Thishowever，thoughaverballyintelligiblesupposition，isonethatcannot
　　berepresentedinthought;sinceunlimitedspaceisinconceivable。Butall
　　finiteformsofthehomogeneous——allformsofitwhichwecanknoworconceive，
　　mustinevitablylapseintoheterogeneity;andthelessheterogeneousmust
　　lapseintothemoreheterogeneous。Inthreeseveralwaysdoesthepersistence
　　offorcenecessitatethis。Settingexternalagenciesaside，eachunitof
　　ahomogeneouswholemustbedifferentlyaffectedfromanyoftherestby
　　theaggregateactionoftherestuponit。Theresultantforceexercisedby
　　theaggregateoneachunit，beinginnotwocasesalikeinbothamountand
　　direction，andusuallynotineither，anyincidentforce，evenifuniform
　　inamountanddirection，cannotproducelikeeffectsontheunits。Andas
　　thevariouspositionsofthepartsinrelationtoanyincidentforce，prevents
　　themfromreceivingitinuniformamountsanddirections，afurtherdifferenceintheeffectswroughtontheminevitablyarises。Onefurtherremarkisneeded。Theconclusionthatthechangeswithwhich
　　Evolutioncommences，arethusnecessitated，hastobesupplementedbythe
　　conclusionthatthesechangesmustcontinue。Theabsolutelyhomogeneous（supposing
　　ittoexist）mustloseitsequilibrium;andtherelativelyhomogeneousmust
　　lapseintotherelativelylesshomogeneous。Thatwhichistrueofanytotal
　　mass，istrueofthepartsintowhichitsegregates。Theuniformityofeach
　　suchpartmustasinevitablybelostinmultiformity，aswasthatofthe
　　originalwhole;andforlikereasons。Andthusthecontinuedchangescharacterizing
　　Evolution，insofarastheyareconstitutedbythelapseofthehomogeneous
　　intotheheterogeneous，andofthelessheterogeneousintothemoreheterogeneous，arenecessaryconsequencesofthepersistenceofforce。[AsmallchangeinthedefinitionofEvolutionindicatedinanoteat
　　theendofChapterXVIIofthispart，mustberecalledasinvolvingacorrelative
　　changeinthischapter。Here，asbefore，therequiredchange，thoughalready
　　implied（page367），hasnotbeensufficientlyemphasized，andlackofthe
　　emphasisinvitesmisinterpretation。Forreasonslikethosebeforegiven，
　　therequisiteexplanationscannotbemadeinthisplace。ThereaderwillfindtheminAppendixA。Repliestocertaincriticismsonthegeneraldoctrinesetforthinthis
　　chapterwillbefoundinAppendixC。]
　　Chapter20TheMultiplicationofEffects§156。Tothecauseofincreasingcomplexitysetforthinthelast
　　chapter，wehaveinthischaptertoaddanother。Thoughsecondaryinorder
　　oftime，itisscarcelysecondaryinorderofimportance。Evenintheabsence
　　ofthecausealreadyassigned，itwouldnecessitateachangefromthehomogeneous
　　totheheterogeneous;andjoinedwithit，itmakesthischangebothmore
　　rapidandmoreinvolved。Tocomeinsightofitwehavebuttopursueastep
　　furtherthatconflictbetweenforceandmatteralreadydelineated。Letusdothis。Asalreadyshown，whenthecomponentsofauniformaggregatearesubject
　　toauniformforce，theybeingdifferentlyconditioned，aredifferentlymodified。
　　Butwhilewehavecontemplatedthevariouspartsoftheaggregateasundergoing
　　unlikechanges，wehavenotyetcontemplatedtheunlikechangessimultaneously
　　producedonthevariouspartsoftheincidentforce。Thesemustbeasnumerous
　　astheothers。Indifferentiatingthepartsonwhichitfallsinunlikeways，
　　theincidentforcemustitselfbecorrespondinglydifferentiated。Instead
　　ofbeingasbefore，auniformforce，itmustthereafterbeamultiformforce
　　——agroupofdissimilarforces。Afewillustrationswillmakethistruthmanifest。Inthecase，latelycited，ofabodyshatteredbyviolentcollision，besides
　　thechangeofthehomogeneousmassintoaheterogeneousgroupofscattered
　　fragments，thereisachangeofthehomogeneousmomentumintoagroupof
　　momenta，heterogeneousinbothamountsanddirections。Similarlywiththe
　　forcesweknowaslightandheat。Afterthedispersionofthesebyaradiating
　　bodytowardsallpoints，theyarere—dispersedtowardsallpointsbythe
　　bodiesonwhichtheyfall。OftheSun'srays，issuingfromhimoneveryside，
　　somefewstriketheMoon。ReflectedatallanglesfromtheMoon'ssurface，
　　somefewofthesestriketheEarth。Byalikeprocessthefewwhichreach
　　theEarthareagaindiffused:someintospace，somefromobjecttoobject。
　　Andoneachoccasion，suchportionsoftheraysasaretransmittedinstead
　　ofreflected，undergorefractionsorotherchangeswhichequallydestroy
　　theiruniformity。Morethanthisistrue。Byconflictwithmatterauniform
　　forceisinpartchangedintoforcesdifferingintheirkinds。Whenonebody
　　isstruckagainstanother，thatwhichweusuallyregardastheeffect，is
　　achangeofpositionormotioninoneorbothbodies。Butthisisavery
　　incompleteviewofthematter。Besidesthevisiblemechanicalresult，sound
　　isproduced——avibrationinoneorbothbodiesandinthesurroundingair;
　　andundersomecircumstanceswecallthistheeffect。Moreover，theairhas
　　notsimplybeenmadetovibrate;ithashadcurrentsraisedinitbythe
　　transitofthebodies。Further，ifthereisnotthatgreatstructuralchange
　　whichwecallfracture，thereisadisarrangementoftheparticlesofthe
　　twobodiesaroundtheirpointofcollision;amountinginsomecasestoa
　　visiblecondensation。Yetmore，thiscondensationisaccompaniedbygenesis
　　ofheat。Insomecasesaspark——thatis，light——resultsfromtheincandescence
　　ofaportionstruckoff。Thusbytheoriginalmechanicalforceexpendedin
　　thecollision，atleastfivekindsofforceshavebeenproduced。Take，again，
　　thelightingofacandle。Primarily，thisisachemicalchangeconsequent
　　onariseoftemperature。Theprocessofcombinationhavingoncebeenset
　　goingbyextraneousheat，thereisacontinuedformationofcarbondioxide，
　　water，etc。Alongwiththisprocessofcombinationthereisaproduction
　　ofheat;thereisaproductionoflight;thereisanattendingcolumnof
　　hotgasesgenerated;therearecurrentscausedinthesurroundingair。Nor
　　doesthedecompositionofoneforceintomanyforcesendhere。Eachofthe
　　severalchangesworkedbecomestheparentoffurtherchanges。Thecarbon
　　dioxideformedwilleventuallycombinewithsomebase;orundertheinfluence
　　ofsunshinegiveupitscarbontotheleafofaplant。Thewaterwillmodify
　　thehygrometricstateoftheairaround;or，ifthecurrentofhotgases
　　containingitcomesagainstacoldbody，willbecondensed:alteringthe
　　temperature，andperhapsthechemicalstate，ofthesurfaceitcovers。The
　　heatgivenoutmeltsthesubjacenttallowandexpandswhateverelseitwarms。
　　Thelight，fallingonvarioussubstances，callsforthfromthemreactions
　　bywhichitisdecomposed，anddiverscoloursarethusproduced。Similarly
　　withthesesecondaryactions，whichmaybetracedoutintoever—multiplying
　　ramifications，untiltheybecometoominutetobeappreciated。Universally，
　　then，theeffectismorecomplexthanthecause。Whethertheaggregateon
　　whichitfallsbehomogeneousorotherwise，anincidentforceistransformed
　　bytheconflictintoanumberofforcesthatdifferintheiramounts，or
　　directions，orkinds;orinalltheserespects。Andofthisgroupofvariously—modifiedforces，eachultimatelyundergoesaliketransformation。Letusnowmarkhowtheprocessofevolutionisfurtheredbythismultiplication
　　ofeffects。Anincidentforcedecomposedbythereactionsofabodyinto
　　agroupofunlikeforces，becomesthecauseofasecondaryincreaseofmultiformity
　　inthebodywhichdecomposesit。Bythereactionsofthevariousparts，differently
　　modifiedaswehaveseentheymustbe，theincidentforceitselfmustbe
　　dividedintodifferentlymodifiedparts。Eachdifferentiateddivisionof
　　theaggregatethusbecomesacentrefromwhichadifferentiateddivision
　　oftheoriginalforceisagaindiffused。Andsinceunlikeforcesmustproduce
　　unlikeresults，eachofthesedifferentiatedforcesmustproduce，throughout
　　theaggregate，afurtherseriesofdifferentiations。Thissecondarycause
　　ofthechangefromhomogeneitytoheterogeneity，obviouslybecomesmorepotent
　　inproportionastheheterogeneityincreases。Whenthepartsintowhichany
　　evolvingwholehassegregateditself，havedivergedwidelyinnature，they
　　willnecessarilyreactverydiverselyonanyincidentforce——theywill
　　divideanincidentforceintosomanystronglycontrastedgroupsofforces。
　　Andeachofthembecomingthecentreofaquitedistinctsetofinfluences，
　　mustaddtothenumberofdistinctsecondarychangeswroughtthroughoutthe
　　aggregate。Yetanothercorollarymustbeadded。Thenumberofunlikeparts
　　ofwhichanaggregateconsists，isanimportantfactorintheprocess。Every
　　additionalspecializeddivisionisanadditionalcentreofspecializedforces，
　　andmustbeafurthersourceofcomplicationamongtheforcesatworkthroughout
　　themass——afurthersourceofheterogeneity。Themultiplicationofeffectsmustproceedingeometricalprogression。§157。Thescatteredpartsofanirregularnebulaincourseofbeing
　　drawntogetherorintegrated，cannotdisplayinadefinitemannerthesecondary
　　traitsofevolution:thesepresupposeanaggregatealreadyformed。Wecan
　　sayonlythatthehalf—independentcomponents，eachattractedbyalland
　　allbyeach，exhibitintheirvariousmomenta，differentintheiramounts
　　anddirections，amultiplicationofeffectsproducedbyasinglegravitativeforce。Butassumingthattheintegrativeprocesshasatlengthgeneratedasingle
　　massofnebulousmatter，thenthesimultaneouscondensationandrotation
　　showushowtwoeffectsoftheaggregativeforce，atfirstbutslightlydivergent，
　　becomeatlastwidelydifferentiated。Anincreaseofoblatenessinthisspheroid
　　musttakeplacethroughthejointactionofthesetwoforces，asthebulk
　　diminishesandtherotationgrowsmorerapid;andthiswemaysetdownas
　　athirdeffect。Thegenesisofheat，accompanyingaugmentationofdensity，
　　isaconsequenceofyetanotherorder——aconsequencebynomeanssimple;
　　sincethevariouspartsofthemass，beingvariouslycondensed，mustbevariously
　　heated。Actingthroughoutagaseousspheroid，ofwhichthepartsareunlike
　　intheirtemperatures，theforcesofaggregationandrotationmustworka
　　furtherseriesofchanges:theymustsetupcirculatingcurrents，bothgeneral
　　andlocal。Atalaterstagelightaswellasheatwillbegenerated。Thus
　　withoutdwellingonthelikelihoodofchemicalcombinationsandelectric
　　disturbances，itismanifestthat，supposingmattertohaveoriginallyexisted
　　inadiffusedstate，theonceuniformforcewhichcauseditsaggregation，
　　musthavebecomegraduallydividedintodifferentforces;andthateachfurther
　　stageofcomplicationintheresultingaggregate，musthaveinitiatedfurther
　　subdivisionsofthisforce——afurthermultiplicationofeffects，increasingthepreviousheterogeneity。Thissectionoftheargumentmayhoweverbeadequatelysustainedwithout
　　havingrecoursetoanysuchhypotheticalillustrationsastheforegoing。
　　TheastronomicalattributesoftheEarthwill，evenbythemselves，suffice
　　forourpurpose。Considerfirsttheeffectsofitsrotation。Thereisthe
　　oblatenessofitsform;thereisthealternationofdayandnight;there
　　arecertainconstantmarinecurrents;andtherearecertainconstantaerial
　　currents。Considernextthesecondaryseriesofconsequencesduetothedivergence
　　oftheEarth'splaneofrotationfromtheplaneofitsorbit。Themanyvariations
　　oftheseasons，bothsimultaneousandsuccessive，whichpervadeitssurface，
　　arethuscaused。ExternalattractionoftheMoonandSunactingontheequatorial
　　protuberanceofthisrotatingspheroidwithinclinedaxis，producesthemotion
　　callednutation，andthatslowerandlargeronefromwhichfollowstheprecession
　　oftheequinoxes，withitsseveralsequences。Andthen，bythissameforce，aregeneratedthetides，aqueousandatmospheric。Perhaps，however，thesimplestwayofshowingthemultiplicationofeffects
　　amongphenomenaofthisorder，willbetosetdowntheinfluencesofany
　　memberoftheSolarSystemontherest。Aplanetdirectlyproducesinneighbouring
　　planetscertainappreciableperturbations，complicatingthoseotherwiseproduced
　　inthem;andintheremoterplanetsitdirectlyproducescertainlessvisible
　　perturbations。Hereisafirstseriesofeffects。Buteachoftheperturbed
　　planetsisitselfasourceofperturbations——eachdirectlyaffectsall
　　theothers。Hence，planetAhavingdrawnplanetBoutofthepositionit
　　wouldhaveoccupiedinA'sabsence，theperturbationswhichBcausesare
　　differentfromwhattheywouldelsehavebeen;andsimilarlywithC，D，E，
　　etc。Herethenisasecondaryseriesofeffects;farmorenumerousthough
　　farsmallerintheiramounts。Astheseindirectperturbationsmusttosome
　　extentmodifythemovementsofeachplanet，thereresultsfromthematertiary
　　series;andsooninevermultiplyinganddiminishingwavesthroughouttheentiresystem。§158。IftheEarthwasformedbytheconcentrationofdiffusedmatter，
　　itmustatfirsthavebeenincandescent;andwhetherthenebularhypothesis
　　beacceptedornot，thisoriginalincandescenceoftheEarthmaynowberegarded
　　asinductivelyestablished——or，ifnotestablished，atleastrenderedso
　　probablethatitisagenerallyadmittedgeologicaldoctrine。Severalresults
　　ofthegradualcoolingoftheEarth——astheformationofacrust，thesolidification
　　ofsublimedelements，theprecipitationofwater，etc。——havebeenalready
　　noticed，andIagainrefertothemmerelytopointoutthattheyaresimultaneous
　　effectsoftheonecause，diminishingheat。Letusnow，however，observe
　　themultipliedchangesafterwardsarisingfromthecontinuanceofthisone
　　cause。TheEarth，fallingintemperature，mustcontract。Hencethesolid
　　crustatanytimeexistingispresentlytoolargefortheshrinkingnucleus，
　　and，beingunabletosupportitself，inevitablyfollowsthenucleus。But
　　aspheroidalenvelopecannotsinkdownintocontactwithasmallerinternal
　　spheroid，withoutdisruption:itwillrunintowrinklesastherindofan
　　appledoeswhenthebulkofitsinteriordecreasesfromevaporation。Asthe
　　coolingprogressesandtheenvelopethickens，theridgesconsequentonthese
　　contractionsmustbecomegreater，risingultimatelyintohillsandmountains;
　　andthelatersystemsofmountainsthusproducedmustnotonlybehigher，
　　aswefindthemtobe，butmustbelonger，aswealsofindthemtobe。Thus，
　　leavingoutofviewothermodifyingforces，weseewhatimmenseheterogeneity
　　ofsurfacearisesfromtheonecause，lossofheat——aheterogeneitywhich
　　thetelescopeshowsustobeparalleledontheMoon，whereaqueousandatmospheric
　　agencieshavebeenabsent。Butwehaveyettonoticeanotherkindofheterogeneity
　　ofsurface，simultaneouslycaused。WhiletheEarth'scrustwasthin，the
　　ridgesproducedbyitscontractionsmustnotonlyhavebeensmallinheight
　　andlength，butthetractsbetweenthemmusthaverestedwithcomparative
　　smoothnessonthesubjacentliquidspheroid;andthewaterinthosearctic
　　andantarcticregionswhereitfirstcondensed，musthavebeenevenlydistributed。
　　Butasfastasthecrustgrewthickerandgainedcorrespondingstrength，
　　thelinesoffracturefromtimetotimecausedinit，occurredatgreater
　　distancesapart;theintermediatesurfacesfollowedthecontractingnucleus
　　withlessuniformity;andthereconsequentlyresultedlargerareasofland
　　andwater。Ifanyone，afterwrappinganorangeintissuepaperandobserving
　　bothhowsmallarethewrinklesand，howevenlytheinterveningspaceslie
　　onthesurfaceoftheorange，willthenwrapitinthickcartridge—paper，
　　andnoteboththegreaterheightoftheridgesandthelargerspacesthroughout
　　whichthepaperdoesnottouchtheorange，hewillseethatastheEarth's
　　solidenvelopethickened，theareasofelevationanddepressionbecamegreater。
　　Inplaceofislandsmoreorlesshomogeneouslyscatteredthroughoutanall—embracing
　　sea，theremusthavegraduallyarisenheterogeneousarrangementsofcontinent
　　andocean，suchaswenowknow。Thesesimultaneouschangesintheextent
　　andintheelevationofthelands，involvedyetanotherspeciesofheterogeneity
　　——thatofcoast—line。Atolerablyevensurfaceraisedoutoftheoceanwill
　　haveasimple，regularsea—margin;butasurfacevariedbytable—landsand
　　intersectedbymountain—chains，will，whenraisedoutoftheocean，have
　　anoutlineextremelyirregular，alikeinitsleadingfeaturesandinits
　　details。Thusendlessistheaccumulationofgeologicalandgeographical
　　resultsbroughtaboutbythisonecause——escapeoftheEarth'sprimitiveheat。Whenwepassfromtheagencywhichgeologiststermigneous，toaqueous
　　andatmosphericagencies，weseealikeever—growingcomplicationofeffects。
　　Thedenudingactionsofairandwaterhave，fromthebeginning，beenmodifying
　　everyexposedsurface:everywhereworkingmanydifferentchanges。Asalready
　　said（§69）theoriginalsourceofthosegaseousandfluidmotionswhich
　　effectdenudation，isthesolarheat。Thetransformationofthisintovarious
　　modesofenergy，accordingtothenatureandconditionsofthematteron
　　whichitfalls，isthefirststageofcomplication。TheSun'srays，striking
　　atallanglesaspherethatfrommomenttomomentpresentedandwithdrew
　　differentpartsofitssurface，andeachofthemforadifferenttimedaily
　　throughouttheyear，wouldproduceaconsiderablevarietyofchangeseven
　　werethesphereuniform。Butfallingastheydoonaspheresurroundedby
　　anatmospherecontainingwideareasofcloud，butwhichhereunveilsvast
　　tractsofsea，thereoflevelland，thereofmountains，thereofsnowand
　　ice，theycauseinitcountlessdifferentmovements。Currentsofairofall
　　sizes，directions，velocities，andtemperatures，aresetup;asarealso
　　marinecurrentssimilarlycontrastedintheircharacters。Inthisregion
　　thesurfaceisgivingoffvapour;inthat，dewisbeingprecipitated;and
　　inanother，rainisdescending——unlikenesseswhicharisefromthechanging
　　ratiobetweentheabsorptionandradiationofheatineachplace。Atone
　　hourarapidfallintemperatureleadstotheformationofice，withanaccompanying
　　expansionthroughoutthemoistbodiesfrozen;whileatanotherathawunlocks
　　thedislocatedfragmentsofthesebodies。Andthen，passingtoasecondstage
　　ofcomplication，weseethatthemanykindsofmotiondirectlyorindirectly
　　causedbytheSun'srays，severallyproduceresultswhichvarywiththeconditions。
　　Oxidation，drought，wind，frost，rain，glaciers，rivers，waves，andother
　　denudingagentseffectdisintegrationsthataredeterminedintheiramounts
　　andqualitiesbylocalcircumstances。Actingonatractofgranite，such
　　agentshereworkscarcelyanappreciableeffect;therecauseexfoliations
　　ofthesurfaceandaresultingheapofdebrisandboulders;andelsewhere，
　　afterdecomposingthefeldsparintoawhiteclay，carryawaythiswiththe
　　accompanyingquartzandmica，anddeposittheminseparatebeds，fluviatile
　　ormarine。Whentheexposedlandconsistsofseveralunlikeformations，sedimentary
　　andigneous，changesproportionatelymoreheterogeneousarewrought。The
　　formationsbeingdisintegrableindifferentdegrees，therefollowsanincreased
　　irregularityofsurface。Theareasdrainedbyadjacentriversbeingdifferently
　　constituted，theseriverscarrydowntotheseaunlikecombinationsofingredients;
　　andsosundrynewstrataofdistinctcompositionsarise。Andhere，indeed，
　　wemayseeveryclearlyhowtheheterogeneityoftheeffectsincreasesin
　　ageometricalprogressionwiththeheterogeneityoftheobjectactedupon。
　　Letus，forthefullerelucidationofthistruthinrelationtotheinorganic
　　world，considerwhatwouldfollowfromanextensivecosmicalcatastrophe
　　——sayagreatsubsidencethroughoutCentralAmerica。Theimmediateresults
　　wouldthemselvesbesufficientlycomplex。Besidesthenumberlessdislocations
　　ofstrata，theejectionsofigneousmatter，thepropagationofearthquake
　　vibrationsmanythousandsofmilesaround，theloudexplosions，andtheescape
　　ofgases，therewouldbeaninrushoftheAtlanticandPacificOceans，a
　　subsequentrecoilofenormouswaves，whichwouldtraverseboththeseoceans
　　andproducemyriadsofchangesalongtheirshores，andcorrespondingatmospheric
　　wavescomplicatedbythecurrentssurroundingeachvolcanicvent，aswell
　　aselectricaldischargeswithwhicheruptionsareaccompanied。Butthese
　　temporaryeffectswouldbeinsignificantcomparedwiththepermanentones。
　　ThecomplexcurrentsoftheAtlanticandPacificwouldbealteredintheir
　　directionsandamounts。Thedistributionofheatachievedbythesecurrents
　　wouldbedifferentfromwhatitis。Thearrangementoftheisothermallines，
　　notonlyontheneighbouringcontinentsbuteventhroughoutEurope，would
　　bechanged。Thetideswouldflowdifferentlyfromwhattheydonow。There
　　wouldbemoreorlessmodificationofthewindsintheirperiods，strengths，
　　directions，qualities;andrainwouldfallscarcelyanywhereatthesame
　　timesandinthesamequantitiesasatpresent。Inthesemanychanges，each
　　includingcountlessminorones，maybeseentheimmenseheterogeneityof
　　theresultswroughtoutbyoneforce，whenthatforceexpendsitselfona
　　previouslycomplicatedarea:theimplicationbeingthatfromthebeginningthecomplicationhasadvancedatanincreasingrate。§159。Wehavenexttotracethroughoutorganicevolution，thissame
　　all—pervadingprinciple。Andhere，wherethetransformationofthehomogeneous
　　intotheheterogeneouswasfirstobserved，theproductionofmanychanges
　　byonecauseisleasteasytodemonstrateinadirectway。Hereditycomplicateseverything。Nevertheless，byindirectevidencewemayestablishourproposition。Bywayofpreparationobservehownumerousarethechangeswhichanymarked
　　stimulusworksonanadultorganism——ahumanbeingforinstance。Analarming
　　soundorsight，besidesimpressionsontheorgansofsenseandthenerves，
　　mayproduceastart，ascream，adistortionoftheface，atremblingconsequent
　　ongeneralmuscularrelaxation，aburstofperspiration，andperhapsanarrest
　　oftheheartfollowedbysyncope;andifthesystembefeeble，anillness
　　withitslongtrainofcomplicatedsymptommaysetin。Similarlyincases
　　ofdisease。Aminuteportionofthesmall—poxvirustakenintothesystem
　　will，inaseverecase，cause，duringthefirststage，rigors，heatofskin，
　　acceleratedpulse，furredtongue，lossofappetite，thirst，epigastricuneasiness，
　　vomiting，headache，patsinthebackandlimbs，muscularweakness，convulsions，
　　delirium，etc。;inthesecondstage，cutaneouseruption，itching，tingling，
　　sorethroat，swelledfauces，salivation，cough，hoarseness，dyspnoea，etc。;
　　andinthethirdstage，oedematousinflammations，pneumonia，pleurisy，diarrhoea，
　　inflammationofthebrain，ophthalmia，erysipelas，etc。:eachofwhichenumerated
　　symptomsisitselfmoreorlesscomplex。Nowitneedsonlytoconsiderthat
　　thisworkingofmanychangesbyoneforceonanadultorganism，mustbepartially
　　paralleledinanembryo—organism，tounderstandthatinittootheremust
　　beamultiplicationofeffects，evertendingtoproduceincreasingheterogeneity。