The economy of the animal kingdom, considered anatomically, physically, and philosophically

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strnini, to the common moveri nor in ali this does it wear any Othur than a generous and Lindly countenance. In no Othermaniter can either the red blood Or the nervous juice circulato,

or the severat paris, together With the Whole, subsist and grow up amid so great a multiplicity of operations. It is thus that this nervo is the vicegerent of the cerebellum, Or rather thus that the cerebellum, by this nervo, applies itself to adjust and consolidato tho inferosis of iis Lingdom. 487. And of the par vagum speciscat . The Other common nervo that is dispalched from the hrains into the regions of thebody, to perform a universat Work, is the eighth pair, or parvagum. Τhis, together With the intercostat nerve, forms a great plexus, by Whicli it enters the sursace of the heari; and it sendsbranches immediately to the auricius. It is vorth While there-

fore to enquire into the nature os iis action; and the rather, Sinee RS abOVe Observed, the nervous fibro is ali in ali in thomuscio. Let iis begin then With a description of this nerve. 488. The eighth patri par vagum, Or nerVUS SympathetiCUS medius, arising by very firm fibres and fascicles Whicli are immediately clothed With pia mater, and Whicli are eight in number, or Recording to others tWolve, comes fortit under the formos a fascia belWeun the restisorm process of the cerebellum, Where the lalter is in a manuer surroWed, si ut the end of the urth ventricte, Dearly under the tuber annulare, and at the Olivary eminences On both fides. The fibres thus coalescing, and afterWards dividing into anterior and posterior, and mount-ing betWeen the olivary process and the cerebellum, enter thenearest orifice in the cranium, betWeen the occipital bone and the petrous portion of the temporal bone, Where the si, Ort canalos the laterat sinuses terminates, or Where the bl ood of the sinuses discliarges isseis into the jugular vetus. Τhere they perforate the dura mater, either conjointly in One place, or a8 tWO trutilis in t O Or more places, separated from each other by exquisitelythin membranous partitions Dom the dura mater, or bony parti

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perior tesser trunk.

The trunk of the par vagum, issuing DOm the cranium through a large semicircular foramen, together With the Spinat ReeeSSOry nerve and the jugular vel , betWeen the StyliformproceSs, and the articulation of the occipiat With the sirst vertebra, immediately prepares itself for the performance of iis peculiar Ossices, and spliis into a superior and inferior trutili; of the8e, the superior, Smulier or firSt trunk, ns SOOn as it Sepn- rates Dom the larger and inferior, Winds to the muscies ut thebase of the tongue, to the pharyngeat muScies, the genio-hyoidei, kc. But the large Whitisti trutili rutis doWn together With the intercostat nerve belWeen the carotid artery and jugular vein; With Which vesseis it communicates on the Way, by a Lind of cellulari silamentary, and membranous stieath. As thetrunk of the right fide passes besore the si clavian arte , it gives oss a branch that turus under the artery, and SO renSCeΠdSto the si de of the trachea, constituting the recurrent nerVC. Tho trutili then traversos the whole body and nil the Viscera, Whereuer any natural motion exisis; to trace it there re throughali the mages of iis erratio course, Would be in saet to run Overali the provinces of the body. This nerve unites in various places by threads and plexuses With the intercostes nerve. Andiu severat places it comes in contact With the aorta, and supplies the muscular tunic of it a d iis branches With nervous fluid. There are severat plexuses that it forms, particularly Withthe great intercostat nerve; Such as the pulmonam Or pneumonicplexus, Whicli is double, and Dom Whicli filaments are sent through the whole of the lungs. The cardiac plexus, at Sodouble; a quantity of sitamenis hom the great cardiac pleXustraverse the peri cardium, and enter the heart. The stomachicnerve Or plexus rami fies over the i per Orifice of the stomach, and runs in a curve to the pylorus. There are also the hepatio, splenio, and renat plexuses, but more particularly the three great meSenteris pleXUSeS, Superior, mi D, and inferior. The lalter of Which goos to the membranes lying upon the sacrat Vertebrae,

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to the coats of the rectum, to the bl adder, the uterus, the ovaries, and the genital members. We may likeWise observe, that the par vagum, together With the insophagus, passes throughthe seshy part of the di aphragm, as does the intercostat be- tWeon tho fleshy fibres of this traiisverse septum, Πear the dorsa

vertebrae.

489. Is we trace this nervo stili surther, into ali the muscies that it penetrates, and is We consider the actions of these mus-cles separalely and coriointly, it Will be evident, that This nerve is the second most generat Osrspring of the cere- bellum ; sor it is sent to ali the viscera of the body Where any natural Or spontaneous motion is going on. For this use thonerve prepares isseis hom iis earli est stages; for it brings out With it as many bundies as there are Origins Os such motions in the body. But since it descends On both sides as a single trunk, it is necessary that eve Where, and particularly in the plexuses, it should bo associaled With the intercostat nervo, that it may berecruited, WheneVer Occasion demands, Mith spiritu ous fluid, as me more particularly sind tO be the case Out the auricles, ventricles and proximate arteries of the heart. But to come to particularS.

490. This nervo is the second most generat ossspring of tho cerebellum; sor it is sent to ali the viscera of the body Where

kidneys, bladder, uterus, and 80me of the genital paris; it also

presides over the motion Os the lungs, Whicli is miXed, or Whose origin is both spontaneous and voluntary; as likeWise over themotions Of many other organs in particular. All the other nerves, Whether arising hom the medulla oblongata or medulla spinalis, are summoned to their motion by the cerebrum, res

may abundantly appear stom a practical and theoretical onquiry

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tricte, it may be inferred, that it springs out of the medulla cerebelli, Where it passes into iis processes; but stili it is not so

evident even from this, as Dom the functions the nerVe performSat iis extremities; sor instance, Dom the faci, that immediatelyaster iis origin, it suffers itself to be acted on by the cerebellum, iis fibres to bo actost upon by the alternate distractions and con- Strictions of the laurili ventricio, and the fascia itself to bo actedupon by the great eminetico itself With iis transverse hoOpWork, Where it emerges betWeen ii and the Olivary proceSSOS.491. For this usu the nerve prepares itself Dom iis earli est stages; sor it brings out With it as many bundies as there are origins of suci, motions in the body. It is Worthy Os ObserVation, that this nervo carries out as manu fascicles Dorn iis natalSOil as there are retiform plexuses, Or What amounts to the Samething, RS there are common Origins os natural motion in the

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plexuses be not regarded distinetly in the fascicles, thon theroare only eight plexuses, becaUSe the laur Smali plexuses coalesceWith the largor; they are also frequently So dependent iapon thelarger, that their beginnings Or fascicles a re convoluted under the fame tunio, just as is the case With the smali cardiac plexus, the pneumonio, and the tWo renes plexuses. This appears to bethe reason Why eaeli fascicle goes immediately under itS OWn en-velope, and Why the different fascicles, before they conleSce, Rre frequently sent out through a separate foramen, Whicli is there- fore called the foramen lacerum. 492. But sindo it descends on both sides as a single trunk, it is necessary that everyWhere, and particularly in the plexuses, it should bu associated With the intercostat nervo, that it may bereeruiten, Whenever occasion demands, With spirituous fluid. For tho intercostat nerve has not less than about Sixty origins,

and is one or more of these bo intercepted, stili the part of any viscus dependent thereon Would be eastly supplied by the otheri Wigs of the nerve : but the casse is different With the par vagum; for is any of iis fascicles or principes branches be amputated orcut of it uo longer derives any Spirit Dom iis cerebellum ortiving fountain. For this reason it is aloined in every part Oftho body to the great intercostat nerve, to live by iis mediation, ns experienee teuches. Thus Willis says : When I put a tight ligature upou both truulis of the par vagum in the necti os a

fame resulis have been Obtained in experiments made by othoranatomisis. The trian k of Oue fide, indeed, comes tu aid of tho cardiac plexus When the trunk of the Other fide is cus, Or rendered useless; but this, in a Very reflex maniter, as Will appenrin the sequel: heuce the resuscitation Of the plexus is oWing

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principalty to the intercostat norve, Whicli perhaps so inseris iis sibres into tho branchus of the plexus, that in penetratingthrough the muscies, it never traxeis alone. Thus these two common nerves are like a married pair; tho intercostat doing the hvsbaud's ossice, and the par vagum, the Wisu's. And thisis the reaSOn Why the par vagum procoens at once to the beds of the other; for as soon us it passes Out of the cranium, it enterSthe cervical ganglion os the intercostat by numerous brancheS.Τherelare it appears, that the proper cardiae nerves, in their functions, and When acting on the muscular fibres, are not distinet, as their origius Would mine them, but intimately united, and that tho fibro of tho Ono is Wodden to the fibre of the other,so that it cannot be affirmen, that either of them, to the exclu- Sion Of the Other, presides OVer the motion of the heart. 493. But perhaps it might seem that were this the case, there Would be no Deed of the par vagum, since the fibre of the intercostat nerve Mone Would be sufficient, because it can be in

no datiger of losing iis fluid; yet is We consider the subjectmore deeply, it Will be evident, that both the one and the otheris requisite and necessary to subordinate aud coordinate thenatural motions of the body, called by some the involuntarymotions; the One to descend by a single trunk, and the other tonrise DOm numerous branches, and associale itself With the formur. For in the body there are subaltern motiones, One ΠOt coincidingWith another; there is the motion of the lungs, of the trachea, of the insophagus, also of the stomach and intestines; there is the motion of the livor, or of the gall-bladder, Which also is excited to action by peculiar causes; there are the reSpectiVe motions of the mesentery, kidneys, bladder, uterus, yc. In Ordersor these motions to be concordant, they must depend entirelyupon a nerve With One trunk; with a trutili that has iis fascicles distinctly compacted aud associated under One tunic. FOr inorder to exist and subsist, they must be under the auspices of One Uni Versat motion, Or under the animation of the bratus. Thetrunk itself, together With ait tho fascicles it oncloses, is in this universat motion; aud manifestly so in iis place of birili, sinceiis fascia is applied to a iobe of the cerebellum, Whicli is So fullos ridges and surrows, that it is carrien to and DO every timethe cerebellum animates; sor it comes out beside the olivary

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procosses, and that they have an alternate action of tho Lind, is plain enough Dom the transverse and perpendiculis notch cutupon them. Then again, the originative fibres of this nervo aroso distributed under the laurili Ventricte, that at every expansionand constriction of the ventricle, that is, of iis inside and fundus,) ad the fibres arising under it, are similarly moved. Addio this, that immediately under the threshold of the cranium,

it applies itself to tho jugular vein, that it may be Lept in tho

Same motion, and on the other hand, that it may also keop thevein in the fame; for the bl ood is driven froin the laterat sinuses into the jugulis vetus at the moments of the expansion of the cerebellum, On Whicli these lateria sinuses lie, and tO WhoSe patron age they are confiden. MoreOver, Dom the moment of iis descent, it runs belWeen the jugular Vein and carotid artery, and osten communicates With them. It likeWise sends out severat branches into the upper cervical ganglion Os the intercostat nervo

ou both sides; Whicli ganglion is evidently Lept in the stream

of the universat motion, or of the animation of the bratus; be- cause the intercostat nerve comes ali along Dom the spinat mar-row, and indoed Dom iis littio hordisorm gangliotis, Whicli areset at tho internodes of the vertebrae thus mOVed, and Rre constructed of tho medullary Lbres, tunios, and even blOOd-Vesseis of the spinal marrOW. TO SV nothing of the manner in Whichthe par vagum descends through the thorax, and perforates thediaphragm, Where it is Lept in the Stream of the pulmonarymotion, Whicli is synchronous With the animato motion os thebrains. These considerations sheW, that the trunk of the par Vagum at iis Origin proceeds under the auspices of the universalmotion; and inasmuch as this motion is the clites of ali, audthat under Whicli ali Other motions subsist, it folioWs that somenerve is required to compaci into a single trunk the fascicles devoted to the subaltern motions, and at every alternation, toreduce and combine them into one universat motion, With a viesto provide against perpetuat discord; for Whereuer the subordi- Date and subaltern is, the universat must also be. Thus in ordor to prevent such a nerve DOm being anyWhere deprived os iis fluid in a degree proportioned to the impetuosities of the motions it excites, as those of the heari, VentricleS, intestines and other organs, it must everyWhere be SO RSSocialed

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to the intercostat nervo as to bo ondosod With life and spiritiander the nuspices of the latior; for Wero it doprived of this conjugal fellowship, one branch or fasciole Os the par Vagum might demand Dom iis parent corobullum more fluid thun theother, und the cerebellum might, for the sine os preserving the generat equilibrium, proffer it more; Whicli novertheless it could not do Without dotriment to itself as the principat viscus, inasmuch as an equabie state Os it is required, because iis notion ismost conStant. The case Would be OtherWise supposing the deficiency os nervous fluid to be everyWhere supplied by the inter- costat nerve in the body, bocause arising as this nervo does homso many disserent solareos, it cannot elicit more DOm One Sinus of tho cerebellum than DOm another.

494. Nos that this is the principes reason Why the par Vagum is sent doWti by a single trutili into tho provinces of the body, may bo evideliced by this consideration, that previous to iis

of the oesophagus and trachea, acting voluntariij in uni son Withthe pharynX, larynX, fauces and longue, the motions Once begunby Whicli organs are continued in a spontaneous surion. Τo theond, then, that What is thus spontaneous may coincide With Whatis voluntary, Or that the effect may correspond With iis causes, the Spinal access0ry nerve and litile superior trunk are added to

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the par vagum under One and the samo tunio, so that both maybe silly relatod by the fibres to the branches, and by the branchesto tho trunk, and by the trunk to the brains, and that thesu respectively distinet paris may aci under the auspices of One universat motion; that eauli, sor instance, may have iis distinctiis , and Dom this distinci lis e perform iis distinct functions; for tho spirituous suid, Whicli is the one Only vital suid, is expollod into ali the fibros Whon the brians animate ; COIISequently, unless ali tho paris Were Lept under the influence of this anima-tOry motion, the animal economy, With each particular part osit, Would collapse and die. 495. Ρerhaps the roader Wili pardon me sor dwelling stili alitile longer on the exposition of the par Vagum; Since the mo-tiou of the hoari depends upon this nervo, in conceri With the intercostat. Is We traue these nerves froin the beginning to the extremities, and inquire into the specific actions of each n. 473), it will bu very evident that the smaller trunk of the par vagum is dosignon to formard tho masticaten Dod into the oesophagus, or is tho internat deglutitory nerve; and at the Same time eu-joys Some generat Sense of taste. That the spinal accessorynerve is designed to forWard the laod sWallowed, frOm the pha- nx to the upper orifice of the stomach; Or is the externat deglutitory, bucause it superadds the force of the externat muscies.

Catory, and at the Same time subtly gustatory; so that tho

functions of the three nerves 11OW mentioned, suceeed eaeli Othor in a given ordor. That the recurrens nerve is the generat regulator Of sound , Or of the air passing out of the lungs by thotrachen and larynX, When the functions os Spenking, Singing, and in a certain respect those of masticating and 8WallOWing, are performed. That the nerve of the ninth puir is properly locutory, auxiliary to Whicli is the branch of the portio dura of the seventhsair, or auditory nerve. Farther, that the si si cervical pair for-wariis the 1 ood through the gullet, but in So doing only arranges the externat forces. That the second cervical pair ad is thestate of the la DX and Windpipe to the motion Of speaking. Norcati the firsi or second discliarge iis function, utiless the lungs and bellD or entire Subjacent region, conspire to favor it, Whichis the office of the third pair of cervical nerves. These act

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ΠΡΟΠ the pectoral or anterior part of the thorax, but tho Durthpair of cervical nerves, With the fame end in vie , net upon thedorsal or posterior pari, kc. n. 368). Ait these particulissmight be proved in a variety of Ways, were We at liberty to transgress the limits of the present Ρart. With respect to the

recurrent nerve, We have said thus much in order to fheW hoWult those fascicles and nerves that contribute to the productionof the Whole natural action, ought to be contained under the integument of the par vagum; to the end that the subordinate natural motions, may ait be comprised as it Were under One

universat motion.

496. The recurrent nervo is termed the generat regulator OssOHDd, Or of the air passing out of the lungs by the trachen, Iarynx, and gluttis, Whenever the function of speaking is performed, and in a certain respeci, that of masticating and sWalloWing. FOr the par Vagum, in commencing itS egress, SendSout a litile branch to the superior cervical ganglion Os the intercosint nerve, and ut the fame time inflects another toWards thelarynx and pharynx : in the larynx this other is insertod into tho recurrent nerve, Whicli arises in the right fide Dom a certain

bel OW, and recurrent, but coalesce With the superior nerve in the larynx. When a single organ, as the longue ser instance,

concurs to perform severat simultaneous and Successive functions, both generalty, particularly, and contingently, there is