darwin and modern science-第59节

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ossesses　many　useless　organs　and　that　many　of　its　relations　to　the　external　world　are　capable　of　considerable　improvement。

In　writing　this　essay　I　have　purposely　refrained　from　taking　a　definite　position　with　regard　to　the　problems　touched。　　My　desire　has　been　to　write　a　chapter　showing　the　influence　of　Darwin's　work　so　far　as　Embryology　is　concerned；　and　the　various　points　which　come　up　for　consideration　in　discussing　his　views。　　Darwin　was　the　last　man　who　would　have　claimed　finality　for　any　of　his　doctrines；　but　he　might　fairly　have　claimed　to　have　set　going　a　process　of　intellectual　fermentation　which　is　still　very　far　from　completion。


XI。　　THE　PALAEONTOLOGICAL　RECORD。

I。　　ANIMALS。

By　W。B。　SCOTT。　Professor　of　Geology　in　the　University　of　Princeton；　U。S。A。

To　no　branch　of　science　did　the　publication　of　〃The　Origin　of　Species〃　prove　to　be　a　more　vivifying　and　transforming　influence　than　to　Palaeontology。　　This　science　had　suffered；　and　to　some　extent；　still　suffers　from　its　rather　anomalous　position　between　geology　and　biology；　each　of　which　makes　claim　to　its　territory；　and　it　was　held　in　strict　bondage　to　the　Linnean　and　Cuvierian　dogma　that　species　were　immutable　entities。　　There　is；　however；　reason　to　maintain　that　this　strict　bondage　to　a　dogma　now　abandoned；　was　not　without　its　good　side；　and　served　the　purpose　of　keeping　the　infant　science　in　leading…strings　until　it　was　able　to　walk　alone；　and　preventing　a　flood　of　premature　generalisations　and　speculations。

As　Zittel　has　said：　　〃Two　directions　were　from　the　first　apparent　in　palaeontological　researcha　stratigraphical　and　a　biological。　　Stratigraphers　wished　from　palaeontology　mainly　confirmation　regarding　the　true　order　or　relative　age　of　zones　of　rock…deposits　in　the　field。　　Biologists　had；　theoretically　at　least；　the　more　genuine　interest　in　fossil　organisms　as　individual　forms　of　life。〃　　（Zittel；　〃History　of　Geology　and　Palaeontology〃；　page　363；　London；　1901。）　　The　geological　or　stratigraphical　direction　of　the　science　was　given　by　the　work　of　William　Smith；　〃the　father　of　historical　geology；〃　in　the　closing　decade　of　the　eighteenth　century。　　Smith　was　the　first　to　make　a　systematic　use　of　fossils　in　determining　the　order　of　succession　of　the　rocks　which　make　up　the　accessible　crust　of　the　earth；　and　this　use　has　continued；　without　essential　change；　to　the　present　day。　　It　is　true　that　the　theory　of　evolution　has　greatly　modified　our　conceptions　concerning　the　introduction　of　new　species　and　the　manner　in　which　palaeontological　data　are　to　be　interpreted　in　terms　of　stratigraphy；　but；　broadly　speaking；　the　method　remains　fundamentally　the　same　as　that　introduced　by　Smith。

The　biological　direction　of　palaeontology　was　due　to　Cuvier　and　his　associates；　who　first　showed　that　fossils　were　not　merely　varieties　of　existing　organisms；　but　belonged　to　extinct　species　and　genera；　an　altogether　revolutionary　conception；　which　startled　the　scientific　world。　　Cuvier　made　careful　studies；　especially　of　fossil　vertebrates；　from　the　standpoint　of　zoology　and　was　thus　the　founder　of　palaeontology　as　a　biological　science。　　His　great　work　on　〃Ossements　Fossiles〃　（Paris；　1821）　has　never　been　surpassed　as　a　masterpiece　of　the　comparative　method　of　anatomical　investigation；　and　has　furnished　to　the　palaeontologist　the　indispensable　implements　of　research。

On　the　other　hand；　Cuvier's　theoretical　views　regarding　the　history　of　the　earth　and　its　successive　faunas　and　floras　are　such　as　no　one　believes　to…　day。　　He　held　that　the　earth　had　been　repeatedly　devastated　by　great　cataclysms；　which　destroyed　every　living　thing；　necessitating　an　entirely　new　creation；　thus　regarding　the　geological　periods　as　sharply　demarcated　and　strictly　contemporaneous　for　the　whole　earth；　and　each　species　of　animal　and　plant　as　confined　to　a　single　period。　　Cuvier's　immense　authority　and　his　commanding　personality　dominated　scientific　thought　for　more　than　a　generation　and　marked　out　the　line　which　the　development　of　palaeontology　was　to　follow。　　The　work　was　enthusiastically　taken　up　by　many　very　able　men　in　the　various　European　countries　and　in　the　United　States；　but；　controlled　as　it　was　by　the　belief　in　the　fixity　of　species；　it　remained　almost　entirely　descriptive　and　consisted　in　the　description　and　classification　of　the　different　groups　of　fossil　organisms。　　As　already　intimated；　this　narrowness　of　view　had　its　compensations；　for　it　deferred　generalisations　until　some　adequate　foundations　for　these　had　been　laid。

Dominant　as　it　was；　Cuvier's　authority　was　slowly　undermined　by　the　progress　of　knowledge　and　the　way　was　prepared　for　the　introduction　of　more　rational　conceptions。　　The　theory　of　〃Catastrophism〃　was　attacked　by　several　geologists；　most　effectively　by　Sir　Charles　Lyell；　who　greatly　amplified　the　principles　enunciated　by　Hutton　and　Playfair　in　the　preceding　century；　and　inaugurated　a　new　era　in　geology。　　Lyell's　uniformitarian　views　of　the　earth's　history　and　of　the　agencies　which　had　wrought　its　changes；　had　undoubted　effect　in　educating　men's　minds　for　the　acceptance　of　essentially　similar　views　regarding　the　organic　world。　　In　palaeontology　too　the　doctrine　of　the　immutability　of　species；　though　vehemently　maintained　and　reasserted；　was　gradually　weakening。　　In　reviewing　long　series　of　fossils；　relations　were　observed　which　pointed　to　genetic　connections　and　yet　were　interpreted　as　purely　ideal。　　Agassiz；　for　example；　who　never　accepted　the　evolutionary　theory；　drew　attention　to　facts　which　could　be　satisfactorily　interpreted　only　in　terms　of　that　theory。　　Among　the　fossils　he　indicated　〃progressive；〃　〃synthetic；〃　〃prophetic；〃　and　〃embryonic〃　types；　and　pointed　out　the　parallelism　which　obtains　between　the　geological　succession　of　ancient　animals　and　the　ontogenetic　development　of　recent　forms。　　In　Darwin's　words：　　〃This　view　accords　admirably　well　with　our　theory。〃　　（〃Origin　of　Species〃　（6th　edition）；　page　310。）　　Of　similar　import　were　Owen's　views　on　〃generalised　types〃　and　〃archetypes。〃

The　appearance　of　〃The　Origin　of　Species〃　in　1859　revolutionised　all　the　biological　sciences。　　From　the　very　nature　of　the　case；　Darwin　was　compelled　to　give　careful　consideration　to　the　palaeontological　evidence；　indeed；　it　was　the　palaeontology　and　modern　distribution　of　animals　in　South　America　which　first　led　him　to　reflect　upon　the　great　problem。　　In　his　own　words：　　〃I　had　been　deeply　impressed　by　discovering　in　the　Pampean　formation　great　fossil　animals　covered　with　armour　like　that　on　the　existing　armadillos；　secondly；　by　the　manner　in　which　closely　allied　animals　replace　one　another　in　proceeding　southward　over　the　Continent；　and　thirdly；　by　the　South　American　character　of　most　of　the　productions　of　the　Galapagos　archipelago；　and　more　especially　by　the　manner　in　which　they　differ　slightly　on　each　island　of　the　group。〃　　（〃Life　and　Letters　of　Charles　Darwin〃；　I。　page　82。）　　In　the　famous　tenth　and　eleventh　chapters　of　the　〃Origin〃；　the　palaeontological　evidence　is　examined　at　length　and　the　imperfection　of　the　geological　record　is　strongly　emphasised。　　The　conclusion　is　reached；　that；　in　view　of　this　extreme　imperfection；　palaeontology　could　not　reasonably　be　expected　to　yield　complete　and　convincing　proof　of　the　evolutionary　theory。　　〃I　look　at　the　geological　record　as　a　history　of　the　world　imperfectly　kept；　and　written　in　a　changing　dialect；　of　this　history　we　possess　the　last　volume　alone；　relating　only　to　two　or　three　countries。　　Of　this　volume；　only　here　and　there　a　short　chapter　has　been　preserved；　and　of　each　page；　only　here　and　there　a　few　lines。〃　　（〃Origin　of　Species〃；　page　289。）　　Yet；　aside　from　these　inevitable　difficulties；　he　concludes；　that　〃the　other　great　leading　facts　in　palaeontology　agree　admirably　with　the　theory　of　descent　with　modification　through　variation　and　natural　selection。〃　　（Ibid。　page　313。）

Darwin's　theory　gave　an　entirely　new　significance　and　importance　to　palaeontology。　　Cuvier's　conception　of　the　science　had　been　a　limited；　though　a　lofty　one。　　〃How　glorious　it　would　be　if　we　could　arrange　the　organised　products　of　the　universe　in　their　chronological　order！。。。The　chronological　succession　of　organised　forms；　the　exact　determination　of　those　types　which　appeared　first；　the　simultaneous　origin　of　certain　species　and　their　gradual　decay；　would　perhaps　teach　us　as　much　about　the　mysteries　of　organisation　as　we　can　possibly　learn　through　experiments　with　living　organisms。〃　　（Zittel　op。　cit。　page　140。）　　This；　however；　was　rather　the　expression　of　a　hope　for　the　distant　future　than　an　account　of　what　was　attainable；　and　in　practice　the　science　remained　almost　purely　descriptive；　until　Darwin　gave　it　a　new　standpoint；　new　problems　and　an　altogether　fresh　interest　and　charm。　　The　revolution　thus　accomplished　is　comparable　only　to　that　produced　by　the　Copernican　astronomy。

From　the　first　it　was　obvious　that　one　of　the　most　searching　tests　of　the　evolutionary　theory　would　be　given　by　the　advance　of　palaeontological　discovery。　　However　imperfect　the　geological　record　might　be；　its　ascertained　facts　would　necessarily　be　consistent；　under　any　reasonable　interpretation；　with　the　demands　of　a　true　theory；　otherwise　the　theory　would　eventually　be　overwhelme