only in a limited sense . I believe this objection to be valid , but that nature has largely pro- vided against it by giving to trees a strong tendency to bear flowers with separated sexes . When the ...
... considered as distinct individuals only in a limited sense . I believe this objection to be valid , but that nature has largely pro- vided against it by giving to trees a strong tendency to bear flowers with separated sexes . When the ...
Página 128
... considered as domestic animals , but they have been transported by man to many parts of the world , and now have a far wider range than any other rodent , living free under the cold climate of Faroe in the north and of the Falklands in ...
... considered as domestic animals , but they have been transported by man to many parts of the world , and now have a far wider range than any other rodent , living free under the cold climate of Faroe in the north and of the Falklands in ...
Página 144
... considered as a variation representing the normal structure of another race , the fantail . I presume that no one will doubt that all such analogous variations are due to the several races of the pigeon having inherited from a common ...
... considered as a variation representing the normal structure of another race , the fantail . I presume that no one will doubt that all such analogous variations are due to the several races of the pigeon having inherited from a common ...
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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