darwin and modern science-第24章

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rofound　obeisance　to　the　sons　of　Noah；　but　that　performed；　they　continue　on　strictly　modern　lines。　　The　question　of　the　mutability　of　species　was　thus　prominently　raised。

Those　who　rate　Lamarck　no　higher　than　did　Huxley　in　his　contemptuous　phrase　〃buccinator　tantum；〃　will　scarcely　deny　that　the　sound　of　the　trumpet　had　carried　far；　or　that　its　note　was　clear。　　If　then　there　were　few　who　had　already　turned　to　evolution　with　positive　conviction；　all　scientific　men　must　at　least　have　known　that　such　views　had　been　promulgated；　and　many　must；　as　Huxley　says；　have　taken　up　his　own　position　of　〃critical　expectancy。〃　　（See　the　chapter　contributed　to　the　〃Life　and　Letters　of　Charles　Darwin〃　II。　page　195。　　I　do　not　clearly　understand　the　sense　in　which　Darwin　wrote　（Autobiography；　ibid。　I。　page　87）：　　〃It　has　sometimes　been　said　that　the　success　of　the　〃Origin〃　proved　'that　the　subject　was　in　the　air；'　or　'that　men's　minds　were　prepared　for　it。'　　I　do　not　think　that　this　is　strictly　true；　for　I　occasionally　sounded　not　a　few　naturalists；　and　never　happened　to　come　across　a　single　one　who　seemed　to　doubt　about　the　permanence　of　species。〃　　This　experience　may　perhaps　have　been　an　accident　due　to　Darwin's　isolation。　　The　literature　of　the　period　abounds　with　indications　of　〃critical　expectancy。〃　　A　most　interesting　expression　of　that　feeling　is　given　in　the　charming　account　of　the　〃Early　Days　of　Darwinism〃　by　Alfred　Newton；　〃Macmillan's　Magazine〃；　LVII。　1888；　page　241。　　He　tells　how　in　1858　when　spending　a　dreary　summer　in　Iceland；　he　and　his　friend；　the　ornithologist　John　Wolley；　in　default　of　active　occupation；　spent　their　days　in　discussion。　　〃Both　of　us　taking　a　keen　interest　in　Natural　History；　it　was　but　reasonable　that　a　question；　which　in　those　days　was　always　coming　up　wherever　two　or　more　naturalists　were　gathered　together；　should　be　continually　recurring。　　That　question　was；　'What　is　a　species？'　and　connected　therewith　was　the　other　question；　'How　did　a　species　begin？'。。。Now　we　were　of　course　fairly　well　acquainted　with　what　had　been　published　on　these　subjects。〃　　He　then　enumerates　some　of　these　publications；　mentioning　among　others　T。　Vernon　Wollaston's　〃Variation　of　Species〃a　work　which　has　in　my　opinion　never　been　adequately　appreciated。　He　proceeds：　　〃Of　course　we　never　arrived　at　anything　like　a　solution　of　these　problems；　general　or　special；　but　we　felt　very　strongly　that　a　solution　ought　to　be　found；　and　that　quickly；　if　the　study　of　Botany　and　Zoology　was　to　make　any　great　advance。〃　　He　then　describes　how　on　his　return　home　he　received　the　famous　number　of　the　〃Linnean　Journal〃　on　a　certain　evening。　　〃I　sat　up　late　that　night　to　read　it；　and　never　shall　I　forget　the　impression　it　made　upon　me。　　Herein　was　contained　a　perfectly　simple　solution　of　all　the　difficulties　which　had　been　troubling　me　for　months　past。。。I　went　to　bed　satisfied　that　a　solution　had　been　found。〃）

Why；　then；　was　it；　that　Darwin　succeeded　where　the　rest　had　failed？　　The　cause　of　that　success　was　two…fold。　　First；　and　obviously；　in　the　principle　of　Natural　Selection　he　had　a　suggestion　which　would　work。　　It　might　not　go　the　whole　way；　but　it　was　true　as　far　as　it　went。　　Evolution　could　thus　in　great　measure　be　fairly　represented　as　a　consequence　of　demonstrable　processes。　　Darwin　seldom　endangers　the　mechanism　he　devised　by　putting　on　it　strains　much　greater　than　it　can　bear。　　He　at　least　was　under　no　illusion　as　to　the　omnipotence　of　Selection；　and　he　introduces　none　of　the　forced　pleading　which　in　recent　years　has　threatened　to　discredit　that　principle。

For　example；　in　the　latest　text　of　the　〃Origin〃　（〃Origin〃；　（6th　edition　（1882）；　page　421。）　we　find　him　saying：

〃But　as　my　conclusions　have　lately　been　much　misrepresented；　and　it　has　been　stated　that　I　attribute　the　modification　of　species　exclusively　to　natural　selection；　I　may　be　permitted　to　remark　that　in　the　first　edition　of　this　work；　and　subsequently；　I　placed　in　a　most　conspicuous　position　namely；　at　the　close　of　the　Introductionthe　following　words：　　'I　am　convinced　that　natural　selection　has　been　the　main　but　not　the　exclusive　means　of　modification。'〃

But　apart　from　the　invention　of　this　reasonable　hypothesis；　which　may　well；　as　Huxley　estimated；　〃be　the　guide　of　biological　and　psychological　speculation　for　the　next　three　or　four　generations；〃　Darwin　made　a　more　significant　and　imperishable　contribution。　　Not　for　a　few　generations；　but　through　all　ages　he　should　be　remembered　as　the　first　who　showed　clearly　that　the　problems　of　Heredity　and　Variation　are　soluble　by　observation；　and　laid　down　the　course　by　which　we　must　proceed　to　their　solution。　　（Whatever　be　our　estimate　of　the　importance　of　Natural　Selection；　in　this　we　all　agree。　　Samuel　Butler；　the　most　brilliant；　and　by　far　the　most　interesting　of　Darwin's　opponentswhose　works　are　at　length　emerging　from　oblivionin　his　Preface　（1882）　to　the　2nd　edition　of　〃Evolution；　Old　and　New〃；　repeats　his　earlier　expression　of　homage　to　one　whom　he　had　come　to　regard　as　an　enemy：　　〃To　the　end　of　time；　if　the　question　be　asked；　'Who　taught　people　to　believe　in　Evolution？'　the　answer　must　be　that　it　was　Mr。　Darwin。　　This　is　true；　and　it　is　hard　to　see　what　palm　of　higher　praise　can　be　awarded　to　any　philosopher。〃）　　The　moment　of　inspiration　did　not　come　with　the　reading　of　Malthus；　but　with　the　opening　of　the　〃first　note…book　on　Transmutation　of　Species。〃　　（〃Life　and　Letters〃；　I。　pages　276　and　83。）　　Evolution　is　a　process　of　Variation　and　Heredity。　　The　older　writers；　though　they　had　some　vague　idea　that　it　must　be　so；　did　not　study　Variation　and　Heredity。　　Darwin　did；　and　so　begat　not　a　theory；　but　a　science。

The　extent　to　which　this　is　true；　the　scientific　world　is　only　beginning　to　realise。　　So　little　was　the　fact　appreciated　in　Darwin's　own　time　that　the　success　of　his　writings　was　followed　by　an　almost　total　cessation　of　work　in　that　special　field。　　Of　the　causes　which　led　to　this　remarkable　consequence　I　have　spoken　elsewhere。　　They　proceeded　from　circumstances　peculiar　to　the　time；　but　whatever　the　causes　there　is　no　doubt　that　this　statement　of　the　result　is　historically　exact；　and　those　who　make　it　their　business　to　collect　facts　elucidating　the　physiology　of　Heredity　and　Variation　are　well　aware　that　they　will　find　little　to　reward　their　quest　in　the　leading　scientific　Journals　of　the　Darwinian　epoch。

In　those　thirty　years　the　original　stock　of　evidence　current　and　in　circulation　even　underwent　a　process　of　attrition。　　As　in　the　story　of　the　Eastern　sage　who　first　wrote　the　collected　learning　of　the　universe　for　his　sons　in　a　thousand　volumes；　and　by　successive　compression　and　burning　reduced　them　to　one；　and　from　this　by　further　burning　distilled　the　single　ejaculation　of　the　Faith；　〃There　is　no　god　but　God　and　Mohamed　is　the　Prophet　of　God；〃　which　was　all　his　maturer　wisdom　deemed　essential：so　in　the　books　of　that　period　do　we　find　the　corpus　of　genetic　knowledge　dwindle　to　a　few　prerogative　instances；　and　these　at　last　to　the　brief　formula　of　an　unquestioned　creed。

And　yet　in　all　else　that　concerns　biological　science　this　period　was；　in　very　truth；　our　Golden　Age；　when　the　natural　history　of　the　earth　was　explored　as　never　before；　morphology　and　embryology　were　exhaustively　ransacked；　the　physiology　of　plants　and　animals　began　to　rival　chemistry　and　physics　in　precision　of　method　and　in　the　rapidity　of　its　advances；　and　the　foundations　of　pathology　were　laid。

In　contrast　with　this　immense　activity　elsewhere　the　neglect　which　befel　the　special　physiology　of　Descent；　or　Genetics　as　we　now　call　it；　is　astonishing。　　This　may　of　course　be　interpreted　as　meaning　that　the　favoured　studies　seemed　to　promise　a　quicker　return　for　effort；　but　it　would　be　more　true　to　say　that　those　who　chose　these　other　pursuits　did　so　without　making　any　such　comparison；　for　the　idea　that　the　physiology　of　Heredity　and　Variation　was　a　coherent　science；　offering　possibilities　of　extraordinary　discovery；　was　not　present　to　their　minds　at　all。　　In　a　word；　the　existence　of　such　a　science　was　well　nigh　forgotten。　　It　is　true　that　in　ancillary　periodicals；　as　for　example　those　that　treat　of　entomology　or　horticulture；　or　in　the　writings　of　the　already　isolated　systematists　（This　isolation　of　the　systematists　is　the　one　most　melancholy　sequela　of　Darwinism。　　It　seems　an　irony　that　we　should　read　in　the　peroration　to　the　〃Origin〃　that　when　the　Darwinian　view　is　accepted　〃Systematists　will　be　able　to　pursue　their　labours　as　at　present；　but　they　will　not　be　incessantly　haunted　by　the　shadowy　doubt　whether　this　or　that　form　be　a　true　species。　　This；　I　feel　sure；　and　I　speak　after　experience；　will　be　no　slight　relief。　　The　endless　disputes　whether　or　not　some　fifty　species　of　British　brambles　are　good　species　will　cease。〃　　〃Origin〃；　6th　edition　（1882）；　page　425。　　True　they　have　ceased　to　attract　the　attention　of　those　who　lead　opinion；　but　anyone　who　will　turn　to　the　literature　of　systematics　will　find　that　they　have　not　ceased　in　any　other　sense。　　Should　there　not　be　something　disquieting　in　the　fact　that　among　the　workers　who　come　most　into　contact　with　specific　differences；　are　to　be　found　the　only　men　who　have　failed　to　be　persuaded　of　the　unreality　of　those　differences？）；　observations　with　this　special　bearing　were　from　time　to　time　related；　but　the　class　of　fact　on　which　Darwin　built　his　conceptions　of　Heredity　and　Variation　was　not　seen　in　the　highways　of　biology。　　It　formed　no　part　of　the　official　curriculum　of　biological　students；　and　found　no　place　among　the　subjects　which　their　teachers　were　investigating。

During　this　period　nevertheless　one　distinct　advance　was　made；　that　with　which　Weismann's　name　is　prominently　connected。　　In　Darwin's　genetic　scheme　the　hereditary　transmission　of　parental　experience　and　its　consequences　played　a　considerable　role。　　Exactly　how　great　that　role　was　supposed　to　be；　he　with　his　habitual　caution　refrained　from　specifying；　for　the　sufficient　reason　that　he　did　not　know。　　Nevertheless　much　of　the　process　of　Evolution；　especially　that　by　which　organs　have　become　degenerate　and　rudimentary；　was　certainly　attributed　by　Darwin　to　such　inheritance；　though　since　belief　in　the　inheritance　of　acquired　characters　fell　into　disrepute；　the　fact　has　been　a　good　deal　overlooked。　　The　〃Origin〃　without　〃use　and　disuse〃　would　be　a　materially　different　book。　　A　certain　vacillation　is　discernible　in　Darwin's　utterances　on　this　question；　and　the　fact　gave　to　the　astute　Butler　an　opportunity　for　his　most　telling　attack。　　The　discussion　which　best　illustrates　the　genetic　views　of　the　period　arose　in　regard　to　the　production　of　the　rudimentary　condition　of　the　wings　of　many　beetles　in　the　Madeira　group　of　islands；　and　by　comparing　passages　from　the　〃Origin〃　（6th　edition　pages　109　and　401。　　See　Butler；　〃Essays　on　Life；　Art；　and　Science〃；　page　265；　reprinted　1908；　and　〃Evolution；　Old　and　New〃；　chapter　XXII。　（2nd　edition）；　1882。）　Butler　convicts　Darwin　of　saying　first　that　this　condition　was　in　the　main　the　result　of　Selection；　with　disuse　aiding；　and　in　another　place　that　the　main　cause　of　degeneration　was　disuse；　but　that　Selection　had　aided。　　To　Darwin　however　I　think　the　point　would　have　seemed　one　of　dialectics　merely。　　To　him　the　one　paramount　pu