162
_
THE SEAS
bud.
This type of coral is best exemplied by the well— '
.
known Meandrina or' Brain—coral, so called because the
'
meandering depressions with which the surface is covered
”resemble very clôsely the convolutions on the surface of
.
the human brain, as a result of which its surface, and so
the
grey matter, is greatly increased.
_
There is a remarkable-solitary coral, common on reefs,
which is worthy of a short description, so peculiar is its
manner‘ of development.
The swimming embryo settles
'
and develops into a little cup—shaped coral, but, on attaining
a certain size, this swells out at the top until it looks almost -
exactly like a mushroom turned upside down so as to expose
the gills (hence the naine of the coral, Fungia).
After a
time this attened upper portion falls off and drops on to
the sand, where it continues to grow until it is often six
inches across.
The whitened skeletons of these stalkless
,
dises, conSisting of a circular disc with radiating septal
plates (Plate 58)… are common” objectson coral shores and
in zoological museums.
The original polyp does not die
when the attened head falls away but starts again, as it
_.
were, and grows a new One which, falling o in its turn, is
an indenite number of '
'
Corals grow like plantsand they further resemble them in
that the form the colohy nally asSuh1es depends very largely -
on the prevailing conditions.
We know that plants
from identicalseeds will Vary- a very great deal if one is
grown ina
and otherwise faVoutable locality,
while the…other is in an unfav0urable situation; A plant
having a luxuriant growth in the valley may have a stunted
growth and=quite-a different appearace‘when
.mountain t0p. In the case of corals, the chief factors
inuenCing growth form are the depth at which they live,
the degree of motion in the water, and the presence or
absence of_sediment in the water.
The commen 'Madrep'ora
_
THE SEAS
bud.
This type of coral is best exemplied by the well— '
.
known Meandrina or' Brain—coral, so called because the
'
meandering depressions with which the surface is covered
”resemble very clôsely the convolutions on the surface of
.
the human brain, as a result of which its surface, and so
the
grey matter, is greatly increased.
_
There is a remarkable-solitary coral, common on reefs,
which is worthy of a short description, so peculiar is its
manner‘ of development.
The swimming embryo settles
'
and develops into a little cup—shaped coral, but, on attaining
a certain size, this swells out at the top until it looks almost -
exactly like a mushroom turned upside down so as to expose
the gills (hence the naine of the coral, Fungia).
After a
time this attened upper portion falls off and drops on to
the sand, where it continues to grow until it is often six
inches across.
The whitened skeletons of these stalkless
,
dises, conSisting of a circular disc with radiating septal
plates (Plate 58)… are common” objectson coral shores and
in zoological museums.
The original polyp does not die
when the attened head falls away but starts again, as it
_.
were, and grows a new One which, falling o in its turn, is
an indenite number of '
'
Corals grow like plantsand they further resemble them in
that the form the colohy nally asSuh1es depends very largely -
on the prevailing conditions.
We know that plants
from identicalseeds will Vary- a very great deal if one is
grown ina
and otherwise faVoutable locality,
while the…other is in an unfav0urable situation; A plant
having a luxuriant growth in the valley may have a stunted
growth and=quite-a different appearace‘when
.mountain t0p. In the case of corals, the chief factors
inuenCing growth form are the depth at which they live,
the degree of motion in the water, and the presence or
absence of_sediment in the water.
The commen 'Madrep'ora