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

151쪽

attribute the circulation to a certain sermontation in the blood, do not appear to have founded their hypothesis upon any generat idea adequale to the phenomena preSented. 173. This littie wane hanino received iis si si impulse from theheari, is a flerwarda moved forward by the whole arteriai system. This is sussiciently proved by the preceding article; Since, RS VOhave Sald, the artery is formed relatively to the undulation Osits fluid; for as the ear is formod with a view to the modulationos the air, and tho pye to the modification of the ether, so is the tunic of the blood-vesset formod in relation to the blood, and the blood in relation to the tunio, and thus the two aut as One and

the Same cause of determination, ns We may more particularly

See ou considering that a liquid injected ut any part of an openedartery, is conveyed aWay to iis litile branchus in like manueras is it had boen inj octon into the artery Dom the heart.

See n. 182. 174. Presentino a rapid current, which acquires an accele

that the severat resistances offer no impediment, the Severat frictions no retardation, nor the various ungies, inflections and

circuitous directions, any check to the course of the blood, it may be observed that this fact is proved by the solioWing considerations : Ist. That every muscle in every part of the body, Whatever be iis mass Or quantity Os sesti, cari turn pale in an instant, be indurated, compressed und convulsed; for it is a teXture and collation Os most minute arteries, Dom Whicli theblood potirs itsulf sortii tho instant that the mind SOunds a re- treat. Yet assuredly the sanguine iis liquor Would Jodge in thelitile pores and sinuosities Whicli are so highly contorted and complicated, is resistance increased in proportion us the dia-

152쪽

bo the case were the impetus of the bloon retarded, the resistance increased, and the rate Os speed diminished, as the vesseis decreased, beca me divided, and inflected. 6th. In animalcula and in secis, We seo that the blood, Whether of a goiden orsit very hue, circulates throuo the arteriai West Without friction or renitency, yet notWilli standing, as Malpighi and Leou-wenhook have both Observed, passes through innumerable circulis, tortuous pleXu8es, and intricate me8hes. For the great artery Of these animais is scareely eques to a capillary Vesset of the human frame, and a WhOle muSele is Scareely as large as a minuto fibro in the human body, and yet there are the mostrapid impetusos in their system, as indeed may be Seen Domthe quicli vibrations of their Wings, Det, and other littio members of their bodies. 7th. TO these arguments may beadded the phenomena presented by revulsion and derivation. 8th. Reason likeWise urges, DOm a variety of experimental facis, that Mere any even imperceptibie reaction exercised by the

SmalleSt Vesset, yet in consequence of the combined efforis os Such an immense number, the heari and largor arteries Would in their turn have to exercise a correlative action to an immense

153쪽

a continuous transflux of the current, mere Obstruction und in-

action Would arise, so that deuth Would supervene and forestalidisense. Το guard against accidents of this kiud, nature is evera8piring to her OWn spontaneity, nor does sile find it excepi inher purer kingdom, While proceeding to Which, she disperses nil obstacles, facilitates ali her pallis, and Recommodates One tonnother her various Substances. 9th. Nor does the science of

physics invalidate or impugii this position of the tendency of the blood to glido rapidly through the smallest vesself, inasmuchas Wo shali seu in the sequel n. 236) that more blood is containod in the minute vesseis than in the triantis, and that themembrane Os a vesset possesses the highest degree of adaptationto the blood it contatus n. 134) ; that thus it reacts as much asit is acted upon, and is ever propelling iis oWn litile volume intho direction of the arterint extremities. 175. In rogard to the seconii part of the proposition, in whicli it is stated that the blood proceeds With accelerated veloci ty, or that through the sinalter vesseis besero mentioned iis current is more expeditious than through the larger, Wo Observe that this faut may in somo mensure bo inferred from thosigure of the arteries, inasmuch as they are conicat. Thus Alorgagni Observes, ad dressing Μauget: YOu might have linown om the anatomy of the ostricli, as given by the experien cedVullisnorius, that Where the great artery of this animal sorsour inchos and a linis gives Osr no branches, it Was olearly

154쪽

meter of the pipo fhould bo tessened, the provious greater Sige of the vesset aud of tho volumo it containod being compensated by the increased celerity of the volume. 2nd. LeeuWODhoeli, Who eve Where ad ns to his statemenis the testimony of sact, maintains his oWn opinion in opposition to that os others Whodissered Dom him, When, as quoted by Verheyen, he remariis, in regard to the smallor arteries for to certain tubes coΠ- Structed to represent them , that unless collectively they areos a calibre not insorior to that of the largor iube, the liquid must run through them more rapidly than through the largerV

But inasmuch as the increments in tho degroes of the velocityof the blood, in iis passage through the largor and Amalter

155쪽

the blood, thoro re, suffers itself most obsequiolasty to be WaftedaWay at a rapid rate into the extremities of the vesseis, and is propelled by a force of the tunic, Whicli the particle, by reasonos iis elastic and yielding nature, cannot resist; sor each has the greatest possibie conformation to the Other. 4th. Thus atovery fresti potnt in advance a Desii pressure is superadded, Whilo tho degrue os resistance offered by the blood hecomesitself gradually less. Hetice arises a ratio os velocity not unlikethat Whicli bolongs to solids or fluids When falling or rising through their severat atmosphores to their centre Os graVity. This is illustrated by the proceding urticle, in Whicli it is stated that tho undulatory motion of the blood rotis With the most porsect facility to the arteriai extremities, directes iis course tothe regions of the purer blood, and multiplies iis rate Os velocity according to iis degree. The subsequent articio likeWisushews that there is a generat pressure of the arteries in the direction of the rumifications, Or that there is as it Were a perpetuat conatus exercised by the tunio upon the enclosed volume of blood; Whenco the undulatory progressive motion is continuatly living in iis oWn perpetuat cause. This being the laci, I havo no hesitation in admitting this additional proposition, that blood solus Dom tho heari in n rapid current and With an

increasing celerity ; or according to the terius of Our theorem, that the circulation is carried On, not Only at a rapid rate, buteven With acceleraten velocity. I am amare that on this potui there are those Who are Os a contrary opinion, With WhOSe Rpprobation therofore I shali not bo favored: but Why should I boso destrous of the good opinion Of Others, as to Seeli to plea se them at the expense Os truth. 176. In the vesseis of the second order, the transsuae of the wave is stili more rapid and more spontaneous: in the vesseis of

thing is stili more perfeci in the superior degree, SO perseet in-

156쪽

deed as to bo considorod as it Were the analogiae, the eminent nud unassignable correspondent, of the similar qualities, s0Wers, faculties, and modes of the inferior degrees. For in things be- longing to the superior degree, there is the highest elasticitu,

Solute correspondence of the vesset to iis fluid, iis passivi tybeing adapted to the nature of tho activity of the agent, so that the Subjeci, the forco, and the cause of the determination ureiatogether one. n. 134-I37, seqq.) A suid of this Lind there-

dullary fibres in the bruitis, Whicli are so son to the touch asalmost to be fluid, and consequently mere WVS of determination, being in such unanimity and agruenient With the fluid they contain, that no impression communiented in any part is tost at the

177. The action of the sbres Ges not depend on the action oflhe oreat or single heuri, but on the actions os an insinite numberos corcula, or as it were lillle hearis, name , the spherules of the cortical and cineritious substance, which are promed to eachsbre in the bratus and their two medulloe. In the anatomy Oftho braiti it Will bo seon that the cortical spherules are perpetuatly animaling, Or exercising an animator motion; that theyomulate the systole und diastole of the hestri; that by this perpetuat animation they cause the bratus alternately to expandand collapso; that thus it is they divido the bl ood, exclude thenoW spirituous fluid, transfuse it into the fibres, nerves, nudVe8Sels ; are in a State Os conatus, and excite motion; Will and perform action S; Vi Visy, renovate, and consorm both the whole

their cause and principie. Ali these resulis, hOWever, Would nottake place, utileSs Spherules Were severalty prefixed to the fibres, and unless the fibres thus derived their animation Dom thelarce Which Wns proper to theso spheriales, and did not dependlar it tapon the large heart; or, in Other Mord S, UnleSS they Vere under the auspices of the universat circulation.

157쪽

178. In order to direct and promote the circulation, there is required a certain senerat pressure, or equilibrium os pressure, Vallthe arteries, tenssino froni the heari in the direction of the arterialemtremities. In order that the undulation, after it is Once begun, may progress continuousty and as it Were spontaneousty Dompotui to potui, Dom the Wider to est the narrower vesseis of the arteriat system, it is absolutely requisite that there should be a certain generat pressure exerciSed by the Whole of this system, consisting as it Were os a conatus and joint nisus of the paris, and tonding in the diruetion in Whicli the wave is to be propn-gated. That there is such a generat pressure exercising this conatus and joint nisus, as Weli as directing, promoting, and urging onWard the undulation, the resulis of experiment Seemto leave no dot t. l. We fastened a dog to a table,V SVS Vieussens, and laid Open iis sidomen. . . . WO . . . SO Ured the descending trunk of the uorta a litile below the diaphragm, and a litile above iis illac branches. We then opened the partos the vesset betWeen the two ligatures With n Scalpel, Rnd .... introduced M litilo tubo that had boen in Warm Water into thecavlty of the artery. . . We tightly lied the artery doWn upon the iube With two ligaturos, so that the aperture in it Was included belWeen them. We proceeded thus far With as much care asPOSSible, . . . Rud We noW laund, manifestly both to sight and touch, that Wheu We unti ed the two first ligatures, the arterypulsated almost as strongly below the iube as above it.V 2. We then plugged the cavlty of the iube itself With a small

158쪽

draWn. In a living animal the artery appears fuit, but it is found smali and nearly empsy in a dead human body, evenWhere no blood has been lost previ usty to dissolution. The arteries resist inflation, forcibb repelling the uir that is drivenin; and in contracting, they rest ut the potnt of the least diameter.' Ibid. When there re We consideri l. that the artery pulsates after a pervious iube is inserted into it: 2. that astor tho tubo has been plugged by a sponge it does not pulsate : 3. that be-low tho ligature the artery collapses : 4. that When the motionos the heari Was intercepted, and an incision made considerablybelow the ligature, the blood Was projected Dom the artery in distinet jeis : 5. that the artery pressed upon the finger Whenthrust into it; that When the finger Was removed the nrtery Spontaneousty contracted; that in a dead body it is empsy; and that Whon collapsed to iis smallest diameter it is at rest: G. that liquor nnyWhere injected into the artery is, Without receiving any impulse Dom the heari, propellen into the vetus, Whieli distend whon tho heari is flaccid : 7. that tho blood flows in a

159쪽

tions; that there is a unanimous conatus eXerciSed by the severat arteriai potnis in propelling the bl ood Dom the arteries into the vetus; or that there is a certain continuous agent extending throughout the whole arteriat system, and of the fame nature With that Whicli appears in the heari, but whicli in thoheari is not continuous, but distinguished into contiguous intervias : consequently that the arteries are exercising the fame ossice With that of the heari itsuis; that talien collectively they rm as it Were one generat heari continuest doWn to the vetus, by vhicli means the severat forces are so Ordinated, that effecisnever fati in ansWering to their cause; but throughout the arteriat system, there is, so to spein, a continuous cause of Osreeis, and at the fame time a continuous effect of causes. Τhis I calltheresore a generat equilibrium os pressure; inasmuch as in Orderthat the circulation may subsist nud continue in iis integrity, the arteries require to be hept expanden to a certain levet bymeans of the litile M avo injected by the heari in distinet moments Or alternationS.

179. Thus We see the reason of the proposition in n. 173, 174, or sor Whicli the wave, having received iis sirst impulsu Dom the heari, is propelled by the Whole arteriat system to iis ultimate Outlet, and this, ut a rapid rate and With an accelerated velocity. For at every single poliat in the line os progressiona neW impelling force is superadded, and lienee there arises a velocity Whicli increases in a duplicate ratio, according to theriale observed by solids or fluids, When descending Or ascend-ing through their atmospheres to the centre of gravity. Τhelightest and purest atmosphore Which belongs to the bl ood, and toWard Whicli the sanguineous current is ever tending, is theregion Os minuter vesseis. This atmosphere is heavier in thetrunks hom Whicli the branches proceed, and is hemiest in thelieart. Thus in arriving at the lighter or purer atmosphere, theblood, properly Speaking, does not descend nor is carried down-ward Dom the hestri, but ascentis and is carried et ward; and

in Order that it may more eastly rise thither, it puristes itsolf asit goes, throWing aside est the impediments Whicli occur in iis Way, and Whicli are sinalty carried oss into the recipient secretory

160쪽

Sy8tem, there is no circulation: as in ed without a circulation noseueral pressure can exist or subsist. I. A generat preSSuredrives ali tho blood into tho extremities, and this, even to the degree of satat exinanition. The Wave propelled into the arteries by the heari, restores and maintaius the equilibrium. Thus the existence of Ono demands the existence of the Other. 2. The generat pressure has a tendency to extinguisti the life of the artery, by the entire expulsion Of the blood; the Wave propellen tuto the arteries restores their lila: so that there is a perpetuat loss and recovery os equilibrium, a perpetuat Struggle asit Were betWeen life and death, the victory alternately Sid ingWith oach; and thus the existence of One implies the existence of the other. When the stern necessity os death at last ar-ri Ves, then the generat pressure is victor, and the circulationcenses. Thus When ali the blood has been expelled hom the arteries into the vetus, it immediately direcis iis course to theright auricle of the hestri, in order that there the lipari may resuscitate lise. 3. The quantity of blood infused into the arteries exactly corresponds to the quantity expressed Dom them

by means of the generat pressure. In this manner again the existetice of One implies the existence of the other. 4. Hencethe generat pressure and the circulation are two distinct things. The generat pressure originates no pulse, this being occasioned by the circulation Mone. 181. As there re the existence of one implies the existence of the Other, so also does the nature of the One accommodateitsolf to the nature of the other. Such, for instance, as is thegerierat pressure, Such is the circulation, and suci, the pulso arising Dom the circulation. The pressure Varies necording to the various changes Or assections experien ced by the brain orthe body in generat. Τhe circulation varies in a Similar manner. Thus the pressure is of One Liud in a State of anger, animosity, rage, sever. It is of another Liud in a state Os fear, terror, Shame, liope, impatience, melancholy, ConSumption, ngue, kC.