a history of science-4-第13部分

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　on　the　subject　before　the　Royal　Society；　and　soon　afterwards　the　efforts　of　Herschel　and　numerous　other　natural　philosophers　contributed　to　the　advancement　of　the　new　method。

In　1843　Dr。　John　W。　Draper；　the　famous　English…American　chemist　and　physiologist；　showed　that　by　photography　the　Fraunhofer　lines　in　the　solar　spectrum　might　be　mapped　with　absolute　accuracy；　also　proving　that　the　silvered　film　revealed　many　lines　invisible　to　the　unaided　eye。　The　value　of　this　method　of　observation　was　recognized　at　once；　and；　as　soon　as　the　spectroscope　was　perfected；　the　photographic　method；　in　conjunction　with　its　use；　became　invaluable　to　the　chemist。　By　this　means　comparisons　of　spectra　may　be　made　with　a　degree　of　accuracy　not　otherwise　obtainable；　and；　in　case　of　the　stars；　whole　clusters　of　spectra　may　be　placed　on　record　at　a　single　observation。

As　the　examination　of　the　sun　and　stars　proceeded；　chemists　were　amazed　or　delighted；　according　to　their　various　preconceptions；　to　witness　the　proof　that　many　familiar　terrestrial　elements　are　to　be　found　in　the　celestial　bodies。　　But　what　perhaps　surprised　them　most　was　to　observe　the　enormous　preponderance　in　the　sidereal　bodies　of　the　element　hydrogen。　Not　only　are　there　vast　quantities　of　this　element　in　the　sun's　atmosphere；　but　some　other　suns　appeared　to　show　hydrogen　lines　almost　exclusively　in　their　spectra。　　Presently　it　appeared　that　the　stars　of　which　this　is　true　are　those　white　stars；　such　as　Sirius；　which　had　been　conjectured　to　be　the　hottest；　whereas　stars　that　are　only　red…hot；　like　our　sun；　show　also　the　vapors　of　many　other　elements；　including　iron　and　other　metals。

In　1878　Professor　J。　Norman　Lockyer；　in　a　paper　before　the　Royal　Society；　called　attention　to　the　possible　significance　of　this　series　of　observations。　He　urged　that　the　fact　of　the　sun　showing　fewer　elements　than　are　observed　here　on　the　cool　earth；　while　stars　much　hotter　than　the　sun　show　chiefly　one　element；　and　that　one　hydrogen；　the　lightest　of　known　elements；　seemed　to　give　color　to　the　possibility　that　our　alleged　elements　are　really　compounds；　which　at　the　temperature　of　the　hottest　stars　may　be　decomposed　into　hydrogen；　the　latter　〃element〃　itself　being　also　doubtless　a　compound；　which　might　be　resolved　under　yet　more　trying　conditions。

Here；　then；　was　what　might　be　termed　direct　experimental　evidence　for　the　hypothesis　of　Prout。　　Unfortunately；　however；　it　is　evidence　of　a　kind　which　only　a　few　experts　are　competent　to　discussso　very　delicate　a　matter　is　the　spectral　analysis　of　the　stars。　What　is　still　more　unfortunate；　the　experts　do　not　agree　among　themselves　as　to　the　validity　of　Professor　Lockyer's　conclusions。　Some；　like　Professor　Crookes；　have　accepted　them　with　acclaim；　hailing　Lockyer　as　〃the　Darwin　of　the　inorganic　world；〃　while　others　have　sought　a　different　explanation　of　the　facts　he　brings　forward。　As　yet　it　cannot　be　said　that　the　controversy　has　been　brought　to　final　settlement。　　Still；　it　is　hardly　to　be　doubted　that　now；　since　the　periodic　law　has　seemed　to　join　hands　with　the　spectroscope；　a　belief　in　the　compound　nature　of　the　so…called　elements　is　rapidly　gaining　ground　among　chemists。　　More　and　more　general　becomes　the　belief　that　the　Daltonian　atom　is　really　a　compound　radical；　and　that　back　of　the　seeming　diversity　of　the　alleged　elements　is　a　single　form　of　primordial　matter。　　Indeed；　in　very　recent　months；　direct　experimental　evidence　for　this　view　has　at　last　come　to　hand；　through　the　study　of　radio…active　substances。　　In　a　later　chapter　we　shall　have　occasion　to　inquire　how　this　came　about。



IV。　ANATOMY　AND　PHYSIOLOGY　IN　THE　EIGHTEENTH　CENTURY

ALBRECHT　VON　HALLER

An　epoch　in　physiology　was　made　in　the　eighteenth　century　by　the　genius　and　efforts　of　Albrecht　von　Haller　（1708…1777）；　of　Berne；　who　is　perhaps　as　worthy　of　the　title　〃The　Great〃　as　any　philosopher　who　has　been　so　christened　by　his　contemporaries　since　the　time　of　Hippocrates。　　Celebrated　as　a　physician；　he　was　proficient　in　various　fields；　being　equally　famed　in　his　own　time　as　poet；　botanist；　and　statesman；　and　dividing　his　attention　between　art　and　science。

As　a　child　Haller　was　so　sickly　that　he　was　unable　to　amuse　himself　with　the　sports　and　games　common　to　boys　of　his　age；　and　so　passed　most　of　his　time　poring　over　books。　　When　ten　years　of　age　he　began　writing　poems　in　Latin　and　German；　and　at　fifteen　entered　the　University　of　Tubingen。　　At　seventeen　he　wrote　learned　articles　in　opposition　to　certain　accepted　doctrines；　and　at　nineteen　he　received　his　degree　of　doctor。　Soon　after　this　he　visited　England；　where　his　zeal　in　dissecting　brought　him　under　suspicion　of　grave…robbery；　which　suspicion　made　it　expedient　for　him　to　return　to　the　Continent。　　After　studying　botany　in　Basel　for　some　time　he　made　an　extended　botanical　journey　through　Switzerland；　finally　settling　in　his　native　city；　Berne；　as　a　practising　physician。　During　this　time　he　did　not　neglect　either　poetry　or　botany；　publishing　anonymously　a　collection　of　poems。

In　1736　he　was　called　to　Gottingen　as　professor　of　anatomy；　surgery；　chemistry；　and　botany。　　During　his　labors　in　the　university　he　never　neglected　his　literary　work；　sometimes　living　and　sleeping　for　days　and　nights　together　in　his　library；　eating　his　meals　while　delving　in　his　books；　and　sleeping　only　when　actually　compelled　to　do　so　by　fatigue。　During　all　this　time　he　was　in　correspondence　with　savants　from　all　over　the　world；　and　it　is　said　of　him　that　he　never　left　a　letter　of　any　kind　unanswered。

Haller's　greatest　contribution　to　medical　science　was　his　famous　doctrine　of　irritability；　which　has　given　him　the　name　of　〃father　of　modern　nervous　physiology；〃　just　as　Harvey　is　called　〃the　father　of　the　modern　physiology　of　the　blood。〃　It　has　been　said　of　this　famous　doctrine　of　irritability　that　〃it　moved　all　the　minds　of　the　centuryand　not　in　the　departments　of　medicine　alonein　a　way　of　which　we　of　the　present　day　have　no　satisfactory　conception；　unless　we　compare　it　with　our　modern　Darwinism。〃＇1＇

The　principle　of　general　irritability　had　been　laid　down　by　Francis　Glisson　（1597…1677）　from　deductive　studies；　but　Haller　proved　by　experiments　along　the　line　of　inductive　methods　that　this　irritability　was　not　common　to　all　〃fibre　as　well　as　to　the　fluids　of　the　body；〃　but　something　entirely　special；　and　peculiar　only　to　muscular　substance。　He　distinguished　between　irritability　of　muscles　and　sensibility　of　nerves。　In　1747　he　gave　as　the　three　forces　that　produce　muscular　movements：　elasticity；　or　〃dead　nervous　force〃；　irritability；　or　〃innate　nervous　force〃；　and　nervous　force　in　itself。　　And　in　1752　he　described　one　hundred　and　ninety　experiments　for　determining　what　parts　of　the　body　possess　〃irritability〃that　is；　the　property　of　contracting　when　stimulated。　His　conclusion　that　this　irritability　exists　in　muscular　substance　alone　and　is　quite　independent　of　the　nerves　proceeding　to　it　aroused　a　controversy　that　was　never　definitely　settled　until　late　in　the　nineteenth　century；　when　Haller's　theory　was　found　to　be　entirely　correct。

It　was　in　pursuit　of　experiments　to　establish　his　theory　of　irritability　that　Haller　made　his　chief　discoveries　in　embryology　and　development。　He　proved　that　in　the　process　of　incubation　of　the　egg　the　first　trace　of　the　heart　of　the　chick　shows　itself　in　the　thirty…eighth　hour；　and　that　the　first　trace　of　red　blood　showed　in　the　forty…first　hour。　By　his　investigations　upon　the　lower　animals　he　attempted　to　confirm　the　theory　that　since　the　creation　of　genus　every　individual　is　derived　from　a　preceding　individualthe　existing　theory　of　preformation；　in　which　he　believed；　and　which　taught　that　〃every　individual　is　fully　and　completely　preformed　in　the　germ；　simply　growing　from　microscopic　to　visible　proportions；　without　developing　any　new　parts。〃

In　physiology；　besides　his　studies　of　the　nervous　system；　Haller　studied　the　mechanism　of　respiration；　refuting　the　teachings　of　Hamberger　（1697…1755）；　who　maintained　that　the　lungs　contract　independently。　Haller；　however；　in　common　with　his　contemporaries；　failed　utterly　to　understand　the　true　function　of　the　lungs。　　The　great　physiologist's　influence　upon　practical　medicine；　while　most　profound；　was　largely　indirect。　He　was　a　theoretical　rather　than　a　practical　physician；　yet　he　is　credited　with　being　the　first　physician　to　use　the　watch　in　counting　the　pulse。


BATTISTA　MORGAGNI　AND　MORBID　ANATOMY

A　great　contemporary　of　Haller　was　Giovanni　Battista　Morgagni　（1682…1771）；　who　pursued　what　Sydenham　had　neglected；　the　investigation　in　anatomy；　thus　supplying　a　necessary　counterpart　to　the　great　Englishman's　work。　　Morgagni's　investigations　were　directed　chiefly　to　the　study　of　morbid　anatomythe　study　of　the　structure　of　diseased　tissue；　both　during　life　and　post　mortem；　in　contrast　to　the　normal　anatomical　structures。　This　work　cannot　be　said　to　have　originated　with　him；　for　as　early　as　1679　Bonnet　had　made　similar；　although　less　extensive；　studies；　and　later　many　investigators；　such　as　Lancisi　and　Haller；　had　made　post…mortem　studies。　　But　Morgagni's　De　sedibus　et　causis　morborum　per　anatomen　indagatis　was　the　largest；　most　accurate；　and　best…illustrated　collection　of　cases　th