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Principles of Selection anciently followed, and their Effects.
1866 1869 |
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Selection
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1859 1860 |
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Selection.
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1861 |
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Principles of Selection anciently followed
,
and their Effects.
1872 |
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| → action 1859 1860 1861 1866 |
| and definite action 1869 1872 |
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by selecting such slight differences, yet they ignore all general arguments, and refuse to sum up in their minds slight differences accumulated during many
generations. May not those naturalists who, knowing far less of the laws of inheritance than does the breeder, and knowing no more than he does of the intermediate links in the long lines of descent, yet admit that many of our domestic races
descended from the same parents — may they not learn a lesson of caution, when they deride the idea of species in a state of nature being lineal descendants of other species? |
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Principles of Selection anciently followed, and their Effects.
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| Let us now briefly consider the steps by which domestic races have been produced, either from one or from several allied species. Some
effect
be attributed to the direct
→action
of the external conditions of life, and some
to habit; but he would be a bold man who would account by such agencies for the differences
a dray and race horse, a greyhound and
a carrier and tumbler pigeon. One of the most remarkable features in our domesticated races is that we see in them adaptation, not indeed to the animal's or plant's own good, but to
use or fancy. Some variations useful to him have probably arisen suddenly, or by one step; many botanists, for instance, believe that the
with its hooks, which cannot be rivalled by any mechanical contrivance, is only a variety of the wild Dipsacus; and this amount of change may have suddenly arisen in a seedling. So it has probably been with the turnspit dog; and this is known to have been the case with the ancon sheep. But when we compare the dray-horse and race-horse, the dromedary and camel, the various breeds of sheep fitted either
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