The Savannah morning news., 1901-12-29
c0RALS AND THEIR REEFS.
A FAIRY TALE OF SCIENCE-PEY-
SONNEL'S DISCOVERY


csion-Discrcdited Theories and
DarVvin's Explanation.
DR.. Andrew Wilson in The New York
Post.
Among all the varied productions of
living nature none perhaps can 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 fic-
ton than in that of actual science.
Yet the scinetifc 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.
Demolition of the Poets Coral Isle.
Every one is familiar, from a visit
to a natural history museum, with the
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 docks. Others are of a more
delicate description, and may assume
the form of miniature organ-pipes,
while the red coral itself, so much
valued for the manufacture of articles
of jewelry, 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 a small tree like 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 enough in museums,
but also often used in the construction
of grotties and ferneries.
Tt 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 especial
ly 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, Peyson-
mel, discovered the fact that coral was
a substance represented by the secre-
ton of an animal. He accurately
enough described 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-
fectiy correct, for the coral animal is
really a kind of insect and familiar
denizen of the sea- side
The Effect of the Budding Process.
There is, however, this difference be-
tween the latter and the coral animal.
The former as a rule is a single animal;
the corals are usually compound. That
is to say, one coral animal gives rise
to another by a process of budding,
and in this way a mass of coral is seen
to be the work, not of one animal, but
of many hundreds or thousands, pro-
duced as a kind of colony in the way
just described. 1t is this power of in-
crease by budding which enables corals
to construct reefs of great magnitude.
Possessing what is practically an un-
limited power of increase, they suc-
coed in producing enormous masses of
rocky substance, and we must not for
get that every coral animal has the
power of producing eggs. Each egg
which comes to full development set
ties down, gives origin to one coral
animal, and as this in turn buds, like
its forefathers, a new colony is thus
commenced.
Regarding coral itself, we find that
substance to be represented by a hard
carbonate of lime. The matter which we
find accumulated in boilers and kettles
in hard water districts, as nearly as
possible represents the coral substance.
The material for making this hard Sc
erection, the possession of which also
constitutes another difference from the
sea anemone, is obtained from the sea
water. Carbonate of lime exists in SOL
ution in the water, and the coral ami
mails, absorbing this material from the
sea, build it up either within or
without their bodies. In this way when
the coral animals themselves die they
leave behind them what a poet has
well called 1.-The imperishable masonry
of the sea-" The power of building is
not of course limited to corals. We
are familiar enough with it in the case
of plants, but many other animals be-
side corals grow into colonies by the
budding process.
Limits In which Coral Life Abounds
Eorals can also add to the number
In colony through another process,
namely simple division of the body. We
can see how thA body simply divided
in two gives rise to two individuals
and thus adds to the numerical 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 a GER
tain depth. The question of heat nat
urally settles the range of the corals
in space, that is, determines their geo.
graphy in the existing earth. The reef
building corals do not flourish in seas
where the water is below &C degrees,
or thereby, of Fahrenheit, 1t will
therefore, be seen that it is only in
tropical regions where we may expect
10 ind the fullest development of coral
life. If we look at a map of the world
and take the equator as a natural
center, and If we measure off a space Of
1900 miles north and the same dis lance
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 carol. 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
II we find coral islands rising in oceans
which are miles deep the matter Of
depfh would MT appaar o. drat