the origination of living beings-第4部分

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which　are　found　are　almost　always　confined　to　four　forms'Oldhamia'；
whose　precise　nature　is　not　known；　whether　plant　or　animal；　'Lingula'；
a　kind　of　mollusc；　'Trilobites'；　a　crustacean　animal；　having　the　same
essential　plan　of　construction；　though　differing　in　many　details　from　a
lobster　or　crab；　and　Hymenocaris；　which　is　also　a　crustacean。　　So　that
you　have　all　the　'Fauna'　reduced；　at　this　period；　to　four　forms：　one　a
kind　of　animal　or　plant　that　we　know　nothing　about；　and　three　undoubted
animalstwo　crustaceans　and　one　mollusc。

I　think；　considering　the　organization　of　these　mollusca　and　crustacea；
and　looking　at　their　very　complex　nature；　that　it　does　indeed　require　a
very　strong　imagination　to　conceive　that　these　were　the　first　created
of　all　living　things。　　And　you　must　take　into　consideration　the　fact
that　we　have　not　the　slightest　proof　that　these　which　we　call　the
oldest　beds　are　really　so：　I　repeat；　we　have　not　the　slightest　proof　of
it。　　When　you　find　in　some　places　that　in　an　enormous　thickness　of
rocks　there　are　but　very　scanty　traces　of　life；　or　absolutely　none　at
all；　and　that　in　other　parts　of　the　world　rocks　of　the　very　same
formation　are　crowded　with　the　records　of　living　forms；　I　think　it　is
impossible　to　place　any　reliance　on　the　supposition；　or　to　feel　oneself
justified　in　supposing　that　these　are　the　forms　in　which　life　first
commenced。　　I　have　not　time　here　to　enter　upon　the　technical　grounds
upon　which　I　am　led　to　this　conclusion；that　could　hardly　be　done
properly　in　half　a　dozen　lectures　on　that　part　alone；I　must　content
myself　with　saying　that　I　do　not　at　all　believe　that　these　are　the
oldest　forms　of　life。

I　turn　to　the　experimental　side　to　see　what　evidence　we　have　there。　　To
enable　us　to　say　that　we　know　anything　about　the　experimental
origination　of　organization　and　life；　the　investigator　ought　to　be　able
to　take　inorganic　matters；　such　as　carbonic　acid；　ammonia；　water；　and
salines；　in　any　sort　of　inorganic　combination；　and　be　able　to　build
them　up　into　Protein　matter；　and　that　that　Protein　matter　ought　to
begin　to　live　in　an　organic　form。　　That；　nobody　has　done　as　yet；　and　I
suspect　it　will　be　a　long　while　before　anybody　does　do　it。　　But　the
thing　is　by　no　means　so　impossible　as　it　looks；　for　the　researches　of
modern　chemistry　have　shown　usI　won't　say　the　road　towards　it；　but；
if　I　may　so　say；　they　have　shown　the　finger…post　pointing　to　the　road
that　may　lead　to　it。

It　is　not　many　years　agoand　you　must　recollect　that　Organic　Chemistry
is　a　young　science；　not　above　a　couple　of　generations　old；you　must
not　expect　too　much　of　it；　it　is　not　many　years　ago　since　it　was　said
to　be　perfectly　impossible　to　fabricate　any　organic　compound；　that　is
to　say；　any　non…mineral　compound　which　is　to　be　found　in　an　organized
being。　　It　remained　so　for　a　very　long　period；　but　it　is　now　a
considerable　number　of　years　since　a　distinguished　foreign　chemist
contrived　to　fabricate　Urea；　a　substance　of　a　very　complex　character；
which　forms　one　of　the　waste　products　of　animal　structures。　　And　of
late　years　a　number　of　other　compounds；　such　as　Butyric　Acid；　and
others；　have　been　added　to　the　list。　　I　need　not　tell　you　that
chemistry　is　an　enormous　distance　from　the　goal　I　indicate；　all　I　wish
to　point　out　to　you　is；　that　it　is　by　no　means　safe　to　say　that　that
goal　may　not　be　reached　one　day。　　It　may　be　that　it　is　impossible　for
us　to　produce　the　conditions　requisite　to　the　origination　of　life；　but
we　must　speak　modestly　about　the　matter；　and　recollect　that　Science　has
put　her　foot　upon　the　bottom　round　of　the　ladder。　　Truly　he　would　be　a
bold　man　who　would　venture　to　predict　where　she　will　be　fifty　years
hence。

There　is　another　inquiry　which　bears　indirectly　upon　this　question；　and
upon　which　I　must　say　a　few　words。　　You　are　all　of　you　aware　of　the
phenomena　of　what　is　called　spontaneous　generation。　　Our　forefathers；
down　to　the　seventeenth　century；　or　thereabouts；　all　imagined；　in
perfectly　good　faith；　that　certain　vegetable　and　animal　forms　gave
birth；　in　the　process　of　their　decomposition；　to　insect　life。　　Thus；　if
you　put　a　piece　of　meat　in　the　sun；　and　allowed　it　to　putrefy；　they
conceived　that　the　grubs　which　soon　began　to　appear　were　the　result　of
the　action　of　a　power　of　spontaneous　generation　which　the　meat
contained。　　And　they　could　give　you　receipts　for　making　various　animal
and　vegetable　preparations　which　would　produce　particular　kinds　of
animals。　　A　very　distinguished　Italian　naturalist；　named　Redi；　took　up
the　question；　at　a　time　when　everybody　believed　in　it；　among　others　our
own　great　Harvey；　the　discoverer　of　the　circulation　of　the　blood。　　You
will　constantly　find　his　name　quoted；　however；　as　an　opponent　of　the
doctrine　of　spontaneous　generation；　but　the　fact　is；　and　you　will　see　it
if　you　will　take　the　trouble　to　look　into　his　works；　Harvey　believed　it
as　profoundly　as　any　man　of　his　time；　but　he　happened　to　enunciate　a
very　curious　propositionthat　every　living　thing　came　from　an　'egg'；
he　did　not　mean　to　use　the　word　in　the　sense　in　which　we　now　employ　it；
he　only　meant　to　say　that　every　living　thing　originated　in　a　little
rounded　particle　of　organized　substance；　and　it　is　from　this
circumstance；　probably；　that　the　notion　of　Harvey　having　opposed　the
doctrine　originated。　　Then　came　Redi；　and　he　proceeded　to　upset　the
doctrine　in　a　very　simple　manner。　　He　merely　covered　the　piece　of　meat
with　some　very　fine　gauze；　and　then　he　exposed　it　to　the　same
conditions。　　The　result　of　this　was　that　no　grubs　or　insects　were
produced；　he　proved　that　the　grubs　originated　from　the　insects　who　came
and　deposited　their　eggs　in　the　meat；　and　that　they　were　hatched　by　the
heat　of　the　sun。　　By　this　kind　of　inquiry　he　thoroughly　upset　the
doctrine　of　spontaneous　generation；　for　his　time　at　least。

Then　came　the　discovery　and　application　of　the　microscope　to　scientific
inquiries；　which　showed　to　naturalists　that　besides　the　organisms　which
they　already　knew　as　living　beings　and　plants；　there　were　an　immense
number　of　minute　things　which　could　be　obtained　apparently　almost　at
will　from　decaying　vegetable　and　animal　forms。　　Thus；　if　you　took　some
ordinary　black　pepper　or　some　hay；　and　steeped　it　in　water；　you　would
find　in　the　course　of　a　few　days　that　the　water　had　become　impregnated
with　an　immense　number　of　animalcules　swimming　about　in　all
directions。　　From　facts　of　this　kind　naturalists　were　led　to　revive　the
theory　of　spontaneous　generation。　　They　were　headed　here　by　an　English
naturalist；Needham；and　afterwards　in　France　by　the　learned　Buffon。
They　said　that　these　things　were　absolutely　begotten　in　the　water　of
the　decaying　substances　out　of　which　the　infusion　was　made。　　It　did　not
matter　whether　you　took　animal　or　vegetable　matter；　you　had　only　to
steep　it　in　water　and　expose　it；　and　you　would　soon　have　plenty　of
animalcules。　　They　made　an　hypothesis　about　this　which　was　a　very　fair
one。　　They　said；　this　matter　of　the　animal　world；　or　of　the　higher
plants；　appears　to　be　dead；　but　in　reality　it　has　a　sort　of　dim　life
about　it；　which；　if　it　is　placed　under　fair　conditions；　will　cause　it
to　break　up　into　the　forms　of　these　little　animalcules；　and　they　will
go　through　their　lives　in　the　same　way　as　the　animal　or　plant　of　which
they　once　formed　a　part。

The　question　now　became　very　hotly　debated。　　Spallanzani；　an　Italian
naturalist；　took　up　opposite　views　to　those　of　Needham　and　Buffon；　and
by　means　of　certain　experiments　he　showed　that　it　was　quite　possible　to
stop　the　process　by　boiling　the　water；　and　closing　the　vessel　in　which
it　was　contained。　　〃Oh！〃　said　his　opponents；　〃but　what　do　you　know　you
may　be　doing　when　you　heat　the　air　over　the　water　in　this　way？　　You　may
be　destroying　some　property　of　the　air　requisite　for　the　spontaneous
generation　of　the　animalcules。〃

However；　Spallanzani's　views　were　supposed　to　be　upon　the　right　side；
and　those　of　the　others　fell　into　discredit；　although　the　fact　was　that
Spallanzani　had　not　made　good　his　views。　　Well；　then；　the　subject
continued　to　be　revived　from　time　to　time；　and　experiments　were　made　by
several　persons；　but　these　experiments　were　not　altogether　satisfactory。
It　was　found　that　if　you　put　an　infusion　in　which　animalcules　would
appear　if　it　were　exposed　to　the　air　into　a　vessel　and　boiled　it；　and
then　sealed　up　the　mouth　of　the　vessel；　so　that　no　air；　save　such　as
had　been　heated　to　212　degrees；　could　reach　its　contents；　that　then　no
animalcules　would　be　found；　but　if　you　took　the　same　vessel　and　exposed
the　infusion　to　the　air；　then　you　would　get　animalcules。　　Furthermore；
it　was　found　that　if　you　connected　the　mouth　of　the　vessel　with　a
red…hot　tube　in　such　a　way　that　the　air　would　have　to　pass　through　the
tube　before　reaching　the　infusion；　that　then　you　would　get　no
animalcules。　　Yet　another　thing　was　noticed：　if　you　took　two　flasks
containing　the　same　kind　of　infusion；　and　left　one　entirely　exposed　to
the　air；　and　in　the　mouth　of　the　other　placed　a　ball　of　cotton　wool；　so
that　the　air　would　have　to　filter　itself　through　it　before　reaching　the
infusion；　that　then；　although　you　might　have　plenty　of　animalcules　in
the　first　flask；　you　wou