[60
THE SEAS
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Mediterranean and in the coral reefs et the tropics.
They
‘
never
form so thick a mass as do the true corals, being
_
essentially encrusting plants forming a compact layer over
any hard surface, rocks, stones or dead coralL “An im—
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portant green weed which also deposits carbonate oflime
in its trends and is so common as to -form an important
constituent of many coral reefs, is called Halimeda.
It has
a characteristic appearance being formed of a number of
broadened, limy lobes united by narrow, uncalcied joints .
which make the plant relatively exible.
,
Having indicated the chief agencies concerned in the
formation of reefs, we must now turn our attention to their
mannerof growth and life in general, because, as we shall ,
see later, these are of the very“ rst importance in the
'
formation oîcoral ree£s.
The ‘great cor'al colèniesdevelop
by a prôCess of budding and division from the original
,
parent individual, in essentially the same manner as a plant
sends out new shoots and branches, amethod of inCrease ;
which isknovärn as vegetative,propag’atiôn, ' Going back“
to the begihningo£ things, theyoüg ïco'rals ;afezinCubated
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Withinthe body
parents_,fora lit—tie _ti—me, —but aat*àg
1 ,cemparaümlysèay age the “.planuïæ” escape and sw1m
aboutm
by means.0fga coatmg of ne _hairs With
WhlCh they
At this Stagetheÿ are minute,
biggerthari a pin-fs head… After a
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tune }
«on; la: sommier—lt» hard— ;sur£aceaf theÏ
out to
discwhe
ànd then
astemachcawtyWmlearounïthem@uth€f°W°ut the
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byatck1ayerofcarb0natwïhmeIf1tlsa S°htæry
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