darwin and modern science- 第4部分

AS　REGARDS　THE　GENERAL　IDEA　OF　ORGANIC　EVOLUTION。

While　it　is　true；　as　Prof。　H。F。　Osborn　puts　it；　that　〃'Before　and　after　Darwin'　will　always　be　the　ante　et　post　urbem　conditam　of　biological　history；〃　it　is　also　true　that　the　general　idea　of　organic　evolution　is　very　ancient。　　In　his　admirable　sketch　〃From　the　Greeks　to　Darwin〃　（〃Columbia　University　Biological　Series〃；　Vol。　I。　New　York　and　London；　1894。　　We　must　acknowledge　our　great　indebtness　to　this　fine　piece　of　work。）；　Prof。　Osborn　has　shown　that　several　of　the　ancient　philosophers　looked　upon　Nature　as　a　gradual　development　and　as　still　in　process　of　change。　　In　the　suggestions　of　Empedocles；　to　take　the　best　instance；　there　were　〃four　sparks　of　truth；first；　that　the　development　of　life　was　a　gradual　process；　second；　that　plants　were　evolved　before　animals；　third；　that　imperfect　forms　were　gradually　replaced　（not　succeeded）　by　perfect　forms；　fourth；　that　the　natural　cause　of　the　production　of　perfect　forms　was　the　extinction　of　the　imperfect。〃　　（Op。　cit。　page　41。）　　But　the　fundamental　idea　of　one　stage　giving　origin　to　another　was　absent。　　As　the　blue　Aegean　teemed　with　treasures　of　beauty　and　threw　many　upon　its　shores；　so　did　Nature　produce　like　a　fertile　artist　what　had　to　be　rejected　as　well　as　what　was　able　to　survive；　but　the　idea　of　one　species　emerging　out　of　another　was　not　yet　conceived。

Aristotle's　views　of　Nature　（See　G。J。　Romanes；　〃Aristotle　as　a　Naturalist〃；　〃Contemporary　Review〃；　Vol。　LIX。　page　275；　1891；　G。　Pouchet　〃La　Biologie　Aristotelique〃；　Paris；　1885；　E。　Zeller；　〃A　History　of　Greek　Philosophy〃；　London；　1881；　and　〃Ueber　die　griechischen　Vorganger　Darwin's〃；　〃Abhandl。　Berlin　Akad。〃　1878；　pages　111…124。）　seem　to　have　been　more　definitely　evolutionist　than　those　of　his　predecessors；　in　this　sense；　at　least；　that　he　recognised　not　only　an　ascending　scale；　but　a　genetic　series　from　polyp　to　man　and　an　age…long　movement　towards　perfection。　　〃It　is　due　to　the　resistance　of　matter　to　form　that　Nature　can　only　rise　by　degrees　from　lower　to　higher　types。〃　　〃Nature　produces　those　things　which；　being　continually　moved　by　a　certain　principle　contained　in　themselves；　arrive　at　a　certain　end。〃

To　discern　the　outcrop　of　evolution…doctrine　in　the　long　interval　between　Aristotle　and　Bacon　seems　to　be　very　difficult；　and　some　of　the　instances　that　have　been　cited　strike　one　as　forced。　　Epicurus　and　Lucretius；　often　called　poets　of　evolution；　both　pictured　animals　as　arising　directly　out　of　the　earth；　very　much　as　Milton's　lion　long　afterwards　pawed　its　way　out。　　Even　when　we　come　to　Bruno　who　wrote　that　〃to　the　sound　of　the　harp　of　the　Universal　Apollo　（the　World　Spirit）；　the　lower　organisms　are　called　by　stages　to　higher；　and　the　lower　stages　are　connected　by　intermediate　forms　with　the　higher；〃　there　is　great　room；　as　Prof。　Osborn　points　out　（op。　cit。　page　81。）；　for　difference　of　opinion　as　to　how　far　he　was　an　evolutionist　in　our　sense　of　the　term。

The　awakening　of　natural　science　in　the　sixteenth　century　brought　the　possibility　of　a　concrete　evolution　theory　nearer；　and　in　the　early　seventeenth　century　we　find　evidences　of　a　new　spiritin　the　embryology　of　Harvey　and　the　classifications　of　Ray。　　Besides　sober　naturalists　there　were　speculative　dreamers　in　the　sixteenth　and　seventeenth　centuries　who　had　at　least　got　beyond　static　formulae；　but；　as　Professor　Osborn　points　out　（op。　cit。　page　87。）；　〃it　is　a　very　striking　fact；　that　the　basis　of　our　modern　methods　of　studying　the　Evolution　problem　was　established　not　by　the　early　naturalists　nor　by　the　speculative　writers；　but　by　the　Philosophers。〃　　He　refers　to　Bacon；　Descartes；　Leibnitz；　Hume；　Kant；　Lessing；　Herder；　and　Schelling。　　〃They　alone　were　upon　the　main　track　of　modern　thought。　　It　is　evident　that　they　were　groping　in　the　dark　for　a　working　theory　of　the　Evolution　of　life；　and　it　is　remarkable　that　they　clearly　perceived　from　the　outset　that　the　point　to　which　observation　should　be　directed　was　not　the　past　but　the　present　mutability　of　species；　and　further；　that　this　mutability　was　simply　the　variation　of　individuals　on　an　extended　scale。〃

Bacon　seems　to　have　been　one　of　the　first　to　think　definitely　about　the　mutability　of　species；　and　he　was　far　ahead　of　his　age　in　his　suggestion　of　what　we　now　call　a　Station　of　Experimental　Evolution。　　Leibnitz　discusses　in　so　many　words　how　the　species　of　animals　may　be　changed　and　how　intermediate　species　may　once　have　linked　those　that　now　seem　discontinuous。　　〃All　natural　orders　of　beings　present　but　a　single　chain〃。。。〃All　advances　by　degrees　in　Nature；　and　nothing　by　leaps。〃　　Similar　evolutionist　statements　are　to　be　found　in　the　works　of　the　other　〃philosophers；〃　to　whom　Prof。　Osborn　refers；　who　were；　indeed；　more　scientific　than　the　naturalists　of　their　day。　　It　must　be　borne　in　mind　that　the　general　idea　of　organic　evolutionthat　the　present　is　the　child　of　the　pastis　in　great　part　just　the　idea　of　human　history　projected　upon　the　natural　world；　differentiated　by　the　qualification　that　the　continuous　〃Becoming〃　has　been　wrought　out　by　forces　inherent　in　the　organisms　themselves　and　in　their　environment。

A　reference　to　Kant　（See　Brock；　〃Die　Stellung　Kant's　zur　Deszendenztheorie；〃　〃Biol。　Centralbl。〃　VIII。　1889；　pages　641…648。　　Fritz　Schultze；　〃Kant　und　Darwin〃；　Jena；　1875。）　should　come　in　historical　order　after　Buffon；　with　whose　writings　he　was　acquainted；　but　he　seems；　along　with　Herder　and　Schelling；　to　be　best　regarded　as　the　culmination　of　the　evolutionist　philosophersof　those　at　least　who　interested　themselves　in　scientific　problems。　　In　a　famous　passage　he　speaks　of　〃the　agreement　of　so　many　kinds　of　animals　in　a　certain　common　plan　of　structure〃。。。an　〃analogy　of　forms〃　which　〃strengthens　the　supposition　that　they　have　an　actual　blood…relationship；　due　to　derivation　from　a　common　parent。〃　　He　speaks　of　〃the　great　Family　of　creatures；　for　as　a　Family　we　must　conceive　it；　if　the　above…mentioned　continuous　and　connected　relationship　has　a　real　foundation。〃　　Prof。　Osborn　alludes　to　the　scientific　caution　which　led　Kant；　biology　being　what　it　was；　to　refuse　to　entertain　the　hope　〃that　a　Newton　may　one　day　arise　even　to　make　the　production　of　a　blade　of　grass　comprehensible；　according　to　natural　laws　ordained　by　no　intention。〃　　As　Prof。　Haeckel　finely　observes；　Darwin　rose　up　as　Kant's　Newton。　　（Mr　Alfred　Russel　Wallace　writes：　　〃We　claim　for　Darwin　that　he　is　the　Newton　of　natural　history；　and　that；　just　so　surely　as　that　the　discovery　and　demonstration　by　Newton　of　the　law　of　gravitation　established　order　in　place　of　chaos　and　laid　a　sure　foundation　for　all　future　study　of　the　starry　heavens；　so　surely　has　Darwin；　by　his　discovery　of　the　law　of　natural　selection　and　his　demonstration　of　the　great　principle　of　the　preservation　of　useful　variations　in　the　struggle　for　life；　not　only　thrown　a　flood　of　light　on　the　process　of　development　of　the　whole　organic　world；　but　also　established　a　firm　foundation　for　all　future　study　of　nature〃　（〃Darwinism〃；　London；　1889；　page　9）。　　See　also　Prof。　Karl　Pearson's　〃Grammar　of　Science〃　（2nd　edition）；　London；　1900；　page　32。　　See　Osborn；　op。　cit。　　Page　100。））

The　scientific　renaissance　brought　a　wealth　of　fresh　impressions　and　some　freedom　from　the　tyranny　of　tradition；　and　the　twofold　stimulus　stirred　the　speculative　activity　of　a　great　variety　of　men　from　old　Claude　Duret　of　Moulins；　of　whose　weird　transformism　（1609）　Dr　Henry　de　Varigny　（〃Experimental　Evolution〃。　　London；　1892。　　Chap。　1。　page　14。）　gives　us　a　glimpse；　to　Lorenz　Oken　（1799…1851）　whose　writings　are　such　mixtures　of　sense　and　nonsense　that　some　regard　him　as　a　far…seeing　prophet　and　others　as　a　fatuous　follower　of　intellectual　will…o'…the…wisps。　　Similarly；　for　De　Maillet；　Maupertuis；　Diderot；　Bonnet；　and　others；　we　must　agree　with　Professor　Osborn　that　they　were　not　actually　in　the　main　Evolution　movement。　　Some　have　been　included　in　the　roll　of　honour　on　very　slender　evidence；　Robinet　for　instance；　whose　evolutionism　seems　to　us　extremely　dubious。　　（See　J。　Arthur　Thomson；　〃The　Science　of　Life〃。　　London；　1899。　　Chap。　XVI。　〃Evolution　of　Evolution　Theory〃。）

The　first　naturalist　to　give　a　broad　and　concrete　expression　to　the　evolutionist　doctrine　of　descent　was　Buffon　（1707…1788）；　but　it　is　interesting　to　recall　the　fact　that　his　contemporary　Linnaeus　（1707…1778）；　protagonist　of　the　counter…doctrine　of　the　fixity　of　species　（See　Carus　Sterne　（Ernest　Krause）；　〃Die　allgemeine　Weltanschauung　in　ihrer　historischen　Entwickelung〃。　　Stuttgart；　1889。　　Chapter　entitled　〃Bestandigkeit　oder　Veranderlichkeit　der　Naturwesen〃。）；　went　the　length　of　admitting　（in　1762）　that　new　species　might　arise　by　intercrossing。　　Buffon's　position　among　the　pioneers　of　the　evolution…doctrine　is　weakened　by　his　habit　of　vacillating　between　his　own　conclusions　and　the　orthodoxy　of　the　Sorbonne；　but　there　is　no　doubt　that　he　had　a　firm　grasp　of　the　general　idea　of　〃l'enchainement　des　etres。〃

Erasmus　Darwin　（1731…1802）；　probably　influenced　by　Buffon；　was　another　firm　evolutionist；　and　the　outline　of　his　argument　in　the　〃Zoonomia〃　（〃Zoonomia；　or　the　Laws　of　Organic　Life〃；　2　vols。　　London；　1794；　Osborn　op。　cit。　page　145。）　might　serve　in　part　at　least　to…day。　　〃When　we　revolve　in　our　minds　the　metamorphoses　of　animals；　as　from　the　tadpole　to　the　frog；　secondly；　the　changes　produced　by　artificial　cultivation；　as　in　the　breeds　of　horses；　dogs；　and　sheep；　thirdly；　the　changes　produced　by　conditions　of　climate　and　of　season；　as　in　the　sheep　of　warm　climates　being　covered　with　hair　instead　of　wool；　and　the　hares　and　partridges　of　northern　climates　becoming　white　in　winter：　　when；　further；　we　observe　the　changes　of　structure　produced　by　habit；　as　seen　especially　in　men　of　different　occupations；　or　the　changes　produced　by　artificial　mutilation　and　prenatal　influences；　as　in　the　crossing　of　species　and　production　of　monsters；　fourth；　when　we　observe　the　essential　unity　of　plan　in　all　warm…blooded　animals；we　are　led　to　conclude　that　they　have　been　alike　produced　from　a　similar　living　filament〃。。。〃From　thus　meditating　upon　the　minute　portion　of　time　in　which　many　of　the　above　changes　have　been　produced；　would　it　be　too　bold　to　imagine；　in　the　great　length　of　time　since　the　earth　began　to　exist；　perhaps　mi