ntain that they diverged rather earlier than even the
turbellaria; others after the schematic worm, if such ever existed.
As far as our argument is concerned it makes little difference which
of these views we adopt.

From our turbellaria, or possibly from some even more primitive
ancestor, many lines diverged. And this was to be expected. The
coelenterata, as we saw in hydra, had developed rude digestive and
reproductive systems. The higher groups of this kingdom had
developed all, or nearly all, the tissues used in building the
bodies of higher animals--muscular, reproductive, connectile,
glandular, nervous, etc. But these are mostly very diffuse. The
muscular fibrils of a jelly-fish are mostly isolated or parallel in
bands, rarely in compact well-defined bundles. The tissues have
generally not yet been moulded into compact masses of definite form.
There are as yet very few structures to which we can give the name
of organs. To form organs and group them in a body of compact
definite form was the work pre-eminently of worms. The material for
the building was ready, but the architecture of the bilateral animal
was not even sketched. And different worms were their own
architects, untrammelled by convention or heredity, hence they built
very different, sometimes almost fantastic, structures.

We must remember, too, the great age of this group. They are present
in highly modified forms in the very oldest palaeozoic strata, and
probably therefore came into existence as the first traces of
continental areas were beginning to rise above the primeval ocean.
They are literally "older than the hills." They were exposed to a
host of rapidly changing conditions, very different in different
areas. This prepares us for the fact that the worms represent a
stage in animal life corresponding fairly well to the Tower of Babel
in biblical history. The animal kingdom seems almost to explode into
a host of fragments. Our genealogical tree fairly bristles with
branches, but the branches do not seem to form any regular whorls or
spirals. Few of them have developed into more than feeble growths.
They now contain generally but few species. Many of them are
largely or entirely parasitic, and in connection with this mode of
life have undergone modifications and degeneration which make it
exceedingly difficult to decipher their descent or relationships.

Four of these branches have reached great prominence in numbers and
importance. One or tw