coral and coral reefs-第1节

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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