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

171쪽

and as it Were meningeni solds interveni g, and Whicli represent the shadoWs belween the branches of the troes. 136. Sitico then the cortical spheriales are so many SalientpOinis, and as it Wero litile hearis, formed sor diffusing thopurer blood, and even the purest or the spirituous suid throughthe nerVes, in the fame manner as the grand and single heartos tho body is formen sor diffusing the red blood, so the type

constitute a triae heari, surrounded as they are for I have morethan otico indistinctly seen it) With muscular flesby portions

an ulmost similar Oval spherule Or vesicle to that of the cortex of the brain. For nature, proceeding by the Simplest Way, is everyWhere similar to herseis. Thus ench of theso tWo have a similar form, euch a similar onvironment of pellucid fibres, nuda similar contexture of suri ace; for the heari Was once a pellucid

172쪽

and Vitreous particio; it Was Once pervaded by the purer bloodand ichor; the litile vetiis and the litile arteries Were alSO pervaded by a similar fluid, so as to be analogous to fibres; a most minute and a simple cavlty received this lymph, and propelledit, and alternateJy expanded and constricted; so that tho littio heari Wns both one and the other; With this disseretice, hoWever, that tho litile hearis of the brain nre innumerabie, more Simple, and formed only for the purer or pellucid blood; While the heartof the body is single and compound, and formed for the redblood and iis serum. But the greatest differetice is, that theprimitive corculum Was embraced by minute Venous Vesseis, justas the large heari is embraeed afterWards by superficiat vesseis Whieli are mere vetus; Whereus the cineritious corculum os thebrain is surrounded by arteries alone, for in these animal liso

We conclude then that the cortical spherules are litile hearis

137. But the way in Whicli these animating hearis of thebrain pass on their blood, is stili bellor illustraled by tho hoaris

representing to OUrselves somo idea of What is carried on With stili greater perfection in these tesser hearis; as sor instance that there are most subile lacunae, sub divided chambers, minute entrRACOS, ValveS, Sine WS, analogical motive fibres, and Othermeans, in Order that this biood may circulate from the minute cavlty to the Sursaces, DOm the sursaces to the cavities, preci Sely

173쪽

according to the requirements of the animul economy. But in these most hiddon things os nature, it is dangerous to proceedio the particulars and specisos of the universals; for is We giveretias to the imagination, Without placing by iis fide the experi- ence of the externat senses, it Will be impossibie to fix the goal, Or to prevent Oursolves Dom running out to infinity, uultl Weare precipitaten into the shadoWs und fallacies of mere conjecture. Hence it is bester to restrian this faculty, and direct Our-Selves to potnis Where there are definen or marhed endes in VieW.Τhe time however Will come, When, having traced ali the effecisin the animal economy distinctly to their causes, We shali beable to ascertain What is done in these minute cortical Spheres, and What Lind of tissuo aud degree of permeability they neces- Sarily possess. But I confess that this is the work of an age, and Will tasti ali iis genius. For us We have potnted out atready, a generat and particular experimental knoWledge of the thingsWhicli at any time reach any sensory, Wili potnt out the essenectos the most minute things of the fame degree; as also of the corresponding things of the stili more simple Or superior de-greeS; Wherelare We are ted into the inmost knowledge of natural things by the doctrine of series and degrees conjoinedWith experience. Ρari I., n. 63I, 632.) And to this knoWled geWe Shali attain With greater certainty, and with mathematical

Science, Whicli, by characteristic martis and letters, in their generat sorin not very unlike the algebraic analysis of infinites,may be capille of expressing those things Whicli are inexpressi-

139. By having in some degree explored the nature Os a pars, We shali be taught the action os a group of paris, or stomthe singular We shali learn the character of the integrat an diotal; for the compotinu possesses nothing of itself as iis OWnbut What it borrows and accepis Dom iis SingularS and paris, and their accidenis internat and externat. Wheres ore let us

140. Since then there are as many origins of motion as thereare Spherules of cortical substanee, it follatos that when the luiterare expanded, the entire mass of this conglobate vi8Cu8, numely, the Surface, the bDoLvesseis, and the interior medulla through0ut,

174쪽

plored the origin of the animation os the brain. So great is the abundance and profusion of these Origins, that We mustrechon them by myriads. They form the entire circumferetice of the cerebrum; they occupy iis amplest spaces internalty; they fili the larger protuberances, as the corpora Striata undthalami nervorum Opticorum; they enter here and there into the smaller protuberances, as the testes, nates, and pineat gland; they penetrate the cerebellum in the forin os a tree With beau-tiful branches; they ruri in layers through the medulla oblongata ; they compose the entire axis of the medulla spinalis, and disappear only abolit the sirst vertebrae of the lumbar region; they are so ordinately, shilsully and Wonderfully disposed, that while they ali spirate and respirate unanimov8ly, eVery Single part of either meuinx, every single tWig of the carotid and vertebrat arteries, every Single fibre of the centrum Ovale and medullary substance, and every single particle of the Whole body, in Whatever corner it be placed, conspires With them. There is nothing in the whole or in any part of the universat Lingdom, but is set so Wonderfulty in the stream Os this very motion,

that it animates When the cortex animates. But to come toparticulnrS.

141. From What Wo have stated above, it is persectly clearthat the blooὐτ seis of the cerebrum, cerebellum, and medulla oblongata and spinalis, are expanded by the constriction of the CorteX, RS a principat cause; for When the purer blood is notadmitted into the cavities of the corcula or litile hearis, thelesser and least of the litile arteries, and by consequence thelargor and largest of the fame, must retain it; and vice versa, When these numerous cavities again Open. Mucii as in the grandheart of the body, Whose auricles and arteries are dilated Wheniis ventricles are constricted; and vice versa. But hoW the arteriai and venous vesseis of the brain are everyWhere SO Situaled,

both on the sursace and in the internat paris, that When thecortical or cineritious substance is constricted, they are dilated

om the receptacles of the carotid and vertebrat arteries, and throw out the antiquated blood With iis serum rejected by thocortex, into the vetus and sinuses;-these With other particulars

175쪽

itS nerVes, muScles, glands, and in the members constructed Ofthem, Where the Outermost and common membrane alWVAdelaches froin the insido a finer membratie, and then a fineSt, Whicli connecis the simple sibi os as the common membrano COn-

necis the fascioles. How this tuli es placo is very evident in thecerebellum; and indoed in the cerebrum too, although here iis continui ty is such that it forms a plexi rm Web. Ruy Sela and LeeuWenti Oeli ench have a figure representing iis Wonderi ut propagation. The former shews that tho itiner sui face of the pia mater exhibiis a mossy covering of vesseis Whicli insinuate

them solves into the cerebellum Ibid. ; the latior, that severat arteries run doWn Dom the pia mater of the pig's brain , undare united to euch other bu throads, whicli ho calis tho fibriis of the brain, and that these arteries ruti perpendicularly, and COH-tain but littio red blood. Ibid., n. 75.) As the arteries '

puli out severat considerabio littio arteries from the brain, be-sides those fro in tho litile branches abovementioned that are

176쪽

WinslOW says : Thuso convolutions are fixed through their Wholo depili to tho septa Or duplicatures of the pia mater, by an infinity of very sine and delicate vascular filaments.V Ρari II., n. 98.) Thus it is evident that there is no contractive und expansive forco inherent in the pia mater, except What it receives 1 roin the cortex of the brain, that is, Doui the brain, Which does not bogin to bo tho brain, but in this iis cortical substanee. Also that the pia mater is so laid upon this substance, and extended botweon it, that tho effect os contraction redounds to the sursacesrom the contres, but not contrariWise to the contres froin thesu ace; and in this Way also these vesseis have the faculty os expanding both Ways ; and vice verSa. 143. The fame is truo also With regard to the dura mater, Whieli, as Wo fhewed in Pari II., Chapter I., is expanded and relaxed by the brain, and rai sed by iis arteries so as to performa Lind of pulsation; Where re We nre again brought to the truthos Ridloy's assertion, that the sinusos thomsolves have no pulsation Other than What is communiented to them froin the subjacent brain.' Ibid., 11. 2I.) Fantoni also is With us in this matter: The dura mater,'' says he, set in motion part the brain, portly by iis own arteries, ' undergoos the Same reciprocal movemenis. Henco I conjecturod that the resiliency os the membrane might be useful for compressing the brain. Yetustor ait this cannot be the faci, sor tho brain collapsos sufficiently by iis oWn Weight and essori, and this being the case Onevery fide equally, So as to amount indoed to a Lind of contraction, there re the brain compressos iiseis. More ver the dura mater does not tightly embraco the brain, but lies very loose

not go too sar Oulside the brain, sor in the dura mater themotion begius to be miXed, and coincident With the pulse of thelieart Ρari II., n. 55-6l). Wheresoro Wo had bellor turn totho interiors of the brain, or to the medullary substanee. 144. It is not to bo doubfod that the meduliary substancentso is exciten to a certain systallic motion by the motion os thecortex alone; lar the medullary substanco consists of meresibres, Whicli are So many perviolis canais; and is to eacti Os

177쪽

these a cortical spherule is prefixest, as tho heart of tho body is prefixed to the uorta, the fibres must beat overy timo With thoircorcula, und AO also the universat Substance appended to them; and this, in suci, Wise, that the lalter must pulsate Or beat whenthe cortex is constricted ; and vice verSa.

cortical Substanee contracis, and vice versa. And thus room is

corpora Striata, and the crura, and the Other eminences of the

medulla oblongata, as also within the medulla spinalis, and allthat ramisies through tho cerebellum; sor it is ali of the fame nature hoWever disserently distributed. Tho substance of thocortex,V says Malpighi, is of the fame character in the ventri-

178쪽

cles of the brain, and at the beginning of the Spinal marrOW; sor aster botling, it has the fortit alid exhibiis the characteristic substance of the glands, being exactly similar in these respectato those in the exterior region Os the brain; . . . and in the inside of almost the whole spinal marroW, the cortex describedelseWhere) has the sume glandular character.'' Ρari II., 11. 76.)Aud Boerlinave says : Throughout the encephalon, hereVerthe minute and invisibie arteries, and corresponditig invisibie

Cranium. Ibid., n. 95.) Wherelare there are fibres proper tothe cerebrum, fibres proper to the cerebellum, fibres properto the medulla oblongata, and fibres proper to the medulla spinalis.146. Truly marveis present themselves When We considerhoW animal nature has distributed, distinguished, multiplied, and by perpetuat communications conjoined, these pulsine and vital substances. How they are distributed W0 shali Ahout in thesequel. HOW they are multiplied' Will be evident is Wo considerthe abundance of them in the circumseretice of the brain, and in the penetralia os the cerebellum and of the two medullae :they are a number ineffabie und unassignable; so that it may in a certain sense be Salii, that there is a universality of the particularities of this substance; for the formative Substance isbound to multiply thus these spherules, as causes Os nil iis operations in the animal system, that essecis may result With certainty thereby, and life never fuit the members; so that isone, Or SeVerat, or perhapS n myriad Os these spheriales shouldbeeome eXtinet, Or re dered incapable of acting, stili the inspiration Os life Dom the found furvivors Would not cense, butWOuid restore the estate of the others, and raise them Dom thebrin k of death. They are distinouished; for each spherule is surrounded With iis oWu litile space or foss, that it may roli inperfeci freedom Within iis sphere os activity : SO also are thecombinationS Or groups Of spheriales collectively; thus eaelispherule most distinctly animates iis oWn fibrii, and influences it

179쪽

to iis very eud in the motive fibre of the bOdy. They are con-Dined by perpetual communications; namely, by the productionSof the pia mater, and ultimately in the form os stamina. Theyare connected also by the blood-vesseis, Whicli communieate So

perpetuatly that thure is no portion os blood in any tWig, that

is not common to est; so that in the cerebrum and cerebellum there is an absolutoly perfeci community of ali imported goodsand fluids.' Thus Whatever the trutilis of the carotin and vertebrat arteries convey, any one Spheriae of the cortex cari Rp- propriate to itself, Whetice the life of One is never extinguishenso long as that os iis consori endures. It is Worthy of con- Sideration, says Ruysoli, that the arteries of every convolutionos the brain, anastomose aud unite With the arteries nexi them. Ibid., Π. 87.) As in the largor branches, so uiso in the least, according to LeeuWeuhoeli 's figure, representing a minute portion Os a pig's brain; Where Ue see that Severat arteries run

TOW, Where a Common Sanguineolis canal runs in front in a Lindos long sissure, and gives oss an infinity of tWigs to the cineritioris axis, so that there is no portion os blood in the canalbut is common to every tWig, and conSequently to eVery particle of the axis. W0 shali bring forWard innumerable confirmations of this in Part IV. Aud in Vari III. it Will be sueti, that the cortical substances are covi Oined by the medullarysibres, or by ali that Will concur to any particular action in thebody.

I 47. In the cerebrum these spherules are So placed and ar-

See the Animal Kinydom, n. 184 u), where the following Occurs : Every gland throughout the animal kingdom eMoys a plenary communion Os iis goods and fluids, as weli as of iis biood. Νot the minutest drop noais in any artery, Whereversitualed, be it even in the heel or in the sole of the Dot, that is not communicated, is required, to any Other artery, Whether in the crown of the head, Or in any of the Viscera, or in any of the glands. That there is such a communion of blood in thebrain, and in the chest, inroughout, and that there is a similar communion Of chyle in the mesentery, is perfectly evident froni the evertasting anastomoses betWeen thedisserent vesseis. And we shali Ahew further, in the Pari on the Blood, that that fluid is various in every artery and vein, in every minute branch, and in eVery tWig. It is by virtve of this communion that the glands supply their WantS and neceSSities

180쪽

raved, that they cun perform their systole and diastole either Siny , Or severat tosether, or ali in common; but not so in thecerebellam, or medulla oblongata and medulla spinalis. For in the cerebrum ali the spherules reside and aut Deely in their OWnlitile spaces, as We have just potnted Oui: Severat again coΠSO-ciato to form a litile bali or glome, Whicli is separaten Dom iisneighbors by iis oWn fissuros and litile spaces: these glomes again associale to form larger and more generat glomes, Whichare bounded oss by litile lasses; and these larger glomes again combining, conglomerate themselves into tracis not unlike theconvolutions os the intestines, and discriminaled by Windiliginterstices, and comparatively Wide surrows. Thus the bra in bydugrees groWs Dom potnis into dimensions; Or springs most

distinctly Dom paris by gradations into a b dy; and this, in

the fame munuer as the cortical. Iis single fibriis enter undera common tunic, in Order to beeOme fascicles; the fasciclos again enter under a Sheath, Or stili more common tunic, in