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See page in:
1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1861
1866
1869

→ closely allied or 1859 1869 1872
closely-allied 1860 1861 1866
→ and wherever many closely-allied species occur, there will be found many forms which some naturalists rank as distinct species, and others as mere varieties; these doubtful forms showing us the steps in the progress of modification. 1869 1872
showing, in accordance with the foregoing view, that at some former period there has been intercommunication or migration between the two regions. 1859 1860 1861
showing, in accordance with the foregoing views, that at some former period there has been intercommunication or migration between the two regions. 1866
↑ 1 blocks not present in 1869 1872; present in 1859 1860 1861 1866
And wherever many closely-allied species occur, there will be found many forms which some naturalists rank as distinct species, and some as varieties; these doubtful forms showing us the steps in the process of modification.
→ OMIT 1869 1872
under different physical conditions, 1859 1860 1861 1866
→ OMIT 1869 1872
allied to it, 1859 1860 1861 1866
→ difficult of proof. 1872
it would be difficult to prove it. 1859 1860 1861 1866 1869
→ the same rule in 1869 1872
it, if we compare 1859 1860 1861 1866
→ of the inhabitants of fresh water, for many of the genera in the most distinct classes 1869 1872
fresh-water productions, in which so many genera 1859 1860 1861 1866
→ all, but that some of 1869 1872
in world- ranging genera all 1859
in world-ranging genera all 1860 1861
all 1866
→ have very wide ranges in the genera which 1872
have a wide range, or even that they have on an average a wide range; but only that some of the species 1859 1860 1861
in world-ranging genera, but that some of them, 1866
in the genera which range very widely, have themselves very wide ranges. 1869
→ Nor is it meant that 1866 1869 1872
For instance, two varieties of the same species inhabit America and Europe, and 1859 1860 1861
→ in such genera have on an average a very wide range; for this will largely depend on how far the process of modification has gone; for instance, 1869 1872
thus has an immense range; but, if the variation had been a little greater, the 1859 1860 1861
have on an average a very wide range; for this will largely depend on how far the process of modification has gone; for instance, 1866
→ of the same species inhabit America and Europe, and thus the species has an immense range; but, if variation were to be carried a little further, the two varieties would be ranked as distinct species, 1869 1872
would have been ranked as distinct species, 1859 1860 1861
of the same species inhabit America and Europe, 1866
→ their range 1872
the common range 1859 1860 1861
the species thus has an immense range; but, if the variation had been carried a little further, the two varieties 1866
the range 1869
→ greatly 1859 1860 1861 1869 1872
ranked as distinct species, and the range would have been greatly 1866
→ a genus, though 1872
a genus having descended from a single parent, though now 1859 1860 1861 1866
the same genus, though now 1869
→ are descended from a single progenitor, we 1869 1872
we 1859 1860 1861 1866
→ OMIT 1869 1872
organisms low in the scale 1859 1860 1861 1866
And it
It
will, I believe, be
universally
....
found
to be
universally
universally
true, that wherever in two regions, let them be ever so distant, many →closely allied or
or representative
representative
species occur, there will likewise be found some identical
species,
species;
→and wherever many closely-allied species occur, there will be found many forms which some naturalists rank as distinct species, and others as mere varieties; these doubtful forms showing us the steps in the progress of modification. ↑
This
The
relation between the power and extent of migration
of a
in a
in certain
species, either at the present
time
....
or at some former
period
period,
→OMIT and the existence at remote points of the world of
other
allied
closely-allied
species
species,
→OMIT is shown in another and more general way. Mr. Gould remarked to me long ago, that in those genera of birds which range over the world, many of the species have very wide ranges. I can hardly doubt that this rule is generally true, though →difficult of proof. Amongst mammals, we see it strikingly displayed in Bats, and in a lesser degree in the Felidæ and Canidæ. We see →the same rule in the distribution of butterflies and beetles. So it is with most →of the inhabitants of fresh water, for many of the genera in the most distinct classes range over the world, and many
individual
of the
species have enormous ranges. It is not meant that →all, but that some of the species →have very wide ranges in the genera which
range
range
very
very
widely;
widely.
widely.
for
OMIT
....
the
OMIT
....
facility
OMIT
....
with
OMIT
....
which
OMIT
....
widely-ranging
OMIT
....
species
OMIT
....
vary
OMIT
....
and
OMIT
....
give
OMIT
....
rise
OMIT
....
to
OMIT
....
new
OMIT
....
forms
OMIT
....
will
OMIT
....
largely
OMIT
....
determine
OMIT
....
their
OMIT
....
average
OMIT
....
range.
OMIT
....
→Nor is it meant that the species →in such genera have on an average a very wide range; for this will largely depend on how far the process of modification has gone; for instance, two varieties →of the same species inhabit America and Europe, and thus the species has an immense range; but, if variation were to be carried a little further, the two varieties would be ranked as distinct species, and →their range would
have been
be
→greatly reduced. Still less is it meant, that
a
....
species which
apparently has
have
the capacity of crossing barriers and ranging
widely
widely,
as in the case of certain powerfully-winged birds, will necessarily range widely; for we should never forget that to range widely implies not only the power of crossing barriers, but the more important power of being victorious in distant lands in the struggle for life with foreign associates. But
on
according to
the view
of
that
all the species of →a genus, though distributed
at
to
the most remote points of the world, →are descended from a single progenitor, we ought to find, and I believe as a general rule we do find, that some at least of the species range very
widely;
widely.
for
....
it
....
is
....
necessary
....
that
....
the
....
unmodified
....
parent
....
should
....
range
have ranged
....
widely,
....
undergoing
....
modification
....
during
....
its
....
diffusion,
....
and
....
should
....
place
have placed
....
itself
....
under
....
diverse
....
conditions
....
favourable
....
for
....
the
....
conversion
....
of
....
its
....
offspring,
....
firstly
first
....
into
....
new
....
varieties
....
and
....
ultimately
....
into
....
new
....
species.
....
We should bear in mind that many genera in all classes are of ancient origin, and the species in this case will have had ample time for dispersal and subsequent modification. There
is,
is
also,
also
some
....
reason to believe from geological
evidence
evidence,
that →OMIT