ther illustration. Classification of organic forms, as
Darwin, Lyell, and Haeckel have pointed out, strongly resembles the
classification of languages. In the case of languages, as in the case of
species, we have genetic affinities strongly marked; so that it is
possible to some extent to construct a Language-tree, the branches of
which shall indicate, in a diagrammatic form, the progressive divergence
of a large group of languages from a common stock. For instance, Latin
may be regarded as a fossil language, which has given rise to a group of
living languages--Italian, Spanish, French, and, to a large extent,
English. Now what would be thought 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 the nations which now
speak them--and that their resemblance to the fossil form, Latin, must
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.

But, quitting now this most general point of view--or the suggestive
fact that what we have before us is a _tree_--let us next approach this
tree for the purpose of examining its structure more in detail. When we
do this, the fact of next greatest generality which we find is as
follows.

In cases where a very old form of life has continued to exist
unmodified, so that by investigation of its anatomy we are brought back
to a more primitive type of structure than that of the newer forms
growing higher up _upon the same branch_, two things are observable. In
the first place, the old form is less differentiated than the newer
ones; and, in the next place, it is seen much more closely to resemble
types of structure belonging to some of the other and larger branches of
the tree. The organization of the older form is not only _simpler_; but
it is, as naturalists say, more _generalized_. It comprises within
itself characters belonging to its own branch, and also characters
belonging to neighbouring branches, or to the trunk from which allied
branches spring. Hence it becomes a general rule of classification, that
it is by the lowest, or by the oldest, forms of any two natura