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so marvellous an instinct as that 1859 1860 1861 1866 1869
the instinct 1872

which has 1860 1861 1866 1869
which have 1859
and which has 1872

shall be here discussed— Instinct 1859 1860 1861
shall be here discussed—Instinct 1866 1869
will here be discussed; some miscellaneous objections in the following chapter; Instinct 1872

separate 1859 1860 1861 1866 1869
the two succeeding 1872

will, as we have seen, 1859 1860 1861
OMIT 1866 1869 1872

hand. 1859 1860 1861 1866 1869
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

as the
eye?
eye,
of
of
which
which
we
we
hardly
hardly
as
as
yet
yet
fully
fully
understand
understand
the
the
inimitable
inimitable
perfection?
perfection?
Thirdly, can instincts be acquired and modified through natural selection? What shall we say to so marvellous an instinct as that which leads the bee to make cells, which has practically anticipated the discoveries of profound mathematicians?
Fourthly, how can we account for species, when crossed, being sterile and producing sterile offspring, whereas, when varieties are crossed, their fertility is unimpaired?
The two first heads shall be here discussed— Instinct and Hybridism in separate 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-form and
parent or
other less-favoured forms with which it comes into competition. Thus extinction and natural selection will, as we have seen, go hand in hand. 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
the formation
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
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
the
imperfection
imperfection
of
of
the
the
record
record
being
being
chiefly
chiefly
due
due
to
to
organic
organic
beings
beings
not
not
inhabiting
inhabiting