第7章

Bythetimethatthebaseoftheeleventhcellisreached,thetransversalpartitionisoncemorealmostperpendiculartotheaxis。

Herewhathappenedatthebottomisrepeated。Thereisnolongitudinalpartition;andthespaciouscell,coveringthewholediameterofthecylinder,receivesafemale。Theedificeendswithtwotransversalpartitionsandonelongitudinalpartition,whichmarkout,onthesamelevel,chamberstwelveandthirteen,bothofwhichcontainmales。

Thereisnothingmorecuriousthanthismixingofthetwosexes,whenweknowwithwhatprecisiontheOsmiaseparatestheminalinearseries,wherethenarrowwidthofthecylinderdemandsthatthecellsshallbesetsingly,oneabovetheother。Here,theBeeismakinguseofatubewhosediameterisnotsuitedtoherwork;sheisconstructingacomplexanddifficultedifice,whichperhapswouldnotpossessthenecessarysolidityiftheceilingsweretoobroad。TheOsmiathereforesupportstheseceilingswithlongitudinalpartitions;

andtheunequalchambersresultingfromtheintroductionofthesepartitionsreceivefemalesatonetimeandmalesatanother,accordingtotheircapacity。

CHAPTER5。PERMUTATIONSOFSEX。

Thesexoftheeggisoptional。Thechoicerestswiththemother,whoisguidedbyconsiderationsofspaceand,accordingtotheaccommodationatherdisposal,whichisfrequentlyfortuitousandincapableofmodification,placesafemaleinthiscellandamaleinthat,sothatbothmayhaveadwellingofasizesuitedtotheirunequaldevelopment。ThisistheunimpeachableevidenceofthenumerousandvariedfactswhichIhavesetforth。Peopleunfamiliarwithinsectanatomy——thepublicforwhomIwrite——wouldprobablygivethefollowingexplanationofthismarvellousprerogativeoftheBee:

themotherhasatherdisposalacertainnumberofeggs,someofwhichareirrevocablyfemaleandtheothersirrevocablymale:sheisabletopickoutofeithergrouptheonewhichshewantsattheactualmoment;andherchoiceisdecidedbytheholdingcapacityofthecellthathastobestocked。Everythingwouldthenbelimitedtoajudiciousselectionfromtheheapofeggs。

Shouldthisideaoccurtohim,thereadermusthastentorejectit。

Nothingcouldbemorefalse,asthemerestreferencetoanatomywillshow。ThefemalereproductiveapparatusoftheHymenopteraconsistsgenerallyofsixovariantubes,somethinglikeglove—fingers,dividedintobunchesofthreeandendinginacommoncanal,theoviduct,whichcarriestheeggsoutside。Eachoftheseglove—fingersisfairlywideatthebase,buttaperssharplytowardsthetip,whichisclosed。Itcontains,arrangedinarow,oneaftertheother,likebeadsonastring,acertainnumberofeggs,fiveorsixforinstance,ofwhichtheloweronesaremoreorlessdeveloped,themiddleoneshalf—waytowardsmaturity,andtheupperonesveryrudimentary。Everystageofevolutionishererepresented,distributedregularlyfrombottomtotop,fromthevergeofmaturitytothevagueoutlinesoftheembryo。Thesheathclaspsitsstringofovulessocloselythatanyinversionoftheorderisimpossible。

Besides,aninversionwouldresultinagrossabsurdity:thereplacingofaripereggbyanotherinanearlierstageofdevelopment。

Therefore,ineachovariantube,ineachglove—finger,theemergenceoftheeggsoccursaccordingtotheordergoverningtheirarrangementinthecommonsheath;andanyothersequenceisabsolutelyimpossible。Moreover,atthenestingperiod,thesixovariansheaths,onebyoneandeachinitsturn,haveattheirbaseaneggwhichinaveryshorttimeswellsenormously。Somehoursorevenadaybeforethelaying,thateggbyitselfrepresentsorevenexceedsinbulkthewholeoftheovigenousapparatus。Thisistheeggwhichisonthepointofbeinglaid。Itisabouttodescendintotheoviduct,initsproperorder,atitspropertime;andthemotherhasnopowertomakeanothertakeitsplace。Itisthisegg,necessarilythiseggandnoother,thatwillpresentlybelaidupontheprovisions,whetherthesebeamessofhoneyoraliveprey;italoneisripe,italoneisattheentrancetotheoviduct;noneoftheothers,sincetheyarefartherbackintherowandnotattherightstageofdevelopment,canbesubstitutedatthiscrisis。Itsbirthisinevitable。

Whatwillityield,amaleorafemale？Nolodginghasbeenprepared,nofoodcollectedforit;andyetbothfoodandlodginghavetobeinkeepingwiththesexthatwillproceedfromit。Andhereisamuchmorepuzzlingcondition:thesexofthategg,whoseadventispredestined,hastocorrespondwiththespacewhichthemotherhappenstohavefoundforacell。Thereisthereforenoroomforhesitation,strangethoughthestatementmayappear:theegg,asitdescendsfromitsovariantube,hasnodeterminedsex。Itisperhapsduringthefewhoursofitsrapiddevelopmentatthebaseofitsovariansheath,itisperhapsonitspassagethroughtheoviductthatitreceives,atthemother\'spleasure,thefinalimpressthatwillproduce,tomatchthecradlewhichithastofill,eitherafemaleoramale。

Thereuponthefollowingquestionpresentsitself。Letusadmitthat,whenthenormalconditionsremain,alayingwouldhaveyieldedmfemalesandnmales。Then,ifmyconclusionsarecorrect,itmustbeinthemother\'spower,whentheconditionsaredifferent,totakefromthemgroupandincreasethengrouptothesameextent;itmustbepossibleforherlayingtoberepresentedasm—1,m—2,m—3,etc。

femalesandbyn+1,n+2,n+3,etc。males,thesumofm+nremainingconstant,butoneofthesexesbeingpartlypermutedintotheother。

Theultimateconclusionevencannotbedisregarded:wemustadmitasetofeggsrepresentedbym—m,orzero,femalesandofn+mmales,oneofthesexesbeingcompletelyreplacedbytheother。Conversely,itmustbepossibleforthefeminineseriestobeaugmentedfromthemasculineseriestotheextentofabsorbingitentirely。ItwastosolvethisquestionandsomeothersconnectedwithitthatI

undertook,forthesecondtime,toreartheThree—hornedOsmiainmystudy。

Theproblemonthisoccasionisamoredelicateone;butIamalsobetter—equipped。Myapparatusconsistsoftwosmall,closedpacking—

cases,withthefrontsideofeachpiercedwithfortyholes,inwhichIcaninsertmyglasstubesandkeeptheminahorizontalposition。I

thusobtainfortheBeesthedarknessandmysterywhichsuittheirworkandformyselfthepowerofwithdrawingfrommyhive,atanytime,anytubethatIwish,withtheOsmiainside,soastocarryittothelightandfollow,ifneedbewiththeaidofthelens,theoperationsofthebusyworker。Myinvestigations,howeverfrequentandminute,innowayhinderthepeaceableBee,whoremainsabsorbedinhermaternalduties。

Imarkaplentifulnumberofmyguestswithavarietyofdotsonthethorax,whichenablesmetofollowanyoneOsmiafromthebeginningtotheendofherlaying。Thetubesandtheirrespectiveholesarenumbered;alist,alwayslyingopenonmydesk,enablesmetonotefromdaytoday,sometimesfromhourtohour,whathappensineachtubeandparticularlytheactionsoftheOsmiaewhosebacksbeardistinguishingmarks。Assoonasonetubeisfilled,Ireplaceitbyanother。Moreover,IhavescatteredinfrontofeitherhiveafewhandfulsofemptySnail—shells,speciallychosenfortheobjectwhichIhaveinview。ReasonswhichIwillexplainlaterledmetoprefertheshellsofHelixcaespitum。Eachoftheshells,asandwhenstocked,receivedthedateofthelayingandthealphabeticalsigncorrespondingwiththeOsmiatowhomitbelonged。Inthisway,I

spentfiveorsixweeksincontinualobservation。Tosucceedinanenquiry,thefirstandforemostconditionispatience。ThisconditionIfulfilled;anditwasrewardedwiththesuccesswhichIwasjustifiedinexpecting。

Thetubesemployedareoftwokinds。Thefirst,whicharecylindricalandofthesamewidththroughout,willbeofuseforconfirmingthefactsobservedinthefirstyearofmyexperimentsinindoorrearing。

Theothers,themajority,consistoftwocylinderswhichareofverydifferentdiameters,setendtoend。Thefrontcylinder,theonewhichprojectsalittlewayoutsidethehiveandformstheentrance—

hole,variesinwidthbetween8and12millimetres。（Between。312to。468inch。——Translator\'sNote。）Thesecond,thebackone,containedentirelywithinmypacking—case,isclosedatitsfarendandis5to6millimetres（。195to。234inch。——Translator\'sNote。）indiameter。

Eachofthetwopartsofthedouble—galleriedtunnel,onenarrowandonewide,measuresatmostadecimetre（3。9inches。——Translator\'sNote。）inlength。Ithoughtitadvisabletohavetheseshorttubes,astheOsmiaisthuscompelledtoselectdifferentlodgings,eachofthembeinginsufficientinitselftoaccommodatethetotallaying。InthiswayIshallobtainagreatervarietyinthedistributionofthesexes。Lastly,atthemouthofeachtube,whichprojectsslightlyoutsidethecase,thereisalittlepapertongue,formingasortofperchonwhichtheOsmiaalightsonherarrivalandgivingeasyaccesstothehouse。Withthesefacilities,theswarmcolonizedfifty—twodouble—galleriedtubes,thirty—sevencylindricaltubes,seventy—eightSnail—shellsandafewoldnestsoftheMason—beeoftheShrubs。FromthisrichmineofmaterialIwilltakewhatIwanttoprovemycase。

Everyseries,evenwhenincomplete,beginswithfemalesandendswithmales。TothisruleIhavenotyetfoundanexception,atleastingalleriesofnormaldiameter。Ineachnewabode,themotherbusiesherselffirstofallwiththemoreimportantsex。Bearingthispointinmind,woulditbepossibleforme,bymanoeuvring,toobtainaninversionofthisorderandmakethelayingbeginwithmales？Ithinkso,fromtheresultsalreadyascertainedandtheirresistibleconclusionstobedrawnfromthem。Thedouble—galleriedtubesareinstalledinordertoputmyconjecturestotheproof。

Thebackgallery,5or6millimetres（。195to。234inch。——

Translator\'sNote。）wide,istoonarrowtoserveasalodgingfornormallydevelopedfemales。If,therefore,theOsmia,whoisveryeconomicalofherspace,wishestooccupythem,shewillbeobligedtoestablishmalesthere。Andherlayingmustnecessarilybeginhere,becausethiscorneristherear—mostpartofthetube。Theforemostgalleryiswide,withanentrance—dooronthefrontofthehive。

Here,findingtheconditionstowhichsheisaccustomed,themotherwillgoonwithherlayingintheorderwhichsheprefers。

Letusnowseewhathashappened。Ofthefifty—twodoublegalleriedtubes,aboutathirddidnothavetheirnarrowpassagecolonized。TheOsmiacloseditsaperturecommunicatingwiththelargepassage;andthelatteralonereceivedtheeggs。Thiswasteofspacewasinevitable。ThefemaleOsmiae,thoughnearlyalwayslargerthanthemales,presentmarkeddifferencesamongoneanother:somearebigger,somearesmaller。IhadtoadjustthewidthofthenarrowgalleriestoBeesofaveragedimensions。Itmayhappenthereforethatagalleryistoosmalltoadmitthelarge—sizedmotherstowhomchanceallotsit。WhentheOsmiaisunabletoenterthetube,obviouslyshewillnotcolonizeit。Shethenclosestheentrancetothisspacewhichshecannotuseanddoesherlayingbeyondit,inthewidetube。HadI

triedtoavoidtheseuselessapparatusbychoosingtubesoflargercalibre,Ishouldhaveencounteredanotherdrawback:themedium—sizedmothers,findingthemselvesalmostcomfortable,wouldhavedecidedtolodgefemalesthere。Ihadtobepreparedforit:aseachmotherselectedherhouseatwillandasIwasunabletointerfereinherchoice,anarrowtubewouldbecolonizedornot,accordingastheOsmiawhoowneditwasorwasnotabletomakeherwayinside。

Thereremainsomefortypairsoftubeswithbothgalleriescolonized。

Inthesetherearetwothingstotakeintoconsideration。Thenarrowreartubesof5or51/2millimetres（。195to。214inch。——

Translator\'sNote。）——andthesearethemostnumerous——containmalesandmalesonly,butinshortseries,betweenoneandfive。Themotherisheresomuchhamperedinherworkthattheyarerarelyoccupiedfromendtoend;theOsmiaseemsinahurrytoleavethemandtogoandcolonizethefronttube,whoseamplespacewillleaveherthelibertyofmovementnecessaryforheroperations。Theotherreartubes,theminority,whosediameterisabout6millimetres（。234

inch。——Translator\'sNote。）,containsometimesonlyfemalesandsometimesfemalesatthebackandmalestowardstheopening。Onecanseethatatubeatriflewiderandamotherslightlysmallerwouldaccountforthisdifferenceintheresults。Nevertheless,asthenecessaryspaceforafemaleisbarelyprovidedinthiscase,weseethatthemotheravoidsasfarasshecanatwo—sexarrangementbeginningwithmalesandthatsheadoptsitonlyinthelastextremity。Finally,whateverthecontentsofthesmalltubemaybe,thoseofthelargeone,followinguponit,nevervaryandconsistoffemalesatthebackandmalesinfront。

Thoughincomplete,becauseofcircumstancesverydifficulttocontrol,theresultoftheexperimentisnonethelessverystriking。

Twenty—fiveapparatuscontainonlymalesintheirnarrowgallery,innumbersvaryingfromaminimumofonetoamaximumoffive。Afterthesecomesthecolonyofthelargegallery,beginningwithfemalesandendingwithmales。Andthelayingsintheseapparatusdonotalwaysbelongtolatesummeroreventotheintermediateperiod:afewsmalltubescontaintheearliesteggsoftheOsmiae。AcoupleofOsmiae,moreforwardthantheothers,settoworkonthe23rdofApril。Bothofthemstartedtheirlayingbyplacingmalesinthenarrowtubes。Themeagresupplyofprovisionswasenoughinitselftoshowthesex,whichprovedlatertobeinaccordancewithmyanticipations。Weseethenthat,bymyartifices,thewholeswarmstartswiththeconverseofthenormalorder。Thisinversioniscontinued,atnomatterwhatperiod,fromthebeginningtotheendoftheoperations。Theserieswhich,accordingtorule,wouldbeginwithfemalesnowbeginswithmales。Oncethelargergalleryisreached,thelayingispursuedintheusualorder。

Wehaveadvancedonestepandthatnosmallone:wehaveseenthattheOsmia,whencircumstancesrequireit,iscapableofreversingthesequenceofthesexes。Woulditbepossible,providedthatthetubewerelongenough,toobtainacompleteinversion,inwhichtheentireseriesofthemalesshouldoccupythenarrowgalleryatthebackandtheentireseriesofthefemalestheroomygalleryinfront？Ithinknot;andIwilltellyouwhy。

LongandnarrowcylindersarebynomeanstotheOsmia\'staste,notbecauseoftheirnarrownessbutbecauseoftheirlength。Rememberthatforeachloadofhoneybroughttheworkerisobligedtomovebackwardstwice。Sheenters,headfirst,tobeginbydisgorgingthehoney—syrupfromhercrop。Unabletoturninapassagewhichsheblocksentirely,shegoesoutbackwards,crawlingratherthanwalking,alaboriousperformanceonthepolishedsurfaceoftheglassandaperformancewhich,withanyothersurface,wouldstillbeveryawkward,asthewingsareboundtorubagainstthewallwiththeirfreeendandareliabletogetrumpledorbent。Shegoesoutbackwards,reachestheoutside,turnsroundandgoesinagain,butthistimetheoppositeway,soastobrushofftheloadofpollenfromherabdomenontotheheap。Ifthegalleryisatalllong,thiscrawlingbackwardsbecomestroublesomeafteratime;andtheOsmiasoonabandonsapassagethatistoosmalltoallowoffreemovement。

Ihavesaidthatthenarrowtubesofmyapparatusare,forthemostpart,onlyveryincompletelycolonized。TheBee,afterlodgingasmallnumberofmalesinthem,hastenstoleavethem。Inthewidefrontgallery,shecanstaywheresheisandstillbeabletoturnroundeasilyforherdifferentmanipulations;shewillavoidthosetwolongjourneysbackwards,whicharesoexhaustingandsobadforherwings。

Anotherreasonnodoubtpromptshernottomaketoogreatauseofthenarrowpassage,inwhichshewouldestablishmales,followedbyfemalesinthepartwherethegallerywidens。Themaleshavetoleavetheircellsacoupleofweeksormorebeforethefemales。Iftheyoccupythebackofthehouse,theywilldieprisonersorelsetheywilloverturneverythingontheirwayout。ThisriskisavoidedbytheorderwhichtheOsmiaadopts。

Inmytubeswiththeirunusualarrangement,themothermightwellfindthedilemmaperplexing:thereisthenarrownessofthespaceatherdisposalandthereistheemergencelateron。Inthenarrowtubes,thewidthisinsufficientforthefemales;ontheotherhand,ifshelodgesmalesthere,theyareliabletoperish,sincetheywillbepreventedfromissuingatthepropermoment。Thiswouldperhapsexplainthemother\'shesitationandherobstinacyinsettlingfemalesinsomeofmyapparatuswhichlookedasiftheycouldsuitnonebutmales。

Asuspicionoccurstome,asuspicionarousedbymyattentiveexaminationofthenarrowtubes。All,whateverthenumberoftheirinmates,arecarefullypluggedattheopening,justasseparatetubeswouldbe。ItmightthereforebethecasethatthenarrowgalleryatthebackwaslookeduponbytheOsmianotastheprolongationofthelargefrontgallery,butasanindependenttube。Thefacilitywithwhichtheworkerturnsassoonasshereachesthewidetube,herlibertyofaction,whichisnowasgreatasinadoorwaycommunicatingwiththeouterair,mightwellbemisleadingandcausetheOsmiatotreatthenarrowpassageatthebackasthoughthewidepassageinfrontdidnotexist。Thiswouldaccountfortheplacingofthefemaleinthelargetubeabovethemalesinthesmalltube,anarrangementcontrarytohercustom。

Iwillnotundertaketodecidewhetherthemotherreallyappreciatesthedangerofmysnares,orwhethershemakesamistakeinconsideringonlythespaceatherdisposalandbeginningwithmales。

Atanyrate,Iperceiveinheratendencytodeviateaslittleaspossiblefromtheorderwhichsafeguardstheemergenceofthetwosexes。Thistendencyisdemonstratedbyherrepugnancetocolonizingmynarrowtubeswithlongseriesofmales。However,sofarasweareconcerned,itdoesnotmattermuchwhatpassesatsuchtimesintheOsmia\'slittlebrain。Enoughforustoknowthatshedislikesnarrowandlongtubes,notbecausetheyarenarrow,butbecausetheyareatthesametimelong。

And,infact,shedoesverywellwithashorttubeofthesamediameter。SucharethecellsintheoldnestsoftheMason—beeoftheShrubsandtheemptyshellsoftheGardenSnail。Withtheshorttube,thetwodisadvantagesofthelongtubeareavoided。ShehasverylittleofthatcrawlingbackwardstodowhenshehasaSnail—shellforthehomeofhereggsandscarcelyanywhenthehomeisthecelloftheMason—bee。Moreover,asthestackofcocoonsnumberstwoorthreeatmost,thedeliverancewillbeexemptfromthedifficultiesattachedtoalongseries。TopersuadetheOsmiatonidifyinasingletubelongenoughtoreceivethewholeofherlayingandatthesametimenarrowenoughtoleaveheronlyjustthepossibilityofadmittanceappearstomeaprojectwithouttheslightestchanceofsuccess:theBeewouldstubbornlyrefusesuchadwellingorwouldcontentherselfwithentrustingonlyaverysmallportionofhereggstoit。Ontheotherhand,withnarrowbutshortcavities,success,withoutbeingeasy,seemstomeatleastquitepossible。Guidedbytheseconsiderations,Iembarkeduponthemostarduouspartofmyproblem:toobtainthecompleteoralmostcompletepermutationofonesexwiththeother;toproducealayingconsistingonlyofmalesbyofferingthemotheraseriesoflodgingssuitedonlytomales。

LetusinthefirstplaceconsulttheoldnestsoftheMason—beeoftheShrubs。Ihavesaidthatthesemortarspheroids,piercedalloverwithlittlecylindricalcavities,areadoptedprettyeagerlybytheThree—hornedOsmia,whocolonizesthembeforemyeyeswithfemalesinthedeepcellsandmalesintheshallowcells。Thatishowthingsgowhentheoldnestremainsinitsnaturalstate。Withagrater,however,Iscrapetheoutsideofanothernestsoastoreducethedepthofthecavitiestosometenmillimetres。（Abouttwo—fifthsofaninch。——Translator\'sNote。）Thisleavesineachcelljustroomforonecocoon,surmountedbytheclosingstopper。Ofthefourteencavitiesinthenests,Ileavetwointact,measuringfifteenmillimetresindepth。（。585inch。——Translator\'sNote。）Nothingcouldbemorestrikingthantheresultofthisexperiment,madeinthefirstyearofmyhomerearing。Thetwelvecavitieswhosedepthhadbeenreducedallreceivedmales;thetwocavitiesleftuntouchedreceivedfemales。

AyearpassesandIrepeattheexperimentwithanestoffifteencells;butthistimeallthecellsarereducedtotheminimumdepthwiththegrater。Well,thefifteencells,fromfirsttolast,areoccupiedbymales。Itmustbequiteunderstoodthat,ineachcase,alltheoffspringbelongedtoonemother,markedwithherdistinguishingspotandkeptinsightaslongasherlayinglasted。

Hewouldindeedbedifficulttopleasewhorefusedtobowbeforetheresultsofthesetwoexperiments。If,however,heisnotyetconvinced,hereissomethingtoremovehislastdoubts。

TheThree—hornedOsmiaoftensettlesherfamilyinoldshells,especiallythoseoftheCommonSnail（Helixaspersa）,whoissocommonunderthestone—heapsandinthecrevicesofthelittleunmortaredwallsthatsupportourterraces。Inthisspecies,thespiraliswideopen,sothattheOsmia,penetratingasfardownasthehelicalpassagepermits,finds,immediatelyabovethepointwhichistoonarrowtopass,thespacenecessaryforthecellofafemale。

Thiscellissucceededbyothers,widerstill,alwaysforfemales,arrangedinalineinthesamewayasinastraighttube。Inthelastwhorlofthespiral,thediameterwouldbetoogreatforasinglerow。Thenlongitudinalpartitionsareaddedtothetransversepartitions,thewholeresultingincellsofunequaldimensionsinwhichmalespredominate,mixedwithafewfemalesinthelowerstoreys。Thesequenceofthesexesisthereforewhatitwouldbeinastraighttubeandespeciallyinatubewithawidebore,wherethepartitioningiscomplicatedbysubdivisionsonthesamelevel。A

singleSnail—shellcontainsroomforsixoreightcells。Alarge,roughearthenstopperfinishesthenestattheentrancetotheshell。

Asadwellingofthissortcouldshowusnothingnew,IchoseformyswarmtheGardenSnail（Helixcaespitum）,whoseshell,shapedlikeasmall,swollenAmmonite,widensbyslowdegrees,thediameteroftheusableportion,rightuptothemouth,beinghardlygreaterthanthatrequiredbyamaleOsmia—cocoon。Moreover,thewidestpart,inwhichafemalemightfindroom,hastoreceiveathickstopping—plug,belowwhichtherewilloftenbeafreespace。Underalltheseconditions,thehousewillhardlysuitanybutmalesarrangedoneaftertheother。

Thecollectionofshellsplacedatthefootofeachhiveincludesspecimensofdifferentsizes。Thesmallestare18millimetres（。7

inch。——Translator\'sNote。）indiameterandthelargest24millimetres（。936inch。——Translator\'sNote。）Thereisroomfortwococoons,orthreeatmost,accordingtotheirdimensions。

Nowtheseshellswereusedbymyvisitorswithoutanyhesitation,perhapsevenwithmoreeagernessthantheglasstubes,whoseslipperysidesmighteasilybealittleannoyingtotheBee。Someofthemwereoccupiedonthefirstfewdaysofthelaying;andtheOsmiawhohadstartedwithahomeofthissortwouldpassnexttoasecondSnail—

shell,intheimmediateneighbourhoodofthefirst,toathird,afourthandothersstill,alwaysclosetooneanother,untilherovarieswereemptied。ThewholefamilyofonemotherwouldthusbelodgedinSnail—shellswhichweredulymarkedwiththedateofthelayingandadescriptionoftheworker。ThefaithfuladherentsoftheSnail—shellwereintheminority。Thegreaternumberleftthetubestocometotheshellsandthenwentbackfromtheshellstothetubes。All,afterfillingthespiralstaircasewithtwoorthreecells,closedthehousewithathickearthenstopperonalevelwiththeopening。Itwasalongandtroublesometask,inwhichtheOsmiadisplayedallherpatienceasamotherandallhertalentsasaplasterer。Therewereevensomewho,scrupuloustoexcess,carefullycementedtheumbilicus,aholewhichseemedtoinspirethemwithdistrustasbeingabletogiveaccesstotheinteriorofthedwelling。Itwasadangerous—lookingcavity,whichforthegreatersafetyofthefamilyitwasprudenttoblockup。

Whenthepupaearesufficientlymatured,Iproceedtoexaminetheseelegantabodes。Thecontentsfillmewithjoy:theyfulfilmyanticipationstotheletter。Thegreat,theverygreatmajorityofthecocoonsturnouttobemales;hereandthere,inthebiggercells,afewrarefemalesappear。Thesmallnessofthespacehasalmostdoneawaywiththesixty—eightSnail—shellscolonized。But,ofthistotalnumber,ImustuseonlythoseserieswhichreceivedanentirelayingandwereoccupiedbythesameOsmiafromthebeginningtotheendoftheegg—season。Hereareafewexamples,takenfromamongthemostconclusive。

>Fromthe6thofMay,whenshestartedoperations,tothe25thofMay,thedateatwhichherlayingceased,theOsmiaoccupiedsevenSnail—

shellsinsuccession。Herfamilyconsistsoffourteencocoons,anumberveryneartheaverage;and,ofthesefourteencocoons,twelvebelongtomalesandonlytwotofemales。Theseoccupytheseventhandthirteenthplacesinchronologicalorder。

Another,betweenthe9thand27thofMay,stockedsixSnail—shellswithafamilyofthirteen,includingtenmalesandthreefemales。Theplacesoccupiedbythelatterintheserieswerenumbers3,4and5。

Athird,betweenthe2ndand29thofMay,colonizedelevenSnail—

shells,aprodigioustask。Thisindustriousonewasalsoexceedinglyprolific。Shesuppliedmewithafamilyoftwenty—six,thelargestwhichIhaveeverobtainedfromoneOsmia。Well,thisabnormalprogenyconsistedoftwenty—fivemalesandonefemale,onealone,occupyingplace17。

Thereisnoneedtogoon,afterthismagnificentexample,especiallyastheotherserieswouldall,withoutexception,giveusthesameresult。Twofactsareimmediatelyobvious。TheOsmiaisabletoreversetheorderofherlayingandtostartwithamoreorlesslongseriesofmalesbeforeproducinganyfemales。Inthefirstcase,thefirstfemaleappearsasnumber7;inthethird,asnumber17。Thereissomethingbetterstill;andthisisthepropositionwhichIwasparticularlyanxioustoprove:thefemalesexcanbepermutedwiththemalesexandcanbepermutedtothepointofdisappearingaltogether。Weseethisespeciallyinthethirdcase,wherethepresenceofasolitaryfemaleinafamilyoftwenty—sixisduetothesomewhatlargerdiameterofthecorrespondingSnail—shellandalso,nodoubt,tosomemistakeonthemother\'spart,forthefemalecocoon,inaseriesoftwo,occupiestheupperstorey,theonenexttotheorifice,anarrangementwhichtheOsmiaappearstometodislike。

ThisresultthrowssomuchlightononeofthedarkestcornersofbiologythatImustattempttocorroborateitbymeansofevenmoreconclusiveexperiments。IproposenextyeartogivetheOsmiaenothingbutSnail—shellsforalodging,pickedoutonebyone,andrigorouslytodeprivetheswarmofanyotherretreatinwhichthelayingcouldbeeffected。Undertheseconditions,Ioughttoobtainnothingbutmales,ornearly,forthewholeswarm。