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

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this Substance is a . . . peculiar parenchyma, fuit of minute pores and passages, that serve as a SieVe by Whicli a portion os coagulabie serum is sisted Dom the blood. Ibid., n. 76.) AndBoerlinave observes, that the smallest branches of the carotidand vertebrat arteries, here convoluted into the structure Os a gland, . . . EXhale n m Ost Subile humor Dom the blood by an infinity of smali mouilis, and instit it in to their proper follicle,' to be conveyed there rom into the emissary. Ibid., n. 93.)125. Since then there are congeries of VesSeis; and the arterial blood, dividen into the purer blood, penetrates them, and the fibres are continued Dom them; and since there are ovalglobules, nos unlike glands, according to Hippocrates, Malpighi, Boerhame, Wepfer, Ridley, Vieussens, Ρacchioni, Win SlOW, Ac.; I do nos see hoW me cati deny them a cavity, through Whichthey pour the ichor they receive, into the continuous fibres. But it is by no means possibi e to See this cavlty in recent subjecis, utiless sirst the dura mater, and second the pia mater, logether With the litile arteries, be torn aWay, Whicli cannot bedone Without loss of life to the pari, and obliteration of the contracted cavlty or litile sinus. I 26. Granting thon that these globules have a cavity, it

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anything prichly Or rough, like saline corpuscules; but they admit only What is sost, yielding, elastic, compliant, divisibie, applicabie to similar pores; as is the purer blood Or spherulethat constitutus the larger globe of the red blood, to the cha

cialty the case With the vesseis of the brain, Which go to and constitute the cortical substancos; for no particle in the bodycan be more sensitive than the cortical substance, Siluated, as itis, betWeen the artery and the fibre, and lo Which, as to theirsrsi and last term, the sensations come DOm the organs by

means of the fluids. Wheresere is anything in applicabie, hard aud potnted in the adjacent passages, should impinge Upon it,

the litile arteries Would contraut at tho flightest touch, and by a generat effori of this substance, conglomerated of SO manyramificatiotis, WOuid expet ii as altogether repugnant alid heterogeneous. It is there re the pure blood that traversos thesecavities, but not the serum, uni ess it be in exact harmony Withthis purer blOOd. 127. Fourthly. But When dividen a second time, or into the purest spirit uous fluid, it penetrates into tho subilest threads of this cortical spheriale, Whicli constitute the sursace, and so ispoured into the sursace of the fibres of the above canals .-Thecavlty of the cortical spherule is itself beset and completely sur- rounded With vascular tracery and lines, in Such quantity, that

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nature, enter those litile vesseis, Whicli are seen in a reti rmmanner distributed amongst, and si xed to the asoresaid pellucidglobules, Whicli sWimming in those litile vesseis, are diseOVeredio make up both the cortical and medullary part of the brain. As also further, that even the tender conis of the smallest Ofthose vesseis Whicli contain the a resuid most minute globularfluid hodies, ure also fuit of yet far more minute veSSel S, thanthey themselves are.' Ibid. , Π. 84.) To adduce more Uponthis subject Would favor of tedious prolixity. MennWhile, the8e Vesseis, Whicli coriointly Wenve and fashion the cortical particle,m V perhaps to Some extent admit os being compared With thesuperficiat vesseis and With the carneo-motive fibres of the hestri, Whicli collectively forin the chambers of the ventricles, and through Whicli vesseis the purer blood runs, ns SheWn in Pari I., n. 454, 455. For is there bo a cavi ty, thon a fluidcomparatively grosser muSt of course run through it, thau through the fibres that forin the sursace Or Walis of the cavity. Wherefore it is necessary that the blood, a second time exalted, or ruised into spirituous fluid, that is, to the highest degree,

the litile canals of tho fibros. So that this pure quid, or is youpleaSe, animal Spirit, does not pursiae iis Way through tho middie of the cortical substance, nor through the middie of the litilucanal of the fibre, but through the furface of each, Whicli it

disposes to contraei and dilate according to the will of the bruin. That these are Dot imaginations, but matters proved by ocular demonstration, Will be seen in Ρari III. For here, as We remarked ab ove Ρari II., n. II p), the cortical substance nione throws buttitilo light, but more is obtutu ed Dom the medullary substanee of tho brain, and stili more Dom the nerves of the body : Where- fore We are bound to eXtend Our en quiry to the nerves also, in Whicli it Will bu perseetly clear, that there are littie canals that p0ur Out a fluid, and around Whicli others exquisitely minute

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are Wound in a spirat form; just in the fame manner us in the Spherule of the cortex prefixen to iis fibro. 128. Fifth . The medullary substance of the brain and the nervous substance of the body are so framen und wOven, that the Whole of the truly sanguineous globules, When resol Vedinto their paris and elemenis, enter them distinctly, and runthrough their substance; so that nothing of the genuine bloodis tost be re it has performed a use in the itinermost penetralia of the animal system.-ΝOW this is the conclusion or corollaryof the foregoing remariis, to Whicli nil the preliminaries of this argument are directed: a problem os Such great utility, as un- questionably to deserve a principes place in the animal economy. For it shews us What the blood does; the siner in preseretice totho viter, the legitimate in preferen ce to the spurious; Whither

anatomicat, medicat and physiological sciences of the animalbody. For ultimately it Will sheW, that the destinies and condition os animal life depend On the nature, constitution, determination, continuity and quantity of the blood ; and that thoblood is the complex, cabinei and semina of ali things in iis body. 129. But as I have collected the truth of this problem Dom

have explainest this satisfactority in Pari I., Where I have SheWn, that it encloses the purer blood, and this, the purest blood ortho spiritu iis fluid; ali of Whicli aro hept in form and combination by means of Saline corpuscules of disserent Linds. But

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hOW are the nerves constructon 8 This question Will bo solvestin Ρari III., Where We shali sileW, that their fibres are eXquisitely fine, round canais, connected together by delicate membranaceous processes, and combined in fascicles Within a common tunic; and that the fascicles ure similarly combinedtogether by membranes, and enclosed in re common Sheath; ann

minute Vesseis ritu in a spirat direction.

What thon do tho nervos convey 3 It solio Ks that throughthe litile tuuio of tho simple fibre rutis the spirituous fluid, Whicli is the purest essendo of the blood; through iis cavityor litile canes the purer blood, or the spherules into Whichthe red blood is resolvest: betWeen the fibres, among loculi

Con Structed Os membranous septa, the most volatile salis, Miththeir Serum, Which have ensered into tho composition Of the purer blood; betWeen the fascicles of the fibres, Whicli fasci-cles are similarly constricted by membranous ligatures, and WhOSe interspaces are also divided into loculi, the other saline corpuscules With their serum, Which have resisted in the blood- globule. That ali theso species are poured into the fibres and nerves, and belWeen the fibros and fascicles, beginning hom their SoHreeS, Or DOm the cortex of the brain, is evidenced by an examination Os the lalter substance, for We have atready SheWn fari II., Π. 127), that the spirit uous fluid enters tho superficialsi bres of the cortex, and so is carried on into the medullary and nervOuS fibres. We have also fhewn that the purer blood tra- Verses the cavlty of the fame cortex Vbid., n. 124 126 . Butthat the most volatile salino corpuscules of this biood ruti in belNeen the fibros, or into the littio interstices betWeen the

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Outer Sursace of the cortex, and consequently floWs doWn to the Outer sursace of each fibre, that is, to the interstices betWeenthe fibres. Further, that a similar grosser matter, namely, the Volatile salin O-urinous substances that enter into and Support

LeeuWenhoeli osten trestis,) is derived belWeen the fascicles of the fibres, wili ho fhewn in the Pari on the Ρia Mater and Arachnoid Membrano. For that the pia mater is irrigated Withan Oily lymph of the Lind, and that this lympii is euulosed be-

tween ii and the arachnoid membrane, and so paSSeS dOWH betWeen the Windings of the brain, and Dom these belWeen the fascioles of nil the nerves that waut it, Will be confirmed by actuat experience. For is it be derived into the Windings and Crannies of this SubStance, no Other passage can be Open sor itthan into the spaces or loculi belween the fascioles of the fibres in the nerves. But I shali agniti talie up this argument in

oulline; Dr We may not expound it in greater delati, Mithout sirst having brought forWard the experiunce Whicli is to justis yit. But the reader Will sese the whole matter satisfactorilycleared up in the sequel. And it Will there be demonstrated, that the red blood, or iis globules, resolved into ad theireSSences and paris, malle Way for themselves, euch discriminately, through the Whole compages of the nerves; and thenWhen they emerge DOm it, eaeli species of humor perform8 iis distinci and peculiar circuit: thus tho spirituous fluid again expires into the blood, so that not the least dros os it is tost Without persorming use, or retiarns to iis Duntain in the cortex of the brain. The purer blood the samo, of Whicli a large portion also is carried up through the lymphatios and thoracic ducti uto the venous blood of the subclavian vein. The most Vola

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tile saline substance, With iis serum, after passing through thespaces betWeen the fascicles of the fibres, is carriod backthrough the periostea and the tunica vaginalis of the vertebrat theca into the dura mater and pericranium. But the saline substance belWeen the fascicles is rejected in the form of effluviatoWard the sursaces of the body, to exhale through the epidermis

132. The cortical and cineritious substance is that which ise an d and constricted, or that from which the brain animates. For each of iis spherules appears to be like a litile heari promed

arteries. It follows that it is this substance that causes the Systallic motion of the cerebrum, cerebellum, medulla oblongata and medulla spinalis, ii We grant that seach part of this Substance has a cavity, into Whicli, and through Whicli, thepellucid, middie or purer blood flows; or that euch part is likea gland providen With iis sollicle, Dom Whicli there is a Way Out

tuto the fibre. Thus these substances are born and made Drpers Orming a nearly similar systole and diastolo to that whichthe grand heari is continuatly carrying on. For in Order that there may be a transflux of the blood of the arteries of the brain

mediately into the fibre, there must be a litile head and pulsat-ing potnt of the Liud prefixen to the lalter, frst to allure theblood Dom the arteries, then to Work and linead it, and then to drive it out through the various lattices of the fibres and nerves, to the very remotest paris of the body; Whicli the brain os itfel Without auxiliary organs, po8Sessing active force, could by nomenΠS Recomplisti; for We Ahewed satisfactority in tho last chapter, that the blood is draWu up and invited by the brain, but is not intruded by the heart. Thus thon it is olear What theacting cause is that ensiles the globules of the red blood toproeeed OnWards, to be comminuted on the Way, to be resin edinto purer globules, and lastly into the purest, to be propelledinto the fibres, and even into the motive fibres of the body; Operations Which We cannot attribute either to the blood itfel or to the pia mater, and stili tess to the dura mater, or even to the fibres; but to the principies of ali these, or to the cortices

substance, to Whicli ali the Other substances are appendIgeS, RH-terior and posterior. In ascending to this substance the arteries

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deerease to their minimum, in descending Dom it the fibros

incrense to their maximum ; thus the intermediate cortical sub- Stanee must be the centre of the two; and Whatever the diameters and sursaces possess, they must of course derive Domtheir centres. TO these centres then We ascribe Systallic mication, DOt systole Or diastole, Whicli properly belong to the heari; and so to the medullary and nervous fibres Wo do not ascribe pulsation, Whicli properly belongs to the arteries, but to the medullary fibres animation, to the nervous fibres modiscation; sor to draW animations, and every time by means of the fibresto vivisy the whole animaled system, is the peculiar function Of

133. It is, as I belleve, useless to attempt to veri sy this position by Ocular demonstration, or the direct evidetice of the Senses; ari Wili never be raised to this pitch by human facultius; for in Order to See the paris expanding and contracting in theliving brain, We must open the Way thither, I do not say by the removat of the plates of the situli, and the division of tho dura mater, but by the division of the pia mater also, Domwhicli the arteriat twigs for the most pari come; Whicli membranu thus injured and brohen through, the vesseis themSelvesare torn, and their communication With the animating substancedestroyed. It is as though Wo fhould Wish to obtain a sight of the systole and diastole of the heari, having first torn aWayboth the venae cavae as Woli as the noria. Besides Whicli, in therecent brain, When the spheriales are concented by an endlesstissue Os vesseis, and furthermore are to the highest degree pellucid, they can never be seen in this their natural state, norwould they be visibio through the microscope, even SuppOSingwe could use it, Whicli of course We cannot do, excepi perii SWhere they protrude as a fungus, and even then it is not a single globule that We see, but a complex os multitudes, in Whichindeed We clearly Observe the motion. Wheresere tu thesepoinis, far removed as they are Dom both the microscope and the lye, We must malle use of the rational sight of the miud. When I examinod . . . the structure of the pig's brain,'' Says

LeeuWenhoeli, I had no difficulty in determining that there

cles of the brain; in order that these particles may be Sup-

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I34. Τhat this vivacious and most nobie substance brenthes in this manner, and takes iis animations alternately, BOerhaave in faci conjectured, With that persistent force of intuition sorWhich he is so peculiar; and afterwariis he thus deduces his OWn Spontaneous idea DOm a connected series of arguments : Since, there re, at every strOke of the heari,' says he, a very large portion of the blood ... is impelled by a poWersul and direct force into the cortex, the lalter must be actualed by a certain stight Systole and diastole, So long as these vesseis are fuit of blood.V Ibid., Π. 92.) ΑΠd again, after laying doWn certain premiSes, he

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Dom the emissaries of the nerves, Seems to require a greater

135. This opinion is favored not only by the figure of the

cortical paris, as approximating to the ovat shape of the primevalheari or corculum, but also by the faci that e very cortical spherule is surrounded With a litile space, Which allows it tomove Out 1 reely, Or expand and contraci, in ali directions. For

Whicli creates certain Obtuse angies, and a great number of pretiyequat intermediate Spaces . . . . A good Way to see the divisions

fuch an extent is it the case, that not only are the glands singlydiscriminuted Dom ench Other, and surrounded With Spaces, butSo uiso are their groups, smali and large: so that each pari canbe expanded distinctly, each number of paris distinctly, and eaeli sum, produci and conglomerate of that number distinctiy. Hetico belween the cortical masses there are Winding surroWS, DOm these proceed chiniis, Dom these again litile open lines: ench forni os composition being len to iis proper liberty. Theseritiges,V says Boerhaave, convoluted in the form os intestines,are again resolvable into Other similar tesser rid ges.' Ibid., n. 90.ὶ The fame thing is very conspicuous in the cerebellumulso, for is We malle a perpendicular Section of it from the vermicular process, Or belWeen iis hemispheres as sar as the murth