admit that natural varieties exist, which are considered admit that natural varieties exist, which are considered 1872 |
have admitted the existence of varieties, which they think 1859 1860 |
have admitted the existence of varieties, which they have considered 1861 1866 |
admit that varieties exist, which are considered 1869 |
sufficiently distinct to be worthy of record in systematic
works. No one
has has 1869 1872 | can 1859 1860 1861 1866 |
drawn drawn 1869 1872 | draw 1859 1860 1861 1866 |
any clear distinction between individual differences and slight varieties; or between more plainly marked varieties and sub-species, and species. 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! ↑1 blocks not present in 1866 1869 1872; present in 1859 1860 1861 | 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, 1872 | then 1859 1860 1861 1866 1869 |
animals and plants do vary, let it be ever so slightly or slowly, animals and plants do vary, let it be ever so slightly or slowly, 1872 |
we have under nature variability and a powerful agent always ready to act and select, 1859 1860 |
we have variability as well as a powerful agent always ready to act, 1861 |
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 |
why should
not variations or individual differences, which are not variations or individual differences, which are 1872 |
we doubt that variations 1859 1860 1861 1866 |
we doubt that the variations or individual differences, which are 1869 |
in any
way
beneficial, beneficial, 1872 |
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 |
be preserved and accumulated through natural selection, or the survival of the fittest? be preserved and accumulated through natural selection, or the survival of the fittest? 1869 1872 |
be preserved, accumulated, and inherited? 1859 1860 1861 |
occasionally occur, and then be preserved and accumulated by natural selection? 1866 |
If If 1869 1872 | Why, if 1859 1860 1861 1866 |
man can by patience select variations
....... 1869 1872 | most 1859 1860 1861 1866 |
useful to
him, why, him, why, 1869 1872 |
himself, should nature fail in selecting variations useful, 1859 1860 1861 |
himself, should nature fail in preserving or selecting variations useful, 1866 |
under changing
and complex conditions and complex conditions 1869 1872 |
conditions 1859 1860 1861 1866 |
of life,
should not variations useful to nature's should not variations useful to nature's 1872 |
to her 1859 1860 1861 1866 |
should not variations useful to natures 1869 |
living
products often arise, and be preserved or selected? products often arise, and be preserved or selected? 1869 1872 |
products? 1859 1860 1861 1866 |
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 selection, even if we
look look 1872 | looked 1859 1860 1861 1866 1869 |
no
farther farther 1861 1866 1869 1872 | further 1859 1860 |
than this, seems to
....... 1872 | me to 1859 1860 1861 1866 1869 |
be in
the highest degree the highest degree 1872 |
itself 1859 1860 1861 1866 1869 |
probable. I have already recapitulated, as fairly as I could, the opposed difficulties and objections: now let us turn to the special facts and arguments in favour of the theory. |