"Hence every detail of structure in every living creature (making some
little allowance for the direct action of physical conditions) may be
viewed either as having been of special use to some ancestral form, or as
being now of special use to the descendants of this form--either directly,
or indirectly, through the complex laws of growth."
But it is one thing to say, Darwinically, that every detail observed in an
animal's structure is of use to it, or has been of use to its ancestors;
and quite another to affirm, teleologically, that every detail of an
animal's structure has been created for its benefit. On the former
hypothesis, for example, the teeth of the foetal _Baltæna_ have a
meaning; on the latter, none. So far as we are aware, there is not a phrase
in the "Origin of Species" inconsistent with Professor Kölliker's position,
that "varieties arise irrespectively of the notion of purpose, or of
utility, according to general laws of Nature, and may be either useful, or
hurtful, or indifferent."