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

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While performing iis oWn proper circle, it reduces itself Dom a

proceuds it purifies itself Dom the serum; so that While accomptishing iis transition into the vel iis, it becomes a pure Volume; the mixed heterogeneous and homogeneous Substances heingsuccessively Separated and ejected. Again, in the vetus theblood passes Dom a pure into a miXed homogeneoUS Volume, and Dom n mixed homogeneous into a mi Xed heterogeneous Volume. The Same process tines place in the volume of the simpler blood, and the fame agnin in that of the spirituous fluid. As both the blood and the vesseis are os a threelald Order,so also is every texture Whicli is formed by the Vesseis; as,sor instance, the glands, Whicli are the receptacles of the secretions, and the ducis of the excretions; for they are com-ΡOHnd, more Simple, and most Simple; and according to thoordor to Whicli they belong, they are called either glands, Vesicles, Or pores; one of Whicli is compounded of the other, and one is dividen into the Other.

In a similar order are carried On the secretions hom thosmali arterius into the above gland 8; as Weli as the excretions : likewiso the commixtion of the SecretionS, and the re-

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Vesseis into the smallest voins, ns Woli as into the numerou Sh OlloWs and recepta cles for the secretions. This circulation is persermed by successive propagations os an undulation, ench os Whicli talios place Within an imperceptibie moment of time :in Consequence Whereos there arises in every part of the permeated vesseis that sensibio olevation Whicli is denominated the

lieari, is asterWards moved forWard by the whole arteriai System, presenting a rapid current, Whicli nequires an accelera ted velocity; so that in the minutor vosseis bolonging to that order, the transflux of the wave, Whicli is so multifarioustydividod, is almost spontaneous : in the Vesseis of the secondorder, the transflux of the wave is stili more rapid and moro spontaneous : in the vesseis of the srst orderi or in the fibres, tho dogroe os velocity and spontaneity is indefinite and immense. Tho action os the fibros does not depend on the action of the great or single heari, but On the actions os an infinite number os corcula, or as it Were litile hearis, namely, the spheriales of the cortical and cineritious substance, Whicli are prefixedio uach sbro in the bratus and their tWo medullae. In ordor to direct and promoto tho circulation, there is required a certain generat pre8Sure, or equilibrium os preSSure, of ali the arteries, tonding froin the heari in the directionos the arteriai extremities; since Without a pressure CXercised by the WhOle arteriat system, there is no circulation; as indoedWithout a circulation no generat pressure cun eXist Or Si Sist. In Order to promote this generat pressure and circulation in the VeSSeis, there is required a muscular tunic, provided With a multisold series of motive rings, and continued DOm the muscleos the heari to the capillary vesseis. There is also required an interior membrano, Whose ossico it shali be to collect thesorings, and to determine them to tho production of this generales et in the manner Whicli me find obtaining in the arteries.

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plisied in liquids 1illing conical vessuis. For in the case of the

Veius, the influx of the sanguineous stream is DOm innumerable Origins of these vesseis, and their reception of the streum does 110t talie place at any regular and given moment, as in the QRSeos the arteries, but at severat disserent moments. This SanguineOHS Rud Venous Stream, more ver, discliarges itsed into

the chambers oti tho right fide of the hestri by a solitary Venous Sinus; thus presenting an arrangement altogether disserent hom the one me sud prevalling in the arteries. Τhe generat pressure and circulation Os the sanguineous Volume being given, and compared With the condition of thouesseis and with the nature of the arteriai and venous blood, itfollows, that the arcana of the science of angiology may be

goes resolution and reuuion. All Of Whicli processes must boin continuat operation.

Τhe apportation, commixtion, and insinuation of the liquid sand elemenis, in a Word, the entire composition of the blood, is essected in the vetus. But the Separation, SequeStration, and elimination, in the arteries. Τhe division of the severat paris of the blood is effected at the entrance into the vesseis, While tho blood is passing out os the vesseis Of One Order into

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Τhe more complete thorosore is the state os purification Domserum in Whicli tho blood is conveyed immediateb Dom the arteries to the vetus, the more Dearly does the circulation approU-mate to iis natural and most persect state. All other particles designen to form an admixture With the pure blood thus propagated hom the arteries into the vetus, stre imported by innumerable recipient vesseis, ducis, and pores, of diverS Orders, andare seiged by the litile vultis. Τhus it is that the arteries holdin aversion and rejeci those things Whicli are nos fuit tu to thoblood, While the vetus seeli Out and procure to themselves suchas the blood necessarily and contingently requires sor iis renovation, and the animal kingdom for iis preservation.

proving detrimental to the animal economy, nature has adopteda precaution in the est lishment of a perpetuat communicationos tho vessuis one With the Other; in the multiplication in eve pars of the system Of causes appotnted to effect one and thos e purpose; and finalty, in the si ordination of vesseis ofone degree to vesseis Of another degree. Whence the certitudo of the effect is ensured, and the SeVeral cauSes Operate in re-

patring Whatever deficiency or Waste had talion place in thethings severat ly caused. ΜOreover, in order that the brnins may be continuatly producing this effect by the agency of thoirown causes and 1irst principies, and also test, through continuityos communication, they should bo assected by any vitiated statosos tho body, both the arteries and vetiis Whicli are proper to thebody, and also those Whicli are proper to the bratus, forin communications With each Other in a manner peculiar to themselves, and their motions are dependent upon disserent Origitis.

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I 29. In this generat Induction, the reactr is prosuntod Withthe science of angiology, or the doctrine of the arterius audVeius, so extendest as to include the doctrine of tho fibros,or neurology; the doctrine of the glandular System, Or nde- nology; and the doctrine of the muSCular SyStem, Or myO

facts adducen, Would be a hag dous enterprige; While, On theother hand, to confine it Within those limiis, Would oblige usto tine very contracted vi eWs Os the subjeci. Τo avoid these inconveniences, I shail be under the necessity of Occasionalty interrupting the coi se of the argument, by the introduction os Observations extra ted DOm the severat Paris Whicli are to solioW, and where the subjecis alluded to are more sully discussed. Seo

130. The blood, in order to solo determinale to iis endsand uses, sotos within tunicated vesseis. For the tunius Or membranes are smali canals and batilis as it Were, by means of Whichtho blood is conveyed and derived to iis final destination. Thus the Vesself, namely, the arteries and Veius, are only the determinations of the blood; and such as is the form resultingsrom their coalition unu complication, Such are the common forces and vital essects of the system, and Such their particular qualifications n. 2). Such also are the mechanism and organigation os the body, Which so Wonderfully correspondWith the various physical and chemicat modes Os action and

operation.

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senses in to that of tho internat, und so sortii. For this ronsonthey likeWise pass into another sphere Os Words and idens. See Chapter VIII. of this Part. 134. In order that both the continent and the content may acta8 One common cause of determination. The continent and the

content, tinen collectively, are called a blood vesset; for thouesset Without the blood is merely a convoluted membrane, and tho blood Without the membrane is merely an indeterminate fluid. Hence as the vesset thus contemplated is biit one thing, so also is the action of tho vessul and of the bl ood collectivolybut One action Or One single cause of determination. Is theres rethe blood and tho iunio stand but for Ono vesset, and thus sorone single cause, it sollOWs, that there is a mutuat dependeticeos one upoti the other; is there bo a mutuat dependen ce, there must be a mutuni correspondenue, assini ty and relationshis be- tWeen them; for the One givos birili to the other; thus the tunicis' tho iunio of the blood, and the blood is the blood of the tunio, the tv o possessing a unanimi ty, and being moSi perseetly accommodatod to the production Os every effeci. Heuce We See Whythe tunic of the vesseis is, lilio tho blood iiseis, os a threusoldorigin, degree, nature, and compOSition. 135. From these premisos it sollows, that the blood or iis nature and mode of notion being giveti, the quality of the tunicmay be inserred; or the tunic being given, the quality of theblood may be inferrest. For the blood is disserent in overy disserent viscus through Whicli it traveis; it is of one fori in thebrain, of another in the lungs, of another respectively in the

variousty formed, So that in one part of the body iis fabrio is sar difforent Dom What it is in another; disserent, sor in Stanee, in respect of the fige of the aperturo With Whicli it originatus

or the tunic is of the blood, and the blood is of the tunic.

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Dom the trunk; in respect of tho thicliness os iis conis, of the number of iis branches, of tho disserent anglos ut Whicli theseare given Osr, of their inflections, interWeming, divi Sion, Ac.V n. 126). Aud Verheyeu remacts of the vena portae, that it

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ΤΠE ARTERIES AND VEIN S.

in ali probabili ty it is carriod to tho internat sursace of tins Or-gan : thetice to the lungs ;' Dom the lunges to the superior region, or to that of the brians and medullae, and indoed evento the cortical and cineritious substance. For the infernalcarotid, leaving the pia mater On the exterior of the brain, and dividod and subdivided into the minutest vesseis forming the most WOndersui ramifications, enters ut innumerable placeSinto the cortical chambers of the brain, n V, into every individual spherule of the cortex; and With iis Own innermost membrane construcis and convolutes it: Wheuce the wholo os that substance is by Ruysch denominated vascular. TheS. Anat. i., a SS. iii., 11. 19, and passim. Next it is continued into tho medullary or fibri lino substance of the nerves, Whence it returnS totis OUn vesseis. Thus in universali ty it surpasses nil the rest. On this subjeci Lancisi says: Tho laurili or last is tho finest os nil the membranes, but strong, and although it containS Onlythe most minute soramina, is nevertheless transparent, and maybe seen through Wheu held up to tho light. This coat of thoarteries corresponds to that Whicli lines the inside of the ventricles of the hoari' n. 121 . And where he troats of the three membranes of the pericarnium, he says: The internat coat, Whicli has ali the appearance of being nervous and tendinous, is reversed, and doubled bach toWards the hestri, so as to investitiose portions of the great vesseis that are contained Within the pericardium; and it is also spreud and extended, SO RS tO COVerthe coronary arteries, and the whole sursace of the heart. De Motu Cordis, A c., lib. i., Sec. i., cap. iii., Prop. Vi.)138. That the membrano Whicli sollows nexi in degree Os

universality is a certain nerveO-motive membrane discOVerable in the smallest vesseis, the reader may See by consulting 11. 142.

On this subjeci LeeuWenhook says, that When he dissectedosy the exquisitely thin, itiner membrane of a minuteJ artery, and submitted it to the microscope, he perceived, to hiS admiration, that it consisted os an incredibie number of Wonderfullyminute paris running one through the Other, and ali connected together in the manner os a nefWork ; and when he Separatedand examined the other part of the tunic that tho formor liud

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139. The membrano Whicli follows nexi in degree os uni VerSalily, is the sanguineo-muscular, Whicli is perceptibie to thenaed eye, and the existence of Whicli is hence generalty kΠOWH. Heister describes it as a dense and thicli tunic made up of nVast number of plain muscular fibres, surround ing the arteries like a circle or ring V and he goos on to say, that iis flesbyfibres ure sar more manifest and of sar greator thichness than in the intestines , and constitute various sufficiently remarii lereddish layers,V adding, as I can AhoW to any one any day heplenses' n. 120 . This coat increases in muscle in proportionas it approaches the hestri, Where it hecomes condensed into One entire muscular body; it is hoWever put Osr, When the internia carotid enters the cavlty of the cranium, and climbs thebrain. Τhis tunic is therelare One Whicli is proper to the VeS- seis of the inferior region, Or of the rest of the body, but notto the vesseis of the Superior region, Or of the brain, and is tess

guineous muscle, at that place Will meet together, by their

fluence of nerves, fibres, litile tendons; there likeWise Will bufound vesicles, sollicles, litile glands, charged With their severat contenis; thetice Will be separated Oily, pinguedinous matter, and lymph; and there Will, sinully, ali those Other functions bedischarged Whicli occur in the region bolonging 1 O the minute Ve8Seis. Ali these things aru biit the requisites and adjuncis of