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See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1866
1869
1872

→ In practice, a fancier is, for instance, 1861 1866 1869 1872
A fancier is 1859 1860
→ the sub-breeds of the tumbler-pigeon) 1861 1866 1869 1872
tumbler-pigeons) 1859 1860
→ one man preferred 1859 1860 1861 1866 1869
of history, the men of one nation or district required 1872
→ another 1859 1860 1861 1866 1869
whilst those of another required 1872
→ by some breeders, 1859 1860 1861 1866 1869
in the one case, 1872
→ As 1859 1860 1861 1866 1869
Ultimately, after the lapse of centuries, these sub-breeds would become converted into two well-established and distinct breeds. As 1872
→ neglected, 1859 1860 1861 1866 1869
used for breeding, 1872
→ (though it was a long time before I saw how), from 1861 1866 1869 1872
from 1859 1860
→ raised. 1859 1860 1861 1866
raised by the latter process. 1869
raised in the latter than in the former case. 1872
→ as 1859 1860 1861 1866 1869
though in a very slight degree, as do the 1872
→ differ from each other, 1859 1860 1861 1866 1869
OMIT 1872
→ thus, 1859 1860 1861 1866 1869
is thus striving, 1872
→ is striving its 1859 1860 1861 1866 1869
to the 1872
during many successive generations. →In practice, a fancier is, for instance, struck by a pigeon having a slightly shorter beak; another fancier is struck by a pigeon having a rather longer beak; and on the acknowledged principle that "fanciers do not and will not admire a medium standard, but like extremes," they both go on (as has actually occurred with →the sub-breeds of the tumbler-pigeon) choosing and breeding from birds with longer and longer beaks, or with shorter and shorter beaks. Again, we may suppose that at an early period →one man preferred swifter
horses,
horses;
→another stronger and
bulkier
more bulky
horses. The early differences would be very slight;
but, in
in
the course of time, from the continued selection of swifter horses →by some breeders, and of stronger ones
in the
by
other,
others,
the differences would become greater, and would be noted as forming two
sub-breeds.
sub-breeds;
finally,
finally,
after
after
the
the
lapse
lapse
of
of
centuries
centuries,
centuries,
the
the
sub-breeds
sub-breeds
would
would
become
become
converted
converted
into
into
two
two
well-established
well-established
and
and
distinct
distinct
breeds.
breeds.
→As the differences
slowly
slowly
became
become
greater, the inferior animals with intermediate characters, being neither very swift nor very strong,
would
would not
will
have been →neglected, and will
thus have
have
tended to
tended to
disappeared.
disappear.
Here, then, we see in
mans
man's
productions the action of what may be called the principle of divergence, causing differences, at first barely appreciable, steadily to increase, and the breeds to diverge in
character,
character
both from each other and from their common parent.
But how, it may be asked, can any analogous principle apply in nature? I believe it can and does apply most
efficiently,
efficiently
→(though it was a long time before I saw how), from the simple circumstance that the more diversified the descendants from any one species become in structure, constitution, and habits, by so much will they be better enabled to seize on many and widely diversified places in the polity of nature, and so be enabled to increase in numbers.
We can clearly
see
discern
this in the case of animals with simple habits. Take the case of a carnivorous quadruped, of which the number that can be supported in any country has long ago arrived at its full average. If its natural
power
powers
of increase be allowed to act, it can succeed in increasing (the country not undergoing any change in
its
its
conditions) only by its varying descendants seizing on places at present occupied by other
animals;
animals:
some of them, for instance, being enabled to feed on new kinds of prey, either dead or alive; some inhabiting new stations, climbing trees, frequenting water, and some perhaps becoming less carnivorous. The more diversified in habits and structure the descendants of our carnivorous
animals
animal
become,
became,
the more places they
will
would
be enabled to occupy. What applies to one animal will apply throughout all time to all animals— that is, if they vary— for otherwise natural selection can
effect
do
nothing. So it will be with plants. It has been experimentally proved, that if a plot of ground be sown with one species of grass, and a similar plot be sown with several distinct genera of grasses, a greater number of plants and a greater weight of dry herbage can
thus
thus
be →raised. The same has been found to hold good when
first
....
one variety and
then
....
several mixed varieties of wheat have been sown on equal spaces of ground. Hence, if any one species of grass were to go on varying, and
the
those
varieties were continually selected which differed from each other in
at all
at all
the same
manner,
manner
→as distinct species and genera of
grasses,
grasses
→differ from each other, a greater number of individual plants of this
species,
species
of grass,
of grass,
including its modified descendants, would succeed in living on the same piece of ground. And we
well
well
know that each species and each variety of grass is annually sowing almost countless
seeds:
seeds;
and →thus, as it may be said, →is striving its utmost to increase
in
its
numbers.
number.
num- bers.