CHAP. I. The Method or Anatomical Administration of Dissecting the Brain is proposed.

AMong the various parts of an animated Body, which are subject to Anato∣mical disquisition, none is presumed to be easier or better known than the Brain; yet in the mean time, there is none less or more imperfectly un∣derstood. All of it that appears, and is commonly described in the fore∣part or forehead, is beheld almost at a sight or two after some rude cutting up; but if you seek what lyes hid in the recesses for that end, new bosoms and productions of Bodies, before hid, are every where laid open: yea the parts of the Brain it self are so complicated and involved, and their respects and habitudes to one another so hard to be extricated, that it may seem a more hard task to institute its perfect Anatomy, than to delineate on a plain, the flexions and Meanders of some Labyrinth: Because, as we are not able to estimate the measure or to paint forth the pattern or draught of the frame of this, so neither of that, unless the bulk or substance of the subject be first searched to the bottom, and its frame broken into pieces. Hence it came to pass, that the old Anatomists in dissecting the Brain, not sufficiently attending what was placed first, what second, and what after that in the order of Nature, cut its Globe as it were into slices or parts, and the Phaenomena arising by chance from such a dissection, they easily esteemed for true parts of the Brain; when yet in the mean time, by others from a dissection otherwise made, the parts and processes of it ap∣pear far different from the former. The reason of which is, because the substance or frame of the Brain and its Appendix lyes so within the Skull, that there are many swellings or tuberous risings, with several tails or little feet compacted together: all which, although distinct one from another, and are endued with figures diversly ex∣panded; yet they, that they may be contained in a lesser room, are thrust as it were into the same Globe, and so complicated among themselves, that it is a hard thing to find out where the beginning and end of the Brain, as also where the limits and partitions of the near adjoyning parts do remain; further, that the several parts of the Encephalon so complicated, may retain their site, nor presently being loosned one from another, may spring forth, they are knit together into due foldings, with Fibres and Membranes stretched out from part to part. And as often as the substance or bulk of the Brain so conglobated or rolled together is cut, there is as often a necessi∣ty that the slips being cut, the portions of divers parts cleaving together, are carried away with them. Wherefore that a true and genuine description of the Brain might be shewed before its substance and continuity is dissolved, before all things its whole frame or substance ought to be explicated, and the knitting of the Membranes being wholly loosned, the several parts ought to be turned over and stretched forth into their proper dimensions. By what means these things may be done, and by what Page  [unnumbered] Method the dissection or Anatomica administration of the Brain may be best per∣formed, ought here in the first place to be shewn; then these things being first done, we will more largely deliver the Description of the Brain, together with the use and action of its several parts.

That the perfect knowledge of the Brain and its parts may be gained, it is necessary not only to dissect and look into mens Heads, but all other kind of living Creatures heads: for besides, that the humane Heads or Bodies are not so readily to be had, that one may from day to day behold the Brain and its frame, and carefully consider the situation of the parts, and search one after another their respects, habitudes, and dependencies; besides also, the immense bulk of an humane Head is in it self an hindrance, whereby its most intricate frame and various recesses and Appendices are the less accurately discerned and investigated: all which being reduced into an Epi∣tomy, are plainly represented more commodiously in the dissection of Beasts. Where∣fore when the form and composition of the Brain in a Dog, Calf, Sheep, Hog, and many other four-footed beasts, were little different (the magnitude only excepted) from the figure of the same, and the disposition of the parts, in a man, I was the more satisfied to compose a certain Anatomy of the Brain by the frequent dissection of all sorts of living Creatures. And in this imployment, for that I shall shew the com∣munities and differences which the subjected parts obtain in various Animals, com∣pared among themselves, and with Man; certainly from such a compared Anatomy, not only the faculties and uses of every Organ, but the impressions, influences, and secret ways of working of the sensitive Soul it self will be discovered. Concerning the Heads of living Creatures, in the dissection of which it happened for us chiefly to be exercised, it was observed, as to the chief parts of the Head, that there was a notable Analogy between Man and four-footed Beasts, also between Birds and Fishes: For when the first Inhabitants of the new-made World were produced, as one day brought forth Fowl and Fishes at once, another in like manner Man and four-footed Beasts; so there is in either twin species a like form of the Brain; but between that Child of the former, and this of the following day, there is found a great difference as to those parts. For as much therefore as Men and four-footed Beasts have got more perfect Brains, and more alike among themselves, we have ordered our Observations from their Inspection: Then afterwards we shall deliver the Anatomy of the Brain in Fowl and Fishes. And here first concerning the Heads of Men and four-footed Beasts, (as we hinted but now) we will propose a Method of Dissection it self, or of Anatomical Administration, and will at once recite all the parts one after another, and as it were in a compendious Catalogue; then we will by and by more largely draw out the Particles of the Brain and of its Appendix, so sha∣dowed, in a short Table, and will design their uses and actions for the exercise of every faculty.

When therefore we had in our hands the Head of a Man, or Dog, Calf, or Sheep, its more outward coverings were taken off; concerning which, as they are well enough known, we are not at all solicitous: then the covering of the Skull being divided by a Saw or Instrument, and taken away, on every side the bones are broken off with a pair of Scissers or a Penknife to the Basis of the Skull, that so the Contents might, as much as may be, be all made plain or open to the Spectators. What therefore comes first in view is the hard Meninx including all the rest with a common covering. This Membrane outwardly and above is knit to the Skull in divers places, especially about the Sutures; but indeed about the foot or Basis it most strictly cleaves to the bones, so that it cannot easily be pulled away. Inwardly (or in its hollow superficies) it is lax and loose enough, unless that nigh all its bosoms by the insertions of the Veins, and in the Basis of the Skull by the Arteries and the Nerves it is tyed to the Pia Mater.

This same Membrane between the Interstitia or division of the Brain, and besides of the Cerebel it self insinuating it self deeply on one side, and rising up again on the other, leaves some duplicatures or infoldings, in which, being shut up above by the increase of the same Membrane, Cavities, which they commonly call Bosoms, are formed: to wit, by this means, almost the three first bosoms are constituted; but the fourth is a smooth and longish, and also hollow process of the same Mem∣brane, which is sent through the Interstitia of the Brain, nigh the end of the callous body, even to the pineal Glandula. The Cavities of the greater Bosoms are severed in many places, as it were into little Cells; as it seems for that end, that the blood Page  57 passing so through the various turnings in those ends, may be hindred from a more rapid motion.

Besides, this Meninx or Film of the Brain admits two Arteries from either side, one conjugation of which arises not far from the Carotick Arteries through the holes of the Cuniform bone, but the other from the bone of the Forehead: all which in∣deed being diffused through the exteriour superficies of the Membrane, water it; but are terminated, partly in the Skull, especially nigh the Sutures, whither they convey the blood, and partly in the bosoms, where, what is superfluous is laid up. More∣over, these Arteries perforate the hard Meninge in several places on the top of the Brain (as Webser observes) and impart some shoots to the Pia Mater. Lastly, the exteriour superficies of this Meninge is no where planted with so many shoots of Veins as Arteries; but from its four Bosoms (which are the veinous Receptacles of the blood) many Veins go out through the interiour superficies of this Membrane, which being inserted in the Pia Mater, are presently dispersed through its whole com∣pass, and the same sliding down on every side from the bosoms, meet every where the Arteries ascending from the Basis of the Head, and being intermingled with them, constitute the manifold infoldings of the Vessels.

That these may be the better beheld, after the Arteries are sufficiently noted, let the hard Meninx be cut round near the border of the broken Skull; then let what∣ever of it serves for a covering and partition to the Brain and Cerebel, be lifted up, that the goings out of the Vessels, viz. the Veins and their distributions into the Pia Mater may be considered; which being afterwards broken asunder, let the Mem∣brane with its bosoms be wholly taken away; but the reliques of this Membrane, which stick to the bones at the bottom of the Skull, should be separated; so that the whole frame or substance of the Brain and its Appendix may be somewhat elevated, and moved here and there, be every where conspicuous, and at length taken from the Skull. But that these things may be performed, you must begin from the an∣terior or fore part, where the bone of the Forehead separates it.

Therefore if the prow of the Brain, hid under this bone, be a little lifted up, the mammillary processes come presently in sight, together with the smelling Nerves hang∣ing to them; which being dissected near the insertion; there will appear an hollow∣ness in either process. These are large and round, also full of clear water in Calves: but in either smelling Nerve a manifest Cavity is found continued on either side to the anterior Ventricles of the Brain, to which if a Pipe be put and blown into, pre∣sently the whole substance of the Brain will swell.

Next the smelling Nerves about the Cocks comb two small Arteries are seen to arise from the Skull, and to be carried towards the Interstitium of the Brain, which in truth are branches of the Carotides, which are knit to the dilated Comb before, and from thence are seen to be reflected to the anterior Brain.

These Vessels being there dissected, the coming together and going out of the Optick Nerves follow, the trunk of which being cut off a little lower, the Tunnel, and out of both its sides the Arteries called Carotides, arising out of the Cuniform-bone, do appear; which are more clearly beheld, if the Brain be lifted up. These also being cut off, and the brain farther bent back, the moving Nerves of the Eyes pre∣sently shew themselves; and so from thence the other pairs of Nerves follow in order, that one pair of them being cut off, and the brain with its Appendix more lifted up, the next is still obvious to those beholding it, till all the Nerves arising within the Skull, and also the Arteries, both the Carotides, and the Vertebral being at length cut off, the whole frame of the Head may be taken out of the Skull.

But (that these Vessels may be described in the same order as they are met with in the cutting them up) two small Nerves follow after those moving Nerves of the Eyes, which, for a reason hereafter rendred, we call Pathetick. These Nerves higher than the rest, arising behind two round Prominences called Nates and Testes, (the Buttocks and Stones of the Brain) and bending down forward, and entring for a little space under the dura Mater, then coming out through the same hole, together with the former, from the Skull, are propagated into the sight of the Eye. This pair is called by Fallopius the eighth, by us the fourth.

Beneath these little Nerves, from both sides of the annulary protuberance, (which being sent from the Cerebel compasses the oblong Marrow) two Nerves of noted magnitude arise, which, after they have passed through the dura Mater, send forth another notable branch on either side straight down without the Skull, the other Page  58 branch, by a longer tract, passing through both sides the Skull near the Turky Chair. These Nerves (as is shewn afterwards) having gotten a larger Province, are inlarged in the Palate, the parts of the Mouth and Face, and also their branches in the Nose and Eyes, yea they impart roots to the intercostal Nerve. We call this pair the fifth, commonly esteemed the third.

Nigh to the beginning of these, out of the lowest foot of the oblong Marrow or Pith, two lesser Nerves, endued with a single trunk, arise, which being dilated for∣ward, and presently entring under the dura Mater, come out of the same hole with the moving Nerves of the Eyes, and are all carried into the balls of the Eyes. This pair is called by us the sixth.

Next to these Nerves follow the auditory or hearing pair, which indeed arises higher from the sides of the oblong Marrow, in what part the Cerebel is hanged to it, viz. nigh the lesser annulary process; from whence it is immediately carried with a double process into the hole of the stony Bone: one of its branches is harder, serving chiefly for motion; the other altogether medullary and softer, as it were only destinated to sense.

A little lower arises the wandring pair, which is commonly called the sixth. This seems to be made of many Nerves, many of which arise together; and to them comes another, endued with a greater trunk, which being brought from the end of the ob∣long Marrow, yea beyond this, out of the spinal Marrow, is united with the former. And so all being made like a bundle of Nerves, go out through the hole of the hinder part of the Head; through which also goes out the greater branch of the internal ju∣gular Vein. This is by us called the eighth pair.

Under the wandring pair, almost out of the Basis of the oblong Marrow, another pair arises, consisting also of many Fibres, which going straight down, and being presently immersed in the dura Mater, comes forth again through a peculiar hole out of the Skull; then either Nerve, being inoculated into the trunk of the wandring pair, is presently bended back towards the Tongue. In a man, a peculiar protube∣rance grows above the oblong Marrow, out of which the beginning of this Nerve proceeds. This we call the ninth pair.

Below this, in the lowest part of the hinder part of the Head, out of the sides of the oblong Marrow, where it is about to go into the spinal, another pair, consisting also of many Fibres, arises; which tending towards the spinal Marrow, enters the dura Mater at the same place where the vertebral Artery ascends into the Brain; yet it arises out of the bosoms of the bones, but below the first Vertebra or Joynt, from whence it is carried into the Muscles of the hinder part of the Neck, so that it is doubt∣ful, whether this pair ought to be called the last of the Skull, or the first of the Vertebrals.

When these parts, viz. the aforesaid Nerves and Arteries, both the Carotides and the Vertebrals, with the jugular Veins (by which the Encephalon is fastned to the foot or basis of the Skull) are cut off, and their ends stretched out as much as may be; either let them remain in the taken out substance or frame, whereby the be∣ginnings of all the Nerves may be plainly noted; or the trunks of them being cut off near the roots, may be left in the holes of the Skull, whereby their goings out and distributions may be observed. The images of either Example are delineated in the first and second Table.

The business of Dissection being thus far brought, the residue of the Skull shews many things worthy consideration, of which we shall speak particularly afterwards. But first we ought to view throughly the taken out frame or substance of the Brain, together with its Appendix, and to examine all its appearances as they follow in the order of Dissection.

The substance or bulk being taken out, which is of a somewhat round figure or spherical, it exhibits to the sight in its superiour and convex part the Brain and Ce∣rebel; but the oblong Marrow, with the utmost borders or edges of the superiour bodies, possesses almost all the basis or its lowest part. The thinner Meninx covers these three placed near, and the outward superficies of them all; nor doth it clothe the same loosly, but deeply insinuating it self into all their cavities and recesses, covers and binds them strictly. And as this Membrane is every where interwoven, with the folds of the Vessels, by its stretching out, it reaches the same to every part and por∣tion, and so waters the whole with a sufficient afflux of blood. Here we must consi∣der the Vessels of this Membrane and its protension.

Page  59As to the former, the whole superficies of the frame of the subject may be seen, covered with the infoldings of Vessels, as it were with a net admirably variegated or flourished, and its sight or aspect shews like the picture of a fruit-bearing wood; the Idea of which, the Vessels of the Brain more aptly represent, and are themselves seen better and more distinctly, if you first squirt into the Carotidick Artery some black li∣quor. The Vessels interwoven within the thin Meninge or Piae Mater are Arteries and Veins. The Arteries are four, viz. two Carotides and two Vertebrals. Out of either side of the Tunnel the ends of the cut off Carotidick Arteries shew themselves, the trunks of which ascending upwards, are presently diffused from either side into the anterior and posterior, or fore and hinder branch. Either pair of these inclining one towards the other, are mutually conjoyned: moreover, the posterior branches so joyned, are united with the Vertebral branches (growing together first into one trunk.) For the Vertebral Arteries, arising from the last hole but one of the Skull, fall at first di∣vided through the sides of the oblong Marrow; then united in its basis, they go into a single chanel, which meeting with the hinder branches of the Carotides, (as it is said) it is joyned with them; and from that place of the joyning of them together, a noted branch ascends on either side under the edge or rim of the Brain, which be∣ing dilated upon the shanks or stocks of the oblong Marrow, is cleft or divided into very many small shoots like hairs, some of which ascend to the Glandula's placed behind the Cerebel, but the rest make the arterious part of the Choroeidal infoldings. The anterior branches of the Carotides, before they are united, send from themselves on either side a noted branch, which creeping upwards like a bounding River, distin∣guishes either Hemisphere of the Brain as it were into two Provinces; but after the aforesaid branches are united, presently departing again from one another, they are carried to the Prow of the Brain, and from thence bending back between its Hemi∣spheres, they fall upon the callous body. All these Arteries, before and after their mutual joyning together, send forth shoots and little branches on every side, which do not only creep through and intimately bind about the utmost compass of its Sphere, but its Penetralia and more inward recesses, like the young branches of Vines. The ramifications or these sorts of branchings, both of the Carotides and of the Vertebrals, are shewn in the first Table, as they are found in a Man, and as in a Sheep in the se∣cond Table.

Moreover, this thinner Meninx or Pia Mater cloathing the whole Brain and its parts, as it receives the Arteries ascending (as hath been said) from a fourfold Fountain, so it is stuffed throughout with Veins, sent from four bosoms. These Vessels mutually meeting, are complicated together, and almost every where constitute by their branches derived from both, and meeting one the other, and variously contorted among them∣selves, the net-like or retiform infoldings; which indeed are not only outwardly in the superficies, but in the dissection, where-ever you may separate one part from another, without breaking it, these kind of infoldings of the Vessels are to be found. Because, if you behold this frame, taken out of the Skull, collecting together the tops of all the turnings and the Interstitia in this Membrane, and covering them with the joynings of the Vessels, it will make the whole compass or frame of the Encephalon appear like a curious quilted ball. But if you go on to cast abroad this Sphere, and to separate the cleaving parts, knit together, of this Membrane, one from another, you will soon find, that this Meninx covers the gapings of the crevices or turning chaps of the Brain, binds the Interstitia of either moity or Hemisphere, draws together the hinder part of the Brain, otherwise being lax and hanging loose, and compassing about every border of it, as it were with a Welt, knits it to the oblong Marrow: and what is the chief of all, the universal Cortical or shelly substance of the Brain (to wit, in which the animal Spirits are procreated) is covered over with this Membrane plant∣ed with most frequent infoldings of the Vessels; notwithstanding the interior super∣ficies of the Brain being stretched out, (which being called the Callous body, is alto∣gether medullary and white) is not cloathed with this Membrane; but instead of it many foldings of Vessels, commonly called Choroeides, are hung and as it were freely flow within its complicature. The reason of which is, because as this part, to wit, the callous body, is rather designed for the Circulation than for the generation of Spirits, therefore it admits not a more plentiful influx of blood: nevertheless, for as much as there is need of heat, whereby the Spirits may be there more easily circulated, the blood being moved, within the Vessels hanging there through the empty space, might afford heat as it were from a fire kindled within a Stove. But within all the Page  [unnumbered] other recesses of the Brain, and besides within the folds or lappets of the Cerebel, yea and the Interstitia or gaps of both these, and of the oblong Marrow, this Meninx insinuates it self, and inserts the distributions of the Vessels. In truth, the proten∣sion or out-stretching of this Membrane seems therefore the more admirable, because having no where a peculiar place of its origine, it not only binds about the Head or Encephalon with a common covering, but also cloaths all its parts with proper co∣verings, and knits together their tops and processes. Yea this Meninx seems to en∣joy a manifold and diverse original: for where-ever the gapings or Interstitia of any parts or processes happen, portions of this Membrane there springing forth, cover them all, and gather them together, and reach to them the ramifications or branch∣ings of the Vessels. In a moister Brain this Meninx may be easily separated, and ample and large portions of it pulled away with the fingers; which being drawn away, the insertions of the Vessels, into the substance of the Brain and its Appendix, every where clearly appear. Lastly, by this means the brain being thus left naked, unclothed of its Membranes and Coverings, its make or fabrick, and the disposition or order of all its parts are next subjected to Anatomical Inspection.

That the Anatomy of the Brain, properly so called, might be rightly celebrated, I judge we ought not to proceed after the common way of Dissection. But whenas the substance of the whole Head, taken out of the Skull, stands in view, first let the hinder partition of the brain, where it is knit to the Cerebel and oblong Marrow or Pith, the Membranes being every where cut or pulled off, be freed (as much as it may be) from its cleaving to the subjected parts; then it will easily appear, that the substance of the brain is not united to those bodies, but of it self is altogether free and independent of them, unless where it is joyned towards the superficies by the knitting of the Membranes. Also this keel or hinder part of the brain being divided by this means from the neighbouring parts, if the fore part be bent back, the shanks of the oblong Marrow will appear wholly naked, and distinct from the brain and Cerebel (unless where they are in some places hung to it.) Moreover, when the partition of the brain, being loosned from its cohesion, is lifted up, the three Ventricles, com∣monly so called, go into one empty space or mere vacuity, resulting from the com∣plication of the brain. Besides, it may be observed, how the brain before is only united to the oblong Marrow; and that in two places of its shanks, as it were the tops, it is fixed; which Fornix so called, or arched Vault, is as it were a string or ligament, which arising before, where the brain is hanging to it, is carried to its hinder border, to which it is united as it were with two stretched out arms, and so it holds together the whole frame of the brain, lest it be rolled out into a plain, still in a spherical figure, and firmly binds the same to the shanks of the oblong Marrow. From the knitting of the other parts of the humane brain divided and lifted upwards, whereby the vacuity resulting from its infolding, and esteemed for Ventricles, also whereby the Fornix or arched Vault and shanks of the oblong Marrow, naked and distinct, may be beheld, is represented by figure in the fourth Table.

And truly, this Position or Aspect of the Brain, to wit, when its hinder border or partition, being freed from its cohesion by the Membranes to the oblong Marrow, and elevated, is bent forward, exposes to be seen by the eyes themselves, its whole frame or substance, to wit, whatever it hath without or within, or before and be∣hind, and also plainly detects what its habitude and respect is to the other parts. The chief things of these I shall add, and in the same order wherein they occurred to Inspection.

The figure of the Brain, especially in a man, shews somewhat globous or spherical: the outward superficies is on all sides noted with chinks turning and winding like to the rollings about of the Intestines: each breach or involution, yea the whole circuit of it contains a twofold substance, viz. the Cortical or rindy, which is the outmost and of an Ash-colour; and the medullary or marrowy, which lyes under it, and ap∣pears white. The brain being as it were plowed with these kind of rollings about, like so many ridges and furrows, is cleft in the middle, and parted as it were into two Hemispheres; yet both the moities come together, and are as it were founded in one like white substance, which covers inwardly, and as it were in Chambers or Vaults, the whole bulk of the brain. This is harder than any other portion of the brain, and as it is altogether medullary, it receives all the marrows of the circumvo∣lutions within it self, and is to them instead of a common basis. In either Hemisphere of the brain, about the fore parts, this callous body or marrowy substance, becomes Page  61 more firm and thick by far than in any other place; and there it is on both sides fastned to the tops of the oblong Marrow. From those tops, as it were its beginning, this medullary substance, covering over or chambering or arching the brain, is stretched out towards the hinder parts, and by degrees lessens in its thickness: at length the outward border of this stretched out, is drawn together more narrowly, and more below, it is conjoyned by the knitting of the Membranes and Vessels (as we but now mentioned) to the tail of the oblong Marrow. Besides, for its more firm connexion, a medullary process arises from the fore part of the callous body to∣wards the tops of it, which stretching under the fissure or cleft of the brain, reaches to its border; to which it is united, as it were with arms bending on either side: which arms indeed embrace the tail of the oblong Marrow, and so more firmly knit to it that border of the brain.

This medullary process, commonly called the Fornix, under its rise or beginning, hath two white and medullary roots, either of them alike going out from the callous body, which roots nigh the tops, where the brain is hung to them, meeting toge∣ther, pass into the Fornix or Vault it self, as if it were a broad process, which stretches under the chamber of the brain, like a beam. Under this twofold root of the Fornix is laid cross-wise, of the same magnitude, a medullary trunk, by which, like a bridge, there is a certain passage and communication between two processes of the form of a Lentil, and chamfer'd or furrowed bodies beaming or shining in them. Further, from the midst of the superficies of this Fornix, a thin and pellucid hedge or pale is erected, which is affixed to the chanel or furrow of the callous body, almost along its whole passage. And for this reason, whilst the three-sided Fornix stretched underneath a chamber, arising from the complication of the brain, it distinguished its appearing cavity as it were into three partitions, and so caused, that in it three Ventricles were represented.

The interior recesses of the Brain will lye yet more clearly open, if the border, being on every side separated and lifted up, as much as may be, from its cohering with the oblong Marrow, be cut a little further through the substance at the sides of the same Marrow, to which it is united, nigh the chamfer'd bodies, and also the Fornix, being cut nigh the roots, be bent back, together with the brain; for then the frame of the brain may be wholly lifted up, turned forward, and unfolded into a plain, so that the whole interior superficies of the callous body being stretched out into a broad floor, may be seen and handled. Where, besides the medullary, and its most white substance, may be observed many white parallel lines, which cut the par∣tition of the brain in right angles, as if they were certain tracts or footsteps, in which the animal Spirits travel from one Hemisphere of the brain to the other, and return back again.

After this manner, in very many perfect four-footed Beasts, the frame or substance of the brain was wont to be turned over, the Sphere being projected into a plain, and its interior superficies to be unfolded into breadth. Also this kind of Method of Dissection may be used in a mans brain, where the same Phaenomena wholly occur to Anatomical observation. The chief difference is, that the bulk of the brain of a man, for that it is very large, and also far thicker, and endued with more turnings and windings; therefore it cannot be so easily and throughly inverted, as that of a Calf or Sheep, and reduced into a broad plain: yet it may be so far expanded and lifted up near its border or partition, that all the interior recesses may appear in view. The third and fourth Figures shew the image of an humane brain bent back: but in the seventh Table is shewn the aspect or sight of a Sheeps brain wholly unfolded, and as it were spread plain.

In the lesser four footed Beasts, as a Mouse, an Hare, Coney, and some others, the superficies of the brain being wholly plain or even, wants the turnings and wind∣ings; however from the complication of the border, and the under-stretching of the Fornix, there results a cavity representing Ventricles.

After that we have throughly viewed all things which belong to the Brain, in the order as we have said, let either Hemisphere, covered within with the callous body, by which it hangs, be divided and removed from the tops of the oblong Marrow: which indeed may be exactly done, by cutting it near to the sides of the Lentiform prominencies, which are found in the vulgar dissection of the Head, within the inte∣rior Ventricles: for those prominences are the tops or heights of the shanks of the oblong Marrow, to which the callous body is immediately fixed. When the brain Page  62 is cut after this manner, that the prominencies, which are the tops of the shanks of the oblong Marrow, may be left naked, let them be cut long ways through the midst (to wit, in the medullary part, where they are conjoyned to the callous body) and their interior substance will appear through the whole chamfered or streaked; viz. medullary streaks or chamferings are seen to ascend and descend forward and back∣ward; that none may doubt, but that these chamferings or streaks were made by Nature, as it were passages or chanels for the passage and return, or going to and fro of the Spirits out of the callous body into the oblong Marrow, and on the con∣trary. The Figure of the shanks of the oblong Marrow, divided from the Brain, with their tops, which are the chamfered bodies, is expressed in the eighth Table.

After these st•iated or streaked bodies, the shanks of the oblong Marrow being divided for a little space, go forward, then being united, they meet together in the same stock, made up as it were of two stems. But the stock or trunk of the oblong Marrow in its whole tract, viz. before and after the coalition of its shanks, hath many Processes, Appendices, Prominences, and Insertions of Vessels, some of which arise from one side, and others from the other side, and make it unequal, with va∣rious productions and protuberances; of which hereafter.