different；　for　out　of　42　leaves　drawn　into　the　burrows；　no　less
  than　i6　were　drawn　in　by　the　tips　of　the　needles。　　These　worms；
  however；　worked　in　a　careless　or　slovenly　manner；　for　the　leaves
  were　often　drawn　in　to　only　a　small　depth；　sometimes　they　were
  merely　heaped　over　the　mouths　of　the　burrows；　and　sometimes　none
  were　drawn　in。　　I　believe　that　this　carelessness　may　be　accounted
  for　either　by　the　warmth　of　the　air；　or　by　its　dampness；　as　the
  pots　were　covered　by　glass　plates；　the　worms　consequently　did　not
  care　about　plugging　up　their　holes　effectually。　　Pots　tenanted　by
  worms　and　covered　with　a　net　which　allowed　the　free　entrance　of
  air；　were　left　out　of　doors　for　several　nights；　and　now　72　leaves
  were　all　properly　drawn　in　by　their　bases。
  It　might　perhaps　be　inferred　from　the　facts　as　yet　given；　that
  worms　somehow　gain　a　general　notion　of　the　shape　or　structure　of
  pine…leaves；　and　perceive　that　it　is　necessary　for　them　to　seize
  the　base　where　the　two　needles　are　conjoined。　　But　the　following
  cases　make　this　more　than　doubtful。　　The　tips　of　a　large　number　of
  needles　of　P。　austriaca　were　cemented　together　with　shell…lac
  dissolved　in　alcohol；　and　were　kept　for　some　days；　until；　as　I
  believe；　all　odour　or　taste　had　been　lost；　and　they　were　then
  scattered　on　the　ground　where　no　pine…trees　grew；　near　burrows　from
  which　the　plugging　had　been　removed。　　Such　leaves　could　have　been
  drawn　into　the　burrows　with　equal　ease　by　either　end；　and　judging
  from　analogy　and　more　especially　from　the　case　presently　to　be
  given　of　the　petioles　of　Clematis　montana；　I　expected　that　the　apex
  would　have　been　preferred。　　But　the　result　was　that　out　of　121
  leaves　with　the　tips　cemented；　which　were　drawn　into　burrows；　108
  were　drawn　in　by　their　bases；　and　only　13　by　their　tips。　　Thinking
  that　the　worms　might　possibly　perceive　and　dislike　the　smell　or
  taste　of　the　shell…lac；　though　this　was　very　improbable；　especially
  after　the　leaves　had　been　left　out　during　several　nights；　the　tips
  of　the　needles　of　many　leaves　were　tied　together　with　fine　thread。
  Of　leaves　thus　treated　150　were　drawn　into　burrows123　by　the　base
  and　27　by　the　tied　tips；　so　that　between　four　land　five　times　as
  many　were　drawn　in　by　the　base　as　by　the　tip。　　It　is　possible　that
  the　short　cut…off　ends　of　the　thread　with　which　they　were　tied；　may
  have　tempted　the　worms　to　drag　in　a　larger　proportional　number　by
  the　tips　than　when　cement　was　used。　　Of　the　leaves　with　tied　and
  cemented　tips　taken　together　（271　in　number）　85　per　cent。　were
  drawn　in　by　the　base　and　15　per　cent。　by　the　tips。　　We　may
  therefore　infer　that　it　is　not　the　divergence　of　the　two　needles
  which　leads　worms　in　a　state　of　nature　almost　invariably　to　drag
  pine…leaves　into　their　burrows　by　the　base。　　Nor　can　it　be　the
  sharpness　of　the　points　of　the　needles　which　determines　them；　for；
  as　we　have　seen；　many　leaves　with　the　points　cut　off　were　drawn　in
  by　their　bases。　　We　are　thus　led　to　conclude；　that　with　pine…leaves
  there　must　be　something　attractive　to　worms　in　the　base；
  notwithstanding　that　few　ordinary　leaves　are　drawn　in　by　the　base
  or　foot…stalk。
  Petioles。We　will　now　turn　to　the　petioles　or　foot…stalks　of
  compound　leaves；　after　the　leaflets　have　fallen　off。　　Those　from
  Clematis　montana；　which　grew　over　a　verandah；　were　dragged　early　in
  January　in　large　numbers　into　the　burrows　on　an　adjoining　gravel…
  walk；　lawn；　and　flower…bed。　　These　petioles　vary　from　2。5　to　4。5
  inches　in　length；　are　rigid　and　of　nearly　uniform　thickness；　except
  close　to　the　base　where　they　thicken　rather　abruptly；　being　here
  about　twice　as　thick　as　in　any　other　part。　　The　apex　is　somewhat
  pointed；　but　soon　withers　and　is　then　easily　broken　off。　　Of　these
  petioles；　314　were　pulled　out　of　burrows　in　the　above　specified
  sites；　and　it　was　found　that　76　per　cent。　had　been　drawn　in　by
  their　tips；　and　24　per　cent　by　their　bases；　so　that　those　drawn　in
  by　the　tip　were　a　little　more　than　thrice　as　many　as　those　drawn　in
  by　the　base。　　Some　of　those　extracted　from　the　well…beaten　gravel…
  walk　were　kept　separate　from　the　others；　and　of　these　（59　in
  number）　nearly　five　times　as　many　had　been　drawn　in　by　the　tip　as
  by　the　base；　whereas　of　those　extracted　from　the　lawn　and　flower…
  bed；　where　from　the　soil　yielding　more　easily；　less　care　would　be
  necessary　in　plugging　up　the　burrows；　the　proportion　of　those　drawn
  in　by　the　tip　（130）　to　those　drawn　in　by　the　base　（48）　was　rather
  less　than　three　to　one。　　That　these　petioles　had　been　dragged　into
  the　burrows　for　plugging　them　up；　and　not　for　food；　was　manifest；
  as　neither　end；　as　far　as　I　could　see；　had　been　gnawed。　　As　several
  petioles　are　used　to　plug　up　the　same　burrow；　in　one　case　as　many
  as　10；　and　in　another　case　as　many　as　15；　the　worms　may　perhaps　at
  first　draw　in　a　few　by　the　thicker　end　so　as　to　save　labour；　but
  afterwards　a　large　majority　are　drawn　in　by　the　pointed　end；　in
  order　to　plug　up　the　hole　securely。
  The　fallen　petioles　of　our　native　ash…tree　were　next　observed；　and
  the　rule　with　most　objects；　viz。；　that　a　large　majority　are　dragged
  into　the　burrows　by　the　more　pointed　end；　had　not　here　been
  followed；　and　this　fact　much　surprised　me　at　first。　　These　petioles
  vary　in　length　from　5　to　8。5　inches；　they　are　thick　and　fleshy
  towards　the　base；　whence　they　taper　gently　towards　the　apex；　which
  is　a　little　enlarged　and　truncated　where　the　terminal　leaflet　had
  been　originally　attached。　　Under　some　ash…trees　growing　in　a　grass…
  field；　229　petioles　were　pulled　out　of　worm　burrows　early　in
  January；　and　of　these　51。5　per　cent。　had　been　drawn　in　by　the　base；
  and　48。5　per　cent。　by　the　apex。　　This　anomaly　was　however　readily
  explained　as　soon　as　the　thick　basal　part　was　examined；　for　in　78
  out　of　103　petioles；　this　part　had　been　gnawed　by　worms；　just　above
  the　horse…shoe　shaped　articulation。　　In　most　cases　there　could　be
  no　mistake　about　the　gnawing；　for　ungnawed　petioles　which　were
  examined　after　being　exposed　to　the　weather　for　eight　additional
  weeks　had　not　become　more　disintegrated　or　decayed　near　the　base
  than　elsewhere。　　It　is　thus　evident　that　the　thick　basal　end　of　the
  petiole　is　drawn　in　not　solely　for　the　sake　of　plugging　up　the
  mouths　of　the　burrows；　but　as　food。　　Even　the　narrow　truncated　tips
  of　some　few　petioles　had　been　gnawed；　and　this　was　the　case　in　6
  out　of　37　which　were　examined　for　this　purpose。　　Worms；　after
  having　drawn　in　and　gnawed　the　basal　end；　often　push　the　petioles
  out　of　their　burrows；　and　then　drag　in　fresh　ones；　either　by　the
  base　for　food；　or　by　the　apex　for　plugging　up　the　mouth　more
  effectually。　　Thus；　out　of　37　petioles　inserted　by　their　tips；　5
  had　been　previously　drawn　in　by　the　base；　for　this　part　had　been
  gnawed。　　Again；　I　collected　a　handful　of　petioles　lying　loose　on
  the　ground　close　to　some　plugged…up　burrows；　where　the　surface　was
  thickly　strewed　with　other　petioles　which　apparently　had　never　been
  touched　by　worms；　and　14　out　of　47　（i。e。　nearly　one…third）；　after
  having　had　their　bases　gnawed　had　been　pushed　out　of　the　burrows
  and　were　now　lying　on　the　ground。　　From　these　several　facts　we　may
  conclude　that　worms　draw　in　some　petioles　of　the　ash　by　the　base　to
  serve　as　food；　and　others　by　the　tip　to　plug　up　the　mouths　of　their
  burrows　in　the　most　efficient　manner。
  The　petioles　of　Robinia　pseudo…acacia　vary　from　4　or　5　to　nearly　12
  inches　in　length；　they　are　thick　close　to　the　base　before　the
  softer　parts　have　rotted　off；　and　taper　much　towards　the　upper　end。
  They　are　so　flexible　that　I　have　seen　some　few　doubled　up　and　thus
  drawn　into　the　burrows　of　worms。　　Unfortunately　these　petioles　were
  not　examined　until　February；　by　which　time　the　softer　parts　had
  completely　rotted　off；　so　that　it　was　impossible　to　ascertain
  whether　worms　had　gnawed　the　bases；　though　this　is　in　itself
  probable。　　Out　of　121　petioles　extracted　from　burrows　early　in
  February；　68　were　imbedded　by　the　base；　and　53　by　the　apex。　　On
  February　5　all　the　petioles　which　had　been　drawn　into　the　burrows
  beneath　a　Robinia；　were　pulled　up；　and　after　an　interval　of　eleven
  days；　35　petioles　had　been　again　dragged　in；　19　by　the　base；　and　16
  by　the　apex。　　Taking　these　two　lots　together；　56　per　cent。　were
  drawn　in　by　the　base；　and　44　per　cent。　by　the　apex。　　As　all　the
  softer　parts　had　long　ago　rotted　off；　we　may　feel　sure；　especially
  in　the　latter　case；　that　none　had　been　drawn　in　as　food。　　At　this
  season；　therefore；　worms　drag　these　petioles　into　their　burrows
  indifferently　by　either　end；　a　slight　preference　being　given　to　the
  base。　　This　latter　fact　may　be　accounted　for　by　the　difficulty　of
  plugging　up　a　burrow　with　objects　so　extremely　thin　as　are　the
  upper　ends。　　In　support　of　this　view；　it　may　be　stated　that　out　of
  the　16　petioles　which　had　been　drawn　in　by　their　upper　ends；　the
  more　attenuated　terminal　portion　of　7　had　been　previously　broken
  off　by　some　accident。
  Triangles　of　paper。Elongated　triangles　were　cut　out　of　moderately
  stiff　writing…paper；　which　was　rubbed　with　raw　fat　on　both　sides；
  so　as　to　prevent　their　becoming　excessively　limp　when