Letusreturntothereed—stumpwhichgivesusthesedetails。Beyondthecotton—woolcylinderwhereintencocoonsarelodgedinarowcomesanemptyspaceofhalfadecimetreormore。（Abouttwoinches。—
—Translator\'sNote。）TheOsmiaeandtheLeaf—cuttersarealsoaccustomedtoleavetheselong,desertedvestibules。Thenestends,attheorificeofthereed,withastrongplugofflockcoarserandlesswhitethanthatofthecells。Thisuseofclosing—materialswhicharelessdelicateintexturebutofgreaterresisting—power,whilenotaninvariablecharacteristic,occursfrequentlyenoughtomakeussuspectthattheinsectknowshowtodistinguishwhatisbestsuitednowtothesnugsleeping—berthofthelarvae,anontothedefensivebarricadeofthehome。Sometimesthechoiceisanexceedinglyjudiciousone,asisshownbythenestoftheDiademAnthidium。Timeaftertime,whereasthecellswerecomposedofthefinestgradeofwhitecotton,gatheredfromCentaureasolsticialis,orSt。Barnaby\'sthistle,thebarrierattheentrance,differingfromtherestoftheworkinitsyellowcolouring,wasaheapofclose—setbristlessuppliedbythescallop—leavedmullein。Thetwofunctionsofthewaddingarehereplainlymarked。Thedelicateskinofthelarvaeneedsawell—paddedcradle;andthemothercollectsthesoftestmaterialsthatthecottonyplantsprovide。Rivallingthebird,whichfurnishestheinsideofthenestwithwoolandstrengthenstheoutsidewithsticks,shereservesforthegrubs\'mattressthefinestdown,sohardtofindandcollectedwithsuchpatience。But,whenitbecomesamatterofshuttingthedooragainstthefoe,thentheentrancebristleswithforbiddingcaltrops,withstiff,pricklyhairs。
ThisingenioussystemofdefenceisnottheonlyoneknowntotheAnthidia。Moredistrustfulstill,theManicateAnthidiumleavesnospaceinthefrontpartofthereed。Immediatelyafterthecolumnofcells,sheheapsup,intheuninhabitedvestibule,aconglomerationofrubbish,whateverchancemayofferintheneighbourhoodofthenest:littlepiecesofgravel,bitsofearth,grainsofsawdust,particlesofmortar,cypress—catkins,brokenleaves,drySnail—
droppingsandanyothermaterialthatcomesherway。Thepile,arealbarricadethistime,blocksthereedcompletelytotheend,exceptabouttwocentimetres（Aboutthree—quartersofaninch。——Translator\'sNote。）leftforthefinalcottonplug。Certainlynofoewillbreakinthroughthedoublerampart;buthewillmakeaninsidiousattackfromtherear。TheLeucopsiswillcomeand,withherlongprobe,thankstosomeimperceptiblefissureinthetube,willinsertherdreadeggsanddestroyeverysingleinhabitantofthefortress。ThusaretheManicateAnthidium\'sanxiousprecautionsoutwitted。
IfwehadnotalreadyseenthesamethingwiththeLeaf—cutters,thiswouldbetheplacetoenlargeupontheuselesstasksundertakenbytheinsectwhen,withitsovariesapparentlydepleted,itgoesonspendingitsstrengthwithnomaternalobjectinviewandforthesolepleasureofwork。Ihavecomeacrossseveralreedsstoppedupwithflockthoughcontainingnothingatall,orelsefurnishedwithone,twoorthreecellsdevoidofprovisionsoreggs。Theever—