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→ made 1859 1860 1861 1866
imperfectly made, and 1869 1872
→ 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 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
Hence we ought not to expect at the present time to meet with numerous 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
→ 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 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? 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
profound
profound
depths
depths
of
of
the
the
sea,
sea,
and
and
to
to
their
their
remains
remains
being
being
embedded
embedded
and
and
preserved
preserved
to
to
a
a
future
future
age
age
only
only
in
in
masses
masses
of
of
sediment
sediment
sufficiently
sufficiently
thick
thick
and
and
extensive
extensive
to
to
withstand
withstand
an
an
enormous
enormous
amount
amount
of
of
future
future
degradation;
degradation;
and
and
such
such
fossiliferous
fossiliferous
masses
masses
can
can
be
be
accumulated
accumulated
only
only
where
where
much
much
sediment
sediment
is
is
deposited
deposited
on
on
the
the
shallow
shallow
bed
bed
of
of
the
the
sea,
sea,
whilst
whilst
it
it
slowly
slowly
subsides.
subsides.
These contingencies will concur only rarely, and after enormously long intervals. Whilst the bed of the sea is stationary or is rising, or when very little sediment is being deposited, there will be blanks in our geological history. The crust of the earth is a vast museum; but the natural collections have been →made only at
long intervals
intervals
of
time.
time
immensely
immensely
remote.
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 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 transitional varieties →between its past and present states. →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.