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tho white substance lios in the iniit ille O1 ench convolution, sothat there is the samo number os inturnia medullary Convolutions as os externat cortical ones; the medullary representingWhito luminae invested and surrounded With cineritious Substance ; but the cortical substance is in many places thickerthan the medullary.V Ibid., Π. 98.)149. A differout composition and insinuation Of this corticulsi stanee is displayed in the cerebellum. In this organ it is insinuated in litile circlos and solds, and penetrates most diS- tinctly, and everyWhere seuds Out fibriis, and this, So visibly,
divided perpendicularly. In this treo of li , in most beautilat
Order, and by unanimous consent, the trunk is relatud to thebranches, the branch to the boughs, the bough to every eyeor particle, and this, SO Wondersully, that the common action is identical With tho particular action Os every pari, and vice Nerδα pand thus the whole mass of the cerebellum is expanded Or Cou- Stricted unanimOusly, While the mass of the cerebrum On tho Other hand can expand or constrici specificatly and individually;sor in the cerebrum there are as many hingos and joinis as thereare paris Or tori; but not so in the cerebellum, uniess perhapsWe excepi iis inferior partitions round about the stem of the medulla oblongata. In the cerebellum,V says Malpighi, asiis productions are propagated in the Way os laminae placed oneupon nΠOther, and the outgoing branches are sent On both sides equalty toWards the externat sursace, SO the circumjacent Cortex RSSumes a Semicircular sorm. Ibid., n. 82.) Respecting the ramification os the cortex and pia mater in the cerebellum, See Heister, Morgagni, and others; alSO Our Pari I., 11. O 60, 561.150. That overy cortical torus of the cerebrum is like a cere- bellum, but capable of particular eXpansion; or that there are
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similar arboreat ramification is displayed to that in ille cerebellum, Only on a smaller scale. These cortical glands,V sayshe, tortuousty placed, malle up the eXterior gyres of the cerebrum, and stre appended to the medullary fibres or VeSSeis aris. ing there om; so that Whereuer the gyreS are Cut RcrOSS, R determinate and firm mass of glands is alWays found Overlying the medulla: and this is stili more evidently tho case in thecerebellum. Pari II., n. 76.) The intermixture and combi nation of the nervous fibres in the cerebellum produces the arborescent appenrance deserit,ed by COrtesius and others, and which also I find is exactly repented by nature in the cerebrum. For is the gyres of the cerebrum With their cortex be cut Ortorn RCrOSS, the Same appenrance Os a tree With iis branches and
n transverse Section of the entire cerebrum, Or of any one of iis
paris.' Ibid., n. 79. I 51. Tho casu is disserent in the medulla oblongata, throughwhicli this substance is dispersed in pulches, in order that it may distinctly a1rord origin and buginning to every fibro as it isubout to go out there Om into the nerves. Atid again, the caseis disserent in tho medulla spinalis, Where this substance collectively forming a long axis, soWs ns it Were from perpetunt centres into iis Own proper fibres, and this, in order that it maybe roused to aut at the samo time by the si bres of the cerebrum and cerebellum, Whieli run through it. Again, there is a disser- enco in disserent Liniis os animais; und also in infecis, Whose spinal marroW is parted into n number of cerebella as it Were, in Such an Order, that When one of the lower molecules acts 1 rom iis cortex, it also suffers itscis to be acted upon by themolecule above it, and thus principally by the highest molecule, or b3 the brain. Respecting the silk-Worm, see Malpighi; and respecting other inSeeis, Spe S Wammerdam. 152. Theres ore the cortical substances os both the cerebrum, the cerebellum, and both the medullae, are so silly subordinaledand coordinated, that nothing in animal nature can be more methodicat, ns indeod we might expect to bo the case With a substance Whieli is the origin of the nervolas fibres, and the be- ginning of the motive fibros os the body, and the cause of allactions both Datural and voluntary. But this is uot the place
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to extend the onquiry further, or into the particular modes in Whicli this substanco acts upon the fibros; for this must be thesubject of Our nexi Paris : here it is our object to treat of this substance Only in Spectat, nud not in generat.153. Hence the cerebrum, ac ordino to the ordinate dispositionos iis substance, has the power and choice of inspirino any Fbresit pleases, or fascicles of sbres, and consequently any nerves and muscies, and exciti, them to act. Thus Wo see Why the cortical substance of the brain Wiuds into spirals and continuat tortuosities, and why it is soldest into serpentino rid ges and intestinat gyres Surrounded by SO many meningeni partitions and insul- caten bantis. We seo that this is in ordor that there may be allthis number os bratiis cap able of animation, and ns it Were Ofturning round on their hinges: for they have corresponding tothem an equat number of fibrillary leashes in the medulla of thebrain, and an equat number of fasciculated nervos in the body,
and lastly, an equat number Os motive si res in the muscies. Experience and time are necessary to ensile iis to trace Out What particular gyre and serpentine eminence in the brain respecisu giVen muscle as iis correspondent in the body. Pacchioni
spontis of the liquids whicli creep through the burrows of thebrain, and refers to Bellini and severat Other Writers. opera, Ed. Qit., p. 87.)154. That tho cortical substando is What inspires the fibres, and by iis animation propeis the spirit, and thus excites thenervous and motive si, res of tho body, is a faut in confirmatio of whicli the history of disenses of the head is so prolisc, that abare enumeration Os the proose Would sil tWO of our pages. Ridloy says : Whon I thrust the potui os a litiise an iuch deopinio tho brain os a dog, the frame Was violently agitated, and the animal exhibited horribie fossings of the bOdy, and convulsions of the fore and hiud Dei. Phil. Trans., Ioc. cit.) Whenthe blade of a knisu Was passed right through to the opposite fide of tho fhul V that is to say, through the cineritious Substance of the medulla Oblongata, so as to divide the medulla fibres in iis passage, horribie spasms Were the result.' Vari II., n. l.) Αnd Pacchioni says : A young lad Who h ad fallen froma height, and received a concussion of the head, and a Wound On one Side of it, died tWenty duys after the accident. We
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percussion in the integuments of the heud, so after he was dead We could find nono in the situli, or the paris under enth it. Onproceeding to examine the brain for the sent of the disease, Went Once discovered it in the dura mater. On the lest fide Wesound a considerable bladder, Whicli at 1irst deceived iis, sor opposite iis convexity We saW a Lind of sinuous recess in the dura
' Wepser does not directly State that the cavlty was in the cortical Substance, although it may be implied in What he Says.- Tr.
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and did. On examining his head aster death, the wholo sursaco of the cerebrum and cerebellum, including both the convolutions and the surroWs belWeen them, seemed to be clogged allover With a gelatinous Substance, Dom Whicli, When it Waspriched With a lances, genuine Serum oOZed Out. And in faci,
Wepser could see most plainly that the very substance of thecorebrum and cerebellum had imbibed a large quantity of serum ; sor both these bratiis Were extremely flaceid and son, ulmostlike pap; so much so, that the stightest touch brohe them, kc. Ibid., p. 15-19.) Were it requisite, We might here introducea host os observations froin the Acta Eruditorum, ali proving that Whon the brain's elevability and faculty of animating are
nbove causos he enumerates est matters that effect a solution in the continuity of the arteriai, Venous and lymphatic vesseis
in tho interior of the brain about the cavities, Whereby liquid escapes and collecis, and by iis pressure injures the archedorigins of the cerebrat nerves. Ibid., 11. 1010, k 4.) Again he SVs, When classisying the causes of epilepsy, that this dis- ense happetis When the brain is morbid ly assected in iis inte
155. Therelare since the cortical and cineritiOus substance of tho tWo braius and medullae, is the fountain of the voluntaryand natural vital motions; and since ali the Other paris arechannuis Whicli convey the bl ood to it, as the arteriai vesseis, Orconvey the spirituous fluid Dom it, as the fibros; or olfe nre barriors and embankments, Whicli hem in the cortex, and confine it Within limits When abo ut to animate, as the erantiam, and the pia and dura mater; hetice ue may eastly inser the proxi-
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male or remoto cause of any particular malady, for there is achain os causes, heginning Dom the substance of the cortex,
156. Frona these facts then, Which have been ascertainedWilli rogard to the wholo braiti by the eXperience of anatomiStS, We come to the folloWing conclusion With regard to the severat cerebella Whicli collectively maho up the cerebrum; namely, that When one or more of these cerebella is thoroughly diseased, the contagion does not immediately extend further than to the appended sibres and subject muscies. Wherelare the cerebrum is so constructed, that either the Whole may be carried aWay in alternate Whiri, or Only the half or one hemisphere of the Semiglobe, or Only SOme of the conVOlutions, or Only a Single UUD, Or OHly n glome, tesser group or part of One convolution. Thus the evidetice that history of diseases prosters of the Whole, it proffers at the fame time of the paris, and of a part of the paris. In faet, animal nature must nee is so dispose the principies aud causes of the motions of its Lingdom in the cerebrum, asto give the foui the poWer and choice of compellitig any fibres it Will to aut, or any fascicles of fibres, and conSequently any
uo fibre of the cerebrum is sent into any motive fibro of thebody, but 0nly the sibi es of the cerebellum and of the tWO medullae; for as to the olfactory and optio fibres, although eventhey arise Dorn the beginning of the medulla oblongata, Set
froin the medulla oblongata. Τhis indoed I admito But stillilio sibres of the cerebrum With the exception of those that are
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expended upon iis chemicat laboratory) run both Dom the superior region abolit the testes, and Dom the inferior region abolitthe annular protuberance, to the medulla oblongata, and so totho medulla spinalis. Thus although the fibre of the cerebrum does not itself play a motive part in the muscies, yet it does play this in the two medullae, Whoso fibres it disposes to aci in this and in no other manuer, as is clearly deducibie Dom thean atomy of the human brain, of the braitis of brutes, and also os insocis. And this it does, in ordor that the voluntary in thecerebrum may pass into the spontaneous and natural by means of the medullae, test the cerebrum be carried aWay into pro undparticular motions every time an action Once begian has to becontinued Dorn the ground of habit; in Whicli casu it Would asosten confuse and disturi, the administration os iis higher offices,
RS also in man those rationat analyses Whicli demand a particularly quiet state of the cerebrum. Wherelare RS SOOn RS OVET VO-luntary action demands a continued series of agenda, the cerebrum
has to be consulted, and to consent, stud indoed to produce theactuality of the actio . Thus to the cerebrum bolongs the principat cause; While to the incinerated medullae the secondarycause is appotnted. I therelare doubt Whether tho scatiored
thalami of the cerebrum rise up every time an Retion OnCO COm-
menced is continued; and whether this be not the case on lyWhen the designed force is first impressed, or every time the Willis Successively continued by open declarations os it sel 158. The foregoing rem artis are supported not only by the Hready osten-mentioned versatilily of the glomules and thalami of the cerebrum, but also by the astonishing distribution of the Sanguineous cannis, and by their confluence in those places Om Whicli the particular actions of the muscies of the bodySpring ; as We find about the projections umbones , and in
the tWo superior lobes, Where arteries of considerable sige arct Seen to enter the cortical substances, and Serve as receptacles tothose substances Whicli are more mobile than any other part of
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figure just alluded to. Also in ille cerebellum, in ordor that the brains by their means may be Lept determinately in a state
os generat expansion. Aud in the cerebrum, in Order to bereceivers and harbors for the blood Whicli the cortex Wanis, When one part of it exeris itSelf more nimbly than another. Is Wo could ponetrate into the living braius by the microscope, and seu nil that is to be seen of these substances, olit hoW theoye Would astound the mind : but as this is hidden Dom us, Wemust rest content With What is visibio in tho confusion os bollodbrains. Which parircular and speciat action emisis under iis generat voluntarν aclion. See Pari I., Π. 287. 159. Thus V we gain a distinoi perception of the coordinationos these substances, we may underatand holo the wiu is determined into act by the cerebrum. We considor it beyond alidoubi, that the cortical substance is the determinant, althoughnoi the prime determinant, of the actions of the body; because itis the determinant of the fibres, as the fibres ure of the muscies, Dom Whicli action resulis. Hence according to the nature, disposition and number of these determinanis, and according totheir connection With the fibres, and the conneetion Os theso with the muscies, the intended effect is produced. Τo thesedeterminanis, principies Or motive forces, that is, to these COrtical substances, suci, a disposition as We have atready Osteniudicaten) is allotted in the cerebrum, and to the motive fibres of the muscies such a correspondence With them in the body, that tho mitid ut any time it chooses, With any celerity, to any degree, and OVer nny eXtent of Space, can cali forti, action bytheir means, and breali it Osr in an instant, and then reproduceit in any other determinate poliis. The casu is disserent in thecerebellum, and again in the medulla oblongata and medulla spinalis. Τhus Dom a distinet perception os the coordination Osthese substances, und of the subordination of their fibres, and finalty of the coordination Os the motive fibres, We may under- stand hoW the Wili is determitied into action. FOr Wheu these substances are deprived of the laculty of expanding either singly, in gr0ups, or nil together in common, they Rre HSOdopriuod of the effect of expansion , as in cases of apopleXy, epilepsy, paralysis, delirium, Suffocation, Strangulation, appa
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160. But these cortical substances, although they are determinant of the actions of their body, yet relatively are only 8 determinant anu mediant, and have corresponding to them thesub determinant substances in the body, that is to say, themotive fibres Ρari I., Π. 598). For by the cortioni substances the wid is doterminod tuto aci, but the principio of the Willmust bo fought sor higher than they. According to account, the paris of this substance are Woven os infinite fibriis, and like litile hearis, are furnished With their oWn cavities; these Withtheir oWn litile Walis and littio superfidial layers : and the fibriis are permeated by their oWn purest and most fluid spirituous blood. Hence to open and close their litile cavities, a bigher, Sublimer, more principes and universat force is required; asorce to contain the principie of the Will, Which by these meansis determinod into not. Hunce there is a spirituous fluid, in Whicli tho liso resides, and consequently the foui Ρari I., Π.
Or parietes contexture must be expandest be re the litile cavityopens and enlarges, So that the fame organigation oblatus in Opening these corcula res obtains in the compound, Oi in thecerebrum iiseis, into Whose expanded arteries the blood flows as
350, 458). The fame puror mlud noW insers that the poWerand force Os expansion resides in the spirituous fluid Whicli pe1 mentes these minute fibriis. And the samo mind finalty concludes, that there is a solii, whicli dWolis finest in this fluid, and Whose privilego it is to determine into act.
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sibriis of tho cortical contexture; and by consequetice throughthis tho littio mesial cavitios of the spherules,-this is above the Sphere of the present fari: as also to consider What the will is, and what iis determining cause, DOm causes internat and externat, proXimate and remote. This alone salis Within ourenquiry,-that the Will is by tio means determinabie into bonilyacts Without the mediation os such a substance, and Without such a disposition thereos as We see in the cerebrum; for Were it nos expansibie both in single paris and in masses, the SOulmight Will induod, but could not do. We may QSO ObSerVO, that the foui, although disrused through iis universat Lingdom, and present everyWhere in the Whole and in the pari, cannot determine the Will otherWise than as the abovementioned mediationand disposition give the opportunity of action. Thus in What-eVer potency or impotence of action this substance may be, stillitie foui emoys the fame representation Os iis universe, and the fame intuition os ends; it is as Wise in embryos and insanis, in idiots and drunkards, as in the most sober, gisted and cultivaledmen. Ρari I., Π. 269. For it is these mediant and subdeterminant organs Mone that are either insane or uneducated; and this, because their connection with their fellows is disturbod, orbecause they have admitted an immoderate influx of impuroblood, Or because their tender structuro is frettud and boset Withdi sorderly particles, or emptied of genuine Ones, or beenusethey are deprived os vitat expansibility, either in general or in
162. How by the cerebellum. It is the common opinion Ofthe learned, that the cerebrum presides over the Voluntaryactions of the body, and the cerebellum Over the naturat, or RSsome cali them, the involuntary, actions. But that the common animation of the cerebellum is equalty voluntary Wheu that os the cerebrum is volunta , is evident hom this, that the cere- bellum is abundantly endoWed With similar cortical substances or principies of nervolis fibres. Stili it differs 1 roin the cerebrum in this, that it is capable os elevation as a Whole or incommon, While the Corresponding masses of the cerebrum, and whicli as minute types represent the grand mass of the cere- bellum Ρari II., n. 150 , are eleVable One by one or in pari.