nature, in the same way as they
generally generally 1859 1860 1861 1866 | generally 1869 1872 |
have varied under
the changed conditions of the changed conditions of 1859 1860 1861 1866 |
OMIT 1869 1872 |
domestication. And if there
be be 1859 1860 1861 1866 1869 | has been 1872 |
any variability under nature, it would be an unaccountable fact if natural selection
had had 1859 1860 1861 1866 1872 | did 1869 |
not come into play. It has often been asserted, but the assertion is
quite quite 1859 1860 1861 1866 | quite 1869 1872 |
incapable of proof, that the amount of variation under nature is a strictly limited quantity. Man, though acting on external characters alone and often capriciously, can produce within a short period a great result by adding up mere individual differences in his domestic productions; and every one admits that
there are at least there are at least 1859 1860 1861 1866 |
species present 1869 1872 |
individual
differences differences 1859 1860 1861 1866 | differences. 1869 1872 |
in in 1859 1860 1861 1866 | in 1869 1872 |
species species 1859 1860 1861 1866 | species 1869 1872 |
under under 1859 1860 1861 1866 | under 1869 1872 |
nature. nature. 1859 1860 1861 1866 | nature. 1869 1872 |
But, besides such differences, all naturalists
have admitted the existence of varieties, which they have considered have admitted the existence of varieties, which they have considered 1861 1866 |
have admitted the existence of varieties, which they think 1859 1860 |
admit that varieties exist, which are considered 1869 |
admit that natural varieties exist, which are considered 1872 |
sufficiently distinct to be worthy of record in
their systematic their systematic 1861 1866 | systematic 1859 1860 1869 1872 |
works. No one
can can 1859 1860 1861 1866 | has 1869 1872 |
draw draw 1859 1860 1861 1866 | drawn 1869 1872 |
any clear distinction between individual differences and slight varieties; or between more plainly marked varieties and sub-species, and species. ↑1 blocks not present in 1859 1860 1861; present in 1866 1869 1872 | On separate continents, and on different parts of the same continent when divided by barriers of any kind, and on outlying islands,
what a multitude
of forms exist, which some experienced naturalists rank as varieties,
others as geographical races or sub-species, and others as distinct, though closely allied species!
|
Let it be observed how naturalists differ in the rank which they assign to the many representative forms in Europe and North America. |
If
then then 1859 1860 1861 1866 1869 | then, 1872 |
we have variability as well as a powerful agent always ready to act, we have variability as well as a powerful agent always ready to act, 1861 |
we have under nature variability and a powerful agent always ready to act and select, 1859 1860 |
animals and plants do vary, let it be ever so slowly or so little, 1866 |
animals and plants do vary, let it be ever so little or so slowly, 1869 |
animals and plants do vary, let it be ever so slightly or slowly, 1872 |
why should
we doubt that variations we doubt that variations 1859 1860 1861 1866 |
we doubt that the variations or individual differences, which are 1869 |
not variations or individual differences, which are 1872 |
in
any any 1859 1860 1861 1869 1872 | some 1866 |
way
useful to beings, under their excessively complex relations of life, would useful to beings, under their excessively complex relations of life, would 1859 1860 1861 |
useful to them under their extremely complex relations of life would 1866 |
beneficial would 1869 |
beneficial, 1872 |
be preserved, accumulated, and inherited? be preserved, accumulated, and inherited? 1859 1860 1861 |
occasionally occur, and then be preserved and accumulated by natural selection? 1866 |
be preserved and accumulated through natural selection, or the survival of the fittest? 1869 1872 |
Why, if Why, if 1859 1860 1861 1866 | If 1869 1872 |
man can by patience select variations
most most 1859 1860 1861 1866 | most 1869 1872 |
useful to
himself, should nature fail in selecting variations useful, himself, should nature fail in selecting variations useful, 1859 1860 1861 |
himself, should nature fail in preserving or selecting variations useful, 1866 |
him, why, 1869 1872 |
under changing
conditions conditions 1859 1860 1861 1866 |
and complex conditions 1869 1872 |
of life,
to her to her 1859 1860 1861 1866 |
should not variations useful to natures 1869 |
should not variations useful to nature's 1872 |
living
products? products? 1859 1860 1861 1866 |
products often arise, and be preserved or selected? 1869 1872 |
What limit can be put to this power, acting during long ages and rigidly scrutinising the whole constitution, structure, and habits of each creature,— favouring the good and rejecting the bad? I can see no limit to this power, in slowly and beautifully adapting each form to the most complex relations of life. The theory of natural
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