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1859
1860
1861
1866
1869
1872

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1859
1861
1866
1869
1872

vary at all in the several 1859 1860 1861 1866
present individual differences in all 1869
present individual differences in almost every 1872

the high geometrical ratio 1860 1861 1866 1869
the high geometrical powers 1859
their geometrical rate 1872

of each species, 1859 1860 1861 1866 1869
a severe struggle for life 1872

a severe struggle for life at some age, season, or year, 1860 1861 1866 1869
at some age, season, or year, a severe struggle for life, 1859
at some age, season, or year, 1872

preservation, 1859 1860 1869
preservation 1861 1866
pre- servation, or the survival of the fittest, 1872

I 1859 1860 1861 1866 1872
or the survival of the fittest, I 1869

for the sake of brevity, 1859 1860 1861 1866
OMIT 1869 1872

Selection; and it leads to the improvement of each creature in relation to its organic and inorganic conditions of life. 1860
Selection. 1859 1861 1866 1869 1872

1 blocks not present in 1859 1860 1869; present in 1861 1866 1872
It leads to the improvement of each creature in relation to its organic and inorganic conditions of life; and consequently, in most cases, to what must be regarded as an advance in organisation.

with 1859 1860 1861 1866
or rivalry with 1872

males. 1859 1860 1861 1866
males; and these characters will be transmitted to one sex or to both sexes, according to the form of inheritance which prevails. 1872

nature, in modifying and 1859 1860 1861 1866
OMIT 1869 1872

vary at all in the several
part
parts
of their
structure,
organisation,
and
I think
I think
this cannot be disputed; if there be, owing to the high geometrical ratio of
increase,
increase
of each species, a severe struggle for life at some age, season, or year, and this certainly cannot be disputed; then, considering the infinite complexity of the relations of all organic beings to each other and to their conditions of
life,
existence,
causing an infinite diversity in structure, constitution, and habits, to be advantageous to them,
I think
I think
it would be a most extraordinary fact if no
variations
variation
had ever
ever
ever had
occurred useful to each
beings
being's
own welfare, in the same
way
manner
as so many variations have occurred useful to man. But if variations useful to any organic being
ever do
do
ever occur,
occur,
assuredly individuals thus characterised will have the best chance of being preserved in the struggle for life; and from the strong principle of
inheritance,
inheritance
these
they
will tend to produce offspring similarly characterised. This principle of preservation, I have
called
called,
for the sake of brevity, Natural Selection; and it leads to the improvement of each creature in relation to its organic and inorganic conditions of life. Natural selection, on the principle of qualities being inherited at corresponding ages, can modify the egg, seed, or young, as easily as the adult. Amongst many animals, sexual selection will
have given
give
its aid to ordinary selection, by assuring to the most vigorous and best adapted males the greatest number of offspring. Sexual selection will also give characters useful to the males alone, in their struggles with other males.
Whether natural selection has really thus acted in nature, in modifying and adapting the various forms of life to their several conditions and stations, must be judged
of
of
by the general
tenor
tenour
and balance of
the evidence
evidence
given in the following chapters. But we
have already
already
seen
see
how it entails extinction; and how largely extinction