o distinct parts of the same organism, having varied in
an analogous manner; and in part to similar modifications, having
been preserved for the same general purpose or function, of which many
instances have been given.

Naturalists frequently speak of the skull as formed of metamorphosed
vertebrae; the jaws of crabs as metamorphosed legs; the stamens and
pistils in flowers as metamorphosed leaves; but it would in most cases
be more correct, as Professor Huxley has remarked, to speak of both
skull and vertebrae, jaws and legs, etc., as having been metamorphosed,
not one from the other, as they now exist, but from some common and
simpler element. Most naturalists, however, use such language only in a
metaphorical sense: they are far from meaning that during a long course
of descent, primordial organs of any kind--vertebrae in the one case and
legs in the other--have actually been converted into skulls or jaws. Yet
so strong is the appearance of this having occurred that naturalists
can hardly avoid employing language having this plain signification.
According to the views here maintained, such language may be used
literally; and the wonderful fact of the jaws, for instance, of a crab
retaining numerous characters, which they probably would have retained
through inheritance, if they had really been metamorphosed from true
though extremely simple legs, is in part explained.

DEVELOPMENT AND EMBRYOLOGY.

This is one of the most important subjects in the whole round of natural
history. The metamorphoses of insects, with which every one is familiar,
are generally effected abruptly by a few stages; but the transformations
are in reality numerous and gradual, though concealed. A certain
ephemerous insect (Chloeon) during its development, moults, as shown by
Sir J. Lubbock, above twenty times, and each time undergoes a certain
amount of change; and in this case we see the act of metamorphosis
performed in a primary and gradual manner. Many insects, and especially
certain crustaceans, show us what wonderful changes of structure can be
effected during development. Such changes, however, reach their acme in
the so-called alternate generations of some of the lower animals. It is,
for instance, an astonishing fact that a delicate branching coralline,
studded with polypi, and attached to a submarine rock, should produce,
first by budding and then by transverse division, a host of huge
floating jelly-fishes; and that these should pro