pilipes,diglongcorridorsleadingtothecells,whicharescatteredhereandthereandonebyone。Thesepassagesremainopenatallseasonsoftheyear。Whenspringcomes,thenewcolonyusesthemjustastheyare,providedthattheyarewellpreservedintheclayeymassbakedbythesun;itincreasestheirlengthifnecessary,runsoutafewmorebranches,butdoesnotdecidetostartboringinnewgrounduntiltheoldcity,which,withitsmanylabyrinths,resemblessomemonstroussponge,istoomuchunderminedforsafety。Theovalniches,thecellsthatopenonthosecorridors,arealsoprofitablyemployed。
TheAnthophorarestorestheirentrance,whichhasbeendestroyedbytheinsect\'srecentemergence;shesmoothstheirwallswithafreshcoatofwhitewash,afterwhichthelodgingisfittoreceivetheheapofhoneyandtheegg。Whentheoldcells,insufficientinnumberandmoreoverpartlyinhabitedbydiverseintruders,arealloccupied,theboringofnewcellsbegins,intheextendedsectionsofthegalleries,andtherestoftheeggsarehoused。Inthisway,theswarmissettledataminimumofexpense。
Toconcludethisbriefaccount,letuschangethezoologicalsettingand,aswehavealreadyspokenoftheSparrow,seewhathecandoasabuilder。Thesimplestformofhisnestisthegreatroundballofstraw,deadleavesandfeathers,intheforkofafewbranches。Itiscostlyinmaterial,butcanbesetupanywhere,whentheholeinthewallortheshelterofatilearelacking。Whatreasonsinducedhimtogiveupthesphericaledifice？Toallseeming,thesamereasonsthatledtheOsmiatoabandontheSnail—shell\'sspiral,whichrequiresafatiguingexpenditureofclay,infavouroftheeconomicalcylinderofthereed。Bymakinghishomeinaholeinthewall,theSparrowescapesthegreaterpartofhiswork。Here,thedomethatservesasaprotectionfromtherainandthethickwallsthatofferresistancetothewindbothbecomesuperfluous。Ameremattressissufficient;thecavityinthewallprovidestherest。Thesavingisgreat;andtheSparrowappreciatesitquiteasmuchastheOsmia。
Thisdoesnotmeanthattheprimitivearthasdisappeared,lostthroughneglect;itremainsanineffaceablecharacteristicofthespecies,everreadytodeclareitselfshouldcircumstancesdemandit。
Thegenerationsofto—dayareasmuchendowedwithitasthegenerationsofyore;withoutapprenticeship,withouttheexampleofothers,theyhavewithinthemselves,inthepotentialstate,theindustrialaptitudeoftheirancestors。Ifarousedbythestimulusofnecessity,thisaptitudewillpasssuddenlyfrominactiontoaction。