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specialised 1859 1860 1861
in part or in whole specialised 1866 1869 1872

2 blocks not present in 1859 1860 1861; present in 1866 1869 1872
We have seen in two beings widely remote from each other in the natural scale, that an organ serving in both for the same purpose and appearing closely similar may have been separately and independently formed; but when such organs are closely examined, essential differences in their structure can almost always be detected; and this naturally follows from the principle of natural selection. On the other hand, the common rule throughout nature is infinite diversity of structure for gaining the same end; and this again naturally follows on the same great principle.

We 1859 1860 1861
In almost every case we 1866 1869
In many cases we 1872

in almost every case, 1859 1860 1861
OMIT 1866 1869 1872

But we may confidently believe that many modifications, wholly due to 1859 1860 1861 1866 1869
In many other cases, modifi- cations are probably the direct result of 1872

growth, and at first in no way advantageous to a species, have been subsequently taken advantage of by the still further modified descendants of this species. 1859 1860 1861 1866 1869
variation or of growth, independently of any good having been thus gained. 1872

1 blocks not present in 1859 1860 1861 1866 1869; present in 1872
But even such structures have often, as we may feel assured, been subsequently taken advantage of, and still further modified, for the good of species under new conditions of life.

natural selection,— a power which acts solely by the preservation of profitable variations in the struggle for life. 1859 1860 1861
natural selection,—a power which acts solely by the preservation of profitable variations in the struggle for life. 1866
natural selection,—a power which acts solely through the survival of the best-fitted individuals in the struggle for life. 1869
means of natural selection. 1872

Natural selection in 1859 1860 1861 1866 1869
In 1872

must act chiefly 1859 1860 1861 1866 1869
natural selection acts 1872

one with another, 1859 1860 1861 1866 1869
OMIT 1872

will produce perfection, or strength 1859 1860 1861 1866 1869
leads to success 1872

according to 1859 1860 1861 1866 1869
in accordance with 1872

as we see they do yield, 1859 1860 1861
OMIT 1866 1869 1872

simultaneously very different functions, and then having been specialised for one function; and two
very
very
distinct organs having performed at the same time the same function, the one having been perfected whilst aided by the other, must often have largely facilitated transitions.
We are far too
ignorant
ignorant,
in almost every case, to be enabled to assert that
a
any
part or organ is so unimportant for the welfare of a species, that modifications in its structure could not have been slowly accumulated by means of natural selection. But we may confidently believe that many modifications, wholly due to the laws of growth, and at first in no way advantageous to a species, have been subsequently taken advantage of by the still further modified descendants of this species. We may, also, believe that a part formerly of high importance has
frequently
often
been retained (as the tail of an aquatic animal by its terrestrial descendants), though it has become of such small importance that it could not, in its present state, have been acquired by natural selection,— a power which acts solely by the preservation of profitable variations in the struggle for life.
Natural selection
can
will
produce nothing in one species for the exclusive good or injury of another; though it may well produce parts, organs, and excretions highly useful or even indispensable, or
again highly
highly
injurious to another species, but in all cases at the same time useful to the
possessor.
owner.
Natural selection in each well-stocked
country
country,
must act chiefly through the competition of the
inhabitants,
inhabitants
one with another, and consequently will produce perfection, or strength in the battle for life, only according to the standard of that
particular country.
country.
Hence the inhabitants of one country, generally the smaller one,
will
will
often
yield
yield,
as we see they do yield, to the inhabitants of another and generally
the larger
larger
country. For in