d as a fossil language,
which has given rise, by way of genetic descent, to a group of living
languages--Italian, Spanish, French, and, to a large extent, English.
Now what should we think of a philologist who should maintain that
English, French, Spanish, and Italian were all specially created
languages--or languages separately constructed by the Deity, and by as
many separate acts of inspiration communicated to these several
nations--and that their resemblance to the fossil form, Latin, is to be
attributed to special design? Yet the evidence of the natural
transmutation of species, is, in one respect, much stronger than that of
the natural transmutation of languages--in respect, namely, of there
being a vastly greater number of cases all bearing testimony to the fact
of genetic relationship.

II.

THE ARGUMENT FROM MORPHOLOGY OR STRUCTURE.

I now pass to another line of argument. The theory of evolution by
natural selection supposes that hereditary characters admit of being
slowly modified wherever their modification will render an organism
better suited to a change in its conditions of life. Let us, then,
observe the evidence we have of such adaptive modifications of
structure, in cases where the need of such modification is apparent. For
the sake of clearness, I shall begin by again taking the case of the
whales and porpoises. The theory of evolution infers, from the whole
structure of these animals, that their progenitors must have been
terrestrial quadrupeds of some kind, which became aquatic in their
habits. Now the change in the conditions of their life thus brought
about would render desirable great modifications of structure. These
changes would, in the first instance, begin to affect the least
typical--that is, the least strongly inherited structures--such as the
skin, claws, and teeth, &c. But as time went on, the adaptation would
begin to extend to the more typical structures, until the shape of the
body began to be affected by the bones and muscles required for
terrestrial locomotion becoming better adapted for aquatic locomotion,
and the whole outline of the animal more fish-like in shape. This is the
stage which we actually observe in the seals, where the hind legs,
although retaining all their typical bones, have become shortened up
almost to rudiments, and directed backwards, so as to be of no use for
walking, but serving to complete the fish-like taper of the body. But in
the whales the mo