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

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must be secretory Vesseis ariSing from these minuto terminat arteries, as in ali Other paris; and. laStly there must be certain emissaryVesseis, although they cannot be Seen. In consequence of the invisibi-

curves, and that the smallest of them Were attached to those nexi themto forni others a litile larger, that these again Were combined to formothers largor stili, and that these lalter Were aggregated into a mass as it Were os convoluted intestines, Whicli immediately constituted the exterior cortex ; so that the smallest branches of the carotid and vertebrat arteries, here convoluted into the structure of a gland, might exhale a most subile

humor froin the blood by an infinity of smali mouilis, and instit it intotheir proper sollicie to be conveyed theres rom into the emissary, the restbeing returned by the smali vetus into the sinuses. This opinion os Malpighi is favored by the eye, and the microscope; by the faci that bollitig dividos the brain into molecules similar to glands; by the experiment of potiring inti upon the cortex, and then Wiping it aWay, When theouilines of the projecting molecules are desined, and the fissures dividing

them hecome visibie; by the case in Whicli the cerebrum Was changed intoa stony concretion Similar in appearance to a mulberry ;' by the degeneration of the contused brain into a Lind of glandular fungus, Sproutingui' through the hole or fracture of the cranium ; and by the change of the paris constituting the exterior of the brain, into manifest spherulesor hydatids, in consequerice of dropsical disorder. For these circumstances prove that there is the fame mechanism here as in the other glands, although of a more subile and delicate character. 94. But whether the minute ultimate twigs of the cortical vesseis become by direct continuation the origin of the fibrous substance of thebrain, ... RS Would appear frOm What Ruysch has Stated, is a question

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95. . . . Throughout the encephalon, Whereuer the minute and invisibie arteries, and corresponding invisibio Velias are continued, the existence of Whicli, notwithstanding that we cannot See them, We are necessarily bound to admit) ; there also we finit this cortical substance, ns weli in the recesses, convolutions, diVisions, interstices, and append- ages, as On the externat sursace neXt to the cranium. Ibid., n. 268.) Whoever considers, 1. The nature of the corteX as stated above, and

saci that the medullary fibriis most distinetly ariso from it. 2. The similarity of this apparatus With that os every other part of the body. 3. The Vast quantity of the finest, purest, and most mobile arterial blood, undespolied of iis subilest pari, that is driven hither With great force by the n0ighboring heari. 4. The exquisitely fine fluid that is every Where

discoverable by the unassisted senses of touch and Sight, and more particularly by the aid of the microscope, Within the medullary substance itselfwhon dissected, and whicli fluid is ostentimes much increased in serious assections of the brain. 5. The vetiis returning the blood from the pia mater, and from the cortex of the cerebrum and cerebellum, into the Venous Sinuses, and so through the jugular vetris to the heart. 6. The constant, regular, and proportional gro th, nutrition, generationand reparation Os the stamina of this pari froni the beginning to the end

judge that the medullary fibres are delicate pervious canais, Whichreceive the subitost of ali the fluids of the human body ; a fluid whichis prepared, Secreted, and driven into these pipes by the wondors ulmechanism Of the cortex, and so collected hom every potnt into the medulla oblongata.

96. Αnd again, Whoever Will consider, I. The character of tho blood that is drivon hither by the carotid and vertebrat arteries, and hOW muchit differs from ali the rest of the blood. 2. The exquisitely subile structure of the litile arteries arising froin the carotids and vertebrais, vanishing in a maniter into a downy halitus, and as it Were melling aWayspontaneouSly by reason of their Sos iness, and by an inscrutable implication and contexture forming the Substance of the cortex. 3. The Singular nature of this humor, Whicli, contained in these canais, exhales Withthe greatest rapidity of iis oWn accord, and is not coagulable by heat, but evaporates ulterly, While ali the other humors of the body either harden by heat, or leave bellind them a considerable residuum. 4. The force and celerity Whicli a cares ut observation of the effecis displayed in

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the nerves and muscies Ahews to exist in this fluid. Whoevor, I say,

Will consider these politis, Will have no difficulty in belloving, that thecomponent paris of this fluid are the most solid, fine, moveable, Simpleand quid of ali the humors of the human bOdy. 97. But when it is considered that the red particles of the bl00dappear by the microscope to be the grossest os ali that are contained in cur healthy humors ; and in the meantime, that the serum, the parti cleSof Whicli are much smaller, is again divisibie into corpuscules incredibiyleSS, as may appear froin the growth of the chich in the incubated egg, Where the humor of the albumen is successively attenuated untd it is adapted to flow through the inconceivably minute vesseis of the litile embryo ; and that in the smallest insecis an infinity of vesseis of Various Linds are penetraled by their oWn peculiar humors ; and that far

Smaller creatures than even these infecis, are discernit,te in human Semen

-When inis is considered, it Will become clearly evident that the paris of this most subile humor, must be conceived to be immenSely minute, beyond what is commonly thought. Ibid., n. 274-276.) Again, We are convinced that the quantity of this humor is large, and that it is made a resti every moment so long as we are alive and Well. For this is taught us in the plainest manner by the large sige of the carotids and vertebrais; by their direct and totally unincumbered courSe;

by the great quantity of bl00d impelled through them; by the great

98. W1NSLow. Νear the sursace of the cerebrum, the convolutions are at Some distanee froni eaeli Other, repreSenting Serpentineridges ; and in the interstices between them, the superficiat vetiis of the cerebrum are lodged belween the two laminae of the pia mater, si omWherice they pass into the duplicature of the dura mater, and So Openitito the sinuses. These convolutions are fixed through their Whole

depili to the septa or duplicatures of the pia mater, by an infinity of very fine and delicate vascular filamenis, as may be seen by pulling the

convolutions a litile afunder With the fingers. When they are cui transversely, We observe that the white substance lies in the middie of each convolution, so that there is the fame number of internat medullary convolutions as Os externat cortical ones; the medullary representing Whitelaminae invested and surrounded With cineritious substance; but thecortical substance is in many places thielier than the medullary. p. Anaf., Pr. de la Te8te, D. 58-60.)99. I might go on accumulating observations upon the corteX Ofthe brain, more particularly is Ι were to resori to the history of the

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diseases of the brain; but What has been cited mill sumce sor thepresent to estabiisti the delatis of our generat inductiori. Meanwhile, the larger the experience supplied, the more clearly are the politis of the inductiori brought out in a practical light, and the truth shines more and more Dearly to iis mid-day brightness.

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100. FRoΜ tho Dregoing experienee We inser, that the cortex is the principes substance of the brain; siluated in the very first term of the fibros and ethe last of the arteries : consequently in the mi dille, in ordor that it may be able to extrael Dom theblood the purer essences and animal spiriis, and transmit them immediately into the finest medullary filamenis, and so into thenervolas filaments of the body. 10 I. The cortical aud cineritious substando is that Whicli is expanded and constricted, or that Dom Whicli tho brain animates. For eaeli os iis spherules appears to bo like a littio

prefixed to iis arteries. Since then there are as many OriginSOf motion as there are spherules of cortical substance, it folioWAthat When the lalter are expanded, the entire mass of this conglobate viscus, namely, the sursaee, the bl OOd-Vesseis, and the interior medulla throughout,) is constricted; and vice vel Sa. 102. In the cerebrum these spheriales are so placed and Rrran ged, that they can persorin their systole aud diastole either Singly, or severat together, Or ali in common; but not so in thecerebellum, or medulla oblongata and medulla spinalis. Hencethe cerebrum, according to the ordinate disposition of iis sub Stance, has the poWer and choice of in spiring any fibres itpleases, or fascicles Os fibres, and consequently any nerVeS and muSeles, and exciting them to aci: Whicli particular and specialaction exisis under iis generat voluntary action.

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I 03. Τhus is Wo gain a distinet perception Os the coordination Os these substances, Wo may understand hoW the Will is determined into aut by the cerebrum; hoW by the cerebellum ;and hoW by the two medullae; also hos in the disserent Linds

I04. Τho brain, by this iis faculty and force of animation,

and transmits it into the fibres, as iis delicate appendages; and ΡOHrS Upon it a neW esse ce, conceived and excluded by a high proce88 of generation in the finest Wombs os iis substance. 105. We may thus understand the course of the circulationos the animal spiriis; namely, that it is hom the cortex into the universat fibres, Dom the fibres in to the blood, hom theblood into tho brain, and so bach into the cortex; Whereby ΠΟportion of these spiriis perishes Without use. We may RiSO UΠ-derstand the moments of this circulation; namely, that theyRre Synchronous With those of the respiration of the lungs, Which Wonderfully concur in promoting and transfusing this truly animal juice through the nerveS.I06. Since this cortical substance resides in the principie of the actions of iis bOdy, and 1 Om above contemptates the restos the system as below it, it is necessata that ali things in the System Should correspond to it, exactly as essecis correspond totheir causes. Wheresere it is right to attributo to ii, byeminence,' everything that performs any Lind of function inthis Whole Lingdom. Thus each part of this substance may be called by eminetice a muscie; also by eminera ce a gland; and in laci by eminence a microcosm, When the entire body is re-

107. The paris of this substance deserve for the Same reRSOnto bo regarded as the Organs of the interior senses, and RS cerebellula; sor by means of the medullary substance and the

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is the principat substance of the brain. We dare uot venture toasseri that this substance is in the place of a principio Over alltho othur fluid, sost and solid materials both of tho brain and tho body, before the severat delatis of the preceding inductio Jhave been explained, for it folioWs ut last as a conclusion Domuli tho particulars that remain to be confirmed and that havo been confirmed. In the meantime, is it be the cortical sub Stanee, us We Shail SheW presently, that animates, that begitis the circulation of the spiriis through the nerves, thnt excites ali paris of the animal system to living motion, or that is thonursing mother of the spiriis; that is the eminent gland; theeminent muscie ; the eminent sensitive Organ; and other things,

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as it Will bo oxplainod that it is, it solioWs that this substance isthe chios os all. But stili that it has another substance OVeis, and whicli in a highor sense is the principat substance, Willbe shewn at the end of this chapter.

III. Silualed in the very si si term of the sbres and the last of

the arteries. That this substance holds a middie place belWoeuthe bl od-vesseis and the fibres of the medulla of the brain, is a faci that we must not infer a priori, Or by rational intuition

eXperienee gives oeular demonstration and reni evidetice. Henco

I Would rather seuk authority firsi and laremost Dom experi- ence, than DOm rational intuition. In What solioWs, it Will bomy endeavor to cali upon eXperience to state the case, to produce the Wit esses, and to explain the subjeci, and Iastly to submit it to tho judgment of the mind. 112. LeeuWenhoeli sheWs that this cortical substance is placed in the last term of the blood-vesseis of the brain, Orthat the vesseis split ut last into the finest stamenis, so as to best to meave the severat paris of the above substance. His WOrds are as solioW : During my investigation of the corticalparis of the brain os the ox, I have osten thought that I could see and observe that the vitreous and highly pellucid matteriliat constitutes the principat part of the corticul Substance, COH-sisis of nothing but very sine lines or vesseis, ali joined toge

See also the whole of his description of the brain of the pig Ibid., n. 75), and the confirmation of it by Ridley Ibid., n. 84 . Malpighi declares the fame thing stili more positively:

It is a universal rule,' says he, that every single gland of the cortex is Supplied by the extremo onds os both arteries and Veius. In the more persect animais then we find, that theblood-Vesself, by means of the meningeni membranes, irrigate the extreme gland 8 of the cortex of whicli the gyros of thebrain are CompoSed, SO that a netWOA Os vesseis is seen in thepia mater, the tWigs Dom Whicli penetrate the intimate substance of these cortical gland 8,V kc. Ibid., n. 78. Ri soli again discovered the fame Willi even additional clearness, by a ne

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ille microscope; sor aster having recourse to his peculiar mothodos dividing the arteries of the brain tuto the minutest branches, utitit in faut they can no longer hold together, he expressed theresuit in his Figures, and described it in thesu Worus : hile

of the litile arteries arising Dom the carotids and VertebralS, Vanishing in a mander into a doWny halitus, and as it Were melling aWay spontaneousty by reason of their Sosiness, and by an inscrutable implication and contexture forming the substance of the cortex.V Ibid., n. 96.)113. The faci that tho blood-vesseis split aud ramisy into Such minute threads, that they are ultimately conglomeraledround every spherule of this substance, and penetrate it, is difficult to discern by tho cyo Without it be assisten With very perfeci microscopes ; sor Whatever does not sali Within iis sphere,

sharper sighted perceive iis distinctions With perfect clearness. And the fame Was the case comparatively With the eye itfelibesore the use of the microscope. SO also it is at the presentday With those objecis that stili liu hid to the most armen sight, or to the most poWersul glasses. And yet it is an eternat truth, that the potnt of no vision is that at Whicli infinitely more numerous and distinct things begiu than ever the eye can detect, though assisted by ali the poWers of ari: Where re When We have arrived by visibie experieuce at this limit, the rationalSight, or the mind, must thencelarWard falle the matter up in iis then State os olearness, and supply the defeci, und unWind theremainder of the clue. For utiless the mind begius Where artisiciat sight terminates, Wo shali never get any further than the

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in like manner in the cortical paris a vast number os extremelyminute bl OOd-Vesseis . . . . This incomprehensibie multitude os

situs ted at the first term or boundary of the fibros. The eye is susticient to setile this questio . The Outer portion of these glands,V says the sagacious Malpighi, is covered by the pia mater and iis blOOd-vesseis, Whicli penetrate de ly into their substance; the inner portion puis forti, a White nervolis fibre, RS it Were a peculiar vesset, as the lucidity and white ess of the glands permit us to observe; the White medullary substance of the brain being in faci produced by the connection and fasciculation Of many of these vesseis or fibros. And is the nature Ofthe cortex may be explained by a familiar example, no beller

Ibid., n. 76.) And a litile aster he says : Since a large quantity of cortical substance is observed in the ventricles, and ni the beginning of the spinal marroW, Where the interior promi-