the formation of vegetable mould-第4部分

按键盘上方向键 ← 或 → 可快速上下翻页，按键盘上的 Enter 键可回到本书目录页，按键盘上方向键 ↑ 可回到本页顶部！
————未阅读完？加入书签已便下次继续阅读！


might　thus　be　warned　of　the　approach　of　an　enemy。　　They　exhibited　
the　same　indifference　to　my　breath　whilst　I　chewed　some　tobacco；　
and　while　a　pellet　of　cotton…wool　with　a　few　drops　of　millefleurs　
perfume　or　of　acetic　acid　was　kept　in　my　mouth。　　Pellets　of　cotton…
wool　soaked　in　tobacco　juice；　in　millefleurs　perfume；　and　in　
paraffin；　were　held　with　pincers　and　were　waved　about　within　two　or　
three　inches　of　several　worms；　but　they　took　no　notice。　　On　one　or　
two　occasions；　however；　when　acetic　acid　had　been　placed　on　the　
pellets；　the　worms　appeared　a　little　uneasy；　and　this　was　probably　
due　to　the　irritation　of　their　skins。　　The　perception　of　such　
unnatural　odours　would　be　of　no　service　to　worms；　and　as　such　timid　
creatures　would　almost　certainly　exhibit　some　signs　of　any　new　
impression；　we　may　conclude　that　they　did　not　perceive　these　
odours。

The　result　was　different　when　cabbage…leaves　and　pieces　of　onion　
were　employed；　both　of　which　are　devoured　with　much　relish　by　
worms。　　Small　square　pieces　of　fresh　and　half…decayed　cabbage…
leaves　and　of　onion　bulbs　were　on　nine　occasions　buried　in　my　pots；　
beneath　about　0。25　of　an　inch　of　common　garden　soil；　and　they　were　
always　discovered　by　the　worms。　　One　bit　of　cabbage　was　discovered　
and　removed　in　the　course　of　two　hours；　three　were　removed　by　the　
next　morning；　that　is；　after　a　single　night；　two　others　after　two　
nights；　and　the　seventh　bit　after　three　nights。　　Two　pieces　of　
onion　were　discovered　and　removed　after　three　nights。　　Bits　of　
fresh　raw　meat；　of　which　worms　are　very　fond；　were　buried；　and　were　
not　discovered　within　forty…eight　hours；　during　which　time　they　had　
not　become　putrid。　　The　earth　above　the　various　buried　objects　was　
generally　pressed　down　only　slightly；　so　as　not　to　prevent　the　
emission　of　any　odour。　　On　two　occasions；　however；　the　surface　was　
well　watered；　and　was　thus　rendered　somewhat　compact。　　After　the　
bits　of　cabbage　and　onion　had　been　removed；　I　looked　beneath　them　
to　see　whether　the　worms　had　accidentally　come　up　from　below；　but　
there　was　no　sign　of　a　burrow；　and　twice　the　buried　objects　were　
laid　on　pieces　of　tin…foil　which　were　not　in　the　least　displaced。　　
It　is　of　course　possible　that　the　worms　whilst　moving　about　on　the　
surface　of　the　ground；　with　their　tails　affixed　within　their　
burrows；　may　have　poked　their　heads　into　the　places　where　the　above　
objects　were　buried；　but　I　have　never　seen　worms　acting　in　this　
manner。　　Some　pieces　of　cabbage…leaf　and　of　onion　were　twice　buried　
beneath　very　fine　ferruginous　sand；　which　was　slightly　pressed　down　
and　well　watered；　so　as　to　be　rendered　very　compact；　and　these　
pieces　were　never　discovered。　　On　a　third　occasion　the　same　kind　of　
sand　was　neither　pressed　down　nor　watered；　and　the　pieces　of　
cabbage　were　discovered　and　removed　after　the　second　night。　　These　
several　facts　indicate　that　worms　possess　some　power　of　smell；　and　
that　they　discover　by　this　means　odoriferous　and　much…coveted　kinds　
of　food。

It　may　be　presumed　that　all　animals　which　feed　on　various　
substances　possess　the　sense　of　taste；　and　this　is　certainly　the　
case　with　worms。　　Cabbage…leaves　are　much　liked　by　worms；　and　it　
appears　that　they　can　distinguish　between　different　varieties；　but　
this　may　perhaps　be　owing　to　differences　in　their　texture。　　On　
eleven　occasions　pieces　of　the　fresh　leaves　of　a　common　green　
variety　and　of　the　red　variety　used　for　pickling　were　given　them；　
and　they　preferred　the　green；　the　red　being　either　wholly　neglected　
or　much　less　gnawed。　　On　two　other　occasions；　however；　they　seemed　
to　prefer　the　red。　　Half…decayed　leaves　of　the　red　variety　and　
fresh　leaves　of　the　green　were　attacked　about　equally。　　When　leaves　
of　the　cabbage；　horse…radish　（a　favourite　food）　and　of　the　onion　
were　given　together；　the　latter　were　always；　and　manifestly　
preferred。　　Leaves　of　the　cabbage；　lime…tree；　Ampelopsis；　parsnip　
（Pastinaca）；　and　celery　（Apium）　were　likewise　given　together；　and　
those　of　the　celery　were　first　eaten。　　But　when　leaves　of　cabbage；　
turnip；　beet；　celery；　wild　cherry　and　carrots　were　given　together；　
the　two　latter　kinds；　especially　those　of　the　carrot；　were　
preferred　to　all　the　others；　including　those　of　celery。　　It　was　
also　manifest　after　many　trials　that　wild　cherry　leaves　were　
greatly　preferred　to　those　of　the　lime…tree　and　hazel　（Corylus）。　　
According　to　Mr。　Bridgman　the　half…decayed　leaves　of　Phlox　verna　
are　particularly　liked　by　worms。　｛16｝

Pieces　of　the　leaves　of　cabbage；　turnip；　horse…radish　and　onion　
were　left　on　the　pots　during　22　days；　and　were　all　attacked　and　had　
to　be　renewed；　but　during　the　whole　of　this　time　leaves　of　an　
Artemisia　and　of　the　culinary　sage；　thyme　and　mint；　mingled　with　
the　above　leaves；　were　quite　neglected　excepting　those　of　the　mint；　
which　were　occasionally　and　very　slightly　nibbled。　　These　latter　
four　kinds　of　leaves　do　not　differ　in　texture　in　a　manner　which　
could　make　them　disagreeable　to　worms；　they　all　have　a　strong　
taste；　but　so　have　the　four　first　mentioned　kinds　of　leaves；　and　
the　wide　difference　in　the　result　must　be　attributed　to　a　
preference　by　the　worms　for　one　taste　over　another。

Mental　Qualities。There　is　little　to　be　said　on　this　head。　　We　
have　seen　that　worms　are　timid。　　It　may　be　doubted　whether　they　
suffer　as　much　pain　when　injured；　as　they　seem　to　express　by　their　
contortions。　　Judging　by　their　eagerness　for　certain　kinds　of　food；　
they　must　enjoy　the　pleasure　of　eating。　　Their　sexual　passion　is　
strong　enough　to　overcome　for　a　time　their　dread　of　light。　　They　
perhaps　have　a　trace　of　social　feeling；　for　they　are　not　disturbed　
by　crawling　over　each　other's　bodies；　and　they　sometimes　lie　in　
contact。　　According　to　Hoffmeister　they　pass　the　winter　either　
singly　or　rolled　up　with　others　into　a　ball　at　the　bottom　of　their　
burrows。　｛17｝　　Although　worms　are　so　remarkably　deficient　in　the　
several　sense…organs；　this　does　not　necessarily　preclude　
intelligence；　as　we　know　from　such　cases　as　those　of　Laura　
Bridgman；　and　we　have　seen　that　when　their　attention　is　engaged；　
they　neglect　impressions　to　which　they　would　otherwise　have　
attended；　and　attention　indicates　the　presence　of　a　mind　of　some　
kind。　　They　are　also　much　more　easily　excited　at　certain　times　than　
at　others。　　They　perform　a　few　actions　instinctively；　that　is；　all　
the　individuals；　including　the　young；　perform　such　actions　in　
nearly　the　same　fashion。　　This　is　shown　by　the　manner　in　which　the　
species　of　Perichaeta　eject　their　castings；　so　as　to　construct　
towers；　also　by　the　manner　in　which　the　burrows　of　the　common　
earth…worm　are　smoothly　lined　with　fine　earth　and　often　with　little　
stones；　and　the　mouths　of　their　burrows　with　leaves。　　One　of　their　
strongest　instincts　is　the　plugging　up　the　mouths　of　their　burrows　
with　various　objects；　and　very　young　worms　act　in　this　manner。　　But　
some　degree　of　intelligence　appears；　as　we　shall　see　in　the　next　
chapter；　to　be　exhibited　in　this　work；a　result　which　has　
surprised　me　more　than　anything　else　in　regard　to　worms。

Food　and　Digestion。Worms　are　omnivorous。　　They　swallow　an　
enormous　quantity　of　earth；　out　of　which　they　extract　any　
digestible　matter　which　it　may　contain；　but　to　this　subject　I　must　
recur。　　They　also　consume　a　large　number　of　half…decayed　leaves　of　
all　kinds；　excepting　a　few　which　have　an　unpleasant　taste　or　are　
too　tough　for　them；　likewise　petioles；　peduncles；　and　decayed　
flowers。　　But　they　will　also　consume　fresh　leaves；　as　I　have　found　
by　repeated　trials。　　According　to　Morren　｛18｝　they　will　eat　
particles　of　sugar　and　liquorice；　and　the　worms　which　I　kept　drew　
many　bits　of　dry　starch　into　their　burrows；　and　a　large　bit　had　its　
angles　well　rounded　by　the　fluid　poured　out　of　their　mouths。　　But　
as　they　often　drag　particles　of　soft　stone；　such　as　of　chalk；　into　
their　burrows；　I　feel　some　doubt　whether　the　starch　was　used　as　
food。　　Pieces　of　raw　and　roasted　meat　were　fixed　several　times　by　
long　pins　to　the　surface　of　the　soil　in　my　pots；　and　night　after　
night　the　worms　could　be　seen　tugging　at　them；　with　the　edges　of　
the　pieces　engulfed　in　their　mouths；　so　that　much　was　consumed。　　
Raw　fat　seems　to　be　preferred　even　to　raw　meat　or　to　any　other　
substance　which　was　given　them；　and　much　was　consumed。　　They　are　
cannibals；　for　the　two　halves　of　a　dead　worm　placed　in　two　of　the　
pots　were　dragged　into　the　burrows　and　gnawed；　but　as　far　as　I　
could　judge；　they　prefer　fresh　to　putrid　meat；　and　in　so　far　I　
differ　from　Hoffmeister。

Leon　Fredericq　states　｛19｝　that　the　digestive　fluid　of　worms　is　of　
the　same　nature　as　the　pancreatic　secretion　of　the　higher　animals；　
and　this　conclusion　agrees　perfectly　with　the　kinds　of　food　which　
worms　consume。　　Pancreatic　juice　emulsifies　fat；　and　we　have　just　
seen　how　greedily　worms　devour　fat；　it　dissolves　fibrin；　and　worms　
eat　raw　meat；　it　converts　starch　into　grape…sugar　with　wonderful　
rapidity；　and　we　shall　presently　show　that　the　digestive　fluid　of　
worms　acts　on　starch。　｛20｝　　But　they　live　chiefly　on　half…decayed　
leaves；　and　these　would　be　useless　to　them　unless　they　could　digest　
the　cellulose　forming　the　cell…walls；　for　it　is　well　known　that　all　
other　nutritious　substances　are　almost　completely　withdrawn　from　
leaves；　shortly　before　they　fall　off。　　It　has；　however；　now　been　
ascertained　that　some　forms　of　cellulose；　though　very　little　or　not　
at　all　attacked　by　the　gastric　secretion　of　the　higher　animals；　are　
acted　on　by　that　from　the　pancreas。　｛21｝

The　half…decayed　or　fresh　leaves　which　worms　intend　to　devour；　are　
dragged　into　the　mouths　of　their　burrows　to　a　depth　of　from　one　to　
three　inches；　and　are　then　moistened　with　a　secreted　fluid。　　It　has　
been　assumed　that　this　fluid　serves　to　hasten　their　decay；　but　a　
large　number　of　leaves　were　twice　pulled　out　of　the　burrows　of　
worms　and　kept　for　many　weeks　in　a　very　moist　atmosphere　under　a　
bell…glass　in　my　study；　and　the　parts　which　had　been　moistened　by　
the　worms　did　not　decay　more　quickly　in　any　plain　manner　than　the　
other　parts。　　When　fresh　leaves　were　given　in　the　evening　to　worms　
kept　in　confinement　and　examined　early