Thatisperfectlytrue;butarethereanyalterations？Tobeginwith,itseemstomehardlypossiblethattheinsectcangobacktothecuttingoncethepieceisdetachedfromtheleaf:itlacksthenecessarysupporttognawtheflimsydiskwithanyprecision。A
tailorwouldspoilhisclothifhehadnotthesupportofatablewhencuttingoutthepiecesforacoat。TheMegachile\'sscissors,sodifficulttowieldonanythingnotfirmlyheld,woulddoequallybadwork。
Besides,IhavebetterevidencethanthisformyrefusaltobelieveintheexistenceofalterationswhentheBeehasthecellinfrontofher。Thelidiscomposedofapileofdiskswhosenumbersometimesreacheshalfascore。Nowthebottompartofallthesedisksistheundersurfaceoftheleaf,whichispalerandmorestronglyveined;
thetoppartistheuppersurface,whichissmoothandgreener。Inotherwords,theinsectplacestheminthepositionwhichtheyoccupywhengathered。Letmeexplain。Inordertocutoutapiece,theBeestandsontheuppersurfaceoftheleaf。Thepiecedetachedisheldinthefeetandisthereforelaidwithitstopsurfaceagainsttheinsect\'schestatthemomentofdeparture。Thereisnopossibilityofitsbeingturnedoveronthejourney。Consequently,thepieceislaidastheBeehasjustpickedit,withthelowersurfacetowardstheinsideofthecellandtheuppersurfacetowardstheoutside。Ifalterationswerenecessarytoreducethelidtothediameterofthepot,thediskwouldbeboundtogetturnedover:thepiece,manipulated,setupright,turnedround,triedthiswayandthat,would,whenfinallylaidinposition,haveitstoporbottomsurfaceinsidejustasithappenedtocome。Butthisisexactlywhatdoesnottakeplace。Therefore,astheorderofstackingneverchanges,thedisksarecut,fromthefirstclipofthescissors,withtheirproperdimensions。Theinsectexcelsusinpracticalgeometry。IlookupontheLeaf—cutter\'spotandlidasanadditiontothemanyothermarvelsofinstinctthatcannotbeexplainedbymechanics;Isubmitittotheconsiderationofscience;andIpasson。
TheSilkyLeaf—cutter（Megachilesericans,FONSCOL。;M。Dufourii,LEP。）makeshernestsinthedisusedgalleriesoftheAnthophorae。I