Coral and Coral ReefsWord格式.docx
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Coral and Coral ReefsWord格式.docx
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oneofthemisthatsubstancewhichIimagineagreatnumberofushavechampedwhenwewereverymuchyoungerthanwearenow,--thecommonredcoral,whichisusedsomuch,asyouknow,fortheedificationandthedelectationofchildrenoftenderyears,andisalsoemployedforthepurposesofornamentforthosewhoaremucholder,andassomethinkmightknowbetter.Theotherkindofcoralisaverydifferentsubstance;
itmayfordistinction'
ssakebecalledthewhitecoral;
itisamaterialwhichmostassuredlynotthehardest-heartedofbabyfarmerswouldgivetoababytochew,anditisasubstancewhichistobeseenonlyinthecabinetsofcuriouspersons,orinmuseums,or,maybe,overthemantelpiecesofsea-faringmen.Butalthoughtheredcoral,asIhavementionedtoyou,hasaccesstotheverybestsociety;
andalthoughthewhitecoraliscomparativelyadespisedproduct,yetinthis,asinmanyothercases,thehumblerthingisinrealitythegreater;
theamountofworkwhichisdoneintheworldbythewhitecoralbeingabsolutelyinfinitecomparedwiththateffectedbyitsdelicateandpamperednamesake.Eachofthesesubstances,thewhitecoralandthered,however,hasarelationshiptotheother.Theyare,inazoologicalsense,cousins,eachofthembeingformedbythesamekindofanimalsinwhatissubstantiallythesameway.Eachofthesebodiesis,infact,thehardskeletonofaverycuriousandaverysimpleanimal,morecomparabletothebonesofsuchanimalsasourselvesthantotheshellsofoystersorcreaturesofthatkind;
foritisthehardeningoftheinternaltissueofthecreature,ofitsinternalsubstance,bythedepositinthebodyofamaterialwhichisexceedinglycommon,notonlyinfreshbutinseawater,andwhichisspeciallyabundantinthosewaterswhichweknowas"
hard,"
thosewaters,forexample,whichleavea"
fur"
uponthebottomofatea-kettle.This"
iscarbonateoflime,thesamesortofsubstanceaslimestoneandchalk.Thatmaterialiscontainedinsolutioninseawater,anditisoutoftheseawaterinwhichthesecoralcreatureslivethattheygetthelimewhichisneededfortheformingoftheirhardskeleton.
Butnowwhatmannerofcreaturesarethesewhichformthesehardskeletons?
Idaresaythatinthesedaysofkeepingaquaria,oflocomotiontothesea-side,mostofthosewhomIamaddressingmayhaveseenoneofthosecreatureswhichusedtobeknownasthe"
seaanemone,"
receivingthatnameonaccountofitsgeneralresemblance,inaroughsortofway,totheflowerwhichisknownasthe"
anemone"
;
butbeingathingwhichlivesinthesea,itwasqualifiedasthe"
seaanemone."
Well,then,youmustsupposeabodyshapedlikeashortcylinder,thetopcutoff,andinthetopaholeratherovalthanround.
Allroundthisaperture,whichisthemouth,imaginethatthereareplacedanumberoffeelersformingacircle.Thecavityofthemouthleadsintoasortofstomach,whichisveryunlikethoseofthehigheranimals,inthecircumstancethatitopensatthelowerendintoacavityofthebody,andallthedigestedmatter,convertedintonourishment,isthusdistributedthroughtherestofthebody.Thatisthegeneralstructureofoneoftheseseaanemones.Ifyoutouchititcontractsimmediatelyintoaheap.Itlooksatfirstquitelikeaflowerinthesea,butifyoutouchityoufindthatitexhibitsallthepeculiaritiesofalivinganimal;
andifanythingwhichcanserveasitspreycomesnearitstentacles,itclosesthemrounditandsucksthematerialintoitsstomachandtheredigestsitandturnsittotheaccountofitsownbody.
Thesecreaturesareveryvoracious,andnotatallparticularwhattheyseize;
andsometimesitmaybethattheylayholdofashellfishwhichisfartoobigtobepackedintothatinteriorcavity,and,ofcourse,inanyordinaryanimalaproceedingofthiskindwouldgiverisetoaveryseverefitofindigestion.Butthisisbynomeansthecaseintheseaanemone,becausewhendigestivedifficultiesofthiskindarisehegetsoutofthembysplittinghimselfintwo;
andtheneachhalfbuildsitselfupintoafreshcreature,andyouhavetwopolypeswheretherewaspreviouslyone,andthebonewhichstuckinthewaylyingbetweenthem!
Notonlycanthesecreaturesmultiplyinthisfashion,buttheycanmultiplybybuds.Abudwillgrowoutofthesideofthebody(I
amnotspeakingofthecommonseaanemone,butofalliedcreatures)
justlikethebudofaplant,andthatwillfashionitselfintoacreaturejustliketheparent.Therearesomeoftheminwhichthesebudsremainconnectedtogether,andyouwillsoonseewhatwouldbetheresultofthat.IfImakeabudgrowouthere,andanotherontheoppositeside,andeachfashionsitselfintoanewpolype,thepracticaleffectwillbethatbeforelongyouwillseeasinglepolypeconvertedintoasortoftreeorbushofpolypes.Andthesewillallremainassociatedtogether,likeakindofco-operativestore,whichisathingIbelieveyouunderstandverywellhere,--eachmouthwillhelptofeedthebodyandeachpartofthebodyhelptosupportthemultifariousmouths.Ithinkthatisasgoodanexampleofazoologicalco-operativestoreasyoucanwellhave.Sucharethesewonderfulcreatures.Buttheyarecapablenotonlyofmultiplyinginthisway,butinotherways,byhavingamoreordinaryandregularkindofoffspring.Littleeggsarehatchedandtheyoungarepassedoutbythewayofthemouth,andtheygoswimmingaboutaslittleovalbodiescoveredwithaverycuriouskindofhairlikeprocesses.Eachoftheseprocessesiscapableofstrikingwaterlikeanoar;
andtheconsequenceisthattheyoungcreatureispropelledthroughthewater.Sothatyouhavetheyoungpolypefloatingaboutinthisfashion,coveredbyits'
vibratilecilia'
astheselongfilaments,whicharecapableofvibrationaretermed.Andthus,althoughthepolypeitselfmaybeafixedcreatureunabletomoveabout,itisabletospreaditsoffspringovergreatareas.Forthesecreaturesnotonlypropelthemselves,butwhileswimmingaboutintheseaformanyhours,orperhapsdays,itwillbeobviousthattheymustbecarriedhitherandthitherbythecurrentsofthesea,whichnotunfrequentlymoveattherateofoneortwomilesanhour.Thus,inthecourseofafewdays,theoffspringofthisstationarycreaturemaybecarriedtoaverygreatdistancefromitsparent;
andhavingbeensocarrieditlosestheseorgansbywhichitispropelled,andsettlesdownuponthebottomoftheseaandgrowsupagainintotheformandconditionofitsparents.Sothatifyousupposeasinglepolypeofthiskindsettleduponthebottomofthesea,itmaybythesevariousmethods--thatistosay,bycuttingitselfintwo,whichwecall"
fission,"
orbybudding;
orbysendingouttheseswimmingembryos,--multiplyitselftoanenormousextent,andgiverisetothousands,ormillions,ofprogenyinacomparativelyshorttime;
andthesethousands,ormillions,ofprogenymaycoveraverylargesurfaceoftheseabottom;
infact,youwillreadilyperceivethat,givethemtime,andthereisnolimittothesurfacewhichtheymaycover.
Havingunderstoodthusfarthegeneralnatureofthesepolypes,whicharethefabricatorsbothoftheredandwhitecoral,letusconsideralittlemoreparticularlyhowtheskeletonsoftheredcoralandofthewhitecoralareformed.Theredcoralpolypeperchesupontheseabottom,itthengrowsupintoasortofstem,andoutofthatstemtheregrowbranches,eachofwhichhasitsownpolypes;
andthusyouhaveakindoftreeformed,everybranchofthetreeterminatedbyitspolype.Itisatree,butattheendofthebranchesthereareopenmouthsofpolypesinsteadofflowers.Thusthereisacommonsoftbodyconnectingthewhole,andasitgrowsupthesoftbodydepositsinitsinterioraquantityofcarbonateoflime,whichacquiresabeautifulredorfleshcolour,andformsakindofstemrunningthroughthewhole,anditisthatstemwhichistheredcoral.TheredcoralgrowsprincipallyatthebottomoftheMediterraneanSea,atverygreatdepths,andthecoralfishers,whoareveryadventurousseamen,taketheirdragnets,ofapeculiarkind,roughlymade,butefficientfortheirpurpose,anddragthemalongthebottomoftheseatocatchthebranchesoftheredcoral,whichbecomeentangledandarethusbroughtuptothesurface.Theyarethenallowedtoputrefy,inordertogetridoftheanimalmatter,andtheredcoralistheskeletonthatisleft.
Inthecaseofthewhitecoral,theskeletonismorecomplete.Intheredcoral,theskeletonbelongstothewhole;
inthewhitecoralthereisaspecialskeletonforeveryoneofthesepolypesinadditiontothatforthewholebody.Thereisaskeletonformedinthebodyofeachofthem,likeacupdividedbyanumberofradiatingpartitionstowardstheoutside;
andthatcupisformedofcarbonateoflime,onlynotstainedred,asinthecaseoftheredcoral.Andallthesecupsarejoinedtogetherintoacommonbranch,theresultofwhichistheformationofabeautifulcoraltree.Thisisagreatmassofmadrepore,andinthelivingstateeveryoneoftheendsofthesebrancheswasterminatedbyabeautifullittlepolype,likeaseaanemone,andalltheskeletonwascoveredbyasoftbodywhichunitedthepolypestogether.Youmustunderstandthatallthisskeletonhasbeenformedintheinteriorofthebody,tosuitthebranchedbodyofthepolypemass,andthatitisasmuchitsskeletonasourownbonesareourskeleton.Inthisnext
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