A systeme of anatomy, treating of the body of man, beasts, birds, fish, insects, and plants illustrated with many schemes, consisting of variety of elegant figures, drawn from the life, and engraven in seventy four folio copper-plates. And after every part of man's body hath been anatomically described, its diseases, cases, and cures are concisely exhibited. The first volume containing the parts of the lowest apartiments of the body of man and other animals, etc. / by Samuel Collins ...

CHAP. XXXVI. Of the Cortex of the Brain.

HAving unvailed the Brain of its upper and lower Vests, and discours∣ed somewhat of the Hemisphaeres, and of the Origen, and Com∣page of the Brain in a general Notion; I conceive it not altogether impro∣per, to give you a more particular account of the Brain, which may be divi∣ded into a Cortical and Medullary substance: The First is Ash-coloured, * 1.1 the other White. The Brain is made up of many parts and Processes, won∣derfully framed, as so many Tubera hanging together, as with short stalks, rarely conjoyned; and though they be distinguished from each other, yet every Process claims to its self its proper form, into which it is expanded, and seemeth to contain a little volume, and there being many Leaves all bound up together, make one entire round Model, in which it is very difficult to discover the beginning and end, and the several confines of eve∣ry distinct part of the Brain; the several Processes being so curiously framed, and enwrapped one within another, that it will require a skilful hand to un∣fold them, without offering a violation to their proper Coats, which are so nearly contiguous to each other.

The ambient part of the Brain, commonly called the Cortex, * 1.2 every way overspreadeth the Medulla, and is adorned with small Sprouts of Arteries and Veins, rarely enwrapping the Surface of the Brain, and resembling so many Tendrels of Vines, encircling an Arched Frame.

The Cortex of the Brain is rendred unequal, with many partitions running, * 1.3 in Labarinths and Maeanders, not unlike the circumvolutions of the Inte∣stines † 1.4 and passing from the fore-part of the Brain to the hinder, in a winding circumference, do encompass both Hemisphaeres, and give a mutual reception to each other. And in a moist Brain, long kept from Interment, * 1.5 and tending to Putrefaction, the Pia Mater may be easily separated from the Brain, and the tops of the Circumvolutions may be parted, so that you may pry into the bottom of the Interstices, and plainly see, as it were, the Fur∣rows made in the substance of the Brain, not carried forthright in any direct progress, but as it were mutual circumvolutions, intersecting each other; so that the bottom of every furrow, taking its rise from the Right side, pas∣seth toward the Left; then the subsequent beginneth from the Left side, * 1.6 and turneth up to the Right, making a decussation with the former, and so con∣sequently, all the Circumvolutions placed in the bottom of the several Fur∣rows, conclude in the substance of the Brain, and observe the same Method and Order.

If any person should be so inquisitive as to demand a reason of these An∣fractus of the Brain, it may be replied, (as I conceive) That the outward Surface and Cortex of the Brain is finely wrought with several small capillary Arteries, and nervous Fibrils, * 1.7 rarely interwoven with the substance of the Pia Mater, and securely lodged within the winding Interstices of the Cortex, and Medullary substance of the Brain, to give the first conception and Birth to the nutricious Liquor; and afterward to distribute it to the inward Reces∣ses. And because this subtle Alimentary Juyce cannot freely expatiate in

large Channels, without the danger of losing its volatil delicate Particles; whereupon Nature hath confined it within some small Pores, for its greater security; and because it is requisite the Brain should be supplied with a due proportion of nutricious Liquor, not only dispensed in an equal surface, but that the Risings and Fallings of it would be garnished with various deep Intersections, that their secret spaces may be more enlarged, to give a free reception to the Alimentary Liquor.

Another reason may be given of the Intestine Flexures of the Brain, * 1.8 to receive more minute Vessels into their soft embraces to secure them from out∣ward accidents, and the brisker motions of the Head. And above all (as I humbly conceive) these Circumvolutions were made by a Divine Hand, to convey the Capillary Vessels of Arteries and Veins in Maeanders, to give the vital Liquor a softer current through the winding Valleys, that when the streams of Blood are imported to the substance of the Brain, a secretion may be made of the Succus nutricius from the florid part of the Blood, which could no way be well performed, if the Blood were hurried through the substance of the Brain, with an over-hasty torrent.

The Cineritious part of the Brain doth not only superficially invest, * 1.9 as the Bark doth enwrap the wood of the Tree, but part of the Cortex (as it may be easily discovered in the dissection of diverse more perfect Animals) is seat∣ed also about the Corpus Callosum; and also part of it is propagated to the Ventricles, and principally near the Origen of the Spinalis Medulla, where the Medullary substance of the Brain is encircled with thin Ash-coloured veils, and some prominences of the Ventricles are partly made up of the Cineriti∣ous substance, which doth not only continue in the Brain, but is also propa∣gated in a long Tract through the Medulla Spinalis, not covering its outward Surface, as in the Brain, but retireth it self through the more inward Reces∣ses of the Medulla Spinalis, which are encompassed with it. * 1.10

But in the Cerebellum as well as the Brain, this Cineritious body plainly appeareth, and its productions like thin Laminae overspreading the Cerebel∣lum, are propagated over its substance, resembling a semicircular Figure.

But what may speak the nature of this Cineritious substance is very hard to determine; I conceive it not altogether improbable to be a Compage made in some sort of Red concreted Blood, adhering to the Interstices of the Vessels; as the Liver is formed in relation to its Red substance, as some will have it; But I apprehend the substance of the Cortex to be naturally White, and of the same colour with the other Processes of the Brain, and recei∣veth its alteration in colour, * 1.11 from an innumerable company of small sanguine∣ous Vesses, which dispnse the more delicate part of the Blood, into the sub∣stance of the Brain, making no long stay in the Cortex, giveth it a Blush of Purple, retaining somewhat of the tincture of Blood, and somewhat of its White primitive colour of the Brain, giving it a mixed colour, making the White in some sort Livescent, which is a kind of Ash-colour.

Ingenious Malpighius pleaseth himself in a kind of description of the Cor∣tex, * 1.12 as it is an aggregate Body, composed of a great number of minute Glands, so finely adapted, and curiously conjoyned, that they seem to make up one continued body; They have (saith this great Author) an Oval Fi∣gure, and somewhat compressed by lying one upon another; whence proceed divers obtuse Angles, * 1.13 and yet are laid in such an excellent order, that they give a kind of evenness to many intermedial spaces. And he farther ex∣plaineth the nature of the Cortex with a familiar instance, resembling the structure of a Pomegranate, whose well composed frame, derived from the

variety of grains fitly united, seemeth to represent the Cortex of the Brain, and the minute Fibres sprouting from every grain, and propagated through their Membranes, seem to give a rough draught of the Cortex.

And the Author farther confirmeth his Opinion, with an illustration ta∣ken from the observation of Mr. John Psil, who in the diessction of a Brain, discovered a stone, and globular Figure, like a Mulberry, compounded of many very little Ash-coloured Stones; it being probable, (saith he) that the Stone was formed of a putrified part of the Cortex of the Brain, retain∣ing the natural Figure of the Glands.

The Cortex of the Brain is curiously framed of a Cortical and Medullary substance, whose thin Processes are so insinuated into each other, and so inti∣mately confederated, that it is impossible by the power of Art to sever them.

The outward surface of it is elegantly enameled with great and numerous branches of Arteries and Veins, and is cut into deep trenches. The reposito∣ries of these Vessels, and of divers transparent Vesicles, lodged both about the Surface, and in the Furrows of it.

In a Humane Brain divested of the Skull, * 1.14 between and upon the Anfractus and Maeanders, running pleasantly both in the anterior and posterior Region of the Brain; I plainly discerned Vessels very much distended with a trans∣parent Liquor embodied with Air; the most eminent cause of its Transpa∣rency, proceedeth from the beams of Light, which being thin and spirituous, are easily transmitted through the Pores of a loose fluid Body.

These vessels being swelled with a thin serous Liquor, * 1.15 were very protu∣berant, as so many Vesicles of different sizes and shapes, some globular, some oval, or triangular, others quadrangular, Parallelograms, or Pyra∣midal.

In some Vessels, the transparent Vesicles, fraught with serous Aereal Juyce, run all along a good way like Beads, being numerous, small, orbicular Bo∣dies. These bubbles are most conspicuous also in the Brain of a Calf, Sheep, and other perfect Animals, and are lodged in the Pia Mater and Surface of the Cortex about their Vessels.

The Dura Mater, and not the Pia and Cortex of the Brain of a Doe, * 1.16 is furnished toward the Ambient parts with variety of Bubbles, or serous Ve∣sicles † 1.17 inspired with Air, which are most conspicuous in their great Transpa∣rency, and are endued with several shapes and sizes.

I discerned also through the Coats of the Cortical Vessels, some Particles (as I conceive) of the serous Liquor, appearing in small round White Bodies, coagulated in the mass of Blood, which were confined within Red Lines, parting those White concreted Globules, * 1.18 being (as I apprehend) the First rudiment of the Animal Liquor. So that in diverse Vessels are lodg∣ed, many White consolidated Bodies of different Forms and Magnitudes, which I conjecture to be part of the Chyme, not assimilated into Blood, whose Compage being loosened in time of Life, the purer Particles of the more fluid serous Liquor, are in a disposition to be secerned from the Red Crassament, when they are transmitted into the Cortical Glands.

Whereupon I am induced upon probable ground to believe, * 1.19 that the ner∣vous Liquor receiveth its Materia substrata from the more delicate Particles of the Chyme, and serous Liquor, severed from the Purple Liquor in the body of the Cortical Glands, where it encountreth the more pure parts of Air, transmitted into these excellent Colatorie, the great instruments in the production of the nervous Liquor.

The Air impregnated with the more noble influence of aethereal Particles, streaming with the beams of Light out of the Sun, and other lesser Planets, is first received into the Caverns of the Nostrils, and thence transmitted through the mammillary Processes into the Ventricles of the Brain; and after∣ward it being a most fluid thin Body insinuateth it self through many mi∣nute Pores of the inward Recesses of the Brain into the substance and ambi∣ent parts of the Cortex, * 1.20 where it meeteth and embodieth it self with the serous parts of the Blood, which are highly refined with the spiri∣tuous parts of the Air, and volatil saline Particles of the Brain: All which mixing together, receive great improvement by Intestine motion, in which the more gross parts of the Albuminous Liquor are separated from the more pure in the body of the Cortex, and are received with the Blood into the Ju∣gulars; whereas the depurated Particles being the nervous Liquor, are transmitted into the Origens and Roots of the nervous Fibrils, and thence propagated through the several Processes of the Brain into the Trunks of the Nerves, made up of numerous Filaments, curiously conjoyned to each other, by the mediation of thin Membranes.

These Cortical Glands, * 1.21 being lodged in variety of Flexures, do make the outward Gyres of the Brain, and are appended to the Medullary Fi∣bres; so that wheresoever you cut the Interstices of the Cortex over∣thwart, the Compage of the Glands seems to overspread the Medulla of the Brain.

And sanguineous Vessels do strew the outward parts of the Cortical Glands, * 1.22 of which the winding intersections of the Brain are formed; so that you may see the Pia Menynx, curiously made up of a reticular Form or Net∣work, wrought with great divarications of Arteries and Veins, which deep∣ly penetrate the inmost substance of the Cortical Glands; and being dis∣sected, the Red points of Blood distilling from the small Vessels, discover-themselves: And those Glands are also furnished with many White Fibres, consigned to convey the White Animal Liquor, which may be set forth by a similitude drawn from Plants, implying that the Herbs and Trees derive their Aliment from the Rind, formed of diverse united Fibres; and the Cor∣tex of the Vine or Tree, holdeth an Analogy with this structure, and there is a like implication of nervous Fibrils, both in the Cortex and Brain it self, to transmit the Alimentary Liquor to the Medulla Oblongata & Medulla Spi∣nalis, and thence to the Nerves.

Learned Dr. Willis relateth, this ingenious Opinion of Malpighius, asserting the sanguineous Vessels (overspreading themselves over the Pia Mater, and the Veins climbing up from the opposite Coats of the Brain) do acost each other, and espousing themselves with mutual Inosculations, do not immediately discharge the vital Liquor, as in other parts of the Body, but being various∣ly complicated, make diverse admirable Plexes, to which are appended many small Glands, * 1.23 which may be seen in those Plexes (which are styled Choroeidal) seated both in the Ventricles of the Brain, and behind the Cerebellum: But Dr. Willis farther affirmeth in his Anatomy of the Brain in these words, Verum ejusmodi vasorum plexus, cum Glandulis intersectis, per totum cerebri & cerebelli ambitum & interius recessus, ac praecipue inter anfractu∣um & interstitionum hiatus ubique sparsi conspiciuntur. And this may be more plainly discovered in a moist Hydropick Brain, where the minute Glands, (otherwise obscuring themselves) being puffed up with serous Liquor, are easily made obvious to our sight. Moreover, these Plexes being every way beset with small Vessels, are propagated from them, into the Cortical and

Medullary Substance of the Brain and its appendage; whence we may plain∣ly perceive, that these two great Authors do agree, that the Cortex is fur∣nished with an innumerable company of Glands, but differ in the assignment of their use. Dr. Willis assigneth them this Office, * 1.24 that when the Albuminous Liquor is separated from the Blood in the Cortex, and passeth through the sub∣stance of the Brain, the superfluous moisture is conveyed to the Glands, and so transmitted into the Veins; But Malpighius is of this opinion, That the Animal Liquor elaborated in the Glands, is conveyed through many nervous Fibres (every Gland claiming its proper Fiber) and thence dispensed through the several Processes of the Brain, to the greater nervous Ducts, seated in the Medulla oblongata, and Spinalis.

Notes

• * 1.1

  The parts of the Brain.
• * 1.2

  The Arteries and Veins of the Cortex.
• * 1.3

  The Cortex is full of Gyres.
• † 1.4

  T. 46. F. 1. e e e e.
• * 1.5

  The Pia Ma∣ter may be severed from the Brain, when it tend∣eth to putre∣faction.
• * 1.6

  The rise of the Circum∣volutions of the Brain.
• * 1.7

  The cause of the Flexures of the Brain.
• * 1.8

  The Second reason of the winding Fur∣rows of the Brain.
• * 1.9

  The Cortex is intermingled with the Me∣dullary parts of the Brain.
• * 1.10

  The Cerebel∣lum is endued with cineriti∣ous Laminae.
• * 1.11

  The colour of the Cortex cometh from a small num∣ber of Blood∣vessels.
• * 1.12

  The Cortex is a Compage of minute Glands.
• * 1.13

  The structure of the Cortex resembleth the frame of a Pomegra∣nate.
• * 1.14

  Serous Ves∣sels seated a∣mong the An∣fractus of the Brain.
• * 1.15

  The Figure of the serous Ve∣sicles.
• * 1.16

  The serous Vesicles in the Brain of a Doe.
• † 1.17

  52. F. 1. c c c c.
• * 1.18

  The 〈◊〉〈◊〉 of the ner∣vous Liquor.
• * 1.19

  The nervous Liquor is made of the more mild part of the Blood.
• * 1.20

  The Air insi∣nuates into the inward parts of the Brain, and mixeth with the Succus Nervosus.
• * 1.21

  The seat of the Cortical Glands.
• * 1.22

  The Blood-vessels of the Cortical Glands.
• * 1.23

  The Glands are appendant to numerous Blood-vessels, endued with various Plexes.
• * 1.24

  The use of the Cortical Glands.