the formation of vegetable mould-第7部分

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truncated　slimy　end　of　the　body　whilst　in　contact　with　the　object；　
and　by　this　means　the　two　adhered　firmly　together。　｛28｝　　That　under　
these　circumstances　a　vacuum　was　produced　was　plainly　seen　on　one　
occasion；　when　a　large　worm　lying　beneath　a　flaccid　cabbage　leaf　
tried　to　drag　it　away；　for　the　surface　of　the　leaf　directly　over　
the　end　of　the　worm's　body　became　deeply　pitted。　　On　another　
occasion　a　worm　suddenly　lost　its　hold　on　a　flat　leaf；　and　the　
anterior　end　of　the　body　was　momentarily　seen　to　be　cup…formed。　　
Worms　can　attach　themselves　to　an　object　beneath　water　in　the　same　
manner；　and　I　saw　one　thus　dragging　away　a　submerged　slice　of　an　
onion…bulb。

The　edges　of　fresh　or　nearly　fresh　leaves　affixed　to　the　ground　
were　often　nibbled　by　the　worms；　and　sometimes　the　epidermis　and　
all　the　parenchyma　on　one　side　was　gnawed　completely　away　over　a　
considerable　space；　the　epidermis　alone　on　the　opposite　side　being　
left　quite　clean。　　The　veins　were　never　touched；　and　leaves　were　
thus　sometimes　partly　converted　into　skeletons。　　As　worms　have　no　
teeth　and　as　their　mouths　consist　of　very　soft　tissue；　it　may　be　
presumed　that　they　consume　by　means　of　suction　the　edges　and　the　
parenchyma　of　fresh　leaves；　after　they　have　been　softened　by　the　
digestive　fluid。　　They　cannot　attack　such　strong　leaves　as　those　of　
sea…kale　or　large　and　thick　leaves　of　ivy；　though　one　of　the　latter　
after　it　had　become　rotten　was　reduced　in　parts　to　the　state　of　a　
skeleton。

Worms　seize　leaves　and　other　objects；　not　only　to　serve　as　food；　
but　for　plugging　up　the　mouths　of　their　burrows；　and　this　is　one　of　
their　strongest　instincts。　　They　sometimes　work　so　energetically　
that　Mr。　D。　F。　Simpson；　who　has　a　small　walled　garden　where　worms　
abound　in　Bayswater；　informs　me　that　on　a　calm　damp　evening　he　
there　heard　so　extraordinary　a　rustling　noise　from　under　a　tree　
from　which　many　leaves　had　fallen；　that　he　went　out　with　a　light　
and　discovered　that　the　noise　was　caused　by　many　worms　dragging　the　
dry　leaves　and　squeezing　them　into　the　burrows。　　Not　only　leaves；　
but　petioles　of　many　kinds；　some　flower…peduncles；　often　decayed　
twigs　of　trees；　bits　of　paper；　feathers；　tufts　of　wool　and　horse…
hairs　are　dragged　into　their　burrows　for　this　purpose。　　I　have　seen　
as　many　as　seventeen　petioles　of　a　Clematis　projecting　from　the　
mouth　of　one　burrow；　and　ten　from　the　mouth　of　another。　　Some　of　
these　objects；　such　as　the　petioles　just　named；　feathers；　&c。；　are　
never　gnawed　by　worms。　　In　a　gravel…walk　in　my　garden　I　found　many　
hundred　leaves　of　a　pine…tree　（P。　austriaca　or　nigricans）　drawn　by　
their　bases　into　burrows。　　The　surfaces　by　which　these　leaves　are　
articulated　to　the　branches　are　shaped　in　as　peculiar　a　manner　as　
is　the　joint　between　the　leg…bones　of　a　quadruped；　and　if　these　
surfaces　had　been　in　the　least　gnawed；　the　fact　would　have　been　
immediately　visible；　but　there　was　no　trace　of　gnawing。　　Of　
ordinary　dicotyledonous　leaves；　all　those　which　are　dragged　into　
burrows　are　not　gnawed。　　I　have　seen　as　many　as　nine　leaves　of　the　
lime…tree　drawn　into　the　same　burrow；　and　not　nearly　all　of　them　
had　been　gnawed；　but　such　leaves　may　serve　as　a　store　for　future　
consumption。　　Where　fallen　leaves　are　abundant；　many　more　are　
sometimes　collected　over　the　mouth　of　a　burrow　than　can　be　used；　so　
that　a　small　pile　of　unused　leaves　is　left　like　a　roof　over　those　
which　have　been　partly　dragged　in。

A　leaf　in　being　dragged　a　little　way　into　a　cylindrical　burrow　is　
necessarily　much　folded　or　crumpled。　　When　another　leaf　is　drawn　
in；　this　is　done　exteriorly　to　the　first　one；　and　so　on　with　the　
succeeding　leaves；　and　finally　all　become　closely　folded　and　
pressed　together。　　Sometimes　the　worm　enlarges　the　mouth　of　its　
burrow；　or　makes　a　fresh　one　close　by；　so　as　to　draw　in　a　still　
larger　number　of　leaves。　　They　often　or　generally　fill　up　the　
interstices　between　the　drawn…in　leaves　with　moist　viscid　earth　
ejected　from　their　bodies；　and　thus　the　mouths　of　the　burrows　are　
securely　plugged。　　Hundreds　of　such　plugged　burrows　may　be　seen　in　
many　places；　especially　during　the　autumnal　and　early　winter　
months。　　But；　as　will　hereafter　be　shown；　leaves　are　dragged　into　
the　burrows　not　only　for　plugging　them　up　and　for　food；　but　for　the　
sake　of　lining　the　upper　part　or　mouth。

When　worms　cannot　obtain　leaves；　petioles；　sticks；　&c。；　with　which　
to　plug　up　the　mouths　of　their　burrows；　they　often　protect　them　by　
little　heaps　of　stones；　and　such　heaps　of　smooth　rounded　pebbles　
may　frequently　be　seen　on　gravel…walks。　　Here　there　can　be　no　
question　about　food。　　A　lady；　who　was　interested　in　the　habits　of　
worms；　removed　the　little　heaps　of　stones　from　the　mouths　of　
several　burrows　and　cleared　the　surface　of　the　ground　for　some　
inches　all　round。　　She　went　out　on　the　following　night　with　a　
lantern；　and　saw　the　worms　with　their　tails　fixed　in　their　burrows；　
dragging　the　stones　inwards　by　the　aid　of　their　mouths；　no　doubt　by　
suction。　　〃After　two　nights　some　of　the　holes　had　8　or　9　small　
stones　over　them；　after　four　nights　one　had　about　30；　and　another　
34　stones。〃　｛29｝　　One　stonewhich　had　been　dragged　over　the　
gravel…walk　to　the　mouth　of　a　burrow　weighed　two　ounces；　and　this　
proves　how　strong　worms　are。　　But　they　show　greater　strength　in　
sometimes　displacing　stones　in　a　well…trodden　gravel…walk；　that　
they　do　so；　may　be　inferred　from　the　cavities　left　by　the　displaced　
stones　being　exactly　filled　by　those　lying　over　the　mouths　of　
adjoining　burrows；　as　I　have　myself　observed。

Work　of　this　kind　is　usually　performed　during　the　night；　but　I　have　
occasionally　known　objects　to　be　drawn　into　the　burrows　during　the　
day。　　What　advantage　the　worms　derive　from　plugging　up　the　mouths　
of　their　burrows　with　leaves；　&c。；　or　from　piling　stones　over　them；　
is　doubtful。　　They　do　not　act　in　this　manner　at　the　times　when　they　
eject　much　earth　from　their　burrows；　for　their　castings　then　serve　
to　cover　the　mouths。　　When　gardeners　wish　to　kill　worms　on　a　lawn；　
it　is　necessary　first　to　brush　or　rake　away　the　castings　from　the　
surface；　in　order　that　the　lime…water　may　enter　the　burrows。　｛30｝　　
It　might　be　inferred　from　this　fact　that　the　mouths　are　plugged　up　
with　leaves；　&c。；　to　prevent　the　entrance　of　water　during　heavy　
rain；　but　it　may　be　urged　against　this　view　that　a　few；　loose；　
well…rounded　stones　are　ill…adapted　to　keep　out　water。　　I　have　
moreover　seen　many　burrows　in　the　perpendicularly　cut　turf…edgings　
to　gravel…walks；　into　which　water　could　hardly　flow；　as　well　
plugged　as　burrows　on　a　level　surface。　　It　is　not　probable　that　the　
plugs　or　piles　of　stones　serve　to　conceal　the　burrows　from　
scolopendras；　which；　according　to　Hoffmeister；　｛31｝　are　the　
bitterest　enemies　of　worms；　or　from　the　larger　species　of　Carabus　
and　Staphylinus　which　attack　them　ferociously；　for　these　animals　
are　nocturnal；　and　the　burrows　are　opened　at　night。　　May　not　worms　
when　the　mouth　of　the　burrow　is　protected　be　able　to　remain　with　
safety　with　their　heads　close　to　it；　which　we　know　that　they　like　
to　do；　but　which　costs　so　many　of　them　their　lives？　　Or　may　not　the　
plugs　check　the　free　ingress　of　the　lowest　stratum　of　air；　when　
chilled　by　radiation　at　night；　from　the　surrounding　ground　and　
herbage？　　I　am　inclined　to　believe　in　this　latter　view：　　firstly；　
because　when　worms　were　kept　in　pots　in　a　room　with　a　fire；　in　
which　case　cold　air　could　not　enter　the　burrows；　they　plugged　them　
up　in　a　slovenly　manner；　and　secondarily；　because　they　often　coat　
the　upper　part　of　their　burrows　with　leaves；　apparently　to　prevent　
their　bodies　from　coming　into　close　contact　with　the　cold　damp　
earth。　　Mr。　E。　Parfitt　has　suggested　to　me　that　the　mouths　of　the　
burrows　are　closed　in　order　that　the　air　within　them　may　be　kept　
thoroughly　damp；　and　this　seems　the　most　probable　explanation　of　
the　habit。　　But　the　plugging…up　process　may　serve　for　all　the　above　
purposes。

Whatever　the　motive　may　be；　it　appears　that　worms　much　dislike　
leaving　the　mouths　of　their　burrows　open。　　Nevertheless　they　will　
reopen　them　at　night；　whether　or　not　they　can　afterwards　close　
them。　　Numerous　open　burrows　may　be　seen　on　recently…dug　ground；　
for　in　this　case　the　worms　eject　their　castings　in　cavities　left　in　
the　ground；　or　in　the　old　burrows　instead　of　piling　them　over　the　
mouths　of　their　burrows；　and　they　cannot　collect　objects　on　the　
surface　by　which　the　mouths　might　be　protected。　　So　again　on　a　
recently　disinterred　pavement　of　a　Roman　villa　at　Abinger　
（hereafter　to　be　described）　the　worms　pertinaciously　opened　their　
burrows　almost　every　night；　when　these　had　been　closed　by　being　
trampled　on；　although　they　were　rarely　able　to　find　a　few　minute　
stones　wherewith　to　protect　them。

Intelligence　shown　by　worms　in　their　manner　of　plugging　up　their　
burrows。If　a　man　had　to　plug　up　a　small　cylindrical　hole；　with　
such　objects　as　leaves；　petioles　or　twigs；　he　would　drag　or　push　
them　in　by　their　pointed　ends；　but　if　these　objects　were　very　thin　
relatively　to　the　size　of　the　hole；　he　would　probably　insert　some　
by　their　thicker　or　broader　ends。　　The　guide　in　his　case　would　be　
intelligence。　　It　seemed　therefore　worth　while　to　observe　carefully　
how　worms　dragged　leaves　into　their　burrows；　whether　by　their　tips　
or　bases　or　middle　parts。　　It　seemed　more　especially　desirable　to　
do　this　in　the　case　of　plants　not　natives　to　our　country；　for　
although　the　habit　of　dragging　leaves　into　their　burrows　is　
undoubtedly　instinctive　with　worms；　yet　instinct　could　not　tell　
them　how　to　act　in　the　case　of　leaves　about　which　their　progenitors　
knew　nothing。　　If；　moreover；　worms　acted　solely　through　instinct　or　
an　unvarying　inherited　impulse；　they　would　draw　all　kinds　of　leaves　
into　their　burrows　in　the　same　manner。　　If　they　have　no　such　
definite　instinct；　we　might　expect　that　chance　would　determine　
whether　the　tip；　base　or　middle　was　seized。　　If　both　these　
alternatives　are　excluded；　intelligence　alone　is　left；　unless　the　
worm　in　each　case　first　tries　many　different　methods；　and　follows　
that　alone　which　proves　possible　or　the　most　easy；　but　to　act　in　
thi