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tion, stretching the sirst thing in the morning : it changes Withali the disenses of the body, With ait the emotions of the animalmiud, as in joy, gries, anxiety, anger, fury, sear, intrepidity,
attention, eagerness. The varieties of this motion are SO greatthat they seem contradictory to cach other. Τhus it is brought out With contraction of the chest and sternum, With eXpan- Sion, With depression, With elevation; With a diversity of bend-ings of the vertebrat column, and with the straightening out of the fame; With an expansion of the abdomen, Or even a drnWing in os the fame; With a yielding, Or With a resistance, of the diaphragm : so that it is impossibie to determine What muscle is out to operate tapon the cavlty of the thorax, utiless the actionbe previ ouSty gi ven Or assumed. At One time there is a poWerfui action os the sub clavius, Serratus, pectoraliS, trapeZiUS, IR-tissimus dorsi, and of many of the cervical and even lumbarmuSeles; at another time, of One or another of the abdominat muscies, Or of the diaphragm and ali Of them ut Once; at anOther time again, of the vertebrat, intercostat and sternes mus cles. Nevertheless, ali these muscies do no more than eXpandor constrict the chamber of the thorax in divers Ways, either inferioriy, SuperiOrty, anteriori y, posterioriy, Or obliquely, in eVery possibie direction. Nor do the intercostat muscies Seem mnnifestly to elevate the ribs, utiless they concur Mith Other muscies externat and more generat. They are moreOver destitute os antagonisis, in order that they may comply With the generat motion of the dorsal nervos; for Whicli reason indoed they deserve properly speaking to be called inspiratory. All the Other mus-cles, Which have an equilibrium, are circumstanced disserently When the spinal marroW and the brattis aut in a generat man-ner ; for then the antagonist of cach muscio is acted on in thesume degree as iis sellOW Or companion. ΤO these remartis I may add, that four of the patra of thecerVical nerves tu a WOndersul maniter correspoud With eachother, in opening or closing the thorax; sor relatively to the muscies they influence, they form a reciprocat proportion, COH- Sisting of tWO ratios or Dur ternis. Thus the sirst pnir bears
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the Same relation to the second, as tho third to the murth; forthe sirst pnir moves the posterior muscies of the necti, the Se-cond iis anterior muscies; the third the anterior muscies of the thorax, and the laurili iis posterior muscies; so that When the posterior part is bent backWariis, the sirst pnir concurs With thelaia th; When tho breast is boni forWards and inWards, the Se- coiid pair concurs With the third; for it is a generat rute, that the rectangle of the means is equat to the rectangle of the eX- fremes ; Or as in arithmetic, that the produci of the means isequat to the produci of the extremes. Henee, the notion Os thesecond and third boing oquat to the action of the sirsi and Durth, We have an equality or equilibrium os actions. But to
369. From these remartis it appears, that there is no motion more universat and generat than that of the lungs, and that theynct on ali potnts of the body, is not in a palpable manner, yet With a conatus toWards it. They aut On the muscies of the nech, occiput, Sinciput, larehead, face, eyeS, Iips; the action extendseven to the muscies of the tibin and DOt, as is olearly and sensibiy perceived When the uir is strongly inspired into the lungs, and lar some time rotat ned there. Any part of the body, there- fore, that is devoid of this action, ceases in a stiori time to beconnected With the rest; and this, especialty because the Iungs by their expansion and constriction aet On the most generalnerves of the body; namely, On the tWO Sympathetic nerves, Orthe intercostat und the par vagum. ΤheSe NerVeS, PRSSingthrough the fleshy substance of the diaphragm, pervade ali theviscera of the body, and penetrate nil their arterieS, Veius, muScles and gland s; and while the lungs operate On these nerves byn Common larce, they exerciSe an action On ali the potnis toWhiel, they penetrate. In Chap. VII., on the Motion of the Heari, it is shewn that each of these nerves arises DOm the medulla of the cerebellum, and that as they are acted on, SO theyaci ori the muscies, Whiel, they enter, according to the origins of the motions existing in the body. Heuce it Would follo' that
the lungs by an externat action on these nerves, Carry On the Samo Cause as the cerebellum carries On by an internat actionthrough the fibres of the fame nervos; that heuce the lungs aet
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tion thus depends upon both the lungs and the brains; accord- ing to the proposition, and to the assertion in n. 279. 370. Wo vili noW, in the last place, add something upon thecirculation os the spirituous suid, as heing the most universat of
this Wholo Lingdom reatly substantial and alive, except the Spirituous fluid in iis fibre, or in the blood; or except the fibre and bl00d With this iis fluid; ali other things are Only paSSiveS and neceSSOries, by meatis of Whicli the spirituous fluid is copulatento sortii fluids of another degreo, and the fibres to form solides Or continuous things of another degree. There re Whereverthis suid is nos present, Deither is the brain present; neither isone part living in consori With another, or fulsit ling the ossico Os an intermediate, so as to reser itself to iis antecedenis, andat the fame time to maintain a relation to iis consequents n. 252 . Hence every part in the body is only so far in theseries and circle of the relations of iis kingdom, as it is connected With other paris by this fluid rightly determined. Thus the circulation os this fluid is the most universal, and net ther the beginning nor the end of it can be determined; and throughiis mediation, everything in iis oWn limited universe is continued, moistened, nourished, renovaled, formed, actualed and
371. Besides these circles os fluxion in the blood, there is also a circle of perpetuat sormation, namely, of the red blood om the puror blood, and of the purer blood froin the spiritu-ous fluid. On this subject We have frequently Spolien above. For in Ordor that subsistence may be perpetuat existence, the Same circle must be perpetuatly continued in the subsisting bodythat had boen in the existing body; henco the blood, in Order tosubsist, ought to be perpetuatly coming into existence; sor Whichreason that Whicli is formed, is alWays rogarded as stili to beformed, and that Whicli is to be formed is regarded as ulready formed sit. 261, 262 . This circle cannot exist and subsist Without the circulations just described, and When these are ser- formed, ali things accord, and the System cohereS.
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372. ΤΗΕ use of the foramen ovale and ductus arteriosus, is SheWn by the heart of the turile more clearly than by any other. For in this animal there are two large arteries, one of Whicli resembles the ductus arteriosus; and tWO foramina, One Os Whicli resembles the foramen Ovale os embryos, Whicli foramina are Opened and shut according as the animal is in the water or in the air. TO mine the subject clear, then, I will adit a bries chapter on the heart of the turile. 373. ΜοRGΑGNI. In the presence of some scientisic hiends DomVenice, me orace dissected a turile of 36 poliniis weight. Aster completely separating the heari stom the pericardium, for it Was connected with the lower portion of the lalter, not by tendinous filamenis, butimmediately) ; and after cares ully observing a number of nerves diStributed particularly over the back of the heari, and aster inspecting the
auricles, and trying in vain to say Which Was the larger of the tWo, We proceeded to open the hestri itself, and made the folio ing observations. The Venae cavae united their tWo charineis in a large and almost entirelymembranous Sinus. This sinus communicatod With the right auricle bya large and nearly circular Orifice, furnished With two membranous Valves p0SSeSsing fleshy fibres. These valves, which were similar in their figure and modo os position to the lids of the eyes, Were longerthan the diameter of the be rementioned orifice, and were So placedunder it, that when they contracted, they could close it altogether. Froin the right auricle there Was a passage into the right ventricte, and Doni the lest auricle into the lest ventricte, and Do valves Were prefixedio ei ther passage but those we are soon about to describe. BetWeenthe auricles there Was a large, thin, membranous septum, but Whicli, in
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respectively, and their inclination Was Such that it Was easy to conjecture, that When the VentricleS contracted, the valves must be raised by the compressed blood, and compelled to Shut the auricles. Os those valves, that Which hung sorWard into the right ventricle was the thichostand largest. MoreOVer, the great artery arose Dom the summit of the right ventricte, and Soon aster divided into a superior and inferior trunk. And from the fame ventricte, but a litile anterioriy, another considerable artery iSSued, Whicli, after mahing a curve of about ten finger-breaditis in tengili, terminated in the inferior trunk of the great arte . At the place Where the two arteries arose froin the heari, two semiiunarvalves Were prefixed to them. But the lest Wali of the right ventricle Was per rated by tWo soramina, one anterior, the other posterior. The anterior foramen, Which Was circular, and had no valves, was large
enough to admit the p0int of the thumb ; the posterior, Which Was asit Were triangular, With the base of the triangle uppermost, Was largerthan the anterior; but Was covered superioriy, for about one third of iis extent, by the two valves that hung sor ard, as We bes re satil, fromthe septum of the auricles into the ventricies: the other two thirdsbeing covered by a most delicate net ork of glistening white fibriis, whicli nevertheless transmitted the blood through their meshes. Bythis foramen the right ventricle communicated with the lest; by theother, it communicated with a certain third ventricie, Which was siluated in front, between the right and test ventricies. This intermediate ventricle, smali as it Was, reached nearly froin the top to the bottoni of thelieari, and at the base of the heari gave Osr the pulmonary artery, thecommericement of which had in like manner two semilianar valves. The pulmonary Veius opened into the lest auricle, and this, into the lest ventricie ; no valves as We could weli perceive) being placed either at theends of these vetus, Or at the orisce of this ventricte; excepi indeed the one Whicli me have mentioned as hanging Dom the septum of the auricles. With respect to the thichness of the ventricles, I remember that the lest had thielior walis than the right, and the right, than theanterior part of the intermediate ventricie. The tength of the bundie into Whicli the arteriai trunks were closely collected above the base of the heari, and the diameter of the severat vesseis, are potnis Whicli ΙΙ do not weli remember. But Ι perfectly recolleci, that there WaS DOorifice through whicli the lest ventricle could send iis biood, except thesOSterior foramen, and nono through Whicli the intermediate ventricle could receive iis biood, except the anterior foramen ; through WhichtWo soramina, as I have stated, each of these ventricleS communicate respectively with the right ventricie. Such being the case, it Was easylo See, With regard to the bicod roturning froin the body, and to that
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returning se in the lungs, that the sortiter Was sent through the right auricle immediately, the lalter, through the lest auricle and the subjacent test ventricie ; and that it Was est driven finalty into the right ventricte, to be propelled by the lalter, and by the communicating intermediate ventricte, into the body universally, as Weli as into the lungs. ItWas easy to see, theres ore, that the lest Ventricle was as it mere a secondauricle added to the right, and the intermediate ventricle an auriculari appendage of the right; and that the right Was in faci the fame aswhat we generalty meet with in fishes as a single ventricte : although in the turile, enlarged by a manis id comminuting as Weli as propellingmechanism to promote the circulation of the blo d. In the turile, Isay, sor although in the land tortoise Ι thought I saW a communicationbetween the ventricles, and in the fresh-water tortoise three ventricles disposed as in the turile, yet on account of the sinati siete of their hearis, and of the stight nature os my observations on the potui, for I hadother objecis in view at the time,) Ι am not able at present to assirm itas certain. But to return to the turile,-although Ι have mithout di ficulty ascertained that the blood is driven from the lest ventricle throughthe posterior foramen into the right, yet I do not clearly understand asa parallel What blood can be transmitted Dom the lest auriclo of the foetus through the foramen Ovale to the right. For the foramen ovale has iis valve on the fide nexi to the lest auricle ; and this valve is capa-ble os entirely closing it; and when the auricle contracis, the valve cannot be listed upwards Dom the foramen by the action of the blood driven doWnWards. Advers. Anat. V., Anim. 17.)
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374. FRo M a comparison os the heart of the turile possess-ing three ventricles, With the heari os land animais, Whicli possess ouly tWO, the disseretice betWeen the cases is evident. Τhus, 1. The heari With three ventricies seuds Out tWO large arteries Dom iis right ventricle; whilo the heari With tWo ventricles SendS out Only One large artery or aorta, and this Dom iis testventricie. 2. The former sends Out the pulmonary artery Domthe intermediate or third ventricte, so that this ventricle appears to be an extension os the canal of the pulmonary artery; While the lalter sends out the fame artery Dom iis right ventricie. 3. The former sends out no artery Dom iis test ventricie, WhichWould seem to be only a sinus sor the receptiou of the pulmO- nary venous blood; but the lalter seuds out the norta immedi-Mely Dom iis test ventricie. 4. Henee in the former case thetWO pOSterior ventricles ought to communicate With the right common ventricle through tWO foramina, the Septum being ac- cordingly perforaten; but in the latter casu, or in the heari With tWo ventricles, this ought not to Obtain. 5. In the former Case, there is a certain venous sinus placed besore the right auricle, hom Whicli the united sanguineous current is dri ven into the Ruricle, through certain valves Whicli are suspended over it, toprevent the blood Dom floWing bach again. In the lalter, or in the heari With two ventricles, there is an influx of blood distinetly and immediately Doui the inferior cava, and again Domthe Superior cava, netther is there any valve to prevent theressuX. Let us noW proceed to the heads of the induction, Which
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or the uir. W0 1iud illo proos of this laci in natural history. FOr the fame reason the turile has lungs, and the pulmonary tery is Sent to a single and peculiar ventricie. This is done in Order that the artery, together With the lungs, may be cl0Sed When the animal is under Water, and oponod When it is in theatmosphere, Without giving rise by these vicissitudes in iis modeos life, to any confusion, Or any generia change in the circulation of the blood, such as Would otherWiso inevit ly take
376. In the air, and when the lunos are open, the three ventricles as weli as the two auricles are ali in play; and this alternately : name , each auricle simultaneousty with the intermediate ventricte, and then the two ventricles, or the righi and Dys, simul- laneous th eiach other. Such appear to be the conditions ;sor When the two laterat ventricles are compressed, room is assorded for the intermediate ventricle to eXpand. The contraryis the case Whon the ventricles are dilaten. This follows Dom a
comparison of this heari With that Whicti has two ventricles n. 374. 2). For is the intermediate ventricle be Only an extension of the canal of the pulmonary artery, iis Systole and diastolo Wili coincide With the systole and diastole of the twonuricles, and likeWise With that of the pulmonary artery in thehoari With tWO ventricies. 377. The anterior latae artery, which issues froin the right ventricte, resembles the arteriat iube of the embryonic heart with two ven ricles. For tWO arteries issue Dom the right ventricle of the formor, of Whi in the great artery, or the real aorta, is alitilo aster divided in the usual Way into a superior and inferior trunk. Then there is another large artery, Whicli aster pursuingan incurvated course for Out teu finger-breastilis, terminates in the inferior triank of the great arte ; not unlike What Wesinit in the humati foetus n. 336 , allowing for the disseretice in
the space traversed, and for the circumstance that this artery is not extended si om the perforaten pulmonary artery, as in the foetus, because the pulmonary artery is sent to a third ventricle proper to itself, Whicli is meant to be alternatoly closed and Opened. Nevertheless it is proximately adjoined to the pul
378. The posterior orifice bemeen the riphi and test ventricles
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resembles the foramen ovale of the foetus. It may be comparest with tho foramen ovale, although it is triangular, and over- lappod in a peculiar manner, to the extent of otio third of iis diameter, With a valve hanging Dom the Septum os the auricles,
meshes. For the foramen leads Dom the right ventricio to thotest, and bach again; it does not hoWever lead Dom One auricleto an other, like the foramen ovale of the human foetus, because in the lalter no arterv is extended Dom the lest ventriclo, butthe blood, in order to flow, is sirst brought bacti into the right ventricie, Whicli is the cause of the foramen being open in both directions. The anterior Or round foramen of the heari os thoturile, Whicli leads into the intermediate ventricte, or canal os the pulmonary nrtery, cannot be compared With the foramenovale of the humati scelus, hecause it does not open into an
379. Loth of these, namely, the quast foramen Ovale and theductus arteriosus, appear to be closed whille the animal is under quater, which is iis oron proper element. Is according to n. 376, ali the throe ventricles and the two auricles are in play Whenthe lungs are Open; and this, alternately; namely, each auricle simultaneousty With the intermediate Ventricte, and thon tho tWO Ventricles, Or the right and test, Simultaneousty With oachother, it solioWs, that the sanguineous stream floWs through thoanterior Or round foramen, that has no valve to close it, into the intermedinte ventricte, und then bach again Dom this ventricle; or fluctuates every time : it does not hoWever floW so Deely Domihu right ventricle into the lest, and bach again Dom the lost into tho right; for the foramen is stopped on both sides by the
nevertheless for some stiori time be a certain flux or refluxthrough the be rementioned foramen, although thus partially
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is attended With dissimilar essecis; the ono tines place While theblood coming Dom tho lungs 1irst distends iis auricle, the Other
While the auricle forces the ventricle to contraci, as in the ense of the heari possessing tWo Ventricies. With respect to the ductus arteriosus, or interior artery Ofthe heari, even this appears at that time to be closed . For illies close to the pulmonary arte , and When this laiter recei Vesiis blood over iis valves, and can nei ther expet it into the Iungs, nor reject it into the ventricte, the space appears at tengili toeularge to such a degree us to press upon the proximate RTtery, and 8o to narrow it that it can admit no blood, and much Iesstransmit any. It is nos easy to conjecture by What Other means this is essected, sor the author We have referred to, minCS mention only of a bundio into Whicli the arteriai trutilis are closelycollected above tho buse of the heart. Ρerhaps it is driven by
nary artery is filled and turgescent, the Other artery is contracted likeWise above iis valves. But I leave these remacts RS mere conjectures. The contrary to What w0 1iud in the foetat heari With tWo ventricles, appears to prevati in the heart of this animal; in the lalter, the foramen ovale and ductus arteriosus are ClOSed When the Iungs are constricted; in the former, they are closed When the lungs are open. For this animal is such that it caniive under mater, While land animais cun live Only in atr. The former, therelare, has a listari With arteries and foramina So
lest and intermediate ventricles would combine into one, as in thecuse of sishes. When the lust ventricte, sor instance, iS con- Stricted Dom the cause we have mentioned, and the blood is dented a passage through the pulmonary artery, the intermediate ventricle Will bo subject to a flux and reflux through thecircular foramen, and the walis of the lest and intermediate ventricle mill each finalty coalesco With that of the right ventricie. For When the lungs no longer admit or transmit blood, the necessity of a lest, and also os an intermediate ventricie, Whicli existonly On account of the pulmonary blood, censes With the uSe.