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空白协议书 更新:2021-02-20 16:45 字数:9321
Coral and Coral Reefs
by Thomas H。 Huxley
THE subject upon which I wish to address you to…night is the structure
and origin of Coral and Coral Reefs。 Under the head of 〃coral〃 there
are included two very different things; one of them is that substance
which I imagine a great number of us have champed when we were very
much younger than we are now;the common red coral; which is used so
much; as you know; for the edification and the delectation of children
of tender years; and is also employed for the purposes of ornament for
those who are much older; and as some think might know better。 The
other kind of coral is a very different substance; it may for
distinction's sake be called the white coral; it is a material which
most assuredly not the hardest…hearted of baby farmers would give to a
baby to chew; and it is a substance which is to be seen only in the
cabinets of curious persons; or in museums; or; may be; over the
mantelpieces of sea…faring men。 But although the red coral; as I have
mentioned to you; has access to the very best society; and although the
white coral is comparatively a despised product; yet in this; as in
many other cases; the humbler thing is in reality the greater; the
amount of work which is done in the world by the white coral being
absolutely infinite compared with that effected by its delicate and
pampered namesake。 Each of these substances; the white coral and the
red; however; has a relationship to the other。 They are; in a
zoological sense; cousins; each of them being formed by the same kind
of animals in what is substantially the same way。 Each of these bodies
is; in fact; the hard skeleton of a very curious and a very simple
animal; more comparable to the bones of such animals as ourselves than
to the shells of oysters or creatures of that kind; for it is the
hardening of the internal tissue of the creature; of its internal
substance; by the deposit in the body of a material which is exceedingly
common; not only in fresh but in sea water; and which is specially
abundant in those waters which we know as 〃hard;〃 those waters; for
example; which leave a 〃fur〃 upon the bottom of a tea…kettle。 This
〃fur〃 is carbonate of lime; the same sort of substance as limestone and
chalk。 That material is contained in solution in sea water; and it is
out of the sea water in which these coral creatures live that they get
the lime which is needed for the forming of their hard skeleton。
But now what manner of creatures are these which form these hard
skeletons? I dare say that in these days of keeping aquaria; of
locomotion to the sea…side; most of those whom I am addressing may have
seen one of those creatures which used to be known as the 〃sea
anemone;〃 receiving that name on account of its general resemblance; in
a rough sort of way; to the flower which is known as the 〃anemone〃; but
being a thing which lives in the sea; it was qualified as the 〃sea
anemone。〃 Well; then; you must suppose a body shaped like a short
cylinder; the top cut off; and in the top a hole rather oval than round。
All round this aperture; which is the mouth; imagine that there are
placed a number of feelers forming a circle。 The cavity of the mouth
leads into a sort of stomach; which is very unlike those of the higher
animals; in the circumstance that it opens at the lower end into a
cavity of the body; and all the digested matter; converted into
nourishment; is thus distributed through the rest of the body。 That is
the general structure of one of these sea anemones。 If you touch it it
contracts immediately into a heap。 It looks at first quite like a
flower in the sea; but if you touch it you find that it exhibits all
the peculiarities of a living animal; and if anything which can serve as
its prey comes near its tentacles; it closes them round it and sucks
the material into its stomach and there digests it and turns it to the
account of its own body。
These creatures are very voracious; and not at all particular what they
seize; and sometimes it may be that they lay hold of a shellfish which
is far too big to be packed into that interior cavity; and; of course;
in any ordinary animal a proceeding of this kind would give rise to a
very severe fit of indigestion。 But this is by no means the case in the
sea anemone; because when digestive difficulties of this kind arise he
gets out of them by splitting himself in two; and then each half builds
itself up into a fresh creature; and you have two polypes where there
was previously one; and the bone which stuck in the way lying between
them! Not only can these creatures multiply in this fashion; but they
can multiply by buds。 A bud will grow out of the side of the body (I
am not speaking of the common sea anemone; but of allied creatures)
just like the bud of a plant; and that will fashion itself into a
creature just like the parent。 There are some of them in which these
buds remain connected together; and you will soon see what would be the
result of that。 If I make a bud grow out here; and another on the
opposite side; and each fashions itself into a new polype; the
practical effect will be that before long you will see a single polype
converted into a sort of tree or bush of polypes。 And these will all
remain associated together; like a kind of co…operative store; which is
a thing I believe you understand very well here;each mouth will help
to feed the body and each part of the body help to support the
multifarious mouths。 I think that is as good an example of a
zoological co…operative store as you can well have。 Such are these
wonderful creatures。 But they are capable not only of multiplying in
this way; but in other ways; by having a more ordinary and regular kind
of offspring。 Little eggs are hatched and the young are passed out by
the way of the mouth; and they go swimming about as little oval bodies
covered with a very curious kind of hairlike processes。 Each of these
processes is capable of striking water like an oar; and the consequence
is that the young creature is propelled through the water。 So that you
have the young polype floating about in this fashion; covered by its
'vibratile cilia'; as these long filaments; which are capable of
vibration are termed。 And thus; although the polype itself may be a
fixed creature unable to move about; it is able to spread its offspring
over great areas。 For these creatures not only propel themselves; but
while swimming about in the sea for many hours; or perhaps days; it
will be obvious that they must be carried hither and thither by the
currents of the sea; which not unfrequently move at the rate of one or
two miles an hour。 Thus; in the course of a few days; the offspring of
this stationary creature may be carried to a very great distance from
its parent; and having been so carried it loses these organs by which
it is propelled; and settles down upon the bottom of the sea and grows
up again into the form and condition of its parents。 So that if you
suppose a single polype of this kind settled upon the bottom of the
sea; it may by these various methodsthat is to say; by cutting itself
in two; which we call 〃fission;〃 or by budding; or by sending out these
swimming embryos;multiply itself to an enormous extent; and give rise
to thousands; or millions; of progeny in a comparatively short time;
and these thousands; or millions; of progeny may cover a very large
surface of the sea bottom; in fact; you will readily perceive that; give
them time; and there is no limit to the surface which they may cover。
Having understood thus far the general nature of these polypes; which
are the fabricators both of the red and white coral; let us consider a
little more particularly how the skeletons of the red coral and of the
white coral are formed。 The red coral polype perches upon the sea
bottom; it then grows up into a sort of stem; and out of that stem there
grow branches; each of which has its own polypes; and thus you have a
kind of tree formed; every branch of the tree terminated by its
polype。 It is a tree; but at the end of the branches there are open
mouths of polypes instead of flowers。 Thus there is a common soft body
connecting the whole; and as it grows up the soft body deposits in its
interior a quantity of carbonate of lime; which acquires a beautiful
red or flesh colour; and forms a kind of stem running through the whole;
and it is that stem which is the red coral。 The red coral grows
principally at the bottom of the Mediterranean Sea; at very great
depths; and the coral fishers; who are very adventurous seamen; take
their drag nets; of a peculiar kind; roughly made; but efficient for
their purpose; and drag them along the bottom of the sea to catch the
branches of the red coral; which become entangled and are thus brought
up to the surface。 They are then allowed to putrefy; in order to get
rid of the animal matter; and the red coral is the skeleton that is
left。
In the case of the white coral; the skeleton is more complete。 In the
red coral; the skeleton belongs to the whole; in the white coral there
is a special skeleton for every one of these polypes in addition to