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

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A similar mode of physical attraction prevatis in every partos tho body, as sor instance in the muscies; DOm Whicli, nosoonor is the blood forcibly ejected, than they immediately aimat the re-impletion of their vesseis. It prevatis more especiallyin tho braitis of embryos, Whicli emulge and milk out the maternat blood by a mode of suction. It prevatis in the chich, vhicli in the incubated ogg attracis ali the nutritive juice Domthe albumen, by the animation of the gones and vesicles. Itprevatis also in the primitive corculum during iis initiation intomotion, the bl ood being pumpud DOm the heari into a certain large sinus of the heud. It prevatis finalty in numerous Other

other of Which We are ignorant. I Would here add, that Doma furvey Of the vesseis of the brains, it is evident, that during the constriction Of the arteries, Veins and sinuses of the brain, Whicli tines place simultaneousty With that os ali iis other ca- vities, such as iis ventricles, convolutionS, ductS, crannieS, &C.,)there is no passage open DOm the arteries into the Veius, norsrom the vetus into the sinuses, but Only into the cortical and

cineritious substance, and DOm One Sinus into another, Or Domihu sulcisorm and laurili sinus, into the laterat sinuses, hence into the jugular vetus, and vice versa. When these things are demonstraled, for they are essected by Wonderfui expedients, it mill bo evident that the draWing open of the vesseis is not Violent, but almost spontaneous; for the blood Dom Within co- Operates With this motion, being compressed against the parietes of the vesseis, and thus aiding them When they come to beexpanded. These remariis are the mere natural consequences Ofthe numerous facts ascertained by experiment, and with Whicli Ιmight fili my pages Were they not devoted to a disserent subjeci. 350. The law that oblatus With rogard to the quality of theblood, is similis to that whicli oblatus With regard to iis quantity; as sor instance, that the bratus do not procure, and Subtraci for their use, blood of any other quality thau Such as their peculiari ty Os state demands. For as Osten as they require a Supply of blood os a superior essetice, Whicli they expend either Upon their fibriis, or upon the interstices betWeen either the fibriis or the lascicles ; tu a Word, upon the nerves of the bOdy;

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then, sor the sine of preserving the naturat equation Os the fluids, a Desii supply of blood os a similar kiud floWs Dom theblood of tho body in tho placo of that Whicli is expended, ne-

cording as the state of the brians requires. For naturo CVery-

the bratus, they Would have no poWer to Seleet such a portionas Was fuit te to their state in regard to quantity and quality. But in order that such a poWer may be conceded to them, alltheir blood is invited through the medium os the physical attraction I have mentioned. Enough, hoWever, has nOW beensaid on this part of the subjeci. 35 I. Thus, as the order of circulation is reversed immediates

and dat ly diministi, uniit at length the former is qui te closed,

and the latter degenerates into an impervious ligament' n. 317). Munniciis observes that the foramen Ovale is closed by noother means than by iis valve, Whicli in potnt of substance, tenuity and transluceneu, alWays retatus iis original valvularcharacterV n. 320 . With respect then to the foramen ovale, it must necessarily be closed by degrees aster the order of the circulation is invertest, or When the influx Dom the venae cavae into the auricles and ventricies of the heari is no longer successive but simultaneous. For the insuX DOm the Venae empe is rendered simultaneous immediately after birili, for Whicli reasonthe Velum or intervening Septum is elevated n. 339 , and the

tWO Sanguineous Streams are intermixed. The expansions of the auricles are also no longer Successive and alternate as besore

n. 335), but simultaneous; for the blood flows Dom the no opened and traversed lungs, into the right auricle, in the samo moment in Whicli it flows tuto the lest auricle; and thus theblood reacts Dom the lest auricle as much as it acis Dom theright. The closure of the foramen is the more effectualty in- Sured by the circumstance, that the valve hangs doWnWard Onthe Side of the pulmonary voin, and being fixed to iis post to

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Ward oss tho fluid, is also depressed When it is compressed. Thischange likowise indicates, that the former circulation Was successive, and that it is solioWed by one that is simultaneous. 352. The arteriat iube noW abandoned at both extremities, is constricted, and the lungs inspiring SpontaneouSty, tine usthe blood. This constriction is the consequence of the Order Of

hoW the lungs, by the simple entrance of air, take up the blood With SO much avidity as to occasion the abundonment of the former unObstructed passage through the arterial tubo 3353. This arises not only Dom there being a larger quantityos blood noW forced into the pulmonary artery, for the blood both of the superior aud inferior cava noW stoWs tuto the right ventricte, but also DOm the circumstance of the litile pulmonaryarteries them selves being so disposed round the vesicles that arein continuity With the bronchial vesseis, that while these Vesicles sKeil With air, the litile arteries are elevated to their naturalsituation, and are at the fame time opened; not unlike What Iliave stated in respect to the arteries of tho brain n. 348, 349ὶ,

but in an inverse Order, so that When the lungs are expanded the arteries also are expanded, but When the brain is expanded, iis arteries are constricted. But the manner in Whicli the arteries are disposed in the lungs, must be reserved for the Special

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treatiSe On those organs.' I Would here only premise, that theliangs collapse in virtve of an effori of their OWn, but are expanded in virtve of the force of the otitering air, Whicli exerciSesa pressure in proportion to the height of iis column. Consequently in producing expiration there is no Deed of any externaland constricting muscle in the thorax, but only in producinginspiration; nei ther in this case is there need of any othermuscle than merely the one Whicli operis the thorax, the atratone effecting ali the rest. Αll these functions are performedaccordantly With the influx of the nervous fibros. Mithout the

moments that the spinal marroW is moved systallicatly, and theliings them selves Synchronousty n. 283). Mithin the lunos, litile nerves enter Dom the tWO pneumonic plexu SeS, and Domthe great cardiac plexus see Chapter VII.) : the nerves Domthe great pneumonic pleXus enter the vesicles that are in continuity with the bronchii; the nerves DOm the smulier pneumonio plexus enter the pulmonary arteries, as Weli as thebronchial: the nerves Dom the great cardiac plexus enter allthose arteries that come Oss DOm the pulmonary artery proceed ing Dom the right ventricle of the heart. Thus while the bronchia are expanded by the air, the fibres of the great pneumonio plexus are put on the Stretch, and are in a perpetuat essori toconstrict the vesicles; Dr Whicli reason the lungs spontaneouslycollapse, and the uir is expelled. But the fibres that are extended Dom the great cardiac plexus, let go the arteries thatare continued DOm the large pulmonary artery proceeding Domihu right ventricle of the heart through the lungs, at thesame moment in Whicli the aorta and lest auricle, and consequently the large pulmonary artery, are expanded; ali of Whichtakes place ut One and the fame time. Hence it solioWs, thatali these pulmonary arteries are in the state os expansion Whenthe lest auricle and the aorta are in the state os dilatation; thatis to say, When the systole and diastole of each auricle and artery, Vig., the norin and the pulmonary artery, become Simultaneous, as is the case aster birth. Such appears to be the

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no longer dram up est the blood of the lest ventriolo, in thatthey do not require a larger quantity than the peculiarity of

exercise of iis muscies, Or of those members that are excited tonet by a certain natural instinet, Such as the Stomach, intestines, kidneys, liver, pancreas and Spleen ; or again of thOSe members

that are exercised by a previous essori of the Will, and hende deliberalely; then, Dom that moment, the blood is determinedfrom the heari stud aorta into the places Where the quantity thus Hected is again required n. 227). Α similar operation talies place here to that We observed With regard to the foramen ovale n. 35 I) ; that is to say, the blood reacts Dom One fide upOn the iube in the fame proportion in Whicli it acts froni the other fide, producing an equilibration, and consequently the Want os a preponderating force to drive the blood through the iube. Thoarterint iube being thus abandonen on both sides, and havitigno longer any office to perform, collapses into a ligament an dtendon, much like the umbilicia vesseis and an infinite number

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355. Neve= theless, in a variety of cases, this foramen may for a long time be kept open from the right auricle towaris theles. We have very frequently seen,'' says Morgagni, that thepart of the valve Whicli extended beyond the anterior and inferior margin Of the foramen Ovale in the foetus, even in old subjecis Was not only not united to the Wali of the pulmonary vein, butpresented the appearanee Of tWo or more unequat Saeculi, Orostener Stili, of One large Saeculus; . . . the orifice of Whichsomelimes looked doWnWards, and frequently for Nards; and admitted a large probe, and even the end of the haud te os ascalpsit, betWeen ii and the Wali of the Vein, to ... a considerable depth. . . . At the Very bottom Of the sacculus, betWeenit and the front and upper border of the soramen Ovale, I have frequently Seen a minute passage stili open for the blood, ando ce of such a Lind as to admit the potnt of the handiu of a scalpsit Without any difficulty into the vena cava. This passage I found in a semate subjeci, and the like Once also in thatos a male ut least forty years oldV n. 322). I observed in n. 351, that When the order os circulation is inverten, the foramen Ovale must Os necessity be graduntly closed, because theblood reacts Dom the lest auriclo us much as it acts froin the

auricle is similar to that Whicli soWs in Dom the venae cavae into the right. The closure of the foramen OVale, theresere, dependson the equation and equilibrium existing betWeen the sanguine-ous stream in the lest auricle, and that in the right. Τhus what-ever cause tends to disturb or destroy this equation, produces iis effect in this firsi and last place of ingress of the blood, thatis to say, in the heart. For in every One Of the three circula- lations abOVe recOunted, an equilibrium of tho flowing blood is designed and provided. It is not there re surprisin g, that Whenthe ordor os circulation is inverted n. 351, yc.), the current cannot be immediately equilibrated, and that the shori chanuel of the foramen ovale is for some time kept open, as in insanis. The causes Whicli operate in so long Leeping the foramen Ovale

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open Dom the right auricle to the lest, or more properly into the pulmonary vein, and lienee directly into the lest ventriclo, are tho following; too smali a bulli and capaci ty in the neWlv- formed lungs; such a State Os the lungs as does not admit os

striction of the breast by Wrappages and 8Wathings; obstructionof the gluttis, trachea, bronchia, and of the pulmonary arteries nud Veius: Sternutation not supervening after birili, net theryaWning, coughing, c ing, Whicli are nil so many incitemenis and means resulting Dom a bliud instinct to divert tho blood orchange the circulation in neW-born insanis; a deficient arousing of the brain, and a lurhing species of primeVal dormancy; nWant of due proportion belWeen the capacity of the auricles and ventricies of the heari, so that should the former be larger, thelaiter are less thau they ought to be; the frequent occurrenceos palpitation of the praecordia; unexpected fright experieuced

agygos vetus; debility of the arteriat system; debility of the mus-cles, so that When the bl od is propellod Dom the lest ventricle

the want of a due est lishment and support of a generat equilibrium os pressure; also the various diseases arising Dom thesecauses, Such as inflammation of the lungs, teipothymia, teipo-ΡSychin, Syncope, apnoen, orthopnaea, insensibili ty or privationos the faculty of perceiving the action Of ObjectS, SpRSmS, COI Vulsions, ataXy or irregular motion os the spiriis, kc. We evenfind that aster the lapse of years, as in adult age, the laxamen, though once closed, may again be opened by the application Osi Orce, and iis valve be ruptured; as in cases of palpitation, Sud-den and Dantie terror, collapse of the lungs : it occurs likeWise in those Who, on having once to ali appearance been dead, arerecorded to have been again restored to lise; hence the valve may be found even in adulis like tWO unequat SaeS, Or more frequently, according to the statuments of Morgagni and the

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Observations of Verheyen and others, like a single large sacfacing forWards, thias appearing as is it had been violently protruded; a circumstance Whicli frequently occurs in the case of divers. For in the hestri there is a confluence of ali the blood, and it endeavors to equilibrate the waves thereos, and When iis

right auricle is too fuit, it is under the necessity of assording avent for the current by Leeping both passages open into the

cava n. 32 l). Heister gives the folloWing shori statement of tho discussions on this subjeci: The use of the foramen ovaleformerly gave rise to considerable discussion belWeen Mery, Who maintained . . . that the blood floWed Dom the lest auricle, through the foramen, into the right auricle, and Duuerney,ΤauVry, Sylvester, Bussiere, Lister and Verheyen, Who ali Upheld the contrary, and contended sor the received Opinion, Whichby the Way is that generalty maintained at present. On this subjeci the reader may consuli the Hist. de PAcad. Nov. de Paris, 1699, and other Writings of the learned. It is to be Observed, that in tho Hist. de VAcad., 1717, WinslOW Seems in Some

tho fame subject in the Hist. de PAcad. Noy., 1725.V Comp. Anai., not. 38.) The foramen may be opened by causes opposite to those above recited. They must hoWever be SO extremely violent, as either to rupture the margin opposed to the bloodand fixod to iis post in the sinus of the lest auricle, or to thrustit forWard aWay Dom iis natural siluation and state into theother and opposite chamber; for the change in the natural orderof things must indoed bo great which shali occasion the vetus tobe siled by a current of the blood pertaining to the arteries. FOr When the arteriai and muscular system are conjointly in astate of essori, is by any chance the passages into the Veins are partialty obstructed, then, unless the foramen Were Open When

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tho ordor os circulation is inverted, or the blood effected an Oxit along this passage, the insant Would Scarcely Survive the crisis,as there Would be Vast danger of the Smallest arteries boiugruptured, or of the larger ones being stretchen to a degrest ofaneurismal tension and laXation, Or Os a dilatation of the praecordia. We may See in Chapter VI., n. 431-444, that undertho soregoing liabilities, an exit is assorded throuo the coronao Vesseis, through Which, as through the foramen Ovale, there is a passage DOm the right fide of the heari to the lest, and Dom the lest to the right. 357. The causes theresore Whicli operate in keeping operithe soramen Ovale are the sollOWing,-an utidue constipation Ofblood in the lest auricle, and a comparatively smali Supply in the right, arising Dom a too eager or insatiabie appetency sorbi0od on the part of the lungs; or Dom the capacity of the lest ventricle of the heari not being proportioned to thnt of the

right; or Dom sucti an obstinate resistance or constriction Osthe arteries that they do not admit tho Wholo of the injectodWave; or Dom the impeded Or repressed egress of the Wave into the vetus, for Whicli reason it is first driven into the small- est arteriai vesseis, So as to occasion great inflammation in the face, Skin and viscera; Or DOm n too energetie notion of the

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rage and fume against any WhO Would impose upon them eventhe semblance of rostraint; and already armed Mith toeth, theybito tho testis of their mothers. But this class of men is rare, and consequently there are but seW instances of the Liud on

359. Hitherio me have spolien of the circulation of the redblood, but be re concluding this chapter, Me Will say a seW WOrdson the circulation of the white or purer blood, as it tines placeboth bosoro and after birili in the embryo and chich. We stated ove n. 279), that the circulation of the purer blood is much promoted by the respiration os the lungs; but since this biood, as noti ced in the besorementioned article, is intermediate be- tweon the spirituous fluid and the red blood, therelare iis motion depends on the motion Of the bratus as Weli as On the motionos the lungs. Had We therelare suppressed this part of the present chapter, the Observations above advanced might have been rejected as pertaining to the Obscure revertes or paradoXes propolin ded On the subject of occult qualities. But that We may proceed in due order, We shali inquire, 1. HOW the spirituous suid, and iis biood, called the purer or simpler blood, are derived froin the brain, through the chemicat organs and members of iis laborator , into the jugular veitis, and thetice into the right chambers of the heart. 2. How the blood is passed throughthe embryonio lungs besere they have respired, and What circle it then performs. 3. What is the nature of the assistance

offered by the lungs, by Whicli the circulation of this bl00d is

promoted after birili.