tely by the complete abortion
of certain parts, by the soldering together of other parts, and by the
doubling or multiplication of others,--variations which we know to be
within the limits of possibility. In the paddles of the extinct gigantic
sea-lizards, and in the mouths of certain suctorial crustaceans, the
general pattern seems to have been thus to a certain extent obscured.

There is another and equally curious branch of the present subject;
namely, the comparison not of the same part in different members of a
class, but of the different parts or organs in the same individual.
Most physiologists believe that the bones of the skull are homologous
with--that is correspond in number and in relative connexion with--the
elemental parts of a certain number of vertebrae. The anterior and
posterior limbs in each member of the vertebrate and articulate classes
are plainly homologous. We see the same law in comparing the wonderfully
complex jaws and legs in crustaceans. It is familiar to almost every
one, that in a flower the relative position of the sepals, petals,
stamens, and pistils, as well as their intimate structure, are
intelligible on the view that they consist of metamorphosed leaves,
arranged in a spire. In monstrous plants, we often get direct evidence
of the possibility of one organ being transformed into another; and we
can actually see in embryonic crustaceans and in many other animals, and
in flowers, that organs, which when mature become extremely different,
are at an early stage of growth exactly alike.

How inexplicable are these facts on the ordinary view of creation! Why
should the brain be enclosed in a box composed of such numerous and such
extraordinarily shaped pieces of bone? As Owen has remarked, the
benefit derived from the yielding of the separate pieces in the act of
parturition of mammals, will by no means explain the same construction
in the skulls of birds. Why should similar bones have been created in
the formation of the wing and leg of a bat, used as they are for such
totally different purposes? Why should one crustacean, which has an
extremely complex mouth formed of many parts, consequently always have
fewer legs; or conversely, those with many legs have simpler mouths?
Why should the sepals, petals, stamens, and pistils in any individual
flower, though fitted for such widely different purposes, be all
constructed on the same pattern?

On the theory of natural selection, we can satisf