darwin and modern science-第95章

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han　three　and　a　half　years　were　given　to　South　American　geology。　　The　heavy　task　of　dealing　with　the　notes　and　specimens　accumulated　during　that　long　period　was　left　by　Darwin　to　the　last。　　Finishing　the　〃Volcanic　Islands〃　on　February　14th；　1844；　he；　in　July　of　the　same　year；　commenced　the　preparation　of　two　important　works　which　engaged　him　till　near　the　end　of　the　year　1846。　　The　first　was　his　〃Geological　Observations　on　South　America〃；　the　second　a　recast　of　his　〃Journal〃；　published　under　the　short　title　of　〃A　Naturalist's　Voyage　round　the　World〃。

The　first　of　these　works　contains　an　immense　amount　of　information　collected　by　the　author　under　great　difficulties　and　not　unfrequently　at　considerable　risk　to　life　and　health。　　No　sooner　had　Darwin　landed　in　South　America　than　two　sets　of　phenomena　powerfully　arrested　his　attention。　　The　first　of　these　was　the　occurrence　of　great　masses　of　red　mud　containing　bones　and　shells；　which　afforded　striking　evidence　that　the　whole　continent　had　shared　in　a　series　of　slow　and　gradual　but　often　interrupted　movements。　The　second　related　to　the　great　masses　of　crystalline　rocks　which；　underlying　the　muds；　cover　so　great　a　part　of　the　continent。　　Darwin；　almost　as　soon　as　he　landed；　was　struck　by　the　circumstance　that　the　direction；　as　shown　by　his　compass；　of　the　prominent　features　of　these　great　crystalline　rock…massestheir　cleavage；　master…joints；　foliation　and　pegmatite　veinswas　the　same　as　the　orientation　described　by　Humboldt　（whose　works　he　had　so　carefully　studied）　on　the　west　of　the　same　great　continent。

The　first　five　chapters　of　the　book　on　South　America　were　devoted　to　formations　of　recent　date　and　to　the　evidence　collected　on　the　east　and　west　coasts　of　the　continent　in　regard　to　those　grand　earth…movements；　some　of　which　could　be　shown　to　have　been　accompanied　by　earthquake…shocks。　　The　fossil　bones；　which　had　given　him　the　first　hint　concerning　the　mutability　of　species；　had　by　this　time　been　studied　and　described　by　comparative　anatomists；　and　Darwin　was　able　to　elaborate　much　more　fully　the　important　conclusion　that　the　existing　fauna　of　South　America　has　a　close　analogy　with　that　of　the　period　immediately　preceding　our　own。

The　remaining　three　chapters　of　the　book　dealt　with　the　metamorphic　and　plutonic　rocks；　and　in　them　Darwin　announced　his　important　conclusions　concerning　the　relations　of　cleavage　and　foliation；　and　on　the　close　analogy　of　the　latter　structure　with　the　banding　found　in　rock…masses　of　igneous　origin。　　With　respect　to　the　first　of　these　conclusions；　he　received　the　powerful　support　of　Daniel　Sharpe；　who　in　the　years　1852　and　1854　published　two　papers　on　the　structure　of　the　Scottish　Highlands；　supplying　striking　confirmation　of　the　correctness　of　Darwin's　views。　　Although　Darwin's　and　Sharpe's　conclusions　were　contested　by　Murchison　and　other　geologists；　they　are　now　universally　accepted。　　In　his　theory　concerning　the　origin　of　foliation；　Darwin　had　been　to　some　extent　anticipated　by　Scrope；　but　he　supplied　many　facts　and　illustrations　leading　to　the　gradual　acceptance　of　a　doctrine　which；　when　first　enunciated；　was　treated　with　neglect；　if　not　with　contempt。

The　whole　of　this　volume　on　South　American　geology　is　crowded　with　the　records　of　patient　observations　and　suggestions　of　the　greatest　value；　but；　as　Darwin　himself　saw；　it　was　a　book　for　the　working　geologist　and　〃caviare　to　the　general。〃　　Its　author；　indeed；　frequently　expressed　his　sense　of　the　〃dryness〃　of　the　book；　he　even　says　〃I　long　hesitated　whether　I　would　publish　it　or　not；〃　and　he　wrote　to　Leonard　Horner　〃I　am　astonished　that　you　should　have　had　the　courage　to　go　right　through　my　book。〃　　（〃M。L。〃　II。　page　221。）

Fortunately　the　second　book；　on　which　Darwin　was　engaged　at　this　time；　was　of　a　very　different　character。　　His　〃Journal〃；　almost　as　he　had　written　it　on　board　ship；　with　facts　and　observations　fresh　in　his　mind；　had　been　published　in　1839　and　attracted　much　attention。　　In　1845；　he　says；　〃I　took　much　pains　in　correcting　a　new　edition；〃　and　the　work　which　was　commenced　in　April；　1845；　was　not　finished　till　August　of　that　year。　　The　volume　contains　a　history　of　the　voyage　with　〃a　sketch　of　those　observations　in　Natural　History　and　Geology；　which　I　think　will　possess　some　interest　for　the　general　reader。〃　　It　is　not　necessary　to　speak　of　the　merits　of　this　scientific　classic。　　It　became　a　great　favourite　with　the　general　public　having　passed　through　many　editionsit　was；　moreover；　translated　into　a　number　of　different　languages。　　Darwin　was　much　gratified　by　these　evidences　of　popularity；　and　naively　remarks　in　his　〃Autobiography〃；　〃The　success　of　this　my　first　literary　child　tickles　my　vanity　more　than　that　of　any　of　my　other　books〃　（〃L。L。〃　I。　page　80。）and　this　was　written　after　the　〃Origin　of　Species〃　had　become　famous！

In　Darwin's　letters　there　are　many　evidences　that　his　labours　during　these　ten　years　devoted　to　the　working　out　of　the　geological　results　of　the　voyage　often　made　many　demands　on　his　patience　and　indomitable　courage。　　Most　geologists　have　experience　of　the　contrast　between　the　pleasures　felt　when　wielding　the　hammer　in　the　field；　and　the　duller　labour　of　plying　the　pen　in　the　study。　　But　in　Darwin's　case；　innumerable　interruptions　from　sickness　and　other　causes；　and　the　oft…deferred　hope　of　reaching　the　end　of　his　task　were　not　the　only　causes　operating　to　make　the　work　irksome。　　The　great　project；　which　was　destined　to　become　the　crowning　achievement　of　his　life；　was　now　gradually　assuming　more　definite　shape；　and　absorbing　more　of　his　time　and　energies。

Nevertheless；　during　all　this　period；　Darwin　so　far　regarded　his　geological　pursuits　as　his　PROPER　〃work；〃　that　attention　to　other　matters　was　always　spoken　of　by　him　as　〃indulging　in　idleness。〃　　If　at　the　end　of　this　period　the　world　had　sustained　the　great　misfortune　of　losing　Darwin　by　death　before　the　age　of　fortyand　several　times　that　event　seemed　only　too　probablehe　might　have　been　remembered　only　as　a　very　able　geologist　of　most　advanced　views；　and　a　traveller　who　had　written　a　scientific　narrative　of　more　than　ordinary　excellence！

The　completion　of　the　〃Geology　of　the　'Beagle'〃　and　the　preparation　of　a　revised　narrative　of　the　voyage　mark　the　termination　of　that　period　of　fifteen　years　of　Darwin's　life　during　which　geological　studies　were　his　principal　occupation。　　Henceforth；　though　his　interest　in　geological　questions　remained　ever　keen；　biological　problems　engaged　more　and　more　of　his　attention　to　the　partial　exclusion　of　geology。

The　eight　years　from　October；　1846；　to　October；　1854；　were　mainly　devoted　to　the　preparation　of　his　two　important　monographs　on　the　recent　and　fossil　Cirripedia。　　Apart　from　the　value　of　his　description　of　the　fossil　forms；　this　work　of　Darwin's　had　an　important　influence　on　the　progress　of　geological　science。　　Up　to　that　time　a　practice　had　prevailed　for　the　student　of　a　particular　geological　formation　to　take　up　the　description　of　the　plant　and　animal　remains　in　itoften　without　having　anything　more　than　a　rudimentary　knowledge　of　the　living　forms　corresponding　to　them。　　Darwin　in　his　monograph　gave　a　very　admirable　illustration　of　the　enormous　advantage　to　be　gainedalike　for　biology　and　geologyby　undertaking　the　study　of　the　living　and　fossil　forms　of　a　natural　group　of　organisms　in　connection　with　one　another。　　Of　the　advantage　of　these　eight　years　of　work　to　Darwin　himself；　in　preparing　for　the　great　task　lying　before　him；　Huxley　has　expressed　a　very　strong　opinion　indeed。　　（〃L。L。〃　II。　pages　247…48。）

But　during　these　eight　years　of　〃species　work；〃　Darwin　found　opportunities　for　not　a　few　excursions　into　the　field　of　geology。　　He　occasionally　attended　the　Geological　Society；　and；　as　we　have　already　seen；　read　several　papers　there　during　this　period。　　His　friend；　Dr　Hooker；　then　acting　as　botanist　to　the　Geological　Survey；　was　engaged　in　studying　the　Carboniferous　flora；　and　many　discussions　on　Palaezoic　plants　and　on　the　origin　of　coal　took　place　at　this　period。　　On　this　last　subject　he　felt　the　deepest　interest　and　told　Hooker；　〃I　shall　never　rest　easy　in　Down　churchyard　without　the　problem　be　solved　by　some　one　before　I　die。〃　　（〃M。L。〃　I。　pages　63；　64。）

As　at　all　times；　conversations　and　letters　with　Lyell　on　every　branch　of　geological　science　continued　with　unabated　vigour；　and　in　spite　of　the　absorbing　character　of　the　work　on　the　Cirripedes；　time　was　found　for　all。　　In　1849　his　friend　Herschel　induced　him　to　supply　a　chapter　of　forty　pages　on　Geology　to　the　Admiralty　〃Manual　of　Scientific　Inquiry〃　which　he　was　editing。　　This　is　Darwin's　single　contribution　to　books　of　an　〃educational〃　kind。　　It　is　remarkable　for　its　clearness　and　simplicity　and　attention　to　minute　details。　　It　may　be　read　by　the　student　of　Darwin's　life　with　much　interest；　for　the　directions　he　gives　to　an　explorer　are　without　doubt　those　which　he；　as　a　self…taught　geologist；　proved　to　be　serviceable　during　his　life　on　the　〃Beagle〃。

On　the　completion　of　the　Cirripede　volumes；　in　1854；　Darwin　was　able　to　grapple　with　the　immense　pile　of　MS。　notes　which　he　had　accumulated　on　the　species　question。　　The　first　sketch　of　35　pages　（1842）；　had　been　enlarged　in　1844　into　one　of　230　pages　（＇The　first　draft　of　the　〃Origin〃　is　being　prepared　for　Press　by　Mr　Francis　Darwin　and　will　be　published　by　the　Cambridge　University　Press　this　year　（1909）。　　A。C。S。＇）；　but　in　1856　was　commenced　the　work　（never　to　be　completed）　which　was　designed　on　a　scale　three　or　four　times　more　extensive　than　that　on　which　the　〃Origin　of　Species〃　was　in　the　end　written。

In　drawing　up　those　two　masterly　chapters　of　the　〃Origin〃；　〃On　the　Imperfection　of　the　Geological　Record；〃　and　〃On　the　Geological　Succession　of　Organic　Beings〃；　Darwin　had　need　of　all　the　experience　and　knowledge　he　had　been　gathering　during　thirty　years；　the　first　half　of　which　had　been　almost　wholly　devoted　to　geological　study。　　The　most　enlightened　geologists　of　the　day　found　much　that　was　new；　and　still　more　that　was　startling　from　the　manner　of　its　presentation；　in　these　wonderful　essays。　　Of　Darwin's　own　sense　of　the　importance　of　the　geological　evidence　in　any　presentation　of　his　theory　a　striking　proof　will　be　found　in　a　passage　of　the　touching　letter　to　his　wife；　enjoining　the　publication　of　his　sketch　of　1844。　　〃In　case　of　my　sudden　death；〃　he　wrote；　〃。。。the　editor　must　be　a　geologist　as　well　as　a　naturalist。〃　　（〃L。L。〃　II。　pages　16；　17。）

In　spite　of　the　numerous　and　valuable　palaeontological　discoveries　made　since　the　publication　of　〃The　Origin　of　Species〃；　the　importance　of　the　first　of　these　two　geological　chapters　is　as　great　as　ever。　　It　still　remains　true　that　〃Those　who　believe　that　the　geological　record　is　in　any　degree　perfect；　will　at　once　reject　the　theory〃as　indeed　they　must　reject　any　theory　of　evolution。　　The　striking　passage　with　which　Darwin　concludes　this　chapterin　which　he　compares　the　record　of　the　rocks　to　the　much　mutilated　volumes　of　a　human　historyremains　as　apt　an　illustration　as　it　did　when　first　written。

And　the　second　geological　chapter；　on　the　Succession　of　Organic　Beings　though　it　has　been　strengthened　in　a　thousand　ways；　by　the　discoveries　concerning　the　pedigrees　of　the　horse；　the　elephant　and　many　other　aberrant　types