InthiswayIobtainedsomemagnificentseriesofAnthidiaandMegachiles,runninguptoadozen。Therewasamelancholysidetothissuccess。Allmyseries,withnotoneexception,wereravagedbyparasites。ThoseoftheMegachile（M。sericans,FONSCOL）,whofashionshergobletswithrobinia—,holm—,andterebinth—leaves,wereinhabitedbyCoelioxysoctodentata（AParasiticBee。——Translator'sNote。）;thoseoftheAnthidium（A。florentinum,LATR。）wereoccupiedbyaLeucopsis。BothkindswereswarmingwithacolonyofpigmyparasiteswhosenameIhavenotyetbeenabletodiscover。Inshort,mypan—pipehives,thoughveryusefultomefromotherpointsofview,taughtmenothingabouttheorderofthesexesamongtheLeaf—
cuttersandthecotton—weavers。
IwasmorefortunatewiththreeOsmiae（O。tricornis,LATR。,O。
cornuta,LATR。,andO。Latreillii,SPIN。）,allofwhomgavemesplendidresults,withreed—stumpsarrangedeitheragainstthewallsofmygarden,asIhavejustsaid,orneartheircustomaryabode,thehugenestsoftheMason—beeoftheSheds。Oneofthem,theThree—
hornedOsmia,didbetterstill:asIhavedescribed,shebuilthernestsinmystudy,asplentifullyasIcouldwish,usingreeds,glasstubesandotherretreatsofmyselectingforhergalleries。
Wewillconsultthislast,whohasfurnishedmewithdocumentsbeyondmyfondesthopes,andbeginbyaskingherofhowmanyeggsheraveragelayingconsists。Ofthewholeheapofcolonizedtubesinmystudy,orelseoutofdoors,inthehurdle—reedsandthepan—pipeappliances,thebest—filledcontainsfifteencells,withafreespaceabovetheseries,aspaceshowingthatthelayingisended,for,ifthemotherhadanymoreeggsavailable,shewouldhavelodgedthemintheroomwhichsheleavesunoccupied。Thisstringoffifteenappearstoberare;itwastheonlyonethatIfound。Myattemptsatindoorrearing,pursuedduringtwoyearswithglasstubesorreeds,taughtmethattheThree—hornedOsmiaisnotmuchaddictedtolongseries。
Asthoughtodecreasethedifficultiesofthecomingdeliverance,sheprefersshortgalleries,inwhichonlyapartofthelayingisstacked。Wemustthenfollowthesamemotherinhermigrationfromonedwellingtothenextifwewouldobtainacompletecensusofherfamily。Aspotofcolour,droppedontheBee'sthoraxwithapaint—
brushwhilesheisabsorbedinclosingupthemouthofthetunnel,enablesustorecognizetheOsmiainhervarioushomes。
Inthisway,theswarmthatresidedinmystudyfurnishedme,inthefirstyear,withanaverageoftwelvecells。Nextyear,thesummerappearedtobemorefavourableandtheaveragebecameratherhigher,reachingfifteen。Themostnumerouslayingperformedundermyeyes,notinatube,butinasuccessionofSnail—shells,reachedthefigureoftwenty—six。Ontheotherhand,layingsofbetweeneightandtenarenotuncommon。Lastly,takingallmyrecordstogether,theresultisthatthefamilyoftheOsmiafluctuatesroundaboutfifteeninnumber。
Ihavealreadyspokenofthegreatdifferencesinsizeapparentinthecellsofoneandthesameseries。Thepartitions,atfirstwidelyspaced,drawgraduallynearertooneanotherastheycomeclosertotheaperture,whichimpliesroomycellsatthebackandnarrowcellsinfront。Thecontentsofthesecompartmentsarenolessunevenbetweenoneportionandanotherofthestring。Withoutanyexceptionknowntome,thelargecells,thosewithwhichtheseriesstarts,havemoreabundantprovisionsthanthestraitenedcellswithwhichtheseriesends。Theheapofhoneyandpolleninthefirstistwiceoreventhriceaslargeasthatinthesecond。Inthelastcells,themostrecentindate,thevictualsarebutapinchofpollen,soniggardlyinamountthatwewonderwhatwillbecomeofthelarvawiththatmeagreration。
OnewouldthinkthattheOsmia,whennearingtheendofthelaying,attachesnoimportancetoherlast—born,towhomshedolesoutspaceandfoodsosparingly。Thefirst—bornreceivethebenefitofherearlyenthusiasm:theirsisthewell—spreadtable,theirsthespaciousapartments。Theworkhasbeguntopallbythetimethatthelasteggsarelaid;andthelast—comershavetoputupwithascurvyportionoffoodandatinycorner。
Thedifferenceshowsitselfinanotherwayafterthecocoonsarespun。Thelargecells,thoseattheback,receivethebulkycocoons;
thesmallones,thoseinfront,havecocoonsonlyahalforathirdasbig。BeforeopeningthemandascertainingthesexoftheOsmiainside,letuswaitforthetransformationintotheperfectinsect,whichwilltakeplacetowardstheendofsummer。Ifimpatiencegetsthebetterofus,wecanopenthemattheendofJulyorinAugust。
Theinsectistheninthenymphalstage;anditiseasy,underthisform,todistinguishthetwosexesbythelengthoftheantennae,whicharelargerinthemales,andbytheglassyprotuberancesontheforehead,thesignofthefuturearmourofthefemales。Well,thesmallcocoons,thoseinthenarrowfrontcells,withtheirscantystoreofprovisions,allbelongtomales;thebigcocoons,thoseinthespaciousandwell—stockedcellsattheback,allbelongtofemales。
Theconclusionisdefinite:thelayingoftheThree—hornedOsmiaconsistsoftwodistinctgroups,firstagroupoffemalesandthenagroupofmales。
Withmypan—pipeapparatusdisplayedonthewallsofmyenclosureandwitholdhurdle—reedsleftlyingflatoutofdoors,IobtainedtheHornedOsmiainfairquantities。IpersuadedLatreille'sOsmiatobuildhernestinreeds,whichshedidwithazealwhichIwasfarfromexpecting。AllthatIhadtodowastolaysomereed—stumpshorizontallywithinherreach,intheimmediateneighbourhoodofherusualhaunts,namely,thenestsoftheMason—beeoftheSheds。
Lastly,Isucceededwithoutdifficultyinmakingherbuildhernestsintheprivacyofmystudy,withglasstubesforahouse。Theresultsurpassedmyhopes。
WithboththeseOsmiae,thedivisionofthegalleryisthesameaswiththeThree—hornedOsmia。Atthebackarelargecellswithplentifulprovisionsandwidely—spacedpartitions;infront,smallcells,withscantyprovisionsandpartitionsclosetogether。Also,thelargercellssuppliedmewithbigcocoonsandfemales;thesmallercellsgavemelittlecocoonsandmales。TheconclusionthereforeisexactlythesameinthecaseofallthreeOsmiae。
BeforedismissingtheOsmiae,letusdevoteamomenttotheircocoons,acomparisonofwhich,inthematterofbulk,willfurnishuswithfairlyaccurateevidenceastotherelativesizeofthetwosexes,forthethingcontained,theperfectinsect,isevidentlyproportionatetothesilkenwrapperinwhichitisenclosed。Thesecocoonsareoval—shapedandmayberegardedasellipsoidsformedbyarevolutionaroundthemajoraxis。Thevolumeofoneofthesesolidsisexpressedinthefollowingformula:
4/3xpixax（bsquared）,inwhich2aisthemajoraxisand2btheminoraxis。
Now,theaveragedimensionsofthecocoonsoftheThree—hornedOsmiaareasfollows:
2a=13mm。（。507inch。——Translator'sNote。）,2b=7mm。（。273inch。—
—Translator'sNote。）inthefemales;
2a=9mm。（。351inch。——Translator'sNote。）,2b=5mm。（。195inch。——
Translator'sNote。）inthemales。
Theratiothereforebetween13x7x7=637and9x5x5=225willbemoreorlesstheratiobetweenthesizesofthetwosexes。Thisratioissomewherebetween2to1and3to1。Thefemalesthereforearetwoorthreetimeslargerthanthemales,aproportionalreadysuggestedbyacomparisonofthemassofprovisions,estimatedsimplybytheeye。
TheHornedOsmiagivesusthefollowingaveragedimensions:
2a=15mm。（。585inch。——Translator'sNote。）,2b=9mm。（。351inch。—
—Translator'sNote。）inthefemales;
2a=12mm。（。468inch。——Translator'sNote。）,2b=7mm。（。273inch。—
—Translator'sNote。）inthemales。
Onceagain,theratiobetween15x9x9=1215and12x7x7=588
liesbetween2to1and3to1。
BesidestheBeeswhoarrangetheirlayinginarow,Ihaveconsultedotherswhosecellsaregroupedinawaythatmakesitpossibletoascertaintherelativeorderofthetwosexes,thoughnotquitesoprecisely。OneoftheseistheMason—beeoftheWalls。Ineednotdescribeagainherdome—shapednest,builtonapebble,whichisnowsowell—knowntous。（Cf。"TheMason—bees":chapter1。——Translator'sNote。）
Eachmotherchoosesherstoneandworksonitinsolitude。Sheisanungraciouslandownerandguardshersitejealously,drivingawayanyMasonwhoevenlooksasthoughshemightalightonit。Theinhabitantsofthesamenestarethereforealwaysbrothersandsisters;theyarethefamilyofonemother。
Moreover,ifthestonepresentsalargeenoughsurface——aconditioneasilyfulfilled——theMason—beehasnoreasontoleavethesupportonwhichshebeganherlayingandgoinsearchofanotherwhereontodeposittherestofhereggs。Sheistoothriftyofhertimeandofhermortartoinvolveherselfinsuchexpenditureexceptforgravereasons。Consequently,eachnest,atleastwhenitisnew,whentheBeeherselfhaslaidthefirstfoundations,containstheentirelaying。Itisadifferentthingwhenanoldnestisrestoredandmadeintoaplacefordepositingtheeggs。Ishallcomebacklatertosuchhouses。
Anewly—builtnestthen,withrareexceptions,containstheentirelayingofonefemale。Countthecellsandweshallhavethetotallistofthefamily。Theirmaximumnumberfluctuatesroundaboutfifteen。Themostluxuriantserieswilloccasionallyreachasmanyaseighteen,thoughtheseareveryscarce。
Whenthesurfaceofthestoneisregularallaroundthesiteofthefirstcell,whenthemasoncanaddtoherbuildingwiththesamefacilityineverydirection,itisobviousthatthegroupsofcells,whenfinished,willhavetheoldestinthecentralportionandthemorerecentinthesurroundingportion。Becauseofthisjuxtapositionofthecells,whichservepartlyasawalltothosewhichcomenext,itispossibletoformsomeestimateofthechronologicalorderofthecellsintheChalicodoma'snestandthustodiscoverthesequenceofthetwosexes。
Inwinter,bywhichtimetheBeehaslongbeenintheperfectstate,IcollectChalicodoma—nests,removingthembodilyfromtheirsupportwithafewsmartsidewardtapsofthehammeronthepebbles。Atthebaseofthemortardomethecellsarewideagapeanddisplaytheircontents。Itakethecocoonfromitsbox,openitandtakenoteofthesexoftheinsectenclosed。
IshouldprobablybeaccusedofexaggerationifImentionedthetotalnumberofthenestswhichIhavegatheredandthecellswhichIhaveinspectedbythismethodduringthelastsixorsevenyears。IwillcontentmyselfwithsayingthattheharvestofasinglemorningsometimesconsistedofasmanyassixtynestsoftheMason—bee。Ihadtohavehelpincarryinghomemyspoils,eventhoughthenestswereremovedfromtheirstonesonthespot。
>FromtheenormousnumberofnestswhichIhaveexamined,Iamabletostatethat,whentheclusterisregular,thefemalecellsoccupythecentreandthemalecellstheedges。Wheretheirregularityofthepebblehaspreventedanevendistributionaroundtheinitialpoint,thesamerulehasbeenobserved。Amalecellisneversurroundedoneverysidebyfemalecells:eitheritoccupiestheedgesofthenest,orelseitadjoins,atleastonsomesides,othermalecells,ofwhichthelastformpartoftheexteriorofthecluster。Asthesurroundingcellsareobviouslyofalaterdatethantheinnercells,itfollowsthattheMason—beeactsliketheOsmiae:shebeginsherlayingwithfemalesandendsitwithmales,eachofthesexesformingaseriesofitsown,independentoftheother。
Somefurthercircumstancesaddtheirtestimonytothatofthesurroundedandsurroundingcells。Whenthepebbleprojectssharplyandformsasortofdihedralangle,oneofwhosefacesismoreorlessverticalandtheotherhorizontal,thisangleisafavouritesitewiththeMason,whothusfindsgreaterstabilityforheredificeinthesupportgivenherbythedoubleplane。ThesesitesappeartometobeingreatrequestwiththeChalicodoma,consideringthenumberofnestswhichIfindthusdoublysupported。Innestsofthiskind,allthecells,asusual,havetheirfoundationsfixedtothehorizontalsurface;butthefirstrow,therowofcellsfirstbuilt,standswithitsbackagainsttheverticalsurface。
Well,theseoldercells,whichoccupytheactualedgeofthedihedralangle,arealwaysfemale,withtheexceptionofthoseateitherendoftherow,which,astheybelongtotheoutside,maybemalecells。
Infrontofthisfirstrowcomeothers。Thefemalecellsoccupythemiddleportionandthemaletheends。Finally,thelastrow,closingintheremainder,containsonlymalecells。Theprogressoftheworkisveryvisiblehere:theMasonhasbegunbyattendingtothecentralgroupoffemalecells,thefirstrowofwhichoccupiesthedihedralangle,andhasfinishedhertaskbydistributingthemalecellsroundtheoutside。
Iftheperpendicularfaceofthedihedralanglebehighenough,itsometimeshappensthatasecondrowofcellsisplacedabovethefirstrowbackingontothatplane;athirdrowoccurslessoften。
Thenestisthenoneofseveralstoreys。Thelowerstoreys,theolder,containonlyfemales;theupper,themorerecentstorey,containsnonebutmales。Itgoeswithoutsayingthatthesurfacelayer,evenofthelowerstoreys,cancontainmaleswithoutinvalidatingtherule,forthislayermayalwaysbelookeduponastheChalicodoma'slastwork。
Everythingthereforecontributestoshowthat,intheMason—bee,thefemalestaketheleadintheorderofprimogeniture。Theirsisthecentralandbest—protectedpartoftheclayfortress;theouterpart,thatmostexposedtotheinclemenciesoftheweatherandtoaccidents,isforthemales。
Themales'cellsdonotdifferfromthefemales'onlybybeingplacedattheoutsideofthecluster;theydifferalsointheircapacity,whichismuchsmaller。Toestimatetherespectivecapacitiesofthetwosortsofcells,Igotoworkasfollows:Ifilltheemptycellwithveryfinesandandpourthissandbackintoaglasstubemeasuring5millimetres（。195inch。——Translator'sNote。）indiameter。
>Fromtheheightofthecolumnofsandwecanestimatethecomparativecapacityofthetwokindsofcells。Iwilltakeoneatrandomamongmynumerousexamplesofcellsthusgauged。
Itcomprisesthirteencellsandoccupiesadihedralangle。Thefemalecellsgivemethefollowingfigures,inmillimetres,astheheightofthecolumnsofsand:
40,44,43,48,48,46,47
（1。56,1。71,1。67,1。87,1。87,1。79,1。83inches。——Translator'sNote。）,averaging45。（1。75inches。——Translator'sNote。）
Themalecellsgiveme:
32,35,28,30,30,31
（1。24,1。36,1。09,1。17,1。17,1。21inches。——Translator'sNote。）,averaging31。（1。21inches。——Translator'sNote。）
Theratioofthecapacityofthecellsforthetwosexesisthereforeroughlyaratioof4to3。Theactualcontentsofthecellbeingproportionatetoitscapacity,theaboveratiomustalsobemoreorlesstheratioofprovisionsandsizesbetweenfemalesandmales。
Thesefigureswillassistuspresentlytotellwhetheranoldcell,occupiedforasecondorthirdtime,belongedoriginallytoafemaleoramale。
TheChalicodomaoftheShedscannotgiveusanyinformationonthismatter。Shebuildsunderthesameeaves,inexcessivelypopulouscolonies;anditisimpossibletofollowthelaboursofanysingleMason,whosecells,distributedhereandthere,aresooncoveredupwiththeworkofherneighbours。Allismuddleandconfusionintheindividualoutputoftheswarmingthrong。
IhavenotwatchedtheworkoftheChalicodomaoftheShrubswithcloseenoughattentiontobeabletostatedefinitelythatthisBeeisasolitarybuilder。Hernestisaballofclayhangingfromabough。Sometimes,thisnestisthesizeofalargewalnutandthenappearstobetheworkofonealone;sometimes,itisthesizeofaman'sfist,inwhichcaseIhavenodoubtthatitistheworkofseveral。Thosebulkynests,comprisingmorethanfiftycells,cantellusnothingexact,asanumberofworkersmustcertainlyhavecollaboratedtoproducethem。
Thewalnut—sizednestsaremoretrustworthy,foreverythingseemstoindicatethattheywerebuiltbyasingleBee。Herefemalesarefoundinthecentreofthegroupandmalesatthecircumference,insomewhatsmallercells,thusrepeatingwhattheMason—beeofthePebbleshastoldus。
Oneclearandsimplerulestandsoutfromthiscollectionoffacts。
ApartfromthestrangeexceptionoftheThree—prongedOsmia,whomixesthesexeswithoutanyorder,theBeeswhomIstudiedandprobablyacrowdofothersproducefirstacontinuousseriesoffemalesandthenacontinuousseriesofmales,thelatterwithlessprovisionsandsmallercells。ThisdistributionofthesexesagreeswithwhatwehavelongknownoftheHive—bee,whobeginsherlayingwithalongsequenceofworkers,orsterilefemales,andendsitwithalongsequenceofmales。Theanalogycontinuesdowntothecapacityofthecellsandthequantitiesofprovisions。Therealfemales,theQueen—bees,havewaxcellsincomparablymorespaciousthanthecellsofthemalesandreceiveamuchlargeramountoffood。Everythingthereforedemonstratesthatwearehereinthepresenceofageneralrule。
Butdoesthisruleexpressthewholetruth？Istherenothingbeyondalayingintwoseries？AretheOsmiae,theChalicodomaeandtherestofthemfatallyboundbythisdistributionofthesexesintotwodistinctgroups,themalegroupfollowinguponthefemalegroup,withoutanymixingofthetwo？Isthemotherabsolutelypowerlesstomakeachangeinthisarrangement,shouldcircumstancesrequireit？
TheThree—prongedOsmiaalreadyshowsusthattheproblemisfarfrombeingsolved。Inthesamebramble—stump,thetwosexesoccurveryirregularly,asthoughatrandom。WhythismixtureintheseriesofcocoonsofaBeecloselyrelatedtotheHornedOsmiaandtheThree—
hornedOsmia,whostacktheirsmethodicallybyseparatesexesinthehollowofareed？WhattheBeeofthebramblesdoescannotherkinswomenofthereedsdotoo？Nothing,sofarasIknow,canexplainthisdifferenceinaphysiologicalactofprimaryimportance。ThethreeBeesbelongtothesamegenus;theyresembleoneanotheringeneraloutline,internalstructureandhabits;and,withthisclosesimilarity,wesuddenlyfindastrangedissimilarity。
ThereisjustonethingthatmightpossiblyarouseasuspicionofthecauseofthisirregularityintheThree—prongedOsmia'slaying。IfI
openabramble—stumpinthewintertoexaminetheOsmia'snest,I
finditimpossible,inthevastmajorityofcases,todistinguishpositivelybetweenafemaleandamalecocoon:thedifferenceinsizeissosmall。Thecells,moreover,havethesamecapacity:thediameterofthecylinderisthesamethroughoutandthepartitionsarealmostalwaysthesamedistanceapart。IfIopenitinJuly,thevictualling—period,itisimpossibleformetodistinguishbetweentheprovisionsdestinedforthemalesandthosedestinedforthefemales。Themeasurementofthecolumnofhoneygivespracticallythesamedepthinallthecells。Wefindanequalquantityofspaceandfoodforbothsexes。
Thisresultmakesusforeseewhatadirectexaminationofthetwosexesintheadultformtellsus。Themaledoesnotdiffermateriallyfromthefemaleinrespectofsize。Ifheisatriflesmaller,itisscarcelynoticeable,whereas,intheHornedOsmiaandtheThree—
hornedOsmia,themaleisonlyhalforathirdthesizeofthefemale,aswehaveseenfromtherespectivebulkoftheircocoons。IntheMason—beeoftheWallsthereisalsoadifferenceinsize,thoughlesspronounced。
TheThree—prongedOsmiahasnotthereforetotroubleaboutadjustingthedimensionsofthedwellingandthequantityofthefoodtothesexoftheeggwhichsheisabouttolay;themeasureisthesamefromoneendoftheseriestotheother。Itdoesnotmatterifthesexesalternatewithoutorder:oneandallwillfindwhattheyneed,whatevertheirpositionintherow。ThetwootherOsmiae,withtheirgreatdisparityinsizebetweenthetwosexes,havetobecarefulaboutthetwofoldconsiderationofboardandlodging。Andthat,I
think,iswhytheybeginwithspaciouscellsandgenerousrationsforthehomesofthefemalesandendwithnarrow,scantily—provisionedcells,thehomesofthemales。Withthissequence,sharplydefinedforthetwosexes,thereislessfearofmistakeswhichmightgivetoonewhatbelongstoanother。Ifthisisnottheexplanationofthefacts,Iseenoother。
ThemoreIthoughtaboutthiscuriousquestion,themoreprobableitappearedtomethattheirregularseriesoftheThree—prongedOsmiaandtheregularseriesoftheotherOsmiae,oftheChalicodomaeandoftheBeesingeneralwerealltraceabletoacommonlaw。Itseemedtomethatthearrangementinasuccessionfirstoffemalesandthenofmalesdidnotaccountforeverything。Theremustbesomethingmore。AndIwasright:thatarrangementinseriesisonlyatinyfractionofthereality,whichisremarkableinaverydifferentway。
ThisiswhatIamgoingtoprovebyexperiment。
CHAPTER4。THEMOTHERDECIDESTHESEXOFTHEEGG。
IwillbeginwiththeMason—beeofthePebbles。（ThisisthesameinsectastheMason—beeoftheWalls。Cf。"TheMason—bees":passim。——
Translator'sNote。）Theoldnestsareoftenused,whentheyareingoodenoughrepair。Earlyintheseasonthemothersquarrelfiercelyoverthem;and,whenoneoftheBeeshastakenpossessionofthecoveteddome,shedrivesanystrangerawayfromit。Theoldhouseisfarfrombeingaruin,onlyitisperforatedwithasmanyholesasitoncehadoccupants。Theworkofrestorationisnogreatmatter。Theheapofearthduetothedestructionofthelidbytheoutgoingtenantistakenoutofthecellandflungawayatadistance,atombyatom。Theremnantsofthecocoonarealsothrownaway,butnotalways,forthedelicatesilkenwrappersometimesadherescloselytothemasonry。
Thevictuallingoftherenovatedcellisnowbegun。Nextcomesthelaying;andlastlytheorificeissealedwithamortarplug。Asecondcellisutilizedinthesameway,followedbyathirdandsoon,oneaftertheother,aslongasanyremainunoccupiedandthemother'sovariesarenotexhausted。Finally,thedomereceives,mainlyovertheaperturesalreadyplugged,acoatofplasterwhichmakesthenestlooklikenew。Ifshehasnotfinishedherlaying,themothergoesinsearchofotheroldneststocompleteit。Perhapsshedoesnotdecidetofoundanewestablishmentexceptwhenshecanfindnosecond—handdwellings,whichmeanagreateconomyoftimeandlabour。Inshort,amongthecountlessnumberofnestswhichIhavecollected,Ifindmanymoreancientthanrecentones。
Howshallwedistinguishonefromtheother？Theoutwardaspecttellsyounothing,owingtothegreatcaretakenbytheMasontorestorethesurfaceoftheolddwellingequaltonew。Toresisttherigoursofthewinter,thissurfacemustbeimpregnable。Themotherknowsthatandthereforerepairsthedome。Inside,itisanothermatter:
theoldneststandsrevealedatonce。Therearecellswhoseprovisions,atleastayearold,areintact,butdriedupormusty,becausetheegghasneverdeveloped。Thereareotherscontainingadeadlarva,reducedbytimetoablackened,curled—upcylinder。Therearesomewhencetheperfectinsectwasneverabletoissue:theChalicodomaworeherselfoutintryingtopiercetheceilingofherchamber;herstrengthfailedherandsheperishedintheattempt。
Othersagainandverymanyareoccupiedbyravagers,Leucopses（Cf。
"TheMason—bees":chapter11。——Translator'sNote。）andAnthrax—flies,whowillcomeoutagooddeallater,inJuly。Altogether,thehouseisfarfromhavingeveryroomvacant;therearenearlyalwaysaconsiderablenumberoccupiedeitherbyparasitesthatwerestillintheegg—stageatthetimewhentheMason—beewasatworkorbydamagedprovisions,driedgrubsorChalicodomaeintheperfectstatewhohavediedwithoutbeingabletoeffecttheirdeliverance。
Shouldalltheroomsbeavailable,arareoccurrence,therestillremainsamethodofdistinguishingbetweenanancientnestandarecentone。Thecocoon,asIhavesaid,adheresprettycloselytothewalls;andthemotherdoesnotalwaystakeawaythisremnant,eitherbecausesheisunabletodoso,orbecausesheconsiderstheremovalunnecessary。Thusthebaseofthenewcocoonissetinthebottomoftheoldcocoon。Thisdoublewrapperpointsveryclearlytotwogenerations,twoseparateyears。Ihaveevenfoundasmanyasthreecocoonsfittingoneintoanotherattheirbases。Consequently,thenestsoftheMason—beeofthePebblesareabletododutyforthreeyears,ifnotmore。Eventuallytheybecomeutterruins,abandonedtotheSpidersandtovarioussmallerBeesorWasps,whotakeuptheirquartersinthecrumblingrooms。
Aswesee,anoldnestishardlyevercapableofcontainingtheMason—bee'sentirelaying,whichcallsforsomefifteenapartments。
Thenumberofroomsatherdisposalismostunequal,butalwaysverysmall。Itissayingmuchwhenthereareenoughtoreceiveabouthalfthelaying。Fourorfivecells,sometimestwoorevenone:thatiswhattheMasonusuallyfindsinanestthatisnotherownwork。ThislargereductionisexplainedwhenwerememberthenumerousparasitesthatliveupontheunfortunateBee。
Now,howarethesexesdistributedinthoselayingswhicharenecessarilybrokenupbetweenoneoldnestandanother？Theyaredistributedinsuchawayasutterlytoupsettheideaofaninvariablesuccessionfirstoffemalesandthenofmales,theideawhichoccurstousonexaminingthenewnests。Ifthisrulewereaconstantone,weshouldbeboundtofindintheolddomesatonetimeonlyfemales,atanotheronlymales,accordingasthelayingwasatitsfirstoratitssecondstage。Thesimultaneouspresenceofthetwosexeswouldthencorrespondwiththetransitionperiodbetweenonestageandthenextandshouldbeveryunusual。Onthecontrary,itisverycommon;and,howeverfewcellstheremaybe,wealwaysfindbothfemalesandmalesintheoldnests,onthesoleconditionthatthecompartmentshavetheregulationholding—capacity,alargecapacityforthefemales,alesserforthemales,aswehaveseen。