The Savannah morning news. (Savannah, Ga.) 1900-current, 1902-03-01
HOW CORAL INSECTS BUILD.
4 PROBLEM THAT LONG WAS A
POSER TO NATURALISTs.

From the st. Louis Globe Democrat.
Among all the varied productions of
living nature none can perhaps vie in
respect of interest with those of the
coral animal From our boyhood's
days we have been accustomed to read
of coral islands. but it is to be feared
that many of the descriptions given of
these structures in the tales we pored
over in our youth must be ranked more
as successful ventures in the line Of
fiction than in that of actual science.
Yet the scientific side of the story of
coral is quite as wondrous in its way
as anything which the fertile brain OF
the story writer is able to conceive.
Every one is familiar, from a visit
general appearance of coral. There are.
of course, very many different species
of structures included under this COM
mon name. We see great masses of
stony hardness assuming fantastic
shapes, and constituting in their way
Veritable rocks. Others are of a more
delicate description AMI may assume
the form of miniature organ pipes,
valued for the manufacture of articles
of jewellery, represents the opposite ex-
IRENE from the coarse limy masses re-
ferred to. l may explode at the outset
an erroneous idea regarding the red
coral. This coral is practically con-
fined to the Mediterranean sea, and
grows in small tree-hke form. The
idea that islands formed of red coral
exist is a piece of pure fiction, and
those corals which more especially con-
Germ us here as the builders of reefs are
represented by the coarse, stony masses
familiar in museums but also often
used in the construction of grottoes and
ferneries.
1t is not so very long ago in the his
tory of science that coral was discov-
cred to be the work of an animal. The
ancients regarded coral, and especially
the red coral which they knew best,
as the work of the marine plant. Latin
poets tell US of the coral plant which
is soft in it's native waters, but be-
comes hard when drawn up from the
sea and exposed to the action of the
air. A young French student, Pey-
sonnet, discovered the fact that coral
was a substance represented by the Sc
erection of an animal. He described ac-
curately enough the kind of animal
which makes coral. He compared this
animal to the sea anemone, which we
find in every rocky hollow around our
own coasts. In so doing he was per-
fectly correct, for the coral animal is
really a kind of insect and a familiar
denizen of the seaside. There is, how
ever, this difference between the latter
and the coral animal. The former as
rule is a single animal; the corals
are usually compound. That is to say
one coral animals gives rise to another
I SC
way a mass of coral is seen to be the
work not of one animal, but of many
hundreds of thousands, produced as
kind of colony in the way just descrlb-
ed 1t is this power of increase by
budding which enables corals to con-
struct reefs of great magnitude. Pos
sessing what is practically an unilm-
tied power of increase, they succeed
| in producing enormous masses of rocky
| substance, and we must not forget
| that every coral animal has the pow
er of producing eggs. Each egg which
comes to full development settles down.
| gives origin to one coral animal, and,
as this in turn buds like its forefath-
ers. a new colony is thus commenced.
Regarding coral itself, we find that
substance to be represented by a nara
carbonate of lime. The matter whlch
we find accumulated in boilers and ket-
as possible represents the coral sub
stance. The material for making this
hard secretion, the possession of which
also constitutes another difference
from the sea anemone, is obtained
from the sea water. Carbonate of lime
exists in solution in the water. and
the coral animals, absorbing TINS ma
terial from the sea, build 1t up in the
form of their hard parts either within
In
when the coral animals themselves die
they leave behid them what poet has
well called the imperishable masonry
Of the sea" The power of budding is
not, of course limited to corals We
are familiar enough with 1T in the case
of plants, but many other animals be-
sides corals grow into colonies by the
budding process.
Corals can also add to the number In
= colony through another process;
namely. simple division of the body.
We see how the body simply divided
in two gives rise to two individuals,
and thus adds to the nmerical
strength of the mass. The conditions
under which corals live and grow are
very simple They may be summed up
in the Words-a certain heat and GER
tain death The question of heat nat
urallv settles the range of the corals
in space; that is, determines their geo
graphy in the existing earth. The
reef building corals do not fluormish in
seas where the water is below Sc de-
grees or thereby of Fahrenheit 1t
will therefore be seen that it is only
in tropical regions where we may ex-
pect to find the fullest development of
coral life.
If we look at a map of the world and
take the equator as natural center,
ard if we measure off a space of 1900
miles north and the same distance
south of the equatorial line, we shall
include between these limits the great
fields of coral life. Thus, within these
limits we shall find included the north
coast of Australia, the Eastern archi-
pelago, the Indian ocean, the Red sea.
Madagascar, and across the Atlantic
the West Indian islands, and also the
South Pacific, which latter may be
called the great region of coral islands.
Round the British coasts there is only
one living coral. This is the little cup
coral of the Devonshire coast, which,
like the last of the Mohicans, remains
with us to remind us of a once plenti-
full coral population in the European
seas.
The second question, that of depth,
requires to be more narrowly studied.
If we find coral islands rising in oceans
which are miles deep, the matter of