of swine have undergone. But we are far
too ignorant to speculate on the relative importance of the several
known and unknown causes of variation; and I have made these remarks
only to show that, if we are unable to account for the characteristic
differences of our several domestic breeds, which nevertheless are
generally admitted to have arisen through ordinary generation from
one or a few parent-stocks, we ought not to lay too much stress on
our ignorance of the precise cause of the slight analogous differences
between true species.

UTILITARIAN DOCTRINE, HOW FAR TRUE: BEAUTY, HOW ACQUIRED.

The foregoing remarks lead me to say a few words on the protest lately
made by some naturalists against the utilitarian doctrine that every
detail of structure has been produced for the good of its possessor.
They believe that many structures have been created for the sake of
beauty, to delight man or the Creator (but this latter point is beyond
the scope of scientific discussion), or for the sake of mere variety,
a view already discussed. Such doctrines, if true, would be absolutely
fatal to my theory. I fully admit that many structures are now of no
direct use to their possessors, and may never have been of any use to
their progenitors; but this does not prove that they were formed
solely for beauty or variety. No doubt the definite action of changed
conditions, and the various causes of modifications, lately specified,
have all produced an effect, probably a great effect, independently of
any advantage thus gained. But a still more important consideration is
that the chief part of the organisation of every living creature is due
to inheritance; and consequently, though each being assuredly is well
fitted for its place in nature, many structures have now no very close
and direct relation to present habits of life. Thus, we can
hardly believe that the webbed feet of the upland goose, or of the
frigate-bird, are of special use to these birds; we cannot believe
that the similar bones in the arm of the monkey, in the fore leg of the
horse, in the wing of the bat, and in the flipper of the seal, are of
special use to these animals. We may safely attribute these structures
to inheritance. But webbed feet no doubt were as useful to the
progenitor of the upland goose and of the frigate-bird, as they now
are to the most aquatic of living birds. So we may believe that the
progenitor of the seal did not possess a flipper, but a foot with