第3章

Theabovequotationssumupprettywellthestatementsofallpreviouswriters。Furthermore，therearesomewritersonNaturalHistorywhohavenotventuredtolaydownthelawinsuchprecisetermsasregardstheveins，butwhoallalikeagreeinassigningtheheadandthebrainasthestarting-pointoftheveins。Andinthisopiniontheyaremistaken。

Theinvestigationofsuchasubject，ashasbeenremarked，isonefraughtwithdifficulties；but，ifanyonebekeenlyinterestedinthematter，hisbestplanwillbetoallowhisanimalstostarvetoemaciation，thentostranglethemonasudden，andthereupontoprosecutehisinvestigations。

Wenowproceedtogiveparticularsregardingthepropertiesandfunctionsoftheveins。Therearetwoblood-vesselsinthethoraxbythebackbone，andlyingtoitsinnerside；andofthesetwothelargeroneissituatedtothefront，andthelesseroneistotherearofit；

andthelargerissituatedrathertotherighthandsideofthebody，andthelesseronetotheleft；andbysomethisveinistermedthe\'aorta\'，fromthefactthatevenindeadbodiespartofitisobservedtobefullofair。Theseblood-vesselshavetheiroriginsintheheart，fortheytraversetheotherviscera，inwhateverdirectiontheyhappentorun，withoutinanywaylosingtheirdistinctivecharacteristicasblood-vessels，whereastheheartisasitwereapartofthem(andthattoomoreinrespecttothefrontwardandlargeroneofthetwo)，owingtothefactthatthesetwoveinsareaboveandbelow，withtheheartlyingmidway。

Theheartinallanimalshascavitiesinsideit。Inthecaseofthesmalleranimalseventhelargestofthechambersisscarcelydiscernible；thesecondlargerisscarcelydiscernibleinanimalsofmediumsize；butinthelargestanimalsallthreechambersaredistinctlyseen。Intheheartthen(withitspointedenddirectedfrontwards，ashasbeenobserved)thelargestofthethreechambersisontheright-handsideandhighestup；theleastoneisontheleft-handside；andthemedium-sizedoneliesinbetwixttheothertwo；andthelargestoneofthethreechambersisagreatdeallargerthaneitherofthetwoothers。Allthree，however，areconnectedwithpassagesleadinginthedirectionofthelung，butallthesecommunicationsareindistinctlydiscerniblebyreasonoftheirminuteness，exceptone。

Thegreatblood-vessel，then，isattachedtothebiggestofthethreechambers，theonethatliesuppermostandontheright-handside；itthenextendsrightthroughthechamber，comingoutasblood-vesselagain；justasthoughthecavityoftheheartwereapartofthevessel，inwhichthebloodbroadensitschannelasariverthatwidensoutinalake。Theaortaisattachedtothemiddlechamber；

only，bytheway，itisconnectedwithitbymuchnarrowerpipe。

Thegreatblood-vesselthenpassesthroughtheheart(andrunsfromtheheartintotheaorta)。Thegreatvessellooksasthoughmadeofmembraneorskin，whiletheaortaisnarrowerthanit，andisverysinewy；andasitstretchesawaytotheheadandtothelowerpartsitbecomesexceedinglynarrowandsinewy。

Firstofall，then，upwardsfromthehearttherestretchesapartofthegreatblood-vesseltowardsthelungandtheattachmentoftheaorta，apartconsistingofalargeundividedvessel。Buttheresplitofffromittwoparts；onetowardsthelungandtheothertowardsthebackboneandthelastvertebraoftheneck。

Thevessel，then，thatextendstothelung，asthelungitselfisduplicate，dividesatfirstintotwo；andthenextendsalongbyeverypipeandeveryperforation，greateralongthegreaterones，lesseralongtheless，socontinuouslythatitisimpossibletodiscernasinglepartwhereinthereisnotperforationandvein；fortheextremitiesareindistinguishablefromtheirminuteness，andinpointoffactthewholelungappearstobefilledwithblood。

Thebranchesoftheblood-vesselslieabovethetubesthatextendfromthewindpipe。Andthatvesselwhichextendstothevertebraoftheneckandthebackbone，stretchesbackagainalongthebackbone；asHomerrepresentsinthelines:-

(Antilochus，asThoonturnedhimround)，Transpierc\'dhisbackwithadishonestwound；

Thehollowveinthattotheneckextends，Alongthechine，theeagerjavelinrends。

Fromthisvesselthereextendsmallblood-vesselsateachribandeachvertebra；andatthevertebraabovethekidneysthevesselbifurcates。Andintheabovewaythepartsbranchofffromthegreatblood-vessel。

Butupaboveallthese，fromthatpartwhichisconnectedwiththeheart，theentireveinbranchesoffintwodirections。Foritsbranchesextendtothesidesandtothecollarbones，andthenpasson，inmenthroughthearmpitstothearms，inquadrupedstotheforelegs，inbirdstothewings，andinfishestotheupperorpectoralfins。

(Seediagram。)Thetrunksoftheseveins，wheretheyfirstbranchoff，arecalledthe\'jugular\'veins；and，wheretheybranchofftotheneckthegreatveinrunalongsidethewindpipe；and，occasionally，iftheseveinsarepressedexternally，men，thoughnotactuallychoked，becomeinsensible，shuttheireyes，andfallflatontheground。Extendinginthewaydescribedandkeepingthewindpipeinbetwixtthem，theypassonuntiltheyreachtheearsatthejunctionofthelowerjawwiththeskull。Henceagaintheybranchoffintofourveins，ofwhichonebendsbackanddescendsthroughtheneckandtheshoulder，andmeetsthepreviousbranchingoffoftheveinatthebendofthearm，whiletherestofitterminatesatthehandandfingers。(Seediagram。)

Eachveinoftheotherpairstretchesfromtheregionoftheeartothebrain，andbranchesoffinanumberoffineanddelicateveinsintotheso-calledmeninx，ormembrane，whichsurroundsthebrain。Thebrainitselfinallanimalsisdestituteofblood，andnovein，greatorsmall，holdsitscoursetherein。Butoftheremainingveinsthatbranchofffromthelastmentionedveinsomeenvelopthehead，othersclosetheircoursesintheorgansofsenseandattherootsoftheteethinveinsexceedinglyfineandminute。

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Andinlikemannerthepartsofthelesseroneofthetwochiefblood-vessels，designatedtheaorta，branchoff，accompanyingthebranchesfromthebigvein；onlythat，inregardtotheaorta，thepassagesarelessinsize，andthebranchesveryconsiderablylessthanarethoseofthegreatvein。Somuchfortheveinsasobservedintheregionsabovetheheart。

Thepartofthegreatveinthatliesunderneaththeheartextends，freelysuspended，rightthroughthemidriff，andisunitedbothtotheaortaandthebackbonebyslackmembranouscommunications。

Fromitonevein，shortandwide，extendsthroughtheliver，andfromitanumberofminuteveinsbranchoffintotheliveranddisappear。Fromtheveinthatpassesthroughthelivertwobranchesseparateoff，ofwhichoneterminatesinthediaphragmorso-calledmidriff，andtheotherrunsupagainthroughthearmpitintotherightarmanduniteswiththeotherveinsattheinsideofthebendofthearm；anditisinconsequenceofthislocalconnexionthat，whenthesurgeonopensthisveinintheforearm，thepatientisrelievedofcertainpainsintheliver；andfromtheleft-handsideofitthereextendsashortbutthickveintothespleenandthelittleveinsbranchingoffitdisappearinthatorgan。Anotherpartbranchesofffromtheleft-handsideofthegreatvein，andascends，byacoursesimilartothecourserecentlydescribed，intotheleftarm；onlythattheascendingveinintheonecaseistheveinthattraversestheliver，whileinthiscaseitisdistinctfromtheveinthatrunsintothespleen。Again，otherveinsbranchofffromthebigvein；

onetotheomentum，andanothertothepancreas，fromwhichveinrunanumberofveinsthroughthemesentery。Alltheseveinscoalesceinasinglelargevein，alongtheentiregutandstomachtotheoesophagus；

aboutthesepartsthereisagreatramificationofbranchveins。

Asfarasthekidneys，eachofthetworemainingundivided，theaortaandthebigveinextend；andheretheygetmorecloselyattachedtothebackbone，andbranchoff，eachofthetwo，intoaAshape，andthebigveingetstotherearoftheaorta。Butthechiefattachmentoftheaortatothebackbonetakesplaceintheregionoftheheart；andtheattachmentiseffectedbymeansofminuteandsinewyvessels。Theaorta，justasitdrawsofffromtheheart，isatubeofconsiderablevolume，but，asitadvancesinitscourse，itgetsnarrowerandmoresinewy。Andfromtheaortathereextendveinstothemesenteryjustliketheveinsthatextendthitherfromthebigvein，onlythatthebranchesinthecaseoftheaortaareconsiderablylessinmagnitude；theyare，indeed，narrowandfibrillar，andtheyendindelicatehollowfibre-likeveinlets。

Thereisnovesselthatrunsfromtheaortaintotheliverorthespleen。

Fromeachofthetwogreatblood-vesselsthereextendbranchestoeachofthetwoflanks，andbothbranchesfastenontothebone。

Vesselsalsoextendtothekidneysfromthebigveinandtheaorta；

onlythattheydonotopenintothecavityoftheorgan，buttheirramificationspenetrateintoitssubstance。Fromtheaortaruntwootherductstothebladder，firmandcontinuous；andthereareotherductsfromthehollowofthekidneys，innowaycommunicatingwiththebigvein。Fromthecentreofeachofthetwokidneysspringsahollowsinewyvein，runningalongthebackbonerightthroughtheloins；byandbyeachofthetwoveinsfirstdisappearsinitsownflank，andsoonafterwardsreappearsstretchinginthedirectionoftheflank。Theextremitiesoftheseattachtothebladder，andalsointhemaletothepenisandinthefemaletothewomb。Fromthebigveinnoveinextendstothewomb，buttheorganisconnectedwiththeaortabyveinsnumerousandcloselypacked。

Furthermore，fromtheaortaandthegreatveinatthepointsofdivaricationtherebranchoffotherveins。Someoftheseruntothegroins-largehollowveins-andthenpassondownthroughthelegsandterminateinthefeetandtoes。And，again，anothersetrunthroughthegroinsandthethighscross-garterfashion，fromrighttoleftandfromlefttoright，anduniteinthehamswiththeotherveins。

Intheabovedescriptionwehavethrownlightuponthecourseoftheveinsandtheirpointsofdeparture。

Inallsanguineousanimalsthecasestandsasheresetforthinregardtothepointsofdepartureandthecoursesofthechiefveins。Butthedescriptiondoesnotholdequallygoodfortheentirevein-systeminalltheseanimals。For，inpointoffact，theorgansarenotidenticallysituatedinthemall；and，whatismore，someanimalsarefurnishedwithorgansofwhichotheranimalsaredestitute。Atthesametime，whilethedescriptionsofarholdsgood，theproofofitsaccuracyisnotequallyeasyinallcases，butiseasiestinthecaseofanimalsofconsiderablemagnitudeandsuppliedabundantlywithblood。Forinlittleanimalsandthosescantilysuppliedwithblood，eitherfromnaturalandinherentcausesorfromaprevalenceoffatinthebody，thoroughaccuracyininvestigationisnotequallyattainable；forinthelatterofthesecreaturesthepassagesgetclogged，likewater-channelschokedwithslush；andtheothershaveafewminutefibrestoserveinsteadofveins。Butinallcasesthebigveinisplainlydiscernible，evenincreaturesofinsignificantsize。

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Thesinewsofanimalshavethefollowingproperties。Forthesealsothepointoforiginistheheart；forthehearthassinewswithinitselfinthelargestofitsthreechambers，andtheaortaisasinew-likevein；infact，atitsextremityitisactuallyasinew，foritistherenolongerhollow，andisstretchedlikethesinewswheretheyterminateatthejointingsofthebones。Beitremembered，however，thatthesinewsdonotproceedinunbrokensequencefromonepointoforigin，asdotheblood-vessels。

Fortheveinshavetheshapeoftheentirebody，likeasketchofamannikin；insuchawaythatthewholeframeseemstobefilledupwithlittleveinsinattenuatedsubjects-forthespaceoccupiedbyfleshinfatindividualsisfilledwithlittleveinsinthinones-whereasthesinewsaredistributedaboutthejointsandtheflexuresofthebones。Now，ifthesinewswerederivedinunbrokensequencefromacommonpointofdeparture，thiscontinuitywouldbediscernibleinattenuatedspecimens。

Intheham，orthepartoftheframebroughtintofullplayintheeffortofleaping，isanimportantsystemofsinews；andanothersinew，adoubleone，isthatcalled\'thetendon\'，andothersarethosebroughtintoplaywhenagreateffortofphysicalstrengthisrequired；thatistosay，theepitonosorback-stayandtheshoulder-sinews。Othersinews，devoidofspecificdesignation，aresituatedintheregionoftheflexuresofthebones；forallthebonesthatareattachedtooneanotherareboundtogetherbysinews，andagreatquantityofsinewsareplacedintheneighbourhoodofallthebones。Only，bytheway，intheheadthereisnosinew；buttheheadisheldtogetherbythesuturesofthebones。

Sinewisfissilelengthwise，butcrosswiseitisnoteasilybroken，butadmitsofaconsiderableamountofhardtension。Inconnexionwithsinewsaliquidmucusisdeveloped，whiteandglutinous，andtheorgan，infact，issustainedbyitandappearstobesubstantiallycomposedofit。Now，veinmaybesubmittedtotheactualcautery，butsinew，whensubmittedtosuchaction，shrivelsupaltogether；and，ifsinewsbecutasunder，theseveredpartswillnotagaincohere。Afeelingofnumbnessisincidentalonlytopartsoftheframewheresinewissituated。

Thereisaveryextensivesystemofsinewsconnectedseverallywiththefeet，thehands，theribs，theshoulder-blades，theneck，andthearms。

Allanimalssuppliedwithbloodarefurnishedwithsinews；butinthecaseofanimalsthathavenoflexurestotheirlimbs，butare，infact，destituteofeitherfeetorhands，thesinewsarefineandinconspicuous；andso，asmighthavebeenanticipated，thesinewsinthefisharechieflydiscernibleinconnexionwiththefin。

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Theines(orfibrousconnectivetissue)areasomethingintermediatebetweensinewandvein。Someofthemaresuppliedwithfluid，thelymph；andtheypassfromsinewtoveinandfromveintosinew。Thereisanotherkindofinesorfibrethatisfoundinblood，butnotinthebloodofallanimalsalike。Ifthisfibrebeleftintheblood，thebloodwillcoagulate；ifitberemovedorextracted，thebloodisfoundtobeincapableofcoagulation。While，however，thisfibrousmatterisfoundinthebloodofthegreatmajorityofanimals，itisnotfoundinall。Forinstance，wefailtofinditinthebloodofthedeer，theroe，theantelope，andsomeotheranimals；and，owingtothisdeficiencyofthefibroustissue，thebloodoftheseanimalsdoesnotcoagulatetotheextentobservedinthebloodofotheranimals。Thebloodofthedeercoagulatestoaboutthesameextentasthatofthehare:thatistothebloodineithercasecoagulates，butnotintoastifforjelly-likesubstance，likethebloodofordinaryanimals，butonlyintoaflaccidconsistencylikethatofmilkwhichisnotsubjectedtotheactionofrennet。Thebloodoftheantelopeadmitsofafirmerconsistencyincoagulation；forinthisrespectitresembles，oronlycomesalittleshortof，thebloodofsheep。Sucharethepropertiesofvein，sinew，andfibroustissue。

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Thebonesinanimalsareallconnectedwithonesinglebone，andareinterconnected，liketheveins，inoneunbrokensequence；andthereisnoinstanceofabonestandingapartbyitself。Inallanimalsfurnishedwithbones，thespineorbackboneisthepointoforiginfortheentireosseoussystem。Thespineiscomposedofvertebrae，anditextendsfromtheheaddowntotheloins。Thevertebraeareallperforated，and，above，thebonyportionoftheheadisconnectedwiththetopmostvertebrae，andisdesignatedthe\'skull\'。Andtheserratedlinesontheskullaretermed\'sutures\'。

Theskullisnotformedalikeinallanimals。Insomeanimalstheskullconsistsofonesingleundividedbone，asinthecaseofthedog；inothersitiscompositeinstructure，asinman；andinthehumanspeciesthesutureiscircularinthefemale，whileinthemaleitismadeupofthreeseparatesutures，unitingaboveinthree-cornerfashion；andinstanceshavebeenknownofaman\'sskullbeingdevoidofsuturealtogether。Theskulliscomposednotoffourbones，butofsix；twooftheseareintheregionoftheears，smallincomparisonwiththeotherfour。Fromtheskullextendthejaws，constitutedofbone。(Animalsingeneralmovethelowerjaw；therivercrocodileistheonlyanimalthatmovestheupperone。)Inthejawsisthetooth-system；andtheteethareconstitutedofbone，andarehalf-wayperforated；andtheboneinquestionistheonlykindofbonewhichitisfoundimpossibletogravewithagravingtool。

Ontheupperpartofthecourseofthebackbonearethecollar-bonesandtheribs。Thechestrestsonribs；andtheseribsmeettogether，whereastheothersdonot；fornoanimalhasboneintheregionofthestomach。Thencometheshoulder-bones，orblade-bones，andthearm-bonesconnectedwiththese，andthebonesinthehandsconnectedwiththebonesofthearms。Withanimalsthathaveforelegs，theosseoussystemoftheforelegresemblesthatofthearminman。

Belowthelevelofthebackbone，afterthehaunch-bone，comesthehip-socket；thentheleg-bones，thoseinthethighsandthoseintheshins，whicharetermedcolenesorlimb-bones，apartofwhichistheankle，whileapartofthesameistheso-called\'plectrum\'

inthosecreaturesthathaveanankle；andconnectedwiththesebonesarethebonesinthefeet。

Now，withallanimalsthataresuppliedwithbloodandfurnishedwithfeet，andareatthesametimeviviparous，thebonesdonotdiffergreatlyonefromanother，butonlyinthewayofrelativehardness，softness，ormagnitude。Afurtherdifference，bytheway，isthatinoneandthesameanimalcertainbonesaresuppliedwithmarrow，whileothersaredestituteofit。Someanimalsmightoncasualobservationappeartohavenomarrowwhatsoeverintheirbones:asisthecasewiththelion，owingtohishavingmarrowonlyinsmallamount，poorandthin，andinveryfewbones；formarrowisfoundinhisthighandarmbones。Thebonesofthelionareexceptionallyhard；sohard，infact，thatiftheyarerubbedhardagainstoneanothertheyemitsparkslikeflint-stones。Thedolphinhasbones，andnotfish-spine。

Oftheotheranimalssuppliedwithblood，somedifferbutlittle，asisthecasewithbirds；othershavesystemsanalogous，asfishes；forviviparousfishes，suchasthecartilaginousspecies，aregristle-spined，whiletheoviparahaveaspinewhichcorrespondstothebackboneinquadrupeds。Thisexceptionalpropertyhasbeenobservedinfishes，thatinsomeofthemtherearefounddelicatespinesscatteredhereandtherethroughoutthefleshyparts。Theserpentissimilarlyconstructedtothefish；inotherwords，hisbackboneisspinous。Withoviparousquadrupeds，theskeletonofthelargeronesismoreorlessosseous；ofthesmallerones，moreorlessspinous。Butallsanguineousanimalshaveabackboneofeitheronekindorother:thatis，composedeitherofboneorofspine。

Theotherportionsoftheskeletonarefoundinsomeanimalsandnotfoundinothers，butthepresenceortheabsenceofthisandthatpartcarrieswithit，asamatterofcourse，thepresenceortheabsenceofthebonesorthespinescorrespondingtothisorthatpart。Foranimalsthataredestituteofarmsandlegscannotbefurnishedwithlimb-bones:andinlikemannerwithanimalsthathavethesameparts，butyethavethemunlikeinform；forintheseanimalsthecorrespondingbonesdifferfromoneanotherinthewayofrelativeexcessorrelativedefect，orinthewayofanalogytakingtheplaceofidentity。Somuchfortheosseousorspinoussystemsinanimals。

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Gristleisofthesamenatureasbone，butdiffersfromitinthewayofrelativeexcessorrelativedefect。Andjustlikebone，cartilagealso，ifcut，doesnotgrowagain。Interrestrialviviparoussanguineathegristleformationsareunperforated，andthereisnomarrowinthemasthereisinbones；intheselachia，however——for，beitobserved，theyaregristle-spined——thereisfoundinthecaseoftheflatspaceintheregionofthebackbone，agristle-likesubstanceanalogoustobone，andinthisgristle-likesubstancethereisaliquidresemblingmarrow。Inviviparousanimalsfurnishedwithfeet，gristleformationsarefoundintheregionoftheears，inthenostrils，andaroundcertainextremitiesofthebones。

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Furthermore，therearepartsofotherkinds，neitheridenticalwith，noraltogetherdiversefrom，thepartsaboveenumerated:suchasnails，hooves，claws，andhorns；andalso，bytheway，beaks，suchasbirdsarefurnishedwith-allintheseveralanimalsthatarefurnishedtherewithal。Allthesepartsareflexibleandfissile；butboneisneitherflexiblenorfissile，butfrangible。

Andthecoloursofhornsandnailsandclawandhooffollowthecolouroftheskinandthehair。Foraccordingastheskinofananimalisblack，orwhite，orofmediumhue，soarethehorns，theclaws，orthehooves，asthecasemaybe，ofhuetomatch。Anditisthesamewithnails。Theteeth，however，followafterthebones。

Thusinblackmen，suchastheAethiopiansandthelike，theteethandbonesarewhite，butthenailsareblack，likethewholeoftheskin。

Hornsingeneralarehollowattheirpointofattachmenttothebonewhichjutsoutfromtheheadinsidethehorn，buttheyhaveasolidportionatthetip，andtheyaresimpleandundividedinstructure。Inthecaseofthestagaloneofallanimalsthehornsaresolidthroughout，andramifyintobranches(orantlers)。And，whereasnootheranimalisknowntosheditshorns，thedeershedsitshornsannually，unlessithasbeencastrated；andwithregardtotheeffectsofcastrationinanimalsweshallhavemuchtosayhereafter。Hornsattachrathertotheskinthantothebone；whichwillaccountforthefactthattherearefoundinPhrygiaandelsewherecattlethatcanmovetheirhornsasfreelyastheirears。

Ofanimalsfurnishedwithnails-and，bytheway，allanimalshavenailsthathavetoes，andtoesthathavefeet，excepttheelephant；andtheelephanthastoesundividedandslightlyarticulated，buthasnonailswhatsoever——ofanimalsfurnishedwithnails，somearestraight-nailed，likeman；othersarecrookednailed，asthelionamonganimalsthatwalk，andtheeagleamonganimalsthatfly。

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Thefollowingarethepropertiesofhairandofpartsanalogoustohair，andofskinorhide。Allviviparousanimalsfurnishedwithfeethavehair；alloviparousanimalsfurnishedwithfeethavehorn-liketessellates；fishes，andfishesonly，havescales-thatis，suchoviparousfishesashavethecrumblingeggorroe。Forofthelankyfishes，thecongerhasnosuchegg，northemuraena，andtheeelhasnoeggatall。

Thehairdiffersinthewayofthicknessandfineness，andoflength，accordingtothelocalityofthepartinwhichitisfound，andaccordingtothequalityofskinorhideonwhichitgrows。For，asageneralrule，thethickerthehide，theharderandthethickeristhehair；andthehairisinclinedtogrowinabundanceandtoagreatlengthinlocalitiesofthebodieshollowandmoist，ifthelocalitiesbefittedforthegrowthofhairatall。Thefactsaresimilarinthecaseofanimalswhethercoatedwithscalesorwithtessellates。

Withsoft-hairedanimalsthehairgetsharderwithgoodfeeding，andwithhard-hairedorbristlyanimalsitgetssofterandscantierfromthesamecause。Hairdiffersinqualityalsoaccordingtotherelativeheatorwarmthofthelocality:justasthehairinmanishardinwarmplacesandsoftincoldones。Again，straighthairisinclinedtobesoft，andcurlyhairtobebristly。

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Hairisnaturallyfissile，andinthisrespectitdiffersindegreeindiverseanimals。Insomeanimalsthehairgoesongraduallyhardeningintobristleuntilitnolongerresembleshairbutspine，asinthecaseofthehedgehog。Andinlikemannerwiththenails；forinsomeanimalsthenaildiffersasregardssolidityinnowayfrombone。

Ofallanimalsmanhasthemostdelicateskin:thatis，ifwetakeintoconsiderationhisrelativesize。Intheskinorhideofallanimalsthereisamucousliquid，scantyinsomeanimalsandplentifulinothers，as，forinstance，inthehideoftheox；formenmanufactureglueoutofit。(And，bytheway，insomecasesglueismanufacturedfromfishesalso。)Theskin，whencut，isinitselfdevoidofsensation；andthisisespeciallythecasewiththeskinonthehead，owingtotherebeingnofleshbetweenitandtheskull。

Andwherevertheskinisquitebyitself，ifitbecutasunder，itdoesnotgrowtogetheragain，asisseeninthethinpartofthejaw，intheprepuce，andtheeyelid。Inallanimalstheskinisoneofthepartsthatextendscontinuousandunbroken，anditcomestoastoponlywherethenaturalductspourouttheircontents，andatthemouthandnails。

Allsanguineousanimals，then，haveskin；butnotallsuchanimalshavehair，saveonlyunderthecircumstancesdescribedabove。Thehairchangesitscolourasanimalsgrowold，andinmanitturnswhiteorgrey。Withanimals，ingeneral，thechangetakesplace，butnotveryobviously，ornotsoobviouslyasinthecaseofthehorse。Hairturnsgreyfromthepointbackwardstotheroots。But，inthemajorityofcases，greyhairsarewhitefromthebeginning；andthisisaproofthatgreynessofhairdoesnot，assomebelievetobethecase，implywitheringordecrepitude，fornopartisbroughtintoexistenceinawitheredordecrepitcondition。

Intheeruptivemaladycalledthewhite-sicknessallthehairsgetgrey；andinstanceshavebeenknownwherethehairbecamegreywhilethepatientswereillofthemalady，whereasthegreyhairsshedoffandblackonesreplacedthemontheirrecovery。(Hairismoreapttoturngreywhenitiskeptcoveredthanwhenexposedtotheactionoftheouterair。)Inmen，thehairoverthetemplesisthefirsttoturngrey，andthehairinthefrontgrowsgreysoonerthanthehairattheback；andthehaironthepubesisthelasttochangecolour。

Somehairsarecongenital，othersgrowafterthematurityoftheanimal；butthisoccursinmanonly。Thecongenitalhairsareonthehead，theeyelids，andtheeyebrows；ofthelatergrowthsthehairsonthepubesarethefirsttocome，thenthoseunderthearmpits，and，thirdly，thoseonthechin；for，singularlyenough，theregionswherecongenitalgrowthsandthesubsequentgrowthsarefoundareequalinnumber。Thehairontheheadgrowsscantyandshedsouttoagreaterextentandsoonerthanalltherest。Butthisremarkappliesonlytohairinfront；fornomanevergetsbaldatthebackofhishead。Smoothnessonthetopoftheheadistermed\'baldness\'，butsmoothnessontheeyebrowsisdenotedbyaspecialtermwhichmeans\'forehead-baldness\'；andneitheroftheseconditionsofbaldnesssupervenesinamanuntilheshallhavecomeundertheinfluenceofsexualpassion。Fornoboyevergetsbald，nowoman，andnocastratedman。Infact，ifamanbecastratedbeforereachingpuberty，thelatergrowthsofhairnevercomeatall；and，iftheoperationtakeplacesubsequently，theaftergrowths，andtheseonly，shedoff；

or，rather，twoofthegrowthsshedoff，butnotthatonthepubes。

Womendonotgrowhairsonthechin；exceptthatascantybeardgrowsonsomewomenafterthemonthlycourseshavestopped；andsimilarphenomenonisobservedattimesinpriestessesinCaria，butthesecasesarelookeduponasportentouswithregardtocomingevents。Theotherafter-growthsarefoundinwomen，butmorescantyandsparse。Menandwomenareattimesbornconstitutionallyandcongenitallyincapableoftheafter-growths；andindividualsthataredestituteevenofthegrowthuponthepubesareconstitutionallyimpotent。

Hairasarulegrowsmoreorlessinlengthasthewearergrowsinage；chieflythehaironthehead，thenthatinthebeard，andfinehairgrowslongestofall。Withsomepeopleastheygrowoldtheeyebrowsgrowthicker，tosuchanextentthattheyhavetobecutoff；

andthisgrowthisowingtothefactthattheeyebrowsaresituatedataconjunctureofbones，andthesebones，asagecomeson，drawapartandexudeagradualincreaseofmoistureorrheum。Theeyelashesdonotgrowinsize，buttheyshedwhenthewearercomesfirstundertheinfluenceofsexualfeelings，andshedallthequickerasthisinfluenceisthemorepowerful；andthesearethelasthairstogrowgrey。

Hairsifpluckedoutbeforematuritygrowagain；buttheydonotgrowagainifpluckedoutafterwards。Everyhairissuppliedwithamucousmoistureatitsroot，andimmediatelyafterbeingpluckedoutitcanliftlightarticlesifittouchthemwiththismucus。

Animalsthatadmitofdiversityofcolourinthehairadmitofasimilardiversitytostartwithintheskinandinthecuticleofthetongue。

Insomecasesamongmentheupperlipandthechinisthicklycoveredwithhair，andinothercasesthesepartsaresmoothandthecheeksarehairy；and，bytheway，smooth-chinnedmenarelessinclinedthanbeardedmentobaldness。

Thehairisinclinedtogrowincertaindiseases，especiallyinconsumption，andinoldage，andafterdeath；andunderthesecircumstancesthehairhardensconcomitantlywithitsgrowth，andthesameduplicatephenomenonisobservableinrespectofthenails。

Inthecaseofmenofstrongsexualpassionsthecongenitalhairsshedthesooner，whilethehairsoftheafter-growthsarethequickertocome。Whenmenareafflictedwithvaricoseveinstheyarelessinclinedtotakeonbaldness；andiftheybebaldwhentheybecomethusafflicted，theyhaveatendencytogettheirhairagain。

Ifahairbecut，itdoesnotgrowatthepointofsection；butitgetslongerbygrowingupwardfrombelow。Infishesthescalesgrowharderandthickerwithage，andwhentheamimalgetsemaciatedorisgrowingoldthescalesgrowharder。Inquadrupedsastheygrowoldthehairinsomeandthewoolinothersgetsdeeperbutscantierinamount:andthehoovesorclawsgetlargerinsize；andthesameisthecasewiththebeaksofbirds。Theclawsalsoincreaseinsize，asdoalsothenails。

12

Withregardtowingedanimals，suchasbirds，nocreatureisliabletochangeofcolourbyreasonofage，exceptingthecrane。

Thewingsofthisbirdareash-colouredatfirst，butasitgrowsoldthewingsgetblack。Again，owingtospecialclimaticinfluences，aswhenunusualfrostprevails，achangeissometimesobservedtotakeplaceinbirdswhoseplumageisofoneuniformcolour；thus，birdsthathaveduskyordownrightblackplumageturnwhiteorgrey，astheraven，thesparrow，andtheswallow；butnocasehaseveryetbeenknownofachangeofcolourfromwhitetoblack。

(Further，mostbirdschangethecolouroftheirplumageatdifferentseasonsoftheyear，somuchsothatamanignorantoftheirhabitsmightbemistakenastotheiridentity。)Someanimalschangethecolouroftheirhairwithachangeintheirdrinking-water，forinsomecountriesthesamespeciesofanimalisfoundwhiteinonedistrictandblackinanother。Andinregardtothecommerceofthesexes，waterinmanyplacesisofsuchpeculiarqualitythatrams，iftheyhaveintercoursewiththefemaleafterdrinkingit，begetblacklambs，asisthecasewiththewaterofthePsychrus(so-calledfromitscoldness)，ariverinthedistrictofAssyritisintheChalcidicPeninsula，onthecoastofThrace；andinAntandriatherearetworiversofwhichonemakesthelambswhiteandtheotherblack。TheriverScamanderalsohasthereputationofmakinglambsyellow，andthatisthereason，theysay，whyHomerdesignatesitthe\'YellowRiver。\'Animalsasageneralrulehavenohairontheirinternalsurfaces，and，inregardtotheirextremities，theyhavehairontheupper，butnotonthelowerside。

Thehare，ordasypod，istheonlyanimalknowntohavehairinsideitsmouthandunderneathitsfeet。Further，theso-calledmousewhaleinsteadofteethhashairsinitsmouthresemblingpigs\'bristles。

Hairsafterbeingcutgrowatthebottombutnotatthetop；iffeathersbecutoff，theygrowneitherattopnorbottom，butshedandfallout。Further，thebee\'swingwillnotgrowagainafterbeingpluckedoff，norwillthewingofanycreaturethathasundividedwings。Neitherwillthestinggrowagainifthebeeloseit，butthecreaturewilldieoftheloss。

13

Inallsanguineousanimalsmembranesarefound。Andmembraneresemblesathinclose-texturedskin，butitsqualitiesaredifferent，asitadmitsneitherofcleavagenorofextension。Membraneenvelopseachoneofthebonesandeachoneoftheviscera，bothinthelargerandthesmalleranimals；thoughinthesmalleranimalsthemembranesareindiscerniblefromtheirextremetenuityandminuteness。

Thelargestofallthemembranesarethetwothatsurroundthebrain，andofthesetwotheonethatlinesthebonyskullisstrongerandthickerthantheonethatenvelopsthebrain；nextinorderofmagnitudecomesthemembranethatenclosestheheart。Ifmembranebebaredandcutasunderitwillnotgrowtogetheragain，andthebonethusstrippedofitsmembranemortifies。

14

Theomentumorcaul，bytheway，ismembrane。Allsanguineousanimalsarefurnishedwiththisorgan；butinsomeanimalstheorganissuppliedwithfat，andinothersitisdevoidofit。Theomentumhasbothitsstarting-pointanditsattachment，withambidentalvivipara，inthecentreofthestomach，wherethestomachhasakindofsuture；innon-ambidentalviviparaithasitsstarting-pointandattachmentinthechiefoftheruminatingstomachs。

15

Thebladderalsoisofthenatureofmembrane，butofmembranepeculiarinkind，foritisextensile。Theorganisnotcommontoallanimals，but，whileitisfoundinallthevivipara，thetortoiseistheonlyoviparousanimalthatisfurnishedtherewithal。

Thebladder，likeordinarymembrane，ifcutasunderwillnotgrowtogetheragain，unlessthesectionbejustatthecommencementoftheurethra:exceptindeedinveryrarecases，forinstancesofhealinghavebeenknowntooccur。Afterdeath，theorganpassesnoliquidexcretion；butinlife，inadditiontothenormalliquidexcretion，itpassesattimesdryexcretionalso，whichturnsintostonesinthecaseofsufferersfromthatmalady。Indeed，instanceshavebeenknownofconcretionsinthebladdersoshapedascloselytoresemblecockleshells。

Sucharetheproperties，then，ofvein，sinewandskin，offibreandmembrane，ofhair，nail，clawandhoof，ofhorns，ofteeth，ofbeak，ofgristle，ofbones，andofpartsthatareanalogoustoanyofthepartshereenumerated。

16

Flesh，andthatwhichisbynatureakintoitinsanguineousanimals，isinallcasessituatedinbetweentheskinandthebone，orthesubstanceanalogoustobone；forjustasspineisacounterpartofbone，soistheflesh-likesubstanceofanimalsthatareconstructedaspinoussystemthecounterpartofthefleshofanimalsconstructedonanosseousone。

Fleshcanbedividedasunderinanydirection，notlengthwiseonlyasisthecasewithsinewandvein。Whenanimalsaresubjectedtoemaciationthefleshdisappears，andthecreaturesbecomeamassofveinsandfibres；whentheyareoverfed，fattakestheplaceofflesh。Wherethefleshisabundantinananimal，itsveinsaresomewhatsmallandthebloodabnormallyred；thevisceraalsoandthestomacharediminutive；whereaswithanimalswhoseveinsarelargethebloodissomewhatblack，thevisceraandthestomacharelarge，andthefleshissomewhatscanty。Andanimalswithsmallstomachsaredisposedtotakeonflesh。

17

Again，fatandsuetdifferfromoneanother。Suetisfrangibleinalldirectionsandcongealsifsubjectedtoextremecold，whereasfatcanmeltbutcannotfreezeorcongeal；andsoupsmadeofthefleshofanimalssuppliedwithfatdonotcongealorcoagulate，asisfoundwithhorse-fleshandpork；butsoupsmadefromthefleshofanimalssuppliedwithsuetdocoagulate，asisseenwithmuttonandgoat\'sflesh。Further，fatandsuetdifferastotheirlocalities:forfatisfoundbetweentheskinandflesh，butsuetisfoundonlyatthelimitofthefleshyparts。Also，inanimalssuppliedwithfattheomentumorcaulissuppliedwithfat，anditissuppliedwithsuetinanimalssuppliedwithsuet。Moreover，ambidentalanimalsaresuppliedwithfat，andnon-ambidentalswithsuet。

Ofthevisceratheliverinsomeanimalsbecomesfatty，as，amongfishes，isthecasewiththeselachia，bythemeltingofwhoseliversanoilismanufactured。Thesecartilaginousfishthemselveshavenofreefatatallinconnexionwiththefleshorwiththestomach。Thesuetinfishisfatty，anddoesnotsolidifyorcongeal。Allanimalsarefurnishedwithfat，eitherintermingledwiththeirflesh，orapart。Suchashavenofreeorseparatefatarelessfatthanothersinstomachandomentum，astheeel；forithasonlyascantysupplyofsuetabouttheomentum。Mostanimalstakeonfatinthebelly，especiallysuchanimalsasarelittleinmotion。

Thebrainsofanimalssuppliedwithfatareoily，asinthepig；

ofanimalssuppliedwithsuet，parchedanddry。Butitisaboutthekidneysmorethananyotherviscerathatanimalsareinclinedtotakeonfat；andtherightkidneyisalwayslesssuppliedwithfatthantheleftkidney，and，bethetwokidneyseversofat，thereisalwaysaspacedevoidoffatinbetweenthetwo。Animalssuppliedwithsuetarespeciallyapttohaveitaboutthekidneys，andespeciallythesheep；forthisanimalisapttodiefromitskidneysbeingentirelyenveloped。Fatorsuetaboutthekidneyissuperinducedbyoverfeeding，asisfoundatLeontiniinSicily；andconsequentlyinthisdistricttheydeferdrivingoutsheeptopastureuntilthedayiswellon，withtheviewoflimitingtheirfoodbycurtailmentofthehoursofpasture。

18

Thepartaroundthepupiloftheeyeisfattyinallanimals，andthispartresemblessuetinallanimalsthatpossesssuchapartandthatarenotfurnishedwithhardeyes。

Fatanimals，whethermaleorfemale，aremoreorlessunfittedforbreedingpurposes。Animalsaredisposedtotakeonfatmorewhenoldthanwhenyoung，andespeciallywhentheyhaveattainedtheirfullbreadthandtheirfulllengthandarebeginningtogrowdepthways。

19

Andnowtoproceedtotheconsiderationoftheblood。Insanguineousanimalsbloodisthemostuniversalandthemostindispensablepart；anditisnotanacquiredoradventitiouspart，butitisaconsubstantialpartofallanimalsthatarenotcorruptormoribund。Allbloodiscontainedinavascularsystem，towit，theveins，andisfoundnowhereelse，exceptingintheheart。Bloodisnotsensitivetotouchinanyanimal，anymorethantheexcretionsofthestomach；andthecaseissimilarwiththebrainandthemarrow。

Whenfleshislacerated，bloodexudes，iftheanimalbealiveandunlessthefleshbegangrened。Bloodinahealthyconditionisnaturallysweettothetaste，andredincolour，bloodthatdeterioratesfromnaturaldecayorfromdiseasemoreorlessblack。

Bloodatitsbest，beforeitundergoesdeteriorationfromeithernaturaldecayorfromdisease，isneitherverythicknorverythin。Inthelivinganimalitisalwaysliquidandwarm，but，onissuingfromthebody，itcoagulatesinallcasesexceptinthecaseofthedeer，theroe，andthelikeanimals；for，asageneralrule，bloodcoagulatesunlessthefibresbeextracted。Bull\'sbloodisthequickesttocoagulate。

Animalsthatareinternallyandexternallyviviparousaremoreabundantlysuppliedwithbloodthanthesanguineousovipara。Animalsthatareingoodcondition，eitherfromnaturalcausesorfromtheirhealthhavingbeenattendedto，havethebloodneithertooabundant-ascreaturesjustafterdrinkinghavetheliquidinsidetheminabundance-noragainveryscanty，asisthecasewithanimalswhenexceedinglyfat。Foranimalsinthisconditionhavepureblood，butverylittleofit，andthefatterananimalgetsthelessbecomesitssupplyofblood；forwhatsoeverisfatisdestituteofblood。

Afatsubstanceisincorruptible，butbloodandallthingscontainingitcorruptrapidly，andthispropertycharacterizesespeciallyallpartsconnectedwiththebones。Bloodisfinestandpurestinman；andthickestandblackestinthebullandtheass，ofallvivipara。Inthelowerandthehigherpartsofthebodybloodisthickerandblackerthaninthecentralparts。

Bloodbeatsorpalpitatesintheveinsofallanimalsalikeallovertheirbodies，andbloodistheonlyliquidthatpermeatestheentireframesoflivinganimals，withoutexceptionandatalltimes，aslongaslifelasts。Bloodisdevelopedfirstofallintheheartofanimalsbeforethebodyisdifferentiatedasawhole。Ifbloodberemovedorifitescapeinanyconsiderablequantity，animalsfallintoafaintorswoon；ifitberemovedorifitescapeinanexceedinglylargequantitytheydie。Ifthebloodgetexceedinglyliquid，animalsfallsick；forthebloodthenturnsintosomethinglikeichor，oraliquidsothinthatitattimeshasbeenknowntoexudethroughtheporeslikesweat。Insomecasesblood，whenissuingfromtheveins，doesnotcoagulateatall，oronlyhereandthere。Whilstanimalsaresleepingthebloodislessabundantlysuppliedneartheexteriorsurfaces，sothat，ifthesleepingcreaturebeprickedwithapin，theblooddoesnotissueascopiouslyasitwouldifthecreaturewereawake。Bloodisdevelopedoutofichorbycoction，andfatinlikemanneroutofblood。Ifthebloodgetdiseased，haemorrhoidsmayensueinthenostrilorattheanus，ortheveinsmaybecomevaricose。Blood，ifitcorruptinthebody，hasatendencytoturnintopus，andpusmayturnintoasolidconcretion。

Bloodinthefemalediffersfromthatinthemale，for，supposingthemaleandfemaletobeonaparasregardsageandgeneralhealth，thebloodinthefemaleisthickerandblackerthaninthemale；andwiththefemalethereisacomparativesuperabundanceofitintheinterior。Ofallfemaleanimalsthefemaleinmanisthemostrichlysuppliedwithblood，andofallfemaleanimalsthemenstruousdischargesarethemostcopiousinwoman。Thebloodofthesedischargesunderdiseaseturnsintoflux。Apartfromthemenstrualdischarges，thefemaleinthehumanspeciesislesssubjecttodiseasesofthebloodthanthemale。

Womenareseldomafflictedwithvaricoseveins，withhaemorrhoids，orwithbleedingatthenose，and，ifanyofthesemaladiessupervene，themensesareimperfectlydischarged。

Blooddiffersinquantityandappearanceaccordingtoage；inveryyounganimalsitresemblesichorandisabundant，intheolditisthickandblackandscarce，andinmiddle-agedanimalsitsqualitiesareintermediate。Inoldanimalsthebloodcoagulatesrapidly，evenbloodatthesurfaceofthebody；butthisisnotthecasewithyounganimals。Ichoris，infact，nothingelsebutunconcoctedblood:eitherbloodthathasnotyetbeenconcocted，orthathasbecomefluidagain。

20

Wenowproceedtodiscussthepropertiesofmarrow；forthisisoneoftheliquidsfoundincertainsanguineousanimals。Allthenaturalliquidsofthebodyarecontainedinvessels:asbloodinveins，marrowinbonesothermoisturesinmembranousstructuresoftheskinInyounganimalsthemarrowisexceedinglysanguineous，but，asanimalsgrowold，itbecomesfattyinanimalssuppliedwithfat，andsuet-likeinanimalswithsuet。Allbones，however，arenotsuppliedwithmarrow，butonlythehollowones，andnotallofthese。Forofthebonesinthelionsomecontainnomarrowatall，andsomeareonlyscantilysuppliedtherewith；andthataccounts，aswaspreviouslyobserved，forthestatementmadebycertainwritersthatthelionismarrowless。Inthebonesofpigsitisfoundinsmallquantities；

andinthebonesofcertainanimalsofthisspeciesitisnotfoundatall。

Theseliquids，then，arenearlyalwayscongenitalinanimals，butmilkandspermcomeatalatertime。Oftheselatter，thatwhich，whensoeveritispresent，issecretedinallcasesready-made，isthemilk；sperm，ontheotherhand，isnotsecretedoutinallcases，butinsomeonly，asinthecaseofwhataredesignatedthoriinfishes。

Whateveranimalshavemilk，haveitintheirbreasts。Allanimalshavebreaststhatareinternallyandexternallyviviparous，asforinstanceallanimalsthathavehair，asmanandthehorse；andthecetaceans，asthedolphin，theporpoise，andthewhale-fortheseanimalshavebreastsandaresuppliedwithmilk。Animalsthatareoviparousoronlyexternallyviviparoushaveneitherbreastsnormilk，asthefishandthebird。

Allmilkiscomposedofawateryserumcalled\'whey\'，andaconsistentsubstancecalledcurd(orcheese)；andthethickerthemilk，themoreabundantthecurd。Themilk，then，ofnon-ambidentalscoagulates，andthatiswhycheeseismadeofthemilkofsuchanimalsunderdomestication；butthemilkofambidentalsdoesnotcoagulate，northeirfateither，andthemilkisthinandsweet。Nowthecamel\'smilkisthethinnest，andthatofthehumanspeciesnextafterit，andthatoftheassnextagain，butcow\'smilkisthethickest。

Milkdoesnotcoagulateundertheinfluenceofcold，butratherrunstowhey；butundertheinfluenceofheatitcoagulatesandthickens。

Asageneralrulemilkonlycomestoanimalsinpregnancy。Whentheanimalispregnantmilkisfound，butforawhileitisunfitforuse，andthenafteranintervalofusefulnessitbecomesunfitforuseagain。Inthecaseoffemaleanimalsnotpregnantasmallquantityofmilkhasbeenprocuredbytheemploymentofspecialfood，andcaseshavebeenactuallyknownwherewomenadvancedinyearsonbeingsubmittedtotheprocessofmilkinghaveproducedmilk，andinsomecaseshaveproduceditinsufficientquantitiestoenablethemtosuckleaninfant。

ThepeoplethatliveonandaboutMountOetatakesuchshe-goatsasdeclinethemaleandrubtheiruddershardwithnettlestocauseanirritationamountingtopain；hereupontheymilktheanimals，procuringatfirstaliquidresemblingblood，thenaliquidmixedwithpurulentmatter，andeventuallymilk，asfreelyasfromfemalessubmittingtothemale。

Asageneralrule，milkisnotfoundinthemaleofmanorofanyotheranimal，thoughfromtimetotimeithasbeenfoundinamale；forinstance，onceinLemnosahe-goatwasmilkedbyitsdugs(forithas，bytheway，twodugsclosetothepenis)，andwasmilkedtosucheffectthatcheesewasmadeoftheproduce，andthesamephenomenonwasrepeatedinamaleofitsownbegetting。Suchoccurrences，however，areregardedassupernaturalandfraughtwithomenastofuturity，andinpointoffactwhentheLemnianowneroftheanimalinquiredoftheoracle，thegodinformedhimthattheportentforeshadowedtheacquisitionofafortune。Withsomemen，afterpuberty，milkcanbeproducedbysqueezingthebreasts；caseshavebeenknownwhereontheirbeingsubjectedtoaprolongedmilkingprocessaconsiderablequantityofmilkhasbeeneduced。

Inmilkthereisafattyelement，whichinclottedmilkgetstoresembleoil。Goat\'smilkismixedwithsheep\'smilkinSicily，andwhereversheep\'smilkisabundant。Thebestmilkforclottingisnotonlythatwherethecheeseismostabundant，butthatalsowherethecheeseisdriest。

Nowsomeanimalsproducenotonlyenoughmilktoreartheiryoung，butasuperfluousamountforgeneraluse，forcheese-makingandforstorage。Thisisespeciallythecasewiththesheepandthegoat，andnextindegreewiththecow。Mare\'smilk，bytheway，andmilkoftheshe-assaremixedinwithPhrygiancheese。Andthereismorecheeseincow\'smilkthaningoat\'smilk；forgrazierstellusthatfromninegallonsofgoat\'smilktheycangetnineteencheesesatanobolapiece，andfromthesameamountofcow\'smilk，thirty。Otheranimalsgiveonlyenoughofmilktoreartheiryoungwithal，andnosuperfluousamountandnonefittedforcheese-making，asisthecasewithallanimalsthathavemorethantwobreastsordugs；forwithnoneofsuchanimalsismilkproducedinsuperabundanceorusedforthemanufactureofcheese。

Thejuiceofthefigandrennetareemployedtocurdlemilk。Thefig-juiceisfirstsqueezedoutintowool；thewoolisthenwashedandrinsed，andtherinsingputintoalittlemilk，andifthisbemixedwithothermilkitcurdlesRennetisakindofmilk，foritisfoundinthestomachoftheanimalwhileitisyetsuckling。

21

Rennetthenconsistsofmilkwithanadmixtureoffire，whichcomesfromthenaturalheatoftheanimal，asthemilkisconcocted。

Allruminatinganimalsproducerennet，and，ofambidentals，thehare。Rennetimprovesinqualitythelongeritiskept；andcow\'srennet，afterbeingkeptagoodwhile，andalsohare\'srennet，isgoodfordiarrhoea，andthebestofallrennetisthatoftheyoungdeer。

Inmilk-producinganimalsthecomparativeamountoftheyieldvarieswiththesizeoftheanimalandthediversitiesofpasturage。

Forinstance，thereareinPhasissmallcattlethatinallcasesgiveacopioussupplyofmilk，andthelargecowsinEpirusyieldeachonedailysomeninegallonsofmilk，andhalfofthisfromeachpairofteats，andthemilkerhastostanderect，stoopingforwardalittle，asotherwise，ifhewereseated，hewouldbeunabletoreachuptotheteats。But，withtheexceptionoftheass，allthequadrupedsinEpirusareoflargesize，andrelatively，thecattleandthedogsarethelargest。Nowlargeanimalsrequireabundantpasture，andthiscountrysuppliesjustsuchpasturage，andalsosuppliesdiversepasturegroundstosuitthediverseseasonsoftheyear。Thecattleareparticularlylarge，andlikewisethesheepoftheso-calledPyrrhicbreed，thenamebeinggiveninhonourofKingPyrrhus。

Somepasturequenchesmilk，asMediangrassorlucerne，andthatespeciallyinruminants；otherfeedingrendersitcopious，ascytisusandvetch；only，bytheway，cytisusinflowerisnotrecommended，asithasburningproperties，andvetchisnotgoodforpregnantkine，asitcausesincreaseddifficultyinparturition。

However，beaststhathaveaccesstogoodfeeding，astheyarebenefitedtherebyinregardtopregnancy，soalsobeingwellnourishedproducemilkinplenty。Someoftheleguminousplantsbringmilkinabundance，asforinstance，alargefeedofbeanswiththeewe，thecommonshe-goat，thecow，andthesmallshe-goat；forthisfeedingmakesthemdroptheirudders。And，bytheway，thepointingoftheuddertothegroundbeforeparturitionisasignoftherebeingplentyofmilkcoming。

Milkremainsforalongtimeinthefemale，ifshebekeptfromthemaleandbeproperlyfed，and，ofquadrupeds，thisisespeciallytrueoftheewe；fortheewecanbemilkedforeightmonths。Asageneralrule，ruminatinganimalsgivemilkinabundance，andmilkfittedforcheesemanufacture。IntheneighbourhoodofToronecowsrundryforafewdaysbeforecalving，andhavemilkalltherestofthetime。Inwomen，milkofalividcolourisbetterthanwhitefornursingpurposes；andswarthywomengivehealthiermilkthanfairones。Milkthatisrichestincheeseisthemostnutritious，butmilkwithascantysupplyofcheeseisthemorewholesomeforchildren。

22

Allsanguineousanimalsejectsperm。Astowhat，andhow，itcontributestogeneration，thesequestionswillbediscussedinanothertreatise。Takingthesizeofhisbodyintoaccount，manemitsmorespermthananyotheranimal。Inhairy-coatedanimalsthespermissticky，butinotheranimalsitisnotso。Itiswhiteinallcases，andHerodotusisunderamisapprehensionwhenhestatesthattheAethiopiansejectblacksperm。

Spermissuesfromthebodywhiteandconsistent，ifitbehealthy，andafterquittingthebodybecomesthinandblack。Infrostyweatheritdoesnotcoagulate，butgetsexceedinglythinandwaterybothincolourandconsistency；butitcoagulatesandthickensundertheinfluenceofheat。Ifitbelonginthewombbeforeissuingout，itcomesmorethanusuallythick；andsometimesitcomesoutdryandcompact。Spermcapableofimpregnatingoroffructificationsinksinwater；spermincapableOfproducingthatresultdissolvesaway。ButthereisnotruthinwhatCtesiashaswrittenaboutthespermoftheelephant。

BookIV

1

Wehavenowtreated，inregardtobloodedanimalsofthepartstheyhaveincommonandofthepartspeculiartothisgenusorthat，andofthepartsbothcompositeandsimple，whetherwithoutorwithin。

Wenowproceedtotreatofanimalsdevoidofblood。Theseanimalsaredividedintoseveralgenera。

Onegenusconsistsofso-called\'molluscs\'；andbytheterm\'mollusc\'wemeanananimalthat，beingdevoidofblood，hasitsflesh-likesubstanceoutside，andanyhardstructureitmayhappentohave，inside-inthisrespectresemblingthered-bloodedanimals，suchasthegenusofthecuttle-fish。

Anothergenusisthatofthemalacostraca。Theseareanimalsthathavetheirhardstructureoutside，andtheirsoftorfleshlikesubstanceinside，andthehardsubstancebelongingtothemhastobecrushedratherthanshattered；andtothisgenusbelongsthecrawfishandthecrab。

Athirdgenusisthatoftheostracodermsor\'testaceans\'。Theseareanimalsthathavetheirhardsubstanceoutsideandtheirflesh-likesubstancewithin，andtheirhardsubstancecanbeshatteredbutnotcrushed；andtothisgenusbelongthesnailandtheoyster。

Thefourthgenusisthatofinsects；andthisgenuscomprehendsnumerousanddissimilarspecies。Insectsarecreaturesthat，asthenameimplies，havenickseitheronthebellyorontheback，oronbothbellyandback，andhavenoonepartdistinctlyosseousandnoonepartdistinctlyfleshy，butarethroughoutasomethingintermediatebetweenboneandflesh；thatistosay，theirbodyishardallthrough，insideandoutside。Someinsectsarewingless，suchastheiulusandthecentipede；somearewinged，asthebee，thecockchafer，andthewasp；andthesamekindisinsomecasesbothwingedandwingless，astheantandtheglow-worm。

Inmolluscstheexternalpartsareasfollows:inthefirstplace，theso-calledfeet；secondly，andattachedtothese，thehead；

thirdly，themantle-sac，containingtheinternalparts，andincorrectlydesignatedbysomewritersthehead；and，fourthly，finsroundaboutthesac。(Seediagram。)Inallmolluscstheheadisfoundtobebetweenthefeetandthebelly。Allmolluscsarefurnishedwitheightfeet，andinallcasesthesefeetareseverallyfurnishedwithadoublerowofsuckers，withtheexceptionofonesinglespeciesofpoulpeoroctopus。Thesepia，thesmallcalamaryandthelargecalamaryhaveanexceptionalorganinapairoflongarmsortentacles，havingattheirextremitiesaportionrenderedroughbythepresenceoftworowsofsuckers；andwiththesearmsortentaclestheyapprehendtheirfoodanddrawitintotheirmouths，andinstormyweathertheyclingbythemtoarockandswayaboutintheroughwaterlikeshipslyingatanchor。Theyswimbytheaidofthefinsthattheyhaveaboutthesac。Inallcasestheirfeetarefurnishedwithsuckers。

Theoctopus，bytheway，useshisfeelerseitherasfeetorhands；

withthetwowhichstandoverhismouthhedrawsinfood，andthelastofhisfeelersheemploysintheactofcopulation；andthislastone，bytheway，isextremelysharp，isexceptionalasbeingofawhitishcolour，andatitsextremityisbifurcate；thatistosay，ithasanadditionalsomethingontherachis，andbyrachisismeantthesmoothsurfaceoredgeofthearmonthefarsidefromthesuckers。

(Seediagram。)

Infrontofthesacandoverthefeelerstheyhaveahollowtube，bymeansofwhichtheydischargeanysea-waterthattheymayhavetakenintothesacofthebodyintheactofreceivingfoodbythemouth。Theycanshiftthetubefromsidetoside，andbymeansofittheydischargetheblackliquidpeculiartotheanimal。

Stretchingoutitsfeet，itswimsobliquelyinthedirectionoftheso-calledhead，andbythismodeofswimmingitcanseeinfront，foritseyesareatthetop，andinthisattitudeithasitsmouthattherear。The\'head\'，whilethecreatureisalive，ishard，andlooksasthoughitwereinflated。Itapprehendsandretainsobjectsbymeansoftheunder-surfaceofitsarms，andthemembraneinbetweenitsfeetiskeptatfulltension；iftheanimalgetontothesanditcannolongerretainitshold。

Thereisadifferencebetweentheoctopusandtheothermolluscsabovementioned:thebodyoftheoctopusissmall，andhisfeetarelong，whereasintheothersthebodyislargeandthefeetshort；soshort，infact，thattheycannotwalkonthem。Comparedwithoneanother，theteuthis，orcalamary，islong-shaped，andthesepiaflat-shaped；andofthecalamariestheso-calledteuthusismuchbiggerthantheteuthis；forteuthihavebeenfoundasmuchasfiveellslong。Somesepiaeattainalengthoftwoells，andthefeelersoftheoctopusaresometimesaslong，orevenlonger。Thespeciesteuthusisnotanumerousone；theteuthusdiffersfromtheteuthisinshape；thatis，thesharpextremityoftheteuthusisbroaderthanthatoftheother，and，further，theencirclingfingoesallroundthetrunk，whereasitisinpartlackingintheteuthis；bothanimalsarepelagic。

Inallcasestheheadcomesafterthefeet，inthemiddleofthefeetthatarecalledarmsorfeelers。Thereisheresituatedamouth，andtwoteethinthemouth；andabovethesetwolargeeyes，andbetwixttheeyesasmallcartilageenclosingasmallbrain；andwithinthemouthithasaminuteorganofafleshynature，andthisitusesasatongue，fornoothertonguedoesitpossess。Nextafterthis，ontheoutside，iswhatlookslikeasac；thefleshofwhichitismadeisdivisible，notinlongstraightstrips，butinannularflakes；

andallmolluscshaveacuticlearoundthisflesh。Nextafteroratthebackofthemouthcomesalongandnarrowoesophagus，andcloseafterthatacroporcraw，largeandspherical，likethatofabird；

thencomesthestomach，likethefourthstomachinruminants；andtheshapeofitresemblesthespiralconvolutioninthetrumpet-shell；

fromthestomachtheregoesbackagain，inthedirectionofthemouth，thingut，andthegutisthickerthantheoesophagus。(Seediagram。)

Molluscshavenoviscera，buttheyhavewhatiscalledamytis，andonitavesselcontainingathickblackjuice；inthesepiaorcuttle-fishthisvesselisthelargest，andthisjuiceismostabundant。Allmolluscs，whenfrightened，dischargesuchajuice，butthedischargeismostcopiousinthecuttle-fish。Themytis，then，issituatedunderthemouth，andtheoesophagusrunsthroughit；anddownbelowatthepointtowhichthegutextendsisthevesicleoftheblackjuice，andtheanimalhasthevesicleandthegutenvelopedinoneandthesamemembrane，andbythesamemembrane，sameorificedischargesboththeblackjuiceandtheresiduum。Theanimalshavealsocertainhair-likeorfurrygrowthsintheirbodies。

Inthesepia，theteuthis，andtheteuthusthehardpartsarewithin，towardsthebackofthebody；thosepartsarecalledinonethesepium，andintheotherthe\'sword\'。Theydifferfromoneanother，forthesepiuminthecuttle-fishandteuthusishardandflat，beingasubstanceintermediatebetweenboneandfishbone，with(inpart)acrumbling，spongytexture，butintheteuthisthepartisthinandsomewhatgristly。Thesepartsdifferfromoneanotherinshape，asdoalsothebodiesoftheanimals。Theoctopushasnothinghardofthiskindinitsinterior，butithasagristlysubstanceroundthehead，which，iftheanimalgrowsold，becomeshard。

Thefemalesdifferfromthemales。Themaleshaveaductinundertheoesophagus，extendingfromthemantle-cavitytothelowerportionofthesac，andthereisanorgantowhichitattaches，resemblingabreast；(seediagram)inthefemaletherearetwooftheseorgans，situatedhigherup；(seediagram)withbothsexesthereareunderneaththeseorganscertainredformations。Theeggoftheoctopusissingle，unevenonitssurface，andoflargesize；thefluidsubstancewithinisalluniformincolour，smooth，andincolourwhite；thesizeoftheeggissogreatastofillavessellargerthanthecreature\'shead。Thesepiahastwosacs，andinsidethemanumberofeggs，likeinappearancetowhitehailstones。ForthedispositionofthesepartsImustrefertomyanatomicaldiagrams。

Themalesofalltheseanimalsdifferfromthefemales，andthedifferencebetweenthesexesismostmarkedinthesepia；forthebackofthetrunk，whichisblackerthanthebelly，isrougherinthemalethaninthefemale，andinthemalethebackisstriped，andtherumpismoresharplypointed。

Thereareseveralspeciesoftheoctopus。Onekeepsclosetothesurface，andisthelargestofthemall，andneartheshorethesizeislargerthanindeepwater；andthereareothers，small，variegatedincolour，whicharenotarticlesoffood。Therearetwoothers，onecalledtheheledone，whichdiffersfromitscongenersinthelengthofitslegsandinhavingonerowofsuckers-alltherestofthemolluscshavingtwo，-theothernicknamedvariouslythebolitainaorthe\'onion，\'andtheozolisorthe\'stinkard\'。

Therearetwoothersfoundinshellsresemblingthoseofthetestaceans。Oneofthemisnicknamedbysomepersonsthenautilusorthepontilus，orbyothersthe\'polypus\'egg\'；andtheshellofthiscreatureissomethinglikeaseparatevalveofadeepscallop-shell。

Thispolypuslivesveryoftenneartotheshore，andisapttobethrownuphighanddryonthebeach；underthesecircumstancesitisfoundwithitsshelldetached，anddiesbyandbyondryland。Thesepolypodsaresmall，andareshaped，asregardstheformoftheirbodies，likethebolbidia。Thereisanotherpolypusthatisplacedwithinashelllikeasnail；itnevercomesoutoftheshell，butlivesinsidetheshelllikethesnail，andfromtimetotimeprotrudesitsfeelers。

Somuchformolluscs。

2

WithregardtotheMalacostracaorcrustaceans，onespeciesisthatofthecrawfish，andasecond，resemblingthefirst，isthatofthelobster；thelobsterdifferingfromthecrawfishinhavingclaws，andinafewotherrespectsaswell。Anotherspeciesisthatofthecarid，andanotheristhatofthecrab，andtherearemanykindsbothofcaridandofcrab。

Ofcaridstherearetheso-calledcyphae，or\'hunch-backs\'，thecrangons，orsquillae，andthelittlekind，orshrimps，andthelittlekinddonotdevelopintoalargerkind。

Ofthecrab，thevarietiesareindefiniteandincalculable。ThelargestofallcrabsisonenicknamedMaia，asecondvarietyisthepagarusandthecrabofHeracleotis，andathirdvarietyisthefresh-watercrab；theothervarietiesaresmallerinsizeanddestituteofspecialdesignations。IntheneighbourhoodofPhoenicetherearefoundonthebeachcertaincrabsthatarenicknamedthe\'horsemen\'，fromtheirrunningwithsuchspeedthatitisdifficulttoovertakethem；thesecrabs，whenopened，areusuallyfoundempty，andthisemptinessmaybeputdowntoinsufficiencyofnutriment。

(Thereisanothervariety，smalllikethecrab，butresemblinginshapethelobster。)Alltheseanimals，ashasbeenstated，havetheirhardandshellypartoutside，wheretheskinisinotheranimals，andthefleshypartinside；andthebellyismoreorlessprovidedwithlamellae，orlittleflaps，andthefemaleheredepositsherspawn。

Thecrawfisheshavefivefeetoneitherside，includingtheclawsattheend；andinlikemannerthecrabshavetenfeetinall，includingtheclaws。Ofthecarids，thehunch-backed，orprawns，havefivefeetoneitherside，whicharesharp-pointed-thosetowardsthehead；andfiveothersoneithersideintheregionofthebelly，withtheirextremitiesflat；theyaredevoidofflapsontheundersidesuchasthecrawfishhas，butonthebacktheyresemblethecrawfish。(Seediagram。)Itisverydifferentwiththecrangon，orsquilla；ithasfourfrontlegsoneitherside，thenthreethinonesclosebehindoneitherside，andtherestofthebodyisforthemostpartdevoidoffeet。(Seediagram。)Ofalltheseanimalsthefeetbendoutobliquely，asisthecasewithinsects；andtheclaws，whereclawsarefound，turninwards。Thecrawfishhasatail，andfivefinsonit；andtheround-backedcaridhasatailandfourfins；thesquillaalsohasfinsatthetailoneitherside。Inthecaseofboththehump-backedcaridandthesquillathemiddleartofthetailisspinous:onlythatinthesquillathepartisflattenedandinthecariditissharp-pointed。Ofallanimalsofthisgenusthecrabistheonlyonedevoidofarump；and，whilethebodyofthecaridandthecrawfishiselongated，thatofthecrabisrotund。

Inthecrawfishthemalediffersfromthefemale:inthefemalethefirstfootisbifurcate，inthemaleitisundivided；thebelly-finsinthefemalearelargeandoverlappingontheneck，whileinthemaletheyaresmalleranddonotoverlap；and，further，onthelastfeetofthemaletherearespur-likeprojections，largeandsharp，whichprojectionsinthefemalearesmallandsmooth。

Bothmaleandfemalehavetwoantennaeinfrontoftheeyes，largeandrough，andotherantennaeunderneath，smallandsmooth。Theeyesofallthesecreaturesarehardandbeady，andcanmoveeithertotheinnerortotheouterside。Theeyesofmostcrabshaveasimilarfacilityofmovement，orrather，inthecrabthisfacilityisdevelopedinahigherdegree。(Seediagram。)

Thelobsterisallovergrey-coloured，withamottlingofblack。

Itsunderorhinderfeet，uptothebigfeetorclaws，areeightinnumber；thencomethebigfeet，farlargerandflatteratthetipsthanthesameorgansinthecrawfish；andthesebigfeetorclawsareexceptionalintheirstructure，fortherightclawhastheextremeflatsurfacelongandthin，whiletheleftclawhasthecorrespondingsurfacethickandround。Eachofthetwoclaws，dividedattheendlikeapairofjaws，hasbothbelowandaboveasetofteeth:onlythatintherightclawtheyareallsmallandsaw-shaped，whileintheleftclawthoseattheapexaresaw-shapedandthosewithinaremolar-shaped，theselatterbeing，intheunderpartofthecleftclaw，fourteethclosetogether，andintheupperpartthreeteeth，notclosetogether。Bothrightandleftclawshavetheupperpartmobile，andbringittobearagainstthelowerone，andbotharecurvedlikebandy-legs，beingtherebyadaptedforapprehensionandconstriction。Abovethetwolargeclawscometwoothers，coveredwithhair，alittleunderneaththemouth；andunderneaththesethegill-likeformationsintheregionofthemouth，hairyandnumerous。Theseorganstheanimalkeepsinperpetualmotion；andthetwohairyfeetitbendsanddrawsintowardsitsmouth。Thefeetnearthemoutharefurnishedalsowithdelicateoutgrowingappendages。Likethecrawfish，thelobsterhastwoteeth，ormandibles，andabovetheseteethareitsantennae，long，butshorterandfinerbyfarthanthoseofthecrawfish，andthenfourotherantennaesimilarinshape，butshorterandfinerthantheothers。Overtheseantennaecometheeyes，smallandshort，notlargeliketheeyesofthecrawfish。Overtheeyesisapeakyroughprojectionlikeaforehead，largerthanthesamepartinthecrawfish；

infact，thefrontalpartismorepointedandthethoraxismuchbroaderinthelobsterthaninthecrawfish，andthebodyingeneralissmootherandmorefullofflesh。Oftheeightfeet，fourarebifurcateattheextremities，andfourareundivided。Theregionoftheso-calledneckisoutwardlydividedintofivedivisions，andsixthlycomestheflattenedportionattheend，andthisportionhasfiveflaps，ortail-fins；andtheinnerorunderparts，intowhichthefemaledropsherspawn，arefourinnumberandhairy，andoneachoftheaforesaidpartsisaspineturnedoutwards，shortandstraight。

Thebodyingeneralandtheregionofthethoraxinparticulararesmooth，notroughasinthecrawfish；butonthelargeclawstheouterportionhaslargerspines。Thereisnoapparentdifferencebetweenthemaleandfemale，fortheybothhaveoneclaw，whicheveritmaybe，largerthantheother，andneithermalenorfemaleiseverfoundwithbothclawsofthesamesize。

Allcrustaceanstakeinwaterclosebythemouth。Thecrabdischargesit，closingup，asitdoesso，asmallportionofthesame，andthecrawfishdischargesitbywayofthegills；and，bytheway，thegill-shapedorgansinthecrawfishareverynumerous。

Thefollowingpropertiesarecommontoallcrustaceans:theyhaveinallcasestwoteeth，ormandibles(forthefrontteethinthecrawfisharetwoinnumber)，andinallcasesthereisinthemouthasmallfleshystructureservingforatongue；andthestomachisclosetothemouth，onlythatthecrawfishhasalittleoesophagusinfrontofthestomach，andthereisastraightgutattachedtoit。Thisgut，inthecrawfishanditscongeners，andinthecarids，extendsinastraightlinetothetail，andterminateswheretheanimaldischargestheresiduum，andwherethefemaledepositsherspawn；inthecrabitterminateswheretheflapissituated，andinthecentreoftheflap。(Andbytheway，inalltheseanimalsthespawnisdepositedoutside。)Further，thefemalehastheplaceforthespawnrunningalongthegut。And，again，alltheseanimalshave，moreorless，anorgantermedthe\'mytis\'，or\'poppyjuice\'。

Wemustnowproceedtoreviewtheirseveraldifferentiae。

Thecrawfishthen，ashasbeensaid，hastwoteeth，largeandhollow，inwhichiscontainedajuiceresemblingthemytis，andinbetweentheteethisafleshysubstance，shapedlikeatongue。Afterthemouthcomesashortoesophagus，andthenamembranousstomachattachedtotheoesophagus，andattheorificeOfthestomacharethreeteeth，twofacingoneanotherandathirdstandingbyitselfunderneath。Comingoffatabendfromthestomachisagut，simpleandofequalthicknessthroughouttheentirelengthofthebodyuntilitreachestheanalvent。