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1859
1860
1861
1866
1869
1872

Compare with:
1859
1860
1861
1866
1869

→ the two succeeding 1872
separate 1859 1860 1861 1866 1869
→ OMIT 1866 1869 1872
will, as we have seen, 1859 1860 1861
→ hand. Hence, if we look at each species as descended from some unknown form, both the parent and all the transitional varieties will generally have been exterminated by the very process of the formation and perfection of the new form. 1872
hand. 1859 1860 1861 1866 1869
↑ 1 blocks not present in 1872; present in 1859 1860 1861 1866 1869
Hence, if we look at each species as descended from some other unknown form, both the parent and all the transitional varieties will generally have been exterminated by the very process of formation and perfection of the new form.
→ imperfectly made, and 1869 1872
made 1859 1860 1861 1866
→ each. 1866 1869 1872
each. By my theory these allied species have descended from a common parent; and during the process of modification, each has become adapted to the conditions of life of its own region, and has supplanted and exterminated its original parent and all the transitional varieties between its past and present states. 1859 1860 1861
→ By my theory these allied species are descended from a common parent; and during the process of modification, each has become adapted to the conditions of life of its own region, and has supplanted and exterminated its original parent-form and all the 1869 1872
Hence we ought not to expect at the present time to meet with numerous 1859 1860 1861
By my theory these allied species have descended from a common parent; and during the process of modification, each has become adapted to the conditions of life of its own region, and has supplanted and exterminated its original parent-form and all the 1866
→ between its past and present states. 1866 1869 1872
in each region, though they must have existed there, and may be embedded there in a fossil condition. 1859 1860 1861
→ Hence we ought not to expect at the present time to meet with numerous transitional varieties in each region, though they must have existed there, and may be embedded there in a fossil condition. 1869 1872
But in the intermediate region, having intermediate conditions of life, why do we not now find closely-linking intermediate varieties? 1859 1860 1861
Hence we ougth not to expect at the present time to meet with numerous transitional varieties in each region, though they must have existed there, and may be embedded there in a fossil condition. 1866
→ But in the intermediate region, having intermediate conditions of life, why do we not now find closely-linking intermediate varieties? 1866 1869 1872
This difficulty for a long time quite confounded me. 1859 1860 1861
→ This difficulty for a long time quite confounded me. 1866 1869 1872
But I think it can be in large part explained. 1859 1860 1861
Hybridism in →the two succeeding chapters.
On
On
the
the
absence
Absence
Absence
or
or
rarity
Rarity
Rarity
of
of
transitional
Transitional
Transitional
varieties .—
varieties. —
Varieties.
Varieties.
Varieties .—
As natural selection acts solely by the preservation of profitable modifications, each new form will tend in a fully-stocked country to take the place of, and finally to exterminate, its own less improved
parent or
parent-form and
other less-favoured forms with which it comes into competition. Thus extinction and natural selection →OMIT go hand in →hand. Hence, if we look at each species as descended from some unknown form, both the parent and all the transitional varieties will generally have been exterminated by the very process of the formation and perfection of the new form. ↑
But, as by this theory innumerable transitional forms must have existed, why do we not find them embedded in countless numbers in the crust of the
earth.
earth?
It will be
much
....
more convenient to discuss this question in the chapter on the Imperfection of the
geological
Geological
record;
Record;
and I will here only state that I believe the answer mainly lies in the record being incomparably less perfect than is generally
supposed;
supposed.
the
....
imperfection
....
of
....
the
....
record
....
being
....
chiefly
....
due
....
to
....
organic
....
beings
....
not
....
inhabiting
....
profound
....
depths
....
of
....
the
....
sea,
....
and
....
to
....
their
....
remains
....
being
....
embedded
....
and
....
preserved
....
to
....
a
....
future
....
age
....
only
....
in
....
masses
....
of
....
sediment
....
sufficiently
....
thick
....
and
....
extensive
....
to
....
withstand
....
an
....
enormous
....
amount
....
of
....
future
....
degradation;
....
and
....
such
....
fossiliferous
....
masses
....
can
....
be
....
accumulated
....
only
....
where
....
much
....
sediment
....
is
....
deposited
....
on
....
the
....
shallow
....
bed
....
of
....
the
....
sea,
....
whilst
....
it
....
slowly
....
subsides.
....
The crust of the earth is a vast museum; but the natural collections have been →imperfectly made, and only at
intervals
long intervals
of
time
time.
immensely
....
remote.
....
But it may be urged that when several closely-allied species inhabit the same
territory
territory,
we surely ought to find at the present time many transitional forms. Let us take a simple case: in travelling from north to south over a continent, we generally meet at successive intervals with closely allied or representative species, evidently filling nearly the same place in the natural economy of the land. These representative species often meet and interlock; and as the one becomes rarer and rarer, the other becomes more and more frequent, till the one replaces the other. But if we compare these species where they intermingle, they are generally as absolutely distinct from each other in every detail of structure as are specimens taken from the metropolis inhabited by →each. →By my theory these allied species are descended from a common parent; and during the process of modification, each has become adapted to the conditions of life of its own region, and has supplanted and exterminated its original parent-form and all the transitional varieties →between its past and present states. →Hence we ought not to expect at the present time to meet with numerous transitional varieties in each region, though they must have existed there, and may be embedded there in a fossil condition. →But in the intermediate region, having intermediate conditions of life, why do we not now find closely-linking intermediate varieties? →This difficulty for a long time quite confounded me.