o will take the
trouble to procure several kinds of fish, and keep them, for the purpose
of proving the fact, in a dark closet.

Of all the minute inhabitants of the deep, that which is to our mind the
most curious, both as to its nature and its stupendous works, is the
coral insect. This creature is much too important to be dragged in at
the tail of a chapter. We will, therefore, commence its history in a
new one.

CHAPTER FIFTEEN.

CORAL INSECTS AND CORAL ISLANDS--POLYNESIA--OPERATIONS OF THE CORAL
INSECT--GROWTH OF CORAL REEFS.

Many of the large and beautiful islands that stud the Pacific Ocean,
like emeralds in a field of blue, are _artificial_; that is to say, they
were made by artists--they were actually _built_ by _artisans_!

These artisans are the coral insects; and as they not only affect the
face of the sea by raising large islands above it, but also, in
consequence of their labours, assist in causing the circulation of the
ocean, we think they are justly entitled to very special attention.

The great archipelago called Polynesia covers an area of the Pacific
nearly 5000 miles in length, and not far short of 2000 in breadth. Some
of the islands of this group are of volcanic origin, and some are
crystal; but by far the greater number are of coral formation--the work
of those curious little insects, which are so small that they inhabit a
dwelling sometimes little larger than a pin-point.

The manner in which these islands are made is, to some extent, a matter
of uncertainty. The most generally received opinion is, that the
insects fasten round the summit of a submarine mountain, and build
upwards until they reach the surface of the sea, where they die, and
their labours cease. As, however, the sea is sometimes unfathomable
close to those islands, it has been supposed that the submarine islands
on which the corallines began to build have gradually subsided, and
that, as they did so, the insects always built a little more, so as to
keep the top of their structures on a level with the sea. Above the sea
they cannot build. To be washed by the waves is essential to their
existence.

We do not think this a very satisfactory theory, because it supposes a
prolonged subsiding of these islands, and then an unaccountably sudden
stoppage. For although the corallines might continue to build during
the whole time of subsidence, it were utterly impossible that the coral
_island_, with its luxuriant herb