Year: 1872




often an outer imperyious layer OF carbonate
of lime over he dead corailum, secreted by |
the lower e.ire of the series of dying polyps.
Then the dead surface becomes the resting |
place bf innumerable small incrustinS species !
of corals besides several other varieties q
marine animals. In many instances the hcheI. Like
nulipore grows at the same rate with the rate OF
death In the coral hemisphere and keeps tse up to
the very limit Of the living part just rs the lIeless
trunk of the forest tree betomes covered with
lchens and fungi or in tropical climcs with other
foliage OF flowers. The older polyps before death
often increase their coral secretions within, filling
the pores as the tissues which occupy them dwindie,
and thus render the coraum nearly solid. This Is
another means by which the trees of coral growth,
though of slender form, are increased in strength
and endurance.


The same result Is promoted by the facility with
which tue polyp repairs wound. The breaking OF
branch is no serious injury TO coral tree. There
is often degree of sensibiity apparent throughout
a clump even of considerable size and the shock
may occasion the polyps to close. But In an hour,
or less time their tentacles viii again have ex-
banded; and such as torn by the fracture Will
at once commence the process OF restoration. Inc
coral dome may be loveled by the action OF the
waves yet like the trodden sod, 1t Will sprout again.
and continue to grow aud flourish as before AS the
sod has roots which are still unhur the coral hemi-
sphere which may be dead at base, has O root, or
center of fe in every poyp that blossoms over It's
surface Each animal might live and grow II sep
arated from the rest, and would ultimately produce
mature coral hemisphere.


With regard to the composition OF coral the usual
specimens are harder than common limestone
marble. which is indicated by the ringing sound
when they are struck with o hammer. 1t IL
an error of ancient date to suppose that coral
when first removed from the water Is soft, and
afterward hardens by exposure. In fact, there Is
| scarcely an appreciable difference. The live coral
may have shiny feel in the fingers but if cleansed
| from the animal matter will be found to be quite
| firm. The common reef-corals consist almost en-
tirely of carbonate Of lime the constituent of Ordi-
| nary limestone.


The sea-water and the ordinary food Of the polyps
are the from which the ingredients OF coral
are derived. The same powers of elaboration which
| exist in other animals belong to poyps-a function
which is the lowest attribute of vitality.


The reef-formng species of pelyps are confined to
| waters of q moderate temperature and of small


depths. As rule they require pure ocean water,
| aboundng especially in the broad inner channels
among the reefs within the large lagoons and in the
| shallow waters outside the breakers. The rate OF
| growth is but little understood.


Coral reefs and coral islands are structures of the
same kind, under somewhat different conditions.
They are made by the same seas and the means,
| but yet the terms not synonymous. Coral


islands are reefs that stand isolated in the ocean,


away from other islands whether raised only to the


waters edge or covered with vegetation, while the


term coral reef, although used for reefs of coral in


general is more especially applied to those which oc-
cur along the shores of high islands and continents


Coral reefs are banks of coral rock built upon the


sea-bottom about the shores of tropical lands In the


Pacific with some important exceptions, these lands


are islands of volcanic growth, often rising to noun


tain hight The coral reefs which skirt their shores


are usually submerged at high tide, but at the ebb,


they present broad fat bare surface of rock, just


above the water level strongly contrasting with the


steep slopes of the encircled island. The first sign


of the reef when the tide is well n line of heavy


breakers perhaps miles in length off great distance


from the land. On closer view some spots Of bare


reef may be distb guished the waves retreat for


another plunge but the next moment all again is an
| interminable line of careering waters.


| All cOral-bound coasts and especially those Of


islands in mid ocean, derive great benefit from their
reefs The wide coral reefs greatly enlarge the
| limits tributary to the lands which they encrcle.


Besides being barriers against the ocean. they are
dikes to detain the detTitus of the hills. They
stop the waters of the streams and cause them to
drop the silt they bearing Off thus securing its
6uQltlOn 10 tne lanu. lUCy prevent, icCOIulnQiy,


the waste which takes place about islands without
such barriers. They also provide extensive fishing


grounds for the natives, aiording abundant fish
their main reliance in the way of animal food The
larger reef regions moreover furnish important
| tributions to the commerce of the world


Coral islands resemble the reefs except that lake
or lagoon is encircled instead of mountainous
island. narrow rim of coral reef, generally but
few hundred yards wide stretches around the in
closed waters The reef is so low in some parts that
the waves still dashing over it into the lagoon,
while in Others it is verdant with the rich foliage of
the tropics The cOral-made land is seldom more
than ten or twelve feet above high tide When first
seen from the deck of vessel, only series
of dayk points appear just above the hor-
zon. Soon after the points enlarge into the
plumed tops of cocoa-nut trees and line of green is
traced along the surface of the water As you ap-
proach still nearer the lake and its belt of verduro
spread out before the eye, presenting Of
interest The surf beating loud along the
gin OF the reef affords strange contrast to the white
coral beach beyond, the dense foliage OF the grove
and the embOsomed lake with its tiny islets. The
water Of the lagoon, although but ten or twenty
fathOms deep. is often as blue the ocean. Where
patches of sand coral knOls rise the surface


shades Of green and yellow are interminged, tho
green of q delicate apple-color quite unlike the
muddy tint Of shallow waters The belt of verdure
is usually broken into isets separated by intervals
of bare reef that in fact the larger coral islands
are n string of slets along a line of reef


|, The appearance of a bed of growing coras is quite
different from the prevailing ideas the subject.
II is often supposed that the submerged reef is an
extended mass of coral, with uniform life over its
upper surface and gradually enlarging upward
through this living growth. But nothing is wider
from the truth. The surface Of growing reef is
better described by the term coral plantation or