See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1860
1861
1866
1869
1872

variability. 1859 1860 1861 1866 1869
it to vary. 1872

to him at the time, 1859 1860
to him at the time 1861
to him 1866
or pleasing to him 1869 1872

uneducated 1859 1860 1861 1866
by an educated 1869 1872

effects of 1859
rapid increase of many animals and plants during 1860 1861 1866 1869 1872

and by the results of naturalisation, as explained in the third chapter. 1859
or when naturalised in a new country. 1860 1861 1866
and when naturalised in a new country. 1869
and when naturalised in new countries. 1872

unintentionally exposes organic beings to new conditions of life, and then nature acts on the
organisation
organisation,
and causes variability. But man can and does select the variations given to him by nature, and thus
accumulates
accumulate
them in any desired manner. He thus adapts animals and plants for his own benefit or pleasure. He may do this methodically, or he may do it unconsciously by preserving the individuals most useful to him at the time, without any
intention
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
inappreciable
except
by an
uneducated eye. This
unconscious process
process
of selection has been the great agency in the
formation
production
of the most distinct and useful domestic breeds. That many
of the
of the
breeds produced by man have to a large extent the character of natural species, is shown by the inextricable doubts whether
very
very
many of them are varieties or
aboriginally
aboriginal
distinct species.
species.
There is no
obvious
obvious
reason why the principles which have acted so efficiently under domestication should not
act
have acted
under nature. In the
survival
preservation
of favoured individuals and races, during the constantly-recurrent Struggle for Existence, we see
a
the most
powerful and ever-acting
form
means
of
Selection.
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,—
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
may
will
determine which
individuals
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
individuals
indi- viduals