a history of science-4-第34章

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microbe　of　anthrax　there　exists　an　essential　difference　which　does　not　allow　the　new　experiment　to　be　verified　by　the　old。　The　microbes　of　chicken　cholera　do　not；　in　effect；　seem　to　resolve　themselves；　in　their　culture；　into　veritable　germs。　The　latter　are　merely　cells；　or　articulations　always　ready　to　multiply　by　division；　except　when　the　particular　conditions　in　which　they　become　true　germs　are　known。

〃The　yeast　of　beer　is　a　striking　example　of　these　cellular　productions；　being　able　to　multiply　themselves　indefinitely　without　the　apparition　of　their　original　spores。　　There　exist　many　mucedines　（Mucedinae？）　of　tubular　mushrooms；　which　in　certain　conditions　of　culture　produce　a　chain　of　more　or　less　spherical　cells　called　Conidae。　　The　latter；　detached　from　their　branches；　are　able　to　reproduce　themselves　in　the　form　of　cells；　without　the　appearance；　at　least　with　a　change　in　the　conditions　of　culture；　of　the　spores　of　their　respective　mucedines。　These　vegetable　organisms　can　be　compared　to　plants　which　are　cultivated　by　slipping；　and　to　produce　which　it　is　not　necessary　to　have　the　fruits　or　the　seeds　of　the　mother　plant。

The　anthrax　bacterium；　in　its　artificial　cultivation；　behaves　very　differently。　　Its　mycelian　filaments；　if　one　may　so　describe　them；　have　been　produced　scarcely　for　twenty…four　or　forty…eight　hours　when　they　are　seen　to　transform　themselves；　those　especially　which　are　in　free　contact　with　the　air；　into　very　refringent　corpuscles；　capable　of　gradually　isolating　themselves　into　true　germs　of　slight　organization。　　Moreover；　observation　shows　that　these　germs；　formed　so　quickly　in　the　culture；　do　not　undergo；　after　exposure　for　a　time　to　atmospheric　air；　any　change　either　in　their　vitality　or　their　virulence。　I　was　able　to　present　to　the　Academy　a　tube　containing　some　spores　of　anthrax　bacteria　produced　four　years　ago；　on　March　21；　1887。　Each　year　the　germination　of　these　little　corpuscles　has　been　tried；　and　each　year　the　germination　has　been　accomplished　with　the　same　facility　and　the　same　rapidity　as　at　first。　Each　year　also　the　virulence　of　the　new　cultures　has　been　tested；　and　they　have　not　shown　any　visible　falling　off。　　Therefore；　how　can　we　experiment　with　the　action　of　the　air　upon　the　anthrax　virus　with　any　expectation　of　making　it　less　virulent？

〃The　crucial　difficulty　lies　perhaps　entirely　in　this　rapid　reproduction　of　the　bacteria　germs　which　we　have　just　related。　In　its　form　of　a　filament；　and　in　its　multiplication　by　division；　is　not　this　organism　at　all　points　comparable　with　the　microbe　of　the　chicken　cholera？

〃That　a　germ；　properly　so　called；　that　a　seed；　does　not　suffer　any　modification　on　account　of　the　air　is　easily　conceived；　but　it　is　conceivable　not　less　easily　that　if　there　should　be　any　change　it　would　occur　by　preference　in　the　case　of　a　mycelian　fragment。　It　is　thus　that　a　slip　which　may　have　been　abandoned　in　the　soil　in　contact　with　the　air　does　not　take　long　to　lose　all　vitality；　while　under　similar　conditions　a　seed　is　preserved　in　readiness　to　reproduce　the　plant。　　If　these　views　have　any　foundation；　we　are　led　to　think　that　in　order　to　prove　the　action　of　the　air　upon　the　anthrax　bacteria　it　will　be　indispensable　to　submit　to　this　action　the　mycelian　development　of　the　minute　organism　under　conditions　where　there　cannot　be　the　least　admixture　of　corpuscular　germs。　Hence　the　problem　of　submitting　the　bacteria　to　the　action　of　oxygen　comes　back　to　the　question　of　presenting　entirely　the　formation　of　spores。　The　question　being　put　in　this　way；　we　are　beginning　to　recognize　that　it　is　capable　of　being　solved。

〃We　can；　in　fact；　prevent　the　appearance　of　spores　in　the　artificial　cultures　of　the　anthrax　parasite　by　various　artifices。　At　the　lowest　temperature　at　which　this　parasite　can　be　cultivatedthat　is　to　say；　about　＋16　degrees　Centigradethe　bacterium　does　not　produce　germsat　any　rate；　for　a　very　long　time。　The　shapes　of　the　minute　microbe　at　this　lowest　limit　of　its　development　are　irregular；　in　the　form　of　balls　and　pearsin　a　word；　they　are　monstrositiesbut　they　are　without　spores。　In　the　last　regard　also　it　is　the　same　at　the　highest　temperatures　at　which　the　parasite　can　be　cultivated；　temperatures　which　vary　slightly　according　to　the　means　employed。　In　neutral　chicken　bouillon　the　bacteria　cannot　be　cultivated　above　45　degrees。　Culture；　however；　is　easy　and　abundant　at　42　to　43　degrees；　but　equally　without　any　formation　of　spores。　　Consequently　a　culture　of　mycelian　bacteria　can　be　kept　entirely　free　from　germs　while　in　contact　with　the　open　air　at　a　temperature　of　from　42　to　43　degrees　Centigrade。　　Now　appear　the　three　remarkable　results。　After　about　one　month　of　waiting　the　culture　diesthat　is　to　say；　if　put　into　a　fresh　bouillon　it　becomes　absolutely　sterile。

〃So　much　for　the　life　and　nutrition　of　this　organism。　In　respect　to　its　virulence；　it　is　an　extraordinary　fact　that　it　disappears　entirely　after　eight　days'　culture　at　42　to　43　degrees　Centigrade；　or；　at　any　rate；　the　cultures　are　innocuous　for　the　guinea…pig；　the　rabbit；　and　the　sheep；　the　three　kinds　of　animals　most　apt　to　contract　anthrax。　We　are　thus　able　to　obtain；　not　only　the　attenuation　of　the　virulence；　but　also　its　complete　suppression　by　a　simple　method　of　cultivation。　Moreover；　we　see　also　the　possibility　of　preserving　and　cultivating　the　terrible　microbe　in　an　inoffensive　state。　What　is　it　that　happens　in　these　eight　days　at　43　degrees　that　suffices　to　take　away　the　virulence　of　the　bacteria？　Let　us　remember　that　the　microbe　of　chicken　cholera　dies　in　contact　with　the　air；　in　a　period　somewhat　protracted；　it　is　true；　but　after　successive　attenuations。　　Are　we　justified　in　thinking　that　it　ought　to　be　the　same　in　regard　to　the　microbe　of　anthrax？　　This　hypothesis　is　confirmed　by　experiment。　Before　the　disappearance　of　its　virulence　the　anthrax　microbe　passes　through　various　degrees　of　attenuation；　and；　moreover；　as　is　also　the　case　with　the　microbe　of　chicken　cholera；　each　of　these　attenuated　states　of　virulence　can　be　obtained　by　cultivation。　Moreover；　since；　according　to　one　of　our　recent　Communications；　anthrax　is　not　recurrent；　each　of　our　attenuated　anthrax　microbes　is；　for　the　better…developed　microbe；　a　vaccinethat　is　to　say；　a　virus　producing　a　less…malignant　malady。　What；　therefore；　is　easier　than　to　find　in　these　a　virus　that　will　infect　with　anthrax　sheep；　cows；　and　horses；　without　killing　them；　and　ultimately　capable　of　warding　off　the　mortal　malady？　We　have　practised　this　experiment　with　great　success　upon　sheep；　and　when　the　season　comes　for　the　assembling　of　the　flocks　at　Beauce　we　shall　try　the　experiment　on　a　larger　scale。

〃Already　M。　Toussaint　has　announced　that　sheep　can　be　saved　by　preventive　inoculations；　but　when　this　able　observer　shall　have　published　his　results；　on　the　subject　of　which　we　have　made　such　exhaustive　studies；　as　yet　unpublished；　we　shall　be　able　to　see　the　whole　difference　which　exists　between　the　two　methodsthe　uncertainty　of　the　one　and　the　certainty　of　the　other。　That　which　we　announce　has；　moreover；　the　very　great　advantage　of　resting　upon　the　existence　of　a　poison　vaccine　cultivable　at　will；　and　which　can　be　increased　indefinitely　in　the　space　of　a　few　hours　without　having　recourse　to　infected　blood。〃＇8＇


This　announcement　was　immediately　challenged　in　a　way　that　brought　it　to　the　attention　of　the　entire　world。　The　president　of　an　agricultural　society；　realizing　the　enormous　importance　of　the　subject；　proposed　to　Pasteur　that　his　alleged　discovery　should　be　submitted　to　a　decisive　public　test。　He　proposed　to　furnish　a　drove　of　fifty　sheep　half　of　which　were　to　be　inoculated　with　the　attenuated　virus　of　Pasteur。　　Subsequently　all　the　sheep　were　to　be　inoculated　with　virulent　virus；　all　being　kept　together　in　one　pen　under　precisely　the　same　conditions。　The　〃protected〃　sheep　were　to　remain　healthy；　the　unprotected　ones　to　die　of　anthrax；　so　read　the　terms　of　the　proposition。　Pasteur　accepted　the　challenge；　he　even　permitted　a　change　in　the　programme　by　which　two　goats　were　substituted　for　two　of　the　sheep；　and　ten　cattle　added；　stipulating；　however；　that　since　his　experiments　had　not　yet　been　extended　to　cattle　these　should　not　be　regarded　as　falling　rigidly　within　the　terms　of　the　test。

It　was　a　test　to　try　the　soul　of　any　man；　for　all　the　world　looked　on　askance；　prepared　to　deride　the　maker　of　so　preposterous　a　claim　as　soon　as　his　claim　should　be　proved　baseless。　Not　even　the　fame　of　Pasteur　could　make　the　public　at　large；　lay　or　scientific；　believe　in　the　possibility　of　what　he　proposed　to　accomplish。　　There　was　time　for　all　the　world　to　be　informed　of　the　procedure；　for　the　first　〃preventive〃　inoculationor　vaccination；　as　Pasteur　termed　itwas　made　on　May　5th；　the　second　on　May　17th；　and　another　interval　of　two　weeks　must　elapse　before　the　final　inoculations　with　the　unattenuated　virus。　Twenty…four　sheep；　one　goat；　and　five　cattle　were　submitted　to　the　preliminary　vaccinations。　　Then；　on　May　31　st；　all　sixty　of　the　animals　were　inoculated；　a　protected　and　unprotected　one　alternately；　with　an　extremely　virulent　culture　of　anthrax　microbes　that　had　been　in　Pasteur's　laboratory　since　1877。　This　accomplished；　the　animals　were　left　together　in　one　enclosure　to　await　the　issue。

Two　days　later；　June　2d；　at　the　appointed　hour　of　rendezvous；　a　vast　crowd；　composed　of　veterinary　surgeons；　newspaper　correspondents；　and　farmers　from　far　and　near；　gathered　to　witness　the　closing　scenes　of　this　scientific　tourney。　What　they　saw　was　one　of　the　most　dramatic　scenes　in　the　history　of　peaceful　sciencea　scene　which；　as　Pasteur　declared　afterwards；　〃amazed　the　assembly。〃　　Scattered　about　the　enclosure；　dead；　dying；　or　manifestly　sick　unto　death；　lay　the　unprotected　animals；　one　and　all；　while　each　and　every　〃protected〃　animal　stalked　unconcernedly　about　with　every　appearance　of　perfect　health。　Twenty　of　the　sheep　and　the　one　goat　were　already　dead；　two　other　sheep　expired　under　the　eyes　of　the　spectators；　the　remaining　victims　lingered　but　a　few　hours　longer。　Thus　in　a　manner　theatrical　enough；　not　to　say　tragic；　was　proclaimed　the　unequivocal　victory　of　science。　Naturally　enough；　the　unbelievers　struck　their　colors　and　surrendered　without　terms；　the　principle　of　protective　vaccination；　with　a　virus　experimentally　prepared　in　the　laboratory；　was　established　beyond　the　reach　of　controversy。

That　memorable　scientific　battle　marked　the　beginning　of　a　new　era　in　medicine。　　It　was　a　foregone　conclusion　that　the　principle　thus　established　would　be　still　further　generalized；　that　it　would　be　applied　to　human　maladies；　that　in　all　probability　it　would　grapple　successfully；　sooner　or　later；　with　many　infectious　diseases。　That　expectation　has　advanced　rapidly　towards　realization。　Pasteur　himself　made　the　application　to　the　human　subject　in　the　disease　hydrophobia　in　1885；　since　which　time　that　hitherto　most　fatal　of　maladies　has　largely　lost　its　terrors。　　Thousands　of　persons　bitten　by　mad　dogs　have　been　snatched　from　the　fatal　consequences　of　that　mishap　by　this　method　at　the　Pasteur　Institute　in　Paris；　and　at　the　similar　institutes；　built　on　the　model　of　this　parent　one；　that　have　been　established　all　over　the　world　in　regions　as　widely　separated　as　New　York　and　Nha…Trang。