Nowwhathavewecometoinourownday？Inthefirstplace，theminutestructureofalltheorganshasbeenmadeoutinthemostsatisfactoryway。Thespecialarrangementsofthevesselsandtheductsofalltheglands，oftheair-tubesandvesiclesofthelungs，ofthepartswhichmakeuptheskinandothermembranes，allthedetailsofthosecomplexparenchymatousorganswhichhadconfoundedinvestigationsolong，havebeenliftedoutoftheinvisibleintothesightofallobservers。Itisfairtomentionhere，thatweoweagreatdealtotheartofminuteinjection，bywhichweareenabledtotracethesmallestvesselsinthemidstofthetissueswheretheyaredistributed。Thisisanoldartificeofanatomists。ThefamousRuysch，whodiedahundredandthirtyyearsago，showedthateachoftheviscerahasitsterminalvesselsarrangedinitsownpeculiarway；thesamefactwhichyoumayseeillustratedinGerber’sfiguresaftertheminuteinjectionsofBerres。Ihopetoshowyoumanyspecimensofthiskindinthemicroscope，theworkofEnglishandAmericanhands。ProfessorAgassizallowsmealsotomakeuseofaveryrichcollectionofinjectedpreparationssenthimbyProfessorHyrtl，formerlyofPrague，nowofVienna，fortheproperexhibitionofwhichIhadanumberofmicroscopesmadeexpressly，byMr。Grunow，duringthepastseason。Allthisillustrateswhathasbeendonefortheelucidationoftheintimatedetailsofformationoftheorgans。
Butthegreattriumphofthemicroscopeasappliedtoanatomyhasbeenintheresolutionoftheorgansandthetissuesintotheirsimpleconstituentanatomicalelements。IthastakenupgeneralanatomywhereBichatleftit。Hehadsucceededinreducingthestructurallanguageofnaturetosyllables，ifyouwillpermitmetousesoboldanimage。Themicroscopicobserverswhohavecomeafterhimhaveanalyzedtheseintoletters，aswemaycallthem，——thesimpleelementsbythecombinationofwhichNaturespellsoutsuccessivelytissues，whicharehersyllables，organswhichareherwords，systemswhichareherchapters，andsogoesonfromthesimpletothecomplex，untilshebindsupinonelivingwholethatwondrousvolumeofpowerandwisdomwhichwecallthehumanbody。
Thealphabetoftheorganizationissoshortandsimple，thatIwillriskfatiguingyourattentionbyrepeatingit，accordingtotheplanIhavelongadopted。
A。Cells，eitherfloating，asintheblood，orfixed，likethoseinthecancellatedstructureofbone，alreadyreferredto。Verycommonlytheyhaveundergoneachangeoffigure，mostfrequentlyaflatteningwhichreducesthemtoscales，asintheepidermisandtheepithelium。
B。Simple，translucent，homogeneoussolid，suchasisfoundatthebackofthecornea，orformingtheintercellularsubstanceofcartilage。
C。Thewhitefibrouselement，consistingofverydelicate，tenaciousthreads。Thisisthelongstapletextilesubstanceofthebody。ItistotheorganismwhatcottonispretendedtobetoourSouthernStates。Itpervadesthewholeanimalfabricasareolartissue，whichistheuniversalpackingandwrappingmaterial。Itformstheligamentswhichbindthewholeframe-worktogether。Itfurnishesthesinews，whicharethechannelsofpower。Itenfoldseverymuscle。
Itwrapsthebraininitshard，insensiblefolds，andtheheartitselfbeatsinapursethatismadeofit。
D。Theyellowelastic，fibrouselement，thecaoutchoucoftheanimalmechanism，whichpullsthingsbackintoplace，astheIndia-rubberbandshutsthedoorwehaveopened。
E。Thestripedmuscularfibre，——theredflesh，whichshortensitselfinobediencetothewill，andthusproducesallvoluntaryactivemotion。
F。Theunstripedmuscularfibre，moreproperlythefusiform-cellfibre，whichcarriesontheinvoluntaryinternalmovements。
G。Thenerve-cylinder，aglassytube，withapithofsomefirmness，whichconveyssensationtothebrainandtheprinciplewhichinducesmotionfromit。
H。Thenerve-corpuscle，thecentreofnervouspower。
I。Themucoustissue，asVirchowcallsit，commoninembryonicstructures，seeninthevitreoushumoroftheadult。
TotheseaddX，granules，ofindeterminateshapeandsize，Y，forinorganicmatters，suchasthesaltsofboneandteeth，andZ，tostandasasymbolofthefluids，andyouhavethelettersofwhatI
haveventuredtocallthealphabetofthebody。
Butjustasinlanguagecertaindiphthongsandsyllablesarefrequentlyrecurring，sowehaveinthebodycertainsecondaryandtertiarycombinations，whichwemeetmorefrequentlythanthesolitaryelementsofwhichtheyarecomposed。
ThusAB，oracollectionofcellsunitedbysimplestructurelesssolid，isseentobeextensivelyemployedinthebodyunderthenameofcartilage。Outofthisthesurfacesofthearticulationsandthespringsofthebreathingapparatusareformed。ButwhenNaturecametothebuffersofthespinalcolumnintervertebraldisksandthewashersofthejointssemilunarfibrocartilagesoftheknee，etc。，sherequiredmoretenacitythancommoncartilagepossessed。Whatdidshedo？Whatdoesmandoinasimilarcaseofneed？Ineedhardlytellyou。Themasonlayshisbricksinsimplemortar。Buttheplastererworkssomehairintothemortarwhichheisgoingtolayinlargesheetsonthewalls。ThechildrenofIsraelcomplainedthattheyhadnostrawtomaketheirbrickswith，thoughportionsofitmaystillbeseeninthecrumblingpyramidofDarshour，whichtheyaresaidtohavebuilt。IvisitedtheoldhouseonWitchHillinSalemayearortwoago，andthereIfoundthewallscoatedwithclayinwhichstrawwasabundantlymingled；——theoldJudaizingwitch-
hangerscopiedtheIsraelitesinagoodmanythings。TheChineseandtheCorsicansblendthefibresofamianthusintheirpotterytogiveittenacity。NowtoreturntoNature。Tomakeherbuffersandwashersholdtogetherintheshockstowhichtheywouldbesubjected，shetookcommoncartilageandmingledthewhitefibroustissuewithit，toservethesamepurposeasthehairinthemortar，thestrawinthebricksandintheplasteroftheoldwall，andtheamianthusintheearthenvessels。ThuswehavethecombinationABC，orfibro-
cartilage。Again，theboneswereonceonlygristleorcartilage，A
B。Togivethemsoliditytheywereinfiltratedwithstone，intheformofsaltsoflime，aninorganicelement，sothatbonewouldbespeltoutbythelettersA，B，andY。
Iffromtheseorganicsyllablesweproceedtoformorganicwords，weshallfindthatNatureemploysthreeprincipalforms；namely，Vessels，Membranes，andParenchyma，orvisceraltissue。Themostcomplexofthemcanberesolvedintoacombinationofthesefewsimpleanatomicalconstituents。
PassingforamomentintothedomainofPATHOLOGICALANATOMY，wefindthesameelementsinmorbidgrowthsthatwehavemetwithinnormalstructures。Thepus-corpuscleandthewhiteblood-corpusclecanonlybedistinguishedbytracingthemtotheirorigin。Afrequentformofso-calledmalignantdiseaseprovestobeonlyacollectionofalteredepithelium-cells。Evencanceritselfhasnospecificanatomicalelement，andthediagnosisofacanceroustumorbythemicroscope，thoughtolerablysureundertheeyeofanexpert，isbaseduponaccidental，andnotessentialpoints，——thecrowdingtogetheroftheelements，thesizeofthecell-nuclei，andsimilarvariablecharacters。
LetusturntoPHYSIOLOGY。Themicroscope，whichhasmadeanewscienceoftheintimatestructureoftheorgans，hasatthesametimeclearedupmanyuncertaintiesconcerningthemechanismofthespecialfunctions。Uptothetimeofthelivinggenerationofobservers，Naturehadkeptoverallherinnerworkshopstheforbiddinginscription，NoAdmittance！Ifanypryingobserverventuredtospythroughhismagnifyingtubesintothemysteriesofherglandsandcanalsandfluids，shecoveredupherworkinblindingmistsandbewilderinghalos，asthedeitiesofoldconcealedtheirfavoredheroesinthemomentofdanger。
Sciencehasatlengthsiftedtheturbidlightofherlenses，andblanchedtheirdelusiverainbows。
Anatomystudiestheorganisminspace。Physiologystudiesitalsointime。Afterthestudyofformandcompositionfollowsclosethatofaction，andthisleadsusalongbacktothefirstmomentofthegerm，andforwardtotheresolutionofthelivingframeintoitslifelesselements。InthiswayAnatomy，orratherthatbranchofitwhichwecallHistology，hasbecomeinseparablyblendedwiththestudyoffunction。Theconnectionbetweenthescienceoflifeandthatofintimatestructureontheonehand，andcompositionontheother，isillustratedinthetitlesoftworecentworksofremarkableexcellence，——“thePhysiologicalAnatomy“ofToddandBowman，andthe“PhysiologicalChemistry“ofLehmann。
LetmebrieflyrecapitulateafewofouracquisitionsinPhysiology，dueinlargemeasuretoournewinstrumentsandmethodsofresearch，andatthesametimeindicatethelimitswhichformthepermanentorthetemporaryboundariesofourknowledge。Iwillbeginwiththelargestfactandwiththemostabsoluteanduniversallyencounteredlimitation。
The“largesttruthinPhysiology“Mr。Pagetconsiderstobe“thedevelopmentofovathroughmultiplicationanddivisionoftheircells。“Iwouldstateitmorebroadlyastheagencyofthecellinalllivingprocesses。ItseemsatpresentnecessarytoabandontheoriginalideaofSchwann，thatwecanobservethebuildingupofacellfromthesimplegranulesofablastema，orformativefluid。Theevidencepointsrathertowardstheaxiom，Omniscellulaacellula；
thatis，thegermofanewcellisalwaysderivedfromapreexistingcell。ThedoctrineofSchwann，asIremarkedlongago1844，runsparallelwiththenebulartheoryinastronomy，andtheymayyetstandorfalltogether。
AswehaveseenNatureanticipatingtheplastererinfibro-cartilage，soweseeherbeforehandwiththeglassblowerinherdealingswiththecell。Theartisanblowshisvitreousbubbles，largeorsmall，tobeusedafterwardsasmaybewanted。SoNatureshapesherhyalinevesiclesandmodifiesthemtoservetheneedsofthepartwheretheyarefound。Theartisanwhirlshisrod，andhisglassbubblebecomesaflatteneddisk，withitsbull’s-eyeforanucleus。Theselipsofoursareallglazedwithmicroscopictilesformedofflattenedcells，eachoneofthemwithitsnucleusstillasplainandrelativelyasprominent，totheeyeofthemicroscopist，asthebull’s-eyeintheold-fashionedwindowpane。Everywherewefindcells，modifiedorunchanged。Theyrollininconceivablemultitudesfivemillionsandmoretothecubicmillimetre，accordingtoVierordtasblood-disksthroughourvessels。Aclose-fittingmailofflattenedcellscoatsoursurfacewithapanoplyofimbricatedscalesmorethantwelvethousandmillions，asHartinghascomputed，astrueadefenceagainstourenemiesasthebucklerofthearmadilloorthecarapaceofthetortoiseagainsttheirs。Thesamelittleprotectingorganspaveallthegreathighwaysoftheinteriorsystem。Cells，again，presideoverthechemicalprocesseswhichelaboratethelivingfluids；theychangetheirformtobecometheagentsofvoluntaryandinvoluntarymotion；thesoulitselfsitsonathroneofnucleatedcells，andflashesitsmandatesthroughskeinsofglassyfilamentswhichonceweresimplechainsofvesicles。And，asiftoreducetheproblemoflivingforcetoitssimplestexpression，weseetheyolkofatransparenteggdividingitselfinwholeorinpart，andagaindividingandsubdividing，untilitbecomesamassofcells，outofwhichtheharmoniousdiversityoftheorgansarrangesitself，wormorman，asGodhaswilledfromthebeginning。
Thisdifferentiationhavingbeeneffected，eachseveralpartassumesitsspecialoffice，havingalifeofitsownadjustedtothatofotherpartsandthewhole。“Justasatreeconstitutesamassarrangedinadefinitemanner，inwhich，ineverysinglepart，intheleavesasintheroot，inthetrunkasintheblossom，cellsarediscoveredtobetheultimateelements，soisitalsowiththeformsofanimallife。Everyanimalpresentsitselfasasumofvitalunities，everyoneofwhichmanifestsallthecharacteristicsoflife。“
Themechanismisasclear，asunquestionable，asabsolutelysettledanduniversallyaccepted，astheorderofmovementoftheheavenlybodies，whichwecomputebackwardtothedaysoftheobservatoriesontheplainsofShinar，andonthefaithofwhichweregulatethemovementsofwarandtradebythepredictionsofourephemeris。
Themechanism，andthatisall。Weseetheworkmanandthetools，buttheskillthatguidestheworkandthepowerthatperformsitareasinvisibleasever。IfearthatnoteverylistenertookthesignificanceofthosepregnantwordsinthepassageIquotedfromJohnBell，——“thinkingtodiscoveritspropertiesinitsform。“Wehavediscoveredtheworkingbeeinthisgreathiveoforganization。
Wehavedetectedthecellintheveryactofformingitselffromanucleus，oftransformingitselfintovarioustissues，ofselectingtheelementsofvarioussecretions。Butwhyonecellbecomesnerveandanothermuscle，whyoneselectsbileandanotherfat，wecannomorepretendtotell，thanwhyonegrapesucksoutofthesoilthegenerousjuicewhichprinceshoardintheircellars，andanotherthewinewhichittakesthreementodrink，——onetopouritdown，anothertoswallowit，andathirdtoholdhimwhileitisgoingdown。
Certainanalogiesbetweenthisselectingpowerandthephenomenaofendosmosisintheelectiveaffinitiesofchemistrywecanfind，buttheproblemofforceremainshere，aseverywhere，unsolvedandinsolvable。