medical essays-第39部分

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contemplate　the　nature　known　to　us　by　experience　in　this　light；　there　is　for　us　no　other　impenetrable　miracle　or　mystery。〃

Let　us　turn　to　a　branch　of　knowledge　which　deals　with　certainties　up　to　the　limit　of　the　senses；　and　is　involved　in　no　speculations　beyond　them。　　In　certain　points　of　view；　HUMAN　ANATOMY　may　be　considered　an　almost　exhausted　science。　　From　time　to　time　some　small　organ　which　had　escaped　earlier　observers　has　been　pointed　out；such　parts　as　the　tensor　tarsi；　the　otic　ganglion；　or　the　Pacinian　bodies；　but　some　of　our　best　anatomical　works　are　those　which　have　been　classic　for　many　generations。　The　plates　of　the　bones　in　Vesalius；　three　centuries　old；　are　still　masterpieces　of　accuracy；　as　of　art。　　The　magnificent　work　of　Albinus　on　the　muscles；　published　in　1747；　is　still　supreme　in　its　department；　as　the　constant　references　of　the　most　thorough　recent　treatise　on　the　subject；　that　of　Theile；　sufficiently　show。　　More　has　been　done　in　unravelling　the　mysteries　of　the　fasciae；　but　there　has　been　a　tendency　to　overdo　this　kind　of　material　analysis。　　Alexander　Thomson　split　them　up　into　cobwebs；　as　you　may　see　in　the　plates　to　Velpeau's　Surgical　Anatomy。　　I　well　remember　how　he　used　to　shake　his　head　over　the　coarse　work　of　Scarpa　and　Astley　Cooper；as　if　Denner；　who　painted　the　separate　hairs　of　the　beard　and　pores　of　the　skin　in　his　portraits；　had　spoken　lightly　of　the　pictures　of　Rubens　and　Vandyk。

Not　only　has　little　been　added　to　the　catalogue　of　parts；　but　some　things　long　known　had　become　half…forgotten。　Louis　and　others　confounded　the　solitary　glands　of　the　lower　part　of　the　small　intestine　with　those　which　〃the　great　Brunner；〃　as　Haller　calls　him；　described　in　1687　as　being　found　in　the　duodenum。　　The　display　of　the　fibrous　structure　of　the　brain　seemed　a　novelty　as　shown　by　Spurzheim。　　One　is　startled　to　find　the　method　anticipated　by　Raymond　Vieussens　nearly　two　centuries　ago。　　I　can　hardly　think　Gordon　had　ever　looked　at　his　figures；　though　he　names　their　author；　when　he　wrote　the　captious　and　sneering　article　which　attracted　so　much　attention　in　the　pages　of　the　〃Edinburgh　Review。〃

This　is　the　place；　if　anywhere；　to　mention　any　observations　I　could　pretend　to　have　made　in　the　course　of　my　teaching　the　structure　of　the　human　body。　　I　can　make　no　better　show　than　most　of　my　predecessors　in　this　well…reaped　field。　　The　nucleated　cells　found　connected　with　the　cancellated　structure　of　the　bones；　which　I　first　pointed　out　and　had　figured　in　1847；　and　have　shown　yearly　from　that　time　to　the　present；　and　the　fossa　masseterica；　a　shallow　concavity　on　the　ramus　of　the　lower　jaw；　for　the　lodgment　of　the　masseter　muscle；　which　acquires　significance　when　examined　by　the　side　of　the　deep　cavity　on　the　corresponding　part　in　some　carnivora　to　which　it　answers；　may　perhaps　be　claimed　as　deserving　attention。　　I　have　also　pleased　myself　by　making　a　special　group　of　the　six　radiating　muscles　which　diverge　from　the　spine　of　the　axis；　or　second　cervical　vertebra；　and　by　giving　to　it　the　name　stella　musculosa　nuchaee。　　But　this　scanty　catalogue　is　only　an　evidence　that　one　may　teach　long　and　see　little　that　has　not　been　noted　by　those　who　have　gone　before　him。　Of　course　I　do　not　think　it　necessary　to　include　rare；　but　already　described　anomalies；　such　as　the　episternal　bones；　the　rectus　sternalis；　and　other　interesting　exceptional　formations　I　have　encountered；　which　have　shown　a　curious　tendency　to　present　themselves　several　times　in　the　same　season；　perhaps　because　the　first　specimen　found　calls　our　attention　to　any　we　may　subsequently　meet　with。

The　anatomy　of　the　scalpel　and　the　amphitheatre　was；　then；　becoming　an　exhausted　branch　of　investigation。　　But　during　the　present　century　the　study　of　the　human　body　has　changed　its　old　aspect；　and　become　fertile　in　new　observations。　　This　rejuvenescence　was　effected　by　means　of　two　principal　agencies；new　methods　and　a　new　instrument。

Descriptive　anatomy；　as　known　from　an　early　date；　is　to　the　body　what　geography　is　to　the　planet。　　Now　geography　was　pretty　well　known　so　long　ago　as　when　Arrowsmith；　who　was　born　in　1750；　published　his　admirable　maps。　　But　in　that　same　year　was　born　Werner；　who　taught　a　new　way　of　studying　the　earth；　since　become　familiar　to　us　all　under　the　name　of　Geology。

What　geology　has　done　for　our　knowledge　of　the　earth；　has　been　done　for　our　knowledge　of　the　body　by　that　method　of　study　to　which　is　given　the　name　of　General　Anatomy。　　It　studies；　not　the　organs　as　such；　but　the　elements　out　of　which　the　organs　are　constructed。　　It　is　the　geology　of　the　body；　as　that　is　the　general　anatomy　of　the　earth。　　The　extraordinary　genius　of　Bichat；　to　whom　more　than　any　other　we　owe　this　new　method　of　study；　does　not　require　Mr。　Buckle's　testimony　to　impress　the　practitioner　with　the　importance　of　its　achievements。　　I　have　heard　a　very　wise　physician　question　whether　any　important　result　had　accrued　to　practical　medicine　from　Harvey's　discovery　of　the　circulation。　　But　Anatomy；　Physiology；　and　Pathology　have　received　a　new　light　from　this　novel　method　of　contemplating　the　living　structures；　which　has　had　a　vast　influence　in　enabling　the　practitioner　at　least　to　distinguish　and　predict　the　course　of　disease。　　We　know　as　well　what　differences　to　expect　in　the　habits　of　a　mucous　and　of　a　serous　membrane；　as　what　mineral　substances　to　look　for　in　the　chalk　or　the　coal　measures。　　You　have　only　to　read　Cullen's　description　of　inflammation　of　the　lungs　or　of　the　bowels；　and　compare　it　with　such　as　you　may　find　in　Laennec　or　Watson；　to　see　the　immense　gain　which　diagnosis　and　prognosis　have　derived　from　general　anatomy。

The　second　new　method　of　studying　the　human　structure；　beginning　with　the　labors　of　Scarpa；　Burns；　and　Colles；　grew　up　principally　during　the　first　third　of　this　century。　　It　does　not　deal　with　organs；　as　did　the　earlier　anatomists；　nor　with　tissues；　after　the　manner　of　Bichat。　　It　maps　the　whole　surface　of　the　body　into　an　arbitrary　number　of　regions；　and　studies　each　region　successively　from　the　surface　to　the　bone；　or　beneath　it。　　This　hardly　deserves　the　name　of　a　science；　although　Velpeau　has　dignified　it　with　that　title；　but　it　furnishes　an　admirable　practical　way　for　the　surgeon　who　has　to　operate　on　a　particular　region　of　the　body　to　study　that　region。　　If　we　are　buying　a　farm；　we　are　not　content　with　the　State　map　or　a　geological　chart　including　the　estate　in　question。　　We　demand　an　exact　survey　of　that　particular　property；　so　that　we　may　know　what　we　are　dealing　with。　　This　is　just　what　regional；　or；　as　it　is　sometimes　called；　surgical　anatomy；　does　for　the　surgeon　with　reference　to　the　part　on　which　his　skill　is　to　be　exercised。　　It　enables　him　to　see　with　the　mind's　eye　through　the　opaque　tissues　down　to　the　bone　on　which　they　lie；　as　if　the　skin　were　transparent　as　the　cornea；　and　the　organs　it　covers　translucent　as　the　gelatinous　pulp　of　a　medusa。

It　is　curious　that　the　Japanese　should　have　anticipated　Europe　in　a　kind　of　rude　regional　anatomy。　　I　have　seen　a　manikin　of　Japanese　make　traced　all　over　with　lines；　and　points　marking　their　intersection。　　By　this　their　doctors　are　guided　in　the　performance　of　acupuncture；　marking　the　safe　places　to　thrust　in　needles；　as　we　buoy　out　our　ship…channels；　and　doubtless　indicating　to　learned　eyes　the　spots　where　incautious　meddling　had　led　to　those　little　accidents　of　shipwreck　to　which　patients　are　unfortunately　liable。

A　change　of　method；　then；　has　given　us　General　and　Regional　Anatomy。　These；　too；　have　been　worked　so　thoroughly；　that；　if　not　exhausted；　they　have　at　least　become　to　a　great　extent　fixed　and　positive　branches　of　knowledge。　　But　the　first　of　them；　General　Anatomy；　would　never；　have　reached　this　positive　condition　but　for　the　introduction　of　that；　instrument　which　I　have　mentioned　as　the　second　great　aid　to　modern　progress。

This　instrument　is　the　achromatic　microscope。　　For　the　history　of　the　successive　steps　by　which　it　became　the　effective　scientific　implement　we　now　possess；　I　must　refer　you　to　the　work　of　Mr。　Quekett；　to　an　excellent　article　in　the　〃Penny　Cyclopaedia；〃　or　to　that　of　Sir　David　Brewster　in　the　〃Encyclopaedia　Britannica。〃　　It　is　a　most　interesting　piece　of　scientific　history；　which　shows　how　the　problem　which　Biot　in　1821　pronounced　insolvable　was　in　the　course　of　a　few　years　practically　solved；　with　a　success　equal　to　that　which　Dollond　had　long　before　obtained　with　the　telescope。　　It　is　enough　for　our　purpose　that　we　are　now　in　possession　of　an　instrument　freed　from　all　confusions　and　illusions；　which　magnifies　a　thousand　diameters；a　million　times　in　surface；without　serious　distortion　or　discoloration　of　its　object。

A　quarter　of　a　century　ago；　or　a　little　more；　an　instructor　would　not　have　hesitated　to　put　John　Bell's　〃Anatomy〃　and　Bostock's　〃Physiology〃　into　a　student's　hands；　as　good　authority　on　their　respective　subjects。　　Let　us　not　be　unjust　to　either　of　these　authors。　　John　Bell　is　the　liveliest　medical　writer　that　I　can　remember　who　has　written　since　the　days　of　delightful　old　Ambroise　Pare。　　His　picturesque　descriptions　and　bold　figures　are　as　good　now　as　they　ever　were；　and　his　book　can　never　become　obsolete。　　But　listen　to　what　John　Bell　says　of　the　microscope　：

〃Philosophers　of　the　last　age　had　been　at　infinite　pains　to　find　the　ultimate　fibre　of　muscles；　thinking　to　discover　its　properties　in　its　form；　but　they　saw　just　in　proportion　to　the　glasses　which　they　used；　or　to　their　practice　and　skill　in　that　art；　which　is　now　almost　forsaken。〃

Dr。　Bostock's　work；　neglected　as　it　is；　is　one　which　I　value　very　highly　as　a　really　learned　compilation；　full　of　original　references。　But　Dr。　Bostock　says：　〃Much　as　the　naturalist　has　been　indebted　to　the　microscope；　by　bringing　into　view　many　beings　of　which　he　could　not　otherwise　have　ascertained　the　existence；　the　physiologist　has　not　yet　derived　any　great　benefit　from　the　instrument。〃

These　are　only　specimens　of　the　manner　in　which　the　microscope　and　its　results　were　generally　regarded　by　the　generation　just　preceding　our　own。

I　have　referred　you　to　the　proper　authorities　for　the　account　of　those　improvements　which　about　the　year　1830　rendered　the　compound　microscope　an　efficient　and　trustwor