Comparison with 1860 |
|
this methodically, or he may do it unconsciously by preserving the individuals most useful
to him at the time, to him at the time, 1859 1860 |
to him at the time 1861 |
to him 1866 |
or pleasing to him 1869 1872 |
without any thought
of altering the breed. It is certain that he can largely influence the character of a breed by selecting, in each successive generation, individual differences so slight as to be
quite quite 1859 1860 | quite 1861 1866 1869 1872 |
inappreciable by an
uneducated
eye. This process
of selection has been the great agency in the production
of the most distinct and useful domestic breeds. That many of the
breeds produced by man have to a large extent the character of natural species, is shown by the inextricable doubts whether very
many of them are varieties or
aboriginal aboriginal 1859 1860 | aboriginally 1861 1866 1869 1872 |
species. species. 1859 1860 | distinct species. 1861 1866 1869 1872 |
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|
There is no obvious
reason why the principles which have acted so efficiently under domestication should not have acted
under nature. In the preservation
of favoured individuals and races, during the constantly-recurrent Struggle for Existence, we see the most
powerful and ever-acting means
of selection. The struggle for existence inevitably follows from the high geometrical ratio of increase which is common to all organic beings. This high rate of increase is proved by calculation,
by the effects of
a succession of peculiar seasons, and by the results of naturalisation, as explained in the third chapter.
More individuals are born than can possibly survive. A grain in the balance will
determine which individual
shall live and which shall die,— which variety or species shall increase in number, and which shall decrease, or finally become extinct. As the indi- viduals
of the same species come in all respects into the closest competition with each other, the struggle will generally be most severe between them; it will be almost equally severe between the varieties of the same species, and next in severity between the species of the same genus. But
the struggle
will often be very
severe between
beings beings 1859 1860 1861 1869 1872 | being 1866 |
most
remote in the scale of nature. The
|
this methodically, or he may do it unconsciously by preserving the individuals most useful
to him to him 1866 |
to him at the time, 1859 1860 |
to him at the time 1861 |
or pleasing to him 1869 1872 |
without any
thought thought 1859 1860 1861 1866 | intention 1869 1872 |
of altering the breed. It is certain that he can largely influence the character of a breed by selecting, in each successive generation, individual differences so slight as to be
....... 1861 1866 1869 1872 | quite 1859 1860 |
inappreciable
by an by an 1859 1860 1861 1866 | except 1869 1872 |
uneducated uneducated 1859 1860 1861 1866 |
by an educated 1869 1872 |
eye. This
process process 1859 1860 1861 1866 1869 | unconscious process 1872 |
of selection has been the great agency in the
production production 1859 1860 1861 1866 | formation 1869 1872 |
of the most distinct and useful domestic breeds. That many
of the of the 1859 1860 1861 1866 | of the 1869 1872 |
breeds produced by man have to a large extent the character of natural species, is shown by the inextricable doubts whether
very very 1859 1860 1861 1866 | very 1869 1872 |
many of them are varieties or
aboriginally aboriginally 1861 1866 1869 1872 | aboriginal 1859 1860 |
distinct species. distinct species. 1861 1866 1869 1872 | species. 1859 1860 |
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|
There is no
obvious obvious 1859 1860 1861 1866 1869 | obvious 1872 |
reason why the principles which have acted so efficiently under domestication should not
have acted have acted 1859 1860 1861 1866 1872 | act 1869 |
under nature. In the
preservation preservation 1859 1860 1861 1866 | survival 1869 1872 |
of favoured individuals and races, during the constantly-recurrent Struggle for Existence, we see
the most the most 1859 1860 1861 1866 | a 1869 1872 |
powerful and ever-acting
means means 1859 1860 1861 1866 | form 1869 1872 |
of
selection. selection. 1859 1860 1861 1866 | Selection. 1869 1872 |
The struggle for existence inevitably follows from the high geometrical ratio of increase which is common to all organic beings. This high rate of increase is proved by
calculation,— calculation,— 1860 1861 1866 1869 1872 | calculation, 1859 |
by the
rapid increase of many animals and plants during rapid increase of many animals and plants during 1860 1861 1866 1869 1872 |
effects of 1859 |
a succession of peculiar seasons,
or when naturalised in a new country. or when naturalised in a new country. 1860 1861 1866 |
and by the results of naturalisation, as explained in the third chapter. 1859 |
and when naturalised in a new country. 1869 |
and when naturalised in new countries. 1872 |
More individuals are born than can possibly survive. A grain in the balance
will will 1859 1860 1861 1866 | may 1869 1872 |
determine which
individual individual 1859 1860 1861 1866 | individuals 1869 1872 |
shall live and which shall die,— which variety or species shall increase in number, and which shall decrease, or finally become extinct. As the
individuals individuals 1860 1861 1866 1869 1872 | indi- viduals 1859 |
of the same species come in all respects into the closest competition with each other, the struggle will generally be most severe between them; it will be almost equally severe between the varieties of the same species, and next in severity between the species of the same genus.
But But 1859 1860 1861 1866 | On 1869 1872 |
the
struggle struggle 1859 1860 1861 1866 |
other hand the struggle 1869 1872 |
will often be
very very 1859 1860 1861 1866 1869 | very 1872 |
severe between
being being 1866 | beings 1859 1860 1861 1869 1872 |
most most 1859 1860 1861 1866 | most 1869 1872 |
remote in the scale of nature. The
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