hardening of the internal tissue of the creature, of
its internal substance, by the deposit in the body of a material which
is exceedingly common, not only in fresh but in sea water, and which
is specially abundant in those waters which we know as "hard,"
those waters, for example, which leave a "fur" upon the bottom of a
tea-kettle. This "fur" is carbonate of lime, the same sort of substance
as limestone and chalk. That material is contained in solution in sea
water, and it is out of the sea water in which these coral creatures
live that they get the lime which is needed for the forming of their
hard skeleton.

But now what manner of creatures are these which form these hard
skeletons? I dare say that in these days of keeping aquaria, of
locomotion to the sea-side, most of those whom I am addressing may have
seen one of those creatures which used to be known as the "sea anemone,"
receiving that name on account of its general resemblance, in a rough
sort of way, to the flower which is known as the "anemone"; but being
a thing which lives in the sea, it was qualified as the "sea anemone."
Well, then, you must suppose a body shaped like a short cylinder, the
top cut off, and in the top a hole rather oval than round. All round
this aperture, which is the mouth, imagine that there are placed a
number of feelers forming a circle. The cavity of the mouth leads into
a sort of stomach, which is very unlike those of the higher animals,
in the circumstance that it opens at the lower end into a cavity of the
body, and all the digested matter, converted into nourishment, is thus
distributed through the rest of the body. That is the general structure
of one of these sea anemones. If you touch it it contracts immediately
into a heap. It looks at first quite like a flower in the sea, but if
you touch it you find that it exhibits all the peculiarities of a living
animal; and if anything which can serve as its prey comes near its
tentacles, it closes them round it and sucks the material into its
stomach and there digests it and turns it to the account of its own
body.

These creatures are very voracious, and not at all particular what they
seize; and sometimes it may be that they lay hold of a shellfish which
is far too big to be packed into that interior cavity, and, of course,
in any ordinary animal a proceeding of this kind would give rise to a
very severe fit of indigestion. But this is by no means the case in the
sea anemone, be