medical essays-第40部分

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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　trustworthy　instrument。　　It　was　now　for　the　first　time　that　a　true　general　anatomy　became　possible。　　As　early　as　1816　Treviranus　had　attempted　to　resolve　the　tissues；　of　which　Bichat　had　admitted　no　less　than　twenty…one；　into　their　simple　microscopic　elements。　　How　could　such　an　attempt　succeed；　Henle　well　asks；　at　a　time　when　the　most　extensively　diffused　of　all　the　tissues；　the　areolar；　was　not　at　all　understood？　　All　that　method　could　do　had　been　accomplished　by　Bichat　and　his　followers。　　It　was　for　the　optician　to　take　the　next　step。　　The　future　of　anatomy　and　physiology；　as　an　enthusiastic　micrologist　of　the　time　said；　was　in　the　hands　of　Messrs。　　Schieck　and　Pistor；　famous　opticians　of　Berlin。

In　those　earlier　days　of　which　I　am　speaking；　all　the　points　of　minute　anatomy　were　involved　in　obscurity。　　Some　found　globules　everywhere；　some　fibres。　　Students　disputed　whether　the　conjunctiva　extended　over　the　cornea　or　not；　and　worried　themselves　over　Gaultier　de　Claubry's　stratified　layers　of　the　skin；　or　Breschet's　blennogenous　and　chromatogenous　organs。　　The　dartos　was　a　puzzle；　the　central　spinal　canal　a　myth；　the　decidua　clothed　in　fable　as　much　as　the　golden　fleece。　　The　structure　of　bone；　now　so　beautifully　made　out；even　that　of　the　teeth；　in　which　old　Leeuwenhoek；　peeping　with　his　octogenarian　eyes　through　the　minute　lenses　wrought　with　his　own　hands；　had　long　ago　seen　the　〃pipes；〃　as　he　called　them；was　hardly　known　at　all。　　The　minute　structure　of　the　viscera　lay　in　the　mists　of　an　uncertain　microscopic　vision。　　The　intimate　recesses　of　the　animal　system　were　to　the　students　of　anatomy　what　the　anterior　of　Africa　long　was　to　geographers；　and　the　stories　of　microscopic　explorers　were　as　much　sneered　at　as　those　of　Bruce　or　Du　Chailly；　and　with　better　reason。

Now　what　have　we　come　to　in　our　own　day？　　In　the　first　place；　the　minute　structure　of　all　the　organs　has　been　made　out　in　the　most　satisfactory　way。　　The　special　arrangements　of　the　vessels　and　the　ducts　of　all　the　glands；　of　the　air…tubes　and　vesicles　of　the　lungs；　of　the　parts　which　make　up　the　skin　and　other　membranes；　all　the　details　of　those　complex　parenchymatous　organs　which　had　confounded　investigation　so　long；　have　been　lifted　out　of　the　invisible　into　the　sight　of　all　observers。　　It　is　fair　to　mention　here；　that　we　owe　a　great　deal　to　the　art　of　minute　injection；　by　which　we　are　enabled　to　trace　the　smallest　vessels　in　the　midst　of　the　tissues　where　they　are　distributed。　　This　is　an　old　artifice　of　anatomists。　　The　famous　Ruysch；　who　died　a　hundred　and　thirty　years　ago；　showed　that　each　of　the　viscera　has　its　terminal　vessels　arranged　in　its　own　peculiar　way；　the　same　fact　which　you　may　see　illustrated　in　Gerber's　figures　after　the　minute　injections　of　Berres。　　I　hope　to　show　you　many　specimens　of　this　kind　in　the　microscope；　the　work　of　English　and　American　hands。　　Professor　Agassiz　allows　me　also　to　make　use　of　a　very　rich　collection　of　injected　preparations　sent　him　by　Professor　Hyrtl；　formerly　of　Prague；　now　of　Vienna；　for　the　proper　exhibition　of　which　I　had　a　number　of　microscopes　made　expressly；　by　Mr。　Grunow；　during　the　past　season。　　All　this　illustrates　what　has　been　done　for　the　elucidation　of　the　intimate　details　of　formation　of　the　organs。

But　the　great　triumph　of　the　microscope　as　applied　to　anatomy　has　been　in　the　resolution　of　the　organs　and　the　tissues　into　their　simple　constituent　anatomical　elements。　　It　has　taken　up　general　anatomy　where　Bichat　left　it。　　He　had　succeeded　in　reducing　the　structural　language　of　nature　to　syllables；　if　you　will　permit　me　to　use　so　bold　an　image。　　The　microscopic　observers　who　have　come　after　him　have　analyzed　these　into　letters；　as　we　may　call　them；the　simple　elements　by　the　combination　of　which　Nature　spells　out　successively　tissues；　which　are　her　syllables；　organs　which　are　her　words；　systems　which　are　her　chapters；　and　so　goes　on　from　the　simple　to　the　complex；　until　she　binds　up　in　one　living　whole　that　wondrous　volume　of　power　and　wisdom　which　we　call　the　human　body。

The　alphabet　of　the　organization　is　so　short　and　simple；　that　I　will　risk　fatiguing　your　attention　by　repeating　it；　according　to　the　plan　I　have　long　adopted。

A。　　Cells；　either　floating；　as　in　the　blood；　or　fixed；　like　those　in　the　cancellated　structure　of　bone；　already　referred　to。　　Very　commonly　they　have　undergone　a　change　of　figure；　most　frequently　a　flattening　which　reduces　them　to　scales；　as　in　the　epidermis　and　the　epithelium。

B。　　Simple；　translucent；　homogeneous　solid；　such　as　is　found　at　the　back　of　the　cornea；　or　forming　the　intercellular　substance　of　cartilage。

C。　　The　white　fibrous　element；　consisting　of　very　delicate；　tenacious　threads。　　This　is　the　long　staple　textile　substance　of　the　body。　　It　is　to　the　organism　what　cotton　is　pretended　to　be　to　our　Southern　States。　　It　pervades　the　whole　animal　fabric　as　areolar　tissue；　which　is　the　universal　packing　and　wrapping　material。　　It　forms　the　ligaments　which　bind　the　whole　frame…work　together。　　It　furnishes　the　sinews；　which　are　the　channels　of　power。　　It　enfolds　every　muscle。　It　wraps　the　brain　in　its　hard；　insensible　folds；　and　the　heart　itself　beats　in　a　purse　that　is　made　of　it。

D。　　The　yellow　elastic；　fibrous　element；　the　caoutchouc　of　the　animal　mechanism；　which　pulls　things　back　into　place；　as　the　India…rubber　band　shuts　the　door　we　have　opened。

E。　　The　striped　muscular　fibre；the　red　flesh；　which　shortens　itself　in　obedience　to　the　will；　and　thus　produces　all　voluntary　active　motion。

F。　　The　unstriped　muscular　fibre；　more　properly　the　fusiform…cell　fibre；　which　carries　on　the　involuntary　internal　movements。

G。　　The　nerve…cylinder；　a　glassy　tube；　with　a　pith　of　some　firmness；　which　conveys　sensation　to　the　brain　and　the　principle　which　induces　motion　from　it。

H。　　The　nerve…corpuscle；　the　centre　of　nervous　power。

I。　　The　mucous　tissue；　as　Virchow　calls　it；　common　in　embryonic　structures；　seen　in　the　vitreous　humor　of　the　adult。

To　these　add　X；　granules；　of　indeterminate　shape　and　size；　Y；　for　inorganic　matters；　such　as　the　salts　of　bone　and　teeth；　and　Z；　to　stand　as　a　symbol　of　the　fluids；　and　you　have　the　letters　of　what　I　have　ventured　to　call　the　alphabet　of　the　body。

But　just　as　in　language　certain　diphthongs　and　syllables　are　frequently　recurring；　so　we　have　in　the　body　certain　secondary　and　tertiary　combinations；　which　we　meet　more　frequently　than　the　solitary　elements　of　which　they　are　composed。

Thus　A　B；　or　a　collection　of　cells　united　by　simple　structureless　solid；　is　seen　to　be　extensively　employed　in　the　body　under　the　name　of　cartilage。　　Out　of　this　the　surfaces　of　the　articulations　and　the　springs　of　the　breathing　apparatus　are　formed。　　But　when　Nature　came　to　the　buffers　of　the　spinal　column　（intervertebral　disks）　and　the　washers　of　the　joints　（semilunar　fibrocartilages　of　the　knee；　etc。）；　she　required　more　tenacity　than　common　cartilage　possessed。　　What　did　she　do？　　What　does　man　do　in　a　similar　case　of　need？　　I　need　hardly　tell　you。　　The　mason　lays　his　bricks　in　simple　mortar。　　But　the　plasterer　works　some　hair　into　the　mortar　which　he　is　going　to　lay　in　large　sheets　on　the　walls。　　The　children　of　Israel　complained　that　they　had　no　straw　to　make　their　bricks　with；　though　portions　of　it　may　still　be　seen　in　the　crumbling　pyramid　of　Darshour；　which　they　are　said　to　have　built。　　I　visited　the　old　house　on　Witch　Hill　in　Salem　a　year　or　two　ago；　and　there　I　found　the　walls　coated　with　clay　in　which　straw　was　abundantly　mingled；the　old　Judaizing　witch…　hangers　copied　the　Israelites　in　a　good　many　things。　　The　Chinese　and　the　Corsicans　blend　the　fibres　of　amianthus　in　their　pottery　to　give　it　tenacity。　　Now　to　return　to　Nature。　　To　make　her　buffers　and　washers　hold　together　in　the　shocks　to　which　they　would　be　subjected；　she　took　common　cartilage　and　mingled　the　white　fibrous　tissue　with　it；　to　serve　the　same　purpose　as　the　hair　in　the　mortar；　the　straw　in　the　bricks　and　in　the　plaster　of　the　old　wall；　and　the　amianthus　in　the　earthen　vessels。　　Thus　we　have　the　combination　A　B　C；　or　fibro…　cartilage。　　Again；　the　bones　were　once　only　gristle　or　cartilage；　A　B。　　To　give　them　solidity　they　were　infiltrated　with　stone；　in　the　form　of　salts　of　lime；　an　inorganic　element；　so　that　bone　would　be　spelt　out　by　the　letters　A；　B；　and　Y。

If　from　these　organic　syllables　we　proceed　to　form　organic　words；　we　shall　find　that　Nature　employs　three　principal　forms；　namely；　Vessels；　Membranes；　and　Parenchyma；　or　visceral　tissue。　　The　most　complex　of　them　can　be　resolved　into　a　combination　of　these　few　simple　anatomical　constituents。


Passing　for　a　moment　into　the　domain　of　PATHOLOGICAL　ANATOMY；　we　find　the　same　elements　in　morbid　growths　that　we　have　met　with　in　normal　structures。　　The　pus…corpuscle　and　the　white　blood…corpuscle　can　only　be　distinguished　by　tracing　them　to　their　origin。　　A　frequent　form　of　so…called　malignant　disease　proves　to　be　only　a　collection　of　altered　epithelium…cells。　　Even　cancer　itself　has　no　specific　anatomical　element；　and　the　diagnosis　of　a　cancerous　tumor　by　the　microscope；　though　tolerably　sure　under　the　eye　of　an　expert；　is　based　upon　accidental；　and　not　essential　points；the　crowding　together　of　the　elements；　the　size　of　the　cell…nuclei；　and　similar　variable　characters。

Let　us　turn　to　PHYSIOLOGY。　　The　microscope；　which　has　made　a　new　science　of　the　intimate　structure　of　the　organs；　has　at　the　same　time　cleared　up　many　uncertainties　concerning　the　mechanism　of　the　special　functions。　　Up　to　the　time　of　the　living　generation　of　observers；　Nature　had　kept　over　all　her　inner　workshops　the　forbidding　inscription；　No　Admittance！　　If　any　prying　observer　ventured　to　spy　through　his　magnifying　tubes　into　the　mysteries　of　her　glands　and　canals　and　fluids；　she　covered　up　her　work　in　blinding　mists　and　bewildering　halos；　as　the　deities　of　old　concealed　their　favored　heroes　in　the　moment　of　danger。

Science　has　at　length　sifted　the　turbid　light　of　her　lenses；　and　blanched　their　delusive　rainbows。

Anatomy　studies　the　organism　in　space。　　Physiology　studies　it　also