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

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bronchia and trachea by membranous and vaseular prolongations, it does not infuse into the cava the sanguineous fluid it contains, excepi at the moments of pulmonary expiration. The inter ostia and other vetus in like manner discliarge into thoagygos their united strems, derived DOm the whole respiratory

members, WOmb, &c. SO that the Veius are receptacles Os a Sanguineous aflux Whicli is continuous and not discriminaled

by the beats of the heart. The casu however is disserent in regard to the arteries, sor here the blood is infused Dom thenorta at the stated moments of the cardiacat bestis, and beingconveyed progressi Vely DOm One place to another, OceaSionS RHelevation, and consequently a pulse coinciding With the benis. Thus the blood has so composed a system Os litile arteries united by anastomosis With those Whicli are more distant, thalat the fame beat the sanguineous elevation can be present atevery poliis, Whatever be the pari Dom Whicli the bicod has floreod, and Whatever the part lo Whicli it is soWing. 4. The blood is nos transferred Dom the arteries to the vetus, nor does it enter into the vetus, the fame either in quantity Or nature as it Was in the arteries. It does not floW into them the fame in quantity, bocause the sorosity of the blood is separated by the arteries; as is proved by the excretion os urine, SWeat, inSen Sible perspiration ; by the occasiones accessions to the blood arising Dom

by the continuat renascetice of the frame : heuce it is not thevhole sanguineous volume that circulates Dom the arteries through the vetus to the heari, but merely a certain selected portion, or that Whicli is reabsorbed Dom the vesicles, ducis, undpores, through the orifices and lips Of the litile vetus. Again, tho blood whieli flows into the vetiis is nos the fame in nature With that whicli soWs into the arteries, for their excretions nudovicast materinis are not sWalloWed again by the Veins, Whichare choice in the selection of their sood, and culi out onlysuch portions as are adapted to reenter into the compositionos tho blood. The volume of arterial blood there re is sor

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the most pari not continuod through the voins, innsmuch asthe blood upon iis arrivat at the veitis is no longer the Sameelther in quantity or naturo. Neithor is tho blood infused into the vetus, but is rather talien up Or received by them, RS RISO by the litile cavities and spacus Where the secretions Rre Persormed n. 205). Hence thero is no injection os volume into the Veliis, consequently Do distinet origin of any WaVe, nor any transmission of the blood originating in the exercise Os a compulsory force, this being an essentiat characteristic of the arterialcirculation. 5. The wave itself, such as it is described in n. 189, cannot be sent through a sinalter into a larger iube, sor is so, itWould immediately disappear, and assume the character Of R

. . . Aster R Shori time . . . the blOOd again resumed iis ordinarydirection and rapidi tyV n. 125 . And Heister observes that, in the extremities of the body, . . . the tWigS become cylindrical canais' u. I 20).193. ΜOreoveri the use and function of the vetiis demandilio substitution Within them os a mere process of impletion auddepletion sor that os a circulation; for they are required to receive the proflared blood at different momenis; to imbibo thosuid whicli is to bo mix0d With it, hom innumerable receptacles and other solarces n. 49, 50, 53) ; to perform the commixtionof the Whole; to recompose the sanguineolis particles in theirorder; and to be the first to commetice the process Os naturalchemistry: Mi Whicli things could not bo done Wore the blood transferred by any violent motion through a circle as in the arteries. Τo accomplisti these purposes, a more quiet and Iessaetive State is necessary, a cOOler temperature, and an equalpressure in every direction.

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194. The state of the arteries themselves likeWise domandes this provision, in order that the arterial blood, after pursuing iis laborious route, may have asylums to Which to resori, whether the quantity of blood be a smali portion, the grentest pari, orthe Whole, as depending upon those Variations of the equilibrium Whicli arise 1 rom the changes of bOdy and mind, Occurring in states of animosity, anger, fear, terror, Ac. n. 18IJ;ns also at death, after Whicli commonly no blood remains in the arteries, but the Whole WithdraWs itfelf into the vetus. Thus the veins may be called the receptacles Or passive Vesseis Ofthe arteries, the subjecis and adjuncis os sueti as are active. 195. Τho motion os the hestri likeWiso demands this provision. For Were the blood potired into the heari in the fame manner in Whicli it issues DOm the arteries, the motion Ostho heari Would be subject to perpetuat changes, and indeed Mould actually be changing every moment, according to thedisserent affections of the arteries. This change in iis motion, hoWever, noes nos appear to be produced, is We may judge Domiis equabie and steady vibration, hoWever largely the vetus may turgesce, Or hoWeVer closely they may collapse, provided the fibro be not incited or stimulated to too Strong a pressure. This Wo seu illustraled by the practice of venefection; in Which wefind, that Dom those Who are in a State of sear frequently not a Single drop escapes, although there is a large quantity of blood in the vel 11s. For the fibres of the heari are inciten to a vis vendi by a cause Whicli is either internal or externat: internat, When they are acted upon by the brain; externat, ulten

Veius are more inert, of R COOler temperament, and much more

expansite than the arteries; their blood not so red and brigh and When draWn, not So rapid ly tending to coagulate; Why theyare os larger diameter; Why they accompany the arteries laterat ly, and frequently climb up upon them, as in the brains,

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there Wore undulations in the vetus as there are in the arteries, and the vave of the one hurri est On With a pulse nud Stream contrary to that of the other; for then opposition, discord, anda destruction of the two motions Would arise. We may See also the reason sor Whicli the vein can be openest Without daΠ-ger, iis membrane groW together again, and the Wound close

197. From these remariis it solioWs, that such a circulationas prevatis in the arteries cannot tine place in the voins, butthat in the extremities of the arteries there is an end of the circulation ,-is by the circulation We understand the successive transference of the undulation. For after tho blood has passed these extremities, it is received into the veins, not as bringingWith it a pulse, but as a simple equation or impletion; althoughthis may perhaps With propriety be called a common or generalcirculation. The case, in sino, is the samo With that in WhichWater is received into a conicia vesset through disserent aperturos. From these remariis it sollows, that While there exisis a larger volume of blood in the venous tWigs below the valves than above them, the volume below depresses und crOSSOS OVOrthem, and pHShes OnWard, in ordor that tho Whole may be in the fame state os equation as iis pari. Henee there nriSes an Rugmentation Os sorces and a conjoint nisus into the largerVesseis, because the blood exercisos iis conatus in the vetus asu afer does in conical vesseis, that is to say, ns much upWard asdoWΠWard; iis force incrensing in the simple ratio Of the areas. Just as is the casu Willi every other liquid enclosed in cavities, and similarly compressed Ou every fide, according to the eXperiments of Ρascat and Others. 198. W0 have thus satisfactortly proved the folloWing propOSition ,-Τhat in the case of the Deins, the insuX of the sanguineous Stream is Dom innumerable orioins of these vesseis, and their reception of the stream does not laste place at any ressular and sivenmoment, as in the case of the arteries, but at severat dii erent mo-

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itself into the chambers on the right fide of the hearl by a solitary

nuted by tho beats of the heart. See n. I92. 199. The generat pressure and circulation of the sanguineous volume beino sive' and compared with the condition of the vesseis and with the nature of the arteriai and venous blood, it follows, that the arcana of the science of anyiolosy may be referred to the followino general heari. I. That proper liquids and elements beconveyed to the blood. Food, sor instance, converten into chyle, must be conveyest throuo the gullet, stomach, intestines; Domthese to the lacteal vesseis, and thetice to the bl od n. 49). Atmospheric aliment must be conveyed to the lungs, and by means of the lungs to the blood n. 50, 5 I). Most subtile ethereat aliment must be conveyed to the bibulous Jayers of the shin, and through these to the blood n. 53-58). ΜOreover, DomeVery pore, VeSicle, and gland, aliment must be provided, Whichlias been repented ly secreted, and whicli is destinod for tho littio vetus to sWalloW and to ruminate. Τhe sirst rule therofore is, that suit te laod be procured, absorbed, and conveyed throughtho body in the forin os a liquid. II. That in the blood theyreceive a lue commixtion. For instance, that the purest aliments be conveyed in to the smallest vesseis; that into the ves-Sels Whicli are someWhat largor, bo conveyed the aliments Whichare nexi in degroe of purity; that in to the vesseis Whicli aren ext larger, und into those Whicli are largest, be conveyed the aliments Whicli are in a grosser state, as exemplified in the chyle Whicli is conveyed, though not alWays pure, into the subclavianuein. For in the sume ordor in Which the bl od is depuratodand resolved, in the fame it is commixed and remade n. 151,154 . All this must be dono, in ordor that in the right fide os the heart there may be a perfeci commixtion and fusion os allthe aliments received, it being there that they aro as it Wero in their state Os chaos, or Only us an undigested volume; for there the inspissated substances are associaled With the thin, the flug-

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With the elastic, the hoavy With the light, or the serum With Salis Of every class, With the spirituous suid, With the simple, and With the compound blood. III. That they be insinuated intound presented to the blood that is to say, through the serum tothe blo d. ΤΟ enter into tho ordor in Whicli these are severallysitted into the individual particles of tho blood, to the intentiliat they may ali exist in a state os combined fitness, is to enter

into the question as to the particulars composing the common Orgenerat Whole; a question Whicli relates therefore to the mannerh0W they do so, and whicli Will, to a certain extent, be ConSidered in an ensuing ch ter. We may hoWever thus sar remarii, in anticipation of What we have there to state, that so skilfullyhas nature devised her manner os progression, that nothing is imperviolis to her in her course, nothing presenis to her the Stightest obstacte, since sile proceeds Dom sirst principies toCRUSOS, -d DOm causes to effecis, Or successively through de-grees. It is by a mode of her oWn that the ethereat elements are engrasted into the pure blood, and the aereo-saline and theterreO-saline into the red blood; to tho end that ali the sub-Stances site has adopted as her OWn may so preserve their form, maintain their connection one With the Other, and perform their severat functions, that they may never cease to Serve the pur-

as We see to be the case in the macrocosin or in the atmosphere,

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lent and mixed volume, after having been puris ed in the lungs and liberated hom flatulent substances, is hurrien through the arteries at a rapid rate; and when at every single pollit theWave is pressed upon by the muscular tunio, it follows that themore fluggisti, inspisSaled, ineri,' inelastic, rude, angular Sub-Stances, in a Word, Such as are the least adapted for fluency, Willoccupy the circumferentiat paris, While ali the rest Will occupythe axis, Whose interior the intermixed spirituous suid Will occupy, and neri in Order, the impurer, darker, heaVier, Or Spurious blood. Mi these things are effecis resulting Dom thecommon preSSUre, and DOm the circulation Os the Wave in the arteries. V. That they be held in a state of sequestration. Forin the minuter vesseis, the blood, during iis si glit, direcis iis course along the axilla y line, and presses the circumfluous Serum so closely to the peripheries, that the latior leaves thestream and is held in a state Os separation. For DOm the extremities of the arteries numerous mucous villi, litile spirals andopen mOuthS are SuSpended, to convey aWay the fluid; thereare also litile celis and sollicles, and cavities and tubes Os every dimension to receive it; each of Whicli is silled with iis owtideWy and Vaporous element, iis oWn liquor and collected stream; so that in no viscus is there any membrane, sold, or ti8Sue, intowhicli tho blood finds iis Way, that does not provide a receptionsor the serum Whicli has escaped DOm the arteries. These teriai extremittes,V says BOerhaave, terminate either in thebegitinings of the litile veins by a continuous canes, Without any intermediate parenchyma for caVernous Structure ; or else in crypis, or sollicles, or in the large Or smali carities in various paris of the body; or in excretory Vesseis; Or in particular Si-

We must suppose that these ineri particles are also unadapted to receive the spirituous fluid exhaled stom the interior tunic, or else the very saci of theirbeing in contact With the tunic Would Only tend to increase their velocity; as is stated to be the case in the capillary vesseis, Where a single particle is embraced on

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monios in favor of this position, it Will bo dustrabie briefly torecapitulate the arguments Which have been adduced. They areas folloW. From the evidenue furuished by experimental facis, wo find that tho blood flows through the capillary arteries, litherundivided, or separated into spherules : that these spherules suffer themselves to be moulded into ovat figures, and that thesmallex Spherules composing these, susser themselves, With thegreatest ductili ty, to be elongated into filamonis: that tho bloodis soster and more flexibie in healthy persons, hardor and more renitunt in tho sicli: that it divosis itself of iis reduess, and assumes disserent colors, v ying Dom black to pale, retaining noneos iis oWn color in any of the smallest stamina, Or in Rny Secretion : that previousty to this the red blood noWhere enters into the cortex of the brain, but deposits Without the volatile salis Which have an ammoniacat Odor; so that the fibriis of the brain distend with an abundatice only of spirituous fluid: that theblood is of one character in the arteries, of another in theveins: that arterial blood is soon coagulabie, is redder and Warmer than venous : that venous blood is thinuer, moro dilutodand colder than arterial: that this is the casu also When theblood is abstracted hom iis vesseis. Hunce it solioWs, that theblood suffors itself to be dividod, is there bo a divisor; and that

such a divisor is found in vesseis and fibriis os a superior Order has ulready been SheWn. For there are as many degrees of Rrteries as there are Of the composition of the blood, and for this reaSOn, that eaeli requires iis OWn correspondent. Is the blood

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Solved and reunited, it is in a state os perpetuatly reneWed sormation and existenco; it is at Vs Desii, and ready for any and BVery USe; it never grows Old Or obsolete, or is it does, Domthat moment it is clud in blach garments and borne aWay to the tombs of tho livor. Heuce it is in a state of perpetuat hirth, death, and rebirth, and is every moment forming Somo incipient stamen both of our life and of iis oWn. That theblood is thus passing through the fame mode Whicli it commetices in the chiok and embryo Dom the sirst state of the egra Will bo demonstrated in the subsequent chapter; and in the

200. But thesu laws of the blood may bo stili reducod in number, and further generaliged. Τhus, I. The individual particles of the rod blood are to be uni ted together, and asterWardes

resolved. Τhis is the cause, or the materia propter quam. 2. The component elements are to be commixed and separated.

This is the cause, or the materia em qua et per quam. Au ofwhich processes must be in continuat operation. But hoW theyare ali carried on in the severat viscera, as in the stomach, inteStines, Spleen, liver, and pancreas; in the lungs, trachea, and palate; in the Womb, mammae, and genital members; in themuseles, bratus, medullae; in the membranes and meninges; in the cartilages and bonos,-this Will be explained in specificfaris On the above subjecis; for the science of these things is

20I. The apportation, commiwtion, and insinuation of theliquids and elementa, in a word, the entire composition of the blood, is effected in the veins. I. That the vetus sucst in the liquidsand elements conveyed to them, Such as the chyle, &c., there is no dolabi; their mouilis and lips lying open Whereuer there is any liquid to be absorbed. That the vetus commis the elements and liquids according to degrees, and that ait these are ulti- mately potired together and rolled about in the heari, as in acauldron Or WhirlpOOl, see n. 199. II. That they are there in-oinualed into the blood, see n. 199. III. Hence the State of the