industrious and sterile sisters? It may be difficult, but we ought to
admire the savage instinctive hatred of the queen-bee, which urges her to
destroy the young queens, her daughters, as soon as they are born, or to
perish herself in the combat; for undoubtedly this is for the good of the
community; and maternal love or maternal hatred, though the latter
fortunately is most rare, is all the same to the inexorable principles of
natural selection. If we admire the several ingenious contrivances by
which orchids and many other plants are fertilised through insect agency,
can we consider as equally perfect the elaboration of dense clouds of
pollen by our fir-trees, so that a few granules may be wafted by chance on
to the ovules?

SUMMARY: THE LAW OF UNITY OF TYPE AND OF THE CONDITIONS OF EXISTENCE
EMBRACED BY THE THEORY OF NATURAL SELECTION.

We have in this chapter discussed some of the difficulties and objections
which may be urged against the theory. Many of them are serious; but I
think that in the discussion light has been thrown on several facts, which
on the belief of independent acts of creation are utterly obscure. We have
seen that species at any one period are not indefinitely variable, and are
not linked together by a multitude of intermediate gradations, partly
because the process of natural selection is always very slow, and at any
one time acts only on a few forms; and partly because the very process of
natural selection implies the continual supplanting and extinction of
preceding and intermediate gradations. Closely allied species, now living
on a continuous area, must often have been formed when the area was not
continuous, and when the conditions of life did not insensibly graduate
away from one part to another. When two varieties are formed in two
districts of a continuous area, an intermediate variety will often be
formed, fitted for an intermediate zone; but from reasons assigned, the