The remaining medical works of that famous and renowned physician Dr. Thomas Willis ...: Viz I. Of fermentation, II. Of feavours, III. Of urines, IV. Of the ascension of the bloud, V. Of musculary motion, VI. Of the anatomy of the brain, VII. Of the description and uses of the nerves, VIII. Of convulsive diseases : the first part, though last published, with large alphabetical tables for the whole, and an index ... : with eighteen copper plates / Englished by S.P. esq.

CHAP. XV. Of the Uses of the Cerebel, and of some of its Parts and Processes.

HAving hitherto continued the former Tract of the oblong Marrow, which as it were the Kings High-way, leads from the Brain, as the Metropolis, into many Provinces of the nervous stock, by private recesses and cross-ways; it follows now that we view the other City of the animal Kingdom. The situation of this being remote enough from the former, its kind of structure is also different from it: yea it seems that there are granted to this, as to a free and municipal City, cer∣tain Priviledges and a peculiar Jurisdiction.

The Cerebel is placed a little below the orbicular Prominences in the hinder part of the Head; where growing to the trunk of the oblong Marrow by a double little foot, it appears almost of a Spherical figure. Its superior gibbosity coheres towards the superficies to the border of the Brain by the intervention of the Pia Mater; but nevertheless it is intimately united to it, nor is there any immediate commerce be∣tween this or that or their parts. There hath been spoken enough already of the figure and situation of the Cerebel, and of its various Processes, and how it is fastned to the oblong Marrow; it now remains that we proceed to design or draw out the offices and uses of it, and its several parts. Where in the first place shall be inquired into, what kind of office the Cerebel is endued with in the animal oeconomy; then when we shall descend to particulars, there are more things worthy to be noted, which will offer themselves to our consideration: viz. first the infoldings of the Ves∣sels covering the whole compass of the Cerebel, and especially its hinder part, with the heap of Kernels: secondly, its folds and lappets ordained with a certain and de∣terminate series, and almost after a like manner in all: thirdly, the double substance of the folds, viz. cortical and marrowy: and the concentring of all the medullary tracts in two large Marrows or middests: fourthly, either little foot or pedestal of the Cerebel made out of those two middle Marrows: and in either pedestal three

distinct medullar Processes to be found: fifthly, the annular Protuberance made by a process of the Cerebel descending into the medullar Trunk: sixthly, some Nerves, which arising immediately from this Protuberance and other Nerves in the neigh∣bourhood, which being designed for the involuntary Function, receive the influences of the animal Spirits from the Cerebel: Lastly, the Ventricle or Cavity lying under the Cerebel ought to be considered.

1. As to the office or use of the Cerebel in general: nothing of it occurs, spoken by the Ancients, worthy its fabrick, or agreeable to its structure. Some affirm this to be another Brain, and to perform the same actions with it: but if any one should have a soft and foolish Brain, I greatly doubt, if he should become wise, though he should obtain perhaps a more hard and solid Cerebel. Others place the Memory in this part, supposing the Cerebel to be as it were a Chest or Box, wherein the Idea's or images of things, before laid up, are kept apart from the incourse of fresh Species. But it is far more probable, that this faculty resides in the cortical spires of the Brain, as we have elsewhere shewn. For as often as we endeavour to remember objects long since past, we rub the Temples and the fore-part of the Head, we erect the Brain, and stir up or awaken the Spirits dwelling in that place, as if endeavouring to find out something lurking there; in the mean time, there is perceived nothing of en∣deavour or striving motion in the hinder part of the Head. Besides, we have shewn, that the Phantasie and Imagination are performed in the Brain; but the Memory depends so upon the Imagination, that it seems to be only a reflected or inverse act of this: wherefore that it should be placed with it in the same Cloister, to wit, in the Brain, is but necessary; for it plainly appears, that there is no immediate commerce between the Brain and the Cerebel.

When some time past I diligently and seriously meditated on the office of the Cere∣bel, and revolved in my mind several things concerning it, at length, from the Ana∣logy and frequent Ratiocination, this (as I think) true and genuine use of it oc∣curred; to wit, that the Cerebel is a peculiar Fountain of animal Spirits designed for some works, and wholly distinct from the Brain. Within the Brain, Imagination, Memory, Discourse, and other more superior Acts of the animal Function are per∣formed; besides, the animal Spirits flow also from it into the nervous stock; by which all the spontaneous motions, to wit, of which we are knowing and will, are performed. But the office of the Cerebel seems to be for the animal Spirits to supply some Nerves; by which involuntary actions (such as are the beating of the Heart, easie Respi∣ration, the Concoction of the Aliment, the protrusion of the Chyle, and many others) which are made after a constant manner unknown to us, or whether we will or no, are performed. As often as we go about voluntary motion, we seem as it were to perceive within us the Spirits residing within the fore-part of the Head to be stirred up to action, or an influx. But the Spirits inhabiting the Cerebel perform unperceivedly and silently their works of Nature without our knowledge or care. Wherefore whilst the Brain is garnished as it were with uncertain Meanders and crankling turnings and windings about, the compass of this is furnished with folds and lappets disposed in an orderly series; in the spaces of which, as in designed Orbs and Tracts, the animal Spirits are expanded according to the Rule and Method naturally impressed on them. For indeed those in the Cerebel, as it were in a certain artificial Machine or Clock, seem orderly disposed after that manner within certain little places and boundaries, that they may flow out orderly of their own accord one series after another without any driver, which may govern or moderate their motions. Wherefore forasmuch as some Nerves perform some kind of motions according to the instincts and wants of Nature, without consulting the government of the will or appe∣tite within the Brain, why may it not be imagined, that the influence of the Spirits is derived wholly from the Cerebel for the performing of these? For it seems inconve∣nient, that for these offices which should be performed without any tumult or pertur∣bation, the Spirits should be called out of the Brain, which are continually driven into fluctuations as it were with the winds of Passions and Cogitations.

As I only imagined of the use of the Cerebel after this manner, I was led to it at length by a certain thread of Ratiocination; to which afterwards happened an Ana∣tomical inspection, which plainly confirmed me in this opinion. For in the frequent Dissection of the Heads of several sorts of Animals certain Observations did occur, which seemed to put this matter out of all doubt. For I first observed, the pairs of Nerves, which did serve to the Functions, wont to be performed by the Instinct of Na∣ture,

or the force of the Passions, rather than by the beck of the will, so immediately to depend on the Cerebel, that from thence only the influence of the animal Spirits seems to be derived into their origines or beginnings. By what means the Nerves arising from the Cerebel, or receiving from it the provision of the animal Spirits, do perform only involuntary actions, shall be declared hereafter; in the mean time, for the confirmation of this Opinion, we have in readiness another Reason of no less moment.

Therefore secondly, we took notice, that not only the conformation or make of the Cerebel was ordained after a certain and peculiar manner, that is, that its frame or bulk was couched together with folds or little circles, disposed in a certain distinct series, and apt method, and proportionate within themselves, as hath been said; whence it may be argued, that the Spirits arising from hence, and flowing outward∣ly, are imployed or bestowed on some certain works determinate to one thing. But further it is observed, that in all Animals, although they differ in form and kind, yet the figure of the Cerebel is always very like or wholly the same. The Brain and oblong Marrow are figured in many after a divers manner; for as we have shewed before, there is some difference of these parts found in man and four-footed beasts: but between either of these, and Fowls and Fishes, there is a notable difference as to these parts. Notwithstanding in all these the Cerebel, furnished wholly with the same lappets or little circles alike infolded one in another, is marked with the same form and proportion; which certainly is a sign that the animal Spirits in this work-house are begotten and dispensed, as it were by a certain dimension, for certain ne∣cessary offices, which are performed in all after the same manner; and which can∣not be any other than the motions and actions of the Viscera and Praecordia. As to the other Faculties, of which sort are Imagination, Memory, Appetite, yea local motions and sense are exercised after one manner in those living Creatures, and after another manner in others; wherefore their brains are formed after a divers manner. But the motions of the Heart and Respiration in all endued with an hot blood, are performed after a like manner, that is, with a perpetual vicissititude of Systoles and Diastoles. Besides, another office is to be assigned to the Cerebel, and different from what is convenient or agreeable to the Brain; because where the folds and turn∣ings are wanting in the Brain, they are constantly found in the Cerebel. Besides these reasons drawn from Anatomy, the Pathology of the humane Body affords many others, which confirm the aforesaid office of the Cerebel. For it oftentimes hap∣pens, that cruel and horrid Symptoms infest the Praecordia and the region of the middle or lowest Belly; whilst in the mean time, the morbifick cause lyes in the Cerebel or nigh its confines. I have known sometimes men labouring only in ap∣pearance with a Dyscrasie of the hinder part of the Head, who complained of fre∣quent Swooning and repeated meltings of the Spirits or Deliquiums, as if they were just dying: in whom notwithstanding nothing more could be detected of the mor∣bifick cause or its seat, but that the Patient perceived a great heaviness and pain in the hinder part of the Head, and that upon any sudden motion or bending back of the Head, they were ready to dye. In truth, the Symptoms which are wont to be raised up in the distemper called the Incubus or Night-mare, viz. loss of speech, and a mighty weight or load that seems to lye upon the breast, proceed altogether from the morbifick matter fixed in the confines of the Cerebel, and obstructing the passages of the Spirits destinated for the Praecordia. But indeed this Hypothesis of the office of the Cerebel shall be more illustrated and confirmed from the uses of its several parts, being rightly designed or drawn forth.

As to the parts and accidents of the Cerebel, 1. we take notice, that the infold∣ings of the Vessels every where cloath the Cerebel no less than the Brain, also that the ridges and furrows of its folds intimately hide or cover it, which certainly is a sign that the animal Spirits are begotten in this other work-house of them from the watering blood, and instilled into its substance: which thing also more clearly ap∣pears, because the Arteries and Veins are not only variously complicated in the super∣ficies of the Cerebel, but both of them in like manner as in the Brain, send forth frequent shoots into its more inward substance; wherefore whilst the most subtil and spirituous part of the blood being carried through long windings about, and as it were serpentine chanels of the Vessels, and so sublimed into Spirits is received within; the bloody part is carried away by the shoots of the Veins sent also deeply down. Further, even as the more watry portion of the blood, destinated for the Brain, runs

into the Choroeidal infolding; (whereby it may there lay aside its unprofitable Phlegm into the Glandula's) so for the sake of separating the Phlegm an heap of Glandula's, with the foldings of the Vessels, as it were a Receptacle fitted for this business, is placed in the hinder region of the Cerebel.

2. From the blood, after this manner cleared from Phlegm, and made subtil by a long circulation, a very pure and spirituous liquor is instilled into the cortical sub∣stance of the Cerebel, which is presently exalted by the Ferment there placed into animal Spirits. For indeed we have affirmed, that the Spirits are procreated only in the cortical part of the Cerebel, as in that of the Brain: wherefore, because this kind of Cortex is wanting to the oblong and spinal Marrow, we think these parts do serve only for the exercise of the animal Spirits, and not for their pro∣duction.

3. The Spirits every where produced within the cortical or exterior compass of the Cerebel, in which they are presently prepared for the work of the animal Fun∣ction, are derived from all the folds into the medullar tract, and thence into two ample middle Marrows; where they keep full as it were the fountain or spring, and there like the bubling up of waters, are circulated within with a perpetual turn∣ing, and from thence they continually stream forth into the parts of the nervous System proper to themselves.

4. As to the ways of Emanation it is observed, that the two middle Marrows of the Cerebel pass as it were into two pedestals or little feet, by which they are fastned to the trunk of the oblong Marrow; and for that in either little foot of it three di∣stinct medullar Processes are found, all these, or at least two of them, are as it were so many paths whereby the animal Spirits stream forth from their fountain and flow back again.

5. The first of these Processes ascends into the Cerebel from the orbicular Pro∣minences: the use of this we have already declared; to wit, that there may be a certain passage between these Prominences and the Cerebel, in which, whilst the animal Spirits, as in a by-path, move this way and that way, to and fro, they may transmit both the force of the Passions from the Brain by the interposition of the Cerebel to the Praecordia, and convey also the natural Instincts delivered to the Ce∣rebel from the Praecordia and Viscera towards the Brain. But the second Process de∣scending straight from the Cerebel, embraces the medullar Trunk, and so going round about it, constitutes the annular or ringy Protuberance, out of which the fifth, sixth, and seventh pair of Nerves take their originals; so indeed, that this Protuberance seems to be the Ware-house or Store-house of the Spirits flowing from the Cerebel, from which they may influence and be derived into the opposite passages of the Nerves. Lastly, the third process of either little foot, descending from the Cerebel into the oblong Marrow, is inserted into its trunk over against where the eighth pair of Nerves have their original; so that it should seem very likely, the provision of the Spirits destinated for this Nerve is derived also by this way from the Cerebel; then what Spirits superabound, remaining longer than this Nerve requires, they sliding down into the common belly or chanel of the oblong and spinal Marrow, increase the plenty of those parts. For this same end the smooth and pyramidal bodies are reached out of the annular Protuberance above the oblong Marrow towards the Spine, to wit, that by the passage of those Processes the Spirits of that provision or stock superabounding, might flow out partly into the beginning of the eighth pair, and partly into the common tract of the medullar Trunk.

Thus much we have spoken briefly and summarily of the Uses of the Cerebel, and of its parts and Processes. But that it may be the better understood, and also that this new thought of Theory concerning the involuntary Function of the animal Re∣giment, may be more clearly illustrated, we shall here give you a more particular Order or Method of the Spirits brought forth in the Cerebel, and as it were take a view of, or muster their Arms or Forces. Further, it will seem to the purpose, that we should design or draw forth more openly the abundance or plenty of the Nerves receiving their gifts from this Fountain of the Spirits concerning the Acts to be per∣formed only of the involuntary Function.