the formation of vegetable mould-第19章

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than　this；　neither　burrows　nor　worms　were　seen。

As　I　wished　to　learn　how　many　worms　lived　beneath　the　floor　of　the　
atriuma　space　of　about　14　by　9　feetMr。　Farrer　was　so　kind　as　to　
make　observations　for　me；　during　the　next　seven　weeks；　by　which　
time　the　worms　in　the　surrounding　country　were　in　full　activity；　
and　were　working　near　the　surface。　　It　is　very　improbable　that　
worms　should　have　migrated　from　the　adjoining　field　into　the　small　
space　of　the　atrium；　after　the　superficial　mould　in　which　they　
prefer　to　live；　had　been　removed。　　We　may　therefore　conclude　that　
the　burrows　and　the　castings　which　were　seen　here　during　the　
ensuing　seven　weeks　were　the　work　of　the　former　inhabitants　of　the　
space。　　I　will　now　give　a　few　extracts　from　Mr。　Farrer's　notes。

Aug。　26th；　1877；　that　is；　five　days　after　the　floor　had　been　
cleared。　　On　the　previous　night　there　had　been　some　heavy　rain；　
which　washed　the　surface　clean；　and　now　the　mouths　of　forty　burrows　
were　counted。　　Parts　of　the　concrete　were　seen　to　be　solid；　and　had　
never　been　penetrated　by　worms；　and　here　the　rain…water　lodged。

Sept。　5th。Tracks　of　worms；　made　during　the　previous　night；　could　
be　seen　on　the　surface　of　the　floor；　and　five　or　six　vermiform　
castings　had　been　thrown　up。　　These　were　defaced。

Sept。　12th。During　the　last　six　days；　the　worms　have　not　been　
active；　though　many　castings　have　been　ejected　in　the　neighbouring　
fields；　but　on　this　day　the　earth　was　a　little　raised　over　the　
mouths　of　the　burrows；　or　castings　were　ejected；　at　ten　fresh　
points。　　These　were　defaced。　　It　should　be　understood　that　when　a　
fresh　burrow　is　spoken　of；　this　generally　means　only　that　an　old　
burrow　has　been　re…opened。　　Mr。　Farrer　was　repeatedly　struck　with　
the　pertinacity　with　which　the　worms　re…opened　their　old　burrows；　
even　when　no　earth　was　ejected　from　them。　　I　have　often　observed　
the　same　fact；　and　generally　the　mouths　of　the　burrows　are　
protected　by　an　accumulation　of　pebbles；　sticks　or　leaves。　　Mr。　
Farrer　likewise　observed　that　the　worms　living　beneath　the　floor　of　
the　atrium　often　collected　coarse　grains　of　sand；　and　such　little　
stones　as　they　could　find；　round　the　mouths　of　their　burrows。

Sept。　13th；　soft　wet　weather。　　The　mouths　of　the　burrows　were　re…
opened；　or　castings　were　ejected；　at　31　points；　these　were　all　
defaced。

Sept。　14th；　34　fresh　holes　or　castings；　all　defaced。

Sept。　15th；　44　fresh　holes；　only　5　castings；　all　defaced。

Sept。　18th；　43　fresh　holes；　8　castings；　all　defaced。

The　number　of　castings　on　the　surrounding　fields　was　now　very　
large。

Sept。　19th；　40　holes；　8　castings；　all　defaced。

Sept。　22nd；　43　holes；　only　a　few　fresh　castings；　all　defaced。

Sept。　23rd；　44　holes；　8　castings。

Sept。　25th；　50　holes；　no　record　of　the　number　of　castings。

Oct。　13th；　　61　holes；　no　record　of　the　number　of　castings。

After　an　interval　of　three　years；　Mr。　Farrer；　at　my　request；　again　
looked　at　the　concrete　floor；　and　found　the　worms　still　at　work。

Knowing　what　great　muscular　power　worms　possess；　and　seeing　how　
soft　the　concrete　was　in　many　parts；　I　was　not　surprised　at　its　
having　been　penetrated　by　their　burrows；　but　it　is　a　more　
surprising　fact　that　the　mortar　between　the　rough　stones　of　the　
thick　walls；　surrounding　the　rooms；　was　found　by　Mr。　Farrer　to　have　
been　penetrated　by　worms。　　On　August　26th；　that　is；　five　days　after　
the　ruins　had　been　exposed；　he　observed　four　open　burrows　on　the　
broken　summit　of　the　eastern　wall　（W　in　Fig。　8）；　and；　on　September　
15th；　other　burrows　similarly　situated　were　seen。　　It　should　also　
be　noted　that　in　the　perpendicular　side　of　the　trench　（which　was　
much　deeper　than　is　represented　in　Fig。　8）　three　recent　burrows　
were　seen；　which　ran　obliquely　far　down　beneath　the　base　of　the　old　
wall。

We　thus　see　that　many　worms　lived　beneath　the　floor　and　the　walls　
of　the　atrium　at　the　time　when　the　excavations　were　made；　and　that　
they　afterwards　almost　daily　brought　up　earth　to　the　surface　from　a　
considerable　depth。　　There　is　not　the　slightest　reason　to　doubt　
that　worms　have　acted　in　this　manner　ever　since　the　period　when　the　
concrete　was　sufficiently　decayed　to　allow　them　to　penetrate　it；　
and　even　before　that　period　they　would　have　lived　beneath　the　
floor；　as　soon　as　it　became　pervious　to　rain；　so　that　the　soil　
beneath　was　kept　damp。　　The　floor　and　the　walls　must　therefore　have　
been　continually　undermined；　and　fine　earth　must　have　been　heaped　
on　them　during　many　centuries；　perhaps　for　a　thousand　years。　　If　
the　burrows　beneath　the　floor　and　walls；　which　it　is　probable　were　
formerly　as　numerous　as　they　now　are；　had　not　collapsed　in　the　
course　of　time　in　the　manner　formerly　explained；　the　underlying　
earth　would　have　been　riddled　with　passages　like　a　sponge；　and　as　
this　was　not　the　case；　we　may　feel　sure　that　they　have　collapsed。　　
The　inevitable　result　of　such　collapsing　during　successive　
centuries；　will　have　been　the　slow　subsidence　of　the　floor　and　of　
the　walls；　and　their　burial　beneath　the　accumulated　worm…castings。　　
The　subsidence　of　a　floor；　whilst　it　still　remains　nearly　
horizontal；　may　at　first　appear　improbable；　but　the　case　presents　
no　more　real　difficulty　than　that　of　loose　objects　strewed　on　the　
surface　of　a　field；　which；　as　we　have　seen；　become　buried　several　
inches　beneath　the　surface　in　the　course　of　a　few　years；　though　
still　forming　a　horizontal　layer　parallel　to　the　surface。　　The　
burial　of　the　paved　and　level　path　on　my　lawn；　which　took　place　
under　my　own　observation；　is　an　analogous　case。　　Even　those　parts　
of　the　concrete　floor　which　the　worms　could　not　penetrate　would　
almost　certainly　have　been　undermined；　and　would　have　sunk；　like　
the　great　stones　at　Leith　Hill　Place　and　Stonehenge；　for　the　soil　
would　have　been　damp　beneath　them。　　But　the　rate　of　sinking　of　the　
different　parts　would　not　have　been　quite　equal；　and　the　floor　was　
not　quite　level。　　The　foundations　of　the　boundary　walls　lie；　as　
shown　in　the　section；　at　a　very　small　depth　beneath　the　surface；　
they　would　therefore　have　tended　to　subside　at　nearly　the　same　rate　
as　the　floor。　　But　this　would　not　have　occurred　if　the　foundations　
had　been　deep；　as　in　the　case　of　some　other　Roman　ruins　presently　
to　be　described。

Finally；　we　may　infer　that　a　large　part　of　the　fine　vegetable　
mould；　which　covered　the　floor　and　the　broken…down　walls　of　this　
villa；　in　some　places　to　a　thickness　of　16　inches；　was　brought　up　
from　below　by　worms。　　From　facts　hereafter　to　be　given　there　can　be　
no　doubt　that　some　of　the　finest　earth　thus　brought　up　will　have　
been　washed　down　the　sloping　surface　of　the　field　during　every　
heavy　shower　of　rain。　　If　this　had　not　occurred　a　greater　amount　of　
mould　would　have　accumulated　over　the　ruins　than　that　now　present。　　
But　beside　the　castings　of　worms　and　some　earth　brought　up　by　
insects；　and　some　accumulation　of　dust；　much　fine　earth　will　have　
been　washed　over　the　ruins　from　the　upper　parts　of　the　field；　since　
it　has　been　under　cultivation；　and　from　over　the　ruins　to　the　lower　
parts　of　the　slope；　the　present　thickness　of　the　mould　being　the　
resultant　of　these　several　agencies。


I　may　here　append　a　modern　instance　of　the　sinking　of　a　pavement；　
communicated　to　me　in　1871　by　Mr。　Ramsay；　Director　of　the　
Geological　Survey　of　England。　　A　passage　without　a　roof；　7　feet　in　
length　by　3　feet　2　inches　in　width；　led　from　his　house　into　the　
garden；　and　was　paved　with　slabs　of　Portland　stone。　　Several　of　
these　slabs　were　16　inches　square；　others　larger；　and　some　a　little　
smaller。　　This　pavement　had　subsided　about　3　inches　along　the　
middle　of　the　passage；　and　two　inches　on　each　side；　as　could　be　
seen　by　the　lines　of　cement　by　which　the　slabs　had　been　originally　
joined　to　the　walls。　　The　pavement　had　thus　become　slightly　concave　
along　the　middle；　but　there　was　no　subsidence　at　the　end　close　to　
the　house。　　Mr。　Ramsay　could　not　account　for　this　sinking；　until　he　
observed　that　castings　of　black　mould　were　frequently　ejected　along　
the　lines　of　junction　between　the　slabs；　and　these　castings　were　
regularly　swept　away。　　The　several　lines　of　junction；　including　
those　with　the　lateral　walls；　were　altogether　39　feet　2　inches　in　
length。　　The　pavement　did　not　present　the　appearance　of　ever　having　
been　renewed；　and　the　house　was　believed　to　have　been　built　about　
eighty…seven　years　ago。　　Considering　all　these　circumstances；　Mr。　
Ramsay　does　not　doubt　that　the　earth　brought　up　by　the　worms　since　
the　pavement　was　first　laid　down；　or　rather　since　the　decay　of　the　
mortar　allowed　the　worms　to　burrow　through　it；　and　therefore　within　
a　much　shorter　time　than　the　eighty…seven　years；　has　sufficed　to　
cause　the　sinking　of　the　pavement　to　the　above　amount；　except　close　
to　the　house；　where　the　ground　beneath　would　have　been　kept　nearly　
dry。

Beaulieu　Abbey；　Hampshire。This　abbey　was　destroyed　by　Henry　
VIII。；　and　there　now　remains　only　a　portion　of　the　southern　aisle…
wall。　　It　is　believed　that　the　king　had　most　of　the　stones　carried　
away　for　building　a　castle；　and　it　is　certain　that　they　have　been　
removed。　　The　positions　of　the　nave　and　transepts　were　ascertained　
not　long　ago　by　the　foundations　having　been　found；　and　the　place　is　
now　marked　by　stones　let　into　the　ground。　　Where　the　abbey　formerly　
stood；　there　now　extends　a　smooth　grass…covered　surface；　which　
resembles　in　all　respects　the　rest　of　the　field。　　The　guardian；　a　
very　old　man；　said　the　surface　had　never　been　levelled　in　his　time。　　
In　the　year　1853；　the　Duke　of　Buccleuch　had　three　holes　dug　in　the　
turf　within　a　few　yards　of　one　another；　at　the　western　end　of　the　
nave；　and　the　old　tesselated　pavement　of　the　abbey　was　thus　
discovered。　　These　holes　were　afterwards　surrounded　by　brickwork；　
and　protected　by　trap…doors；　so　that　the　pavement　might　be　readily　
inspected　and　preserved。　　When　my　son　William　examined　the　place　on　
January　5；　1872；　he　found　that　the　pavement　in　the　three　holes　lay　
at　depths　of　6。75；　10　and　11。5　inches　beneath　the　surrounding　turf…
covered　surface。　　The　old　guardian　asserted　that　he　was　often　
forced　to　remove　worm…castings　from　the　pavement；　and　that　he　had　
done　so　about　six　months　before。　　My　son　collected　all　from　one　of　
the　holes；　the　area　of　which　was　5。32　square　feet；　and　they　weighed　
7。97　ounces。　　Assuming　that　this　amount　had　accumulated　in　six　
months；　the　accumulation　during　a　year　on　a　square　yard　would　be　
1。68　pounds；　which；　though　a　large　amount；　is　very　small　compared　
with　what；　as　we　have　seen；　is　often　ejected　on　fields　and　commons。　　
When　I　visited　the　abbey　on　June　22；　1877；　the　old　man　said　that　he　
had　cleared　out　the　holes　about　a　month　before；　but　a　good　many　
castings　had　since　been　ejected。　　I　suspect　that　he　imagined　that　
he　swept　the　pavements　oftener　than　he　really　did；　for　the　
conditions　were　in　several　respects　very　unfavourable　for　the　
accumulation　of　even　a　moderate　amount　of　castings。　　The　tiles　are　
rather　large；　viz。；　about　5。5　inches　square；　and　the　mortar　between　
them　was　in　most　places　sound；　so　that　the　worms　were　able　to　bring　
up　earth　from　below　only　at　certain　points。　　The　tiles　rested　on　a　
bed