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 produce eggs, from which are hatched swimming
animalcules, which attach themselves to rocks and become developed into
branching corallines; and so on in an endless cycle.
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