Arteries unless the Arteries they accompany discharge their Blood into the Sinusses which as hereafter shall be shown they plainly do not for otherwise seeing they both grow capillary in their ascent from the Basis of the Cranium they must necessarily be both adductory Vessels than which by the Laws of Circulation there can be no greater an Absurdity Wepfer not knowing of these Veins was forced to think and consequently to affirm That the Arteries leave the Dura Mater in their extremities and terminate in the Pia Mater and so have their Blood reduced by the Veins there but this is evidently not so to the Eye of any who heedfully separates this Membrane from the other Before therefore I proceed to the description of the Blood-vessels belonging to the Brain it self which by the exactness of method I ought to do I hope it may be pardonable if I make a short enquiry after the unaccustom'd distribution of Blood-vessels Nature hath furnish'd the Brain in general with and the Reasons of its procedure therein The Truth then concerning this affair is That contrary to what hath hitherto been observed the Blood-vessels belonging to this part in general as hath already been observed are of two sorts the one belonging to the Brain it self the other to its outmost Integuments Now as to the first 't is observable that the Veins enter not the Brain nor run concomitantly like as in other parts of the Body with the Arteries the carotid entring at the fourth hole in the Basis of the Skull and the internal Jugular at the eighth the Vertebral Artery at the last and largest hole of the Skull and the Vertebral Vein at the ninth which Vieussenius mistakenly calls the tenth thro' which it runs into the internal Jugular Vieâ—ssen p. 163. par 3. at that Veins entrance into the round hole at the bottom of the Skull under the Styliform Process where the Sinus Lateralis meets it where after having advanc'd into certain venous productions called Sinus's they descend from thence in large Trunks growing capillary all-along in their passage till they meet the Extremities of the Arteries and are indeed no other than meer Branches of the Sinus's and consequently I look upon the Sinus's themselves no other than large Veins The common reason all modern Authors give for this different distribution of Blood-vessels belonging to the Brain from the other parts of the Body is that it may receive an equal warmth at the top as at the bottom as being thereby very much assisted in the production of Animal Spirits in an equal proportion all over and that it is so may very well be granted but that Nature had yet another provident Intention will be as evident if we consider that if the Veins had ascended with the Arteries thro' the holes in the bottom of the Cranium upon all great Ebulitions of the Blood the pulsation of the Arteries would in that Stricture of the Vessels made by the Bone of necessity hinder the freedom of its return by the Veins and consequently occasion a stagnation of Blood through the whole Brain to the utter subversion of all its faculties nothing being more certain than that upon any considerable abatement of circulation there presently happens by way of restagnation a secession of the watery and thin from the more gross and red part of the Blood The other way of the Veins entring the Brain viz. those appertaining to its outward Integument one at the sixth hole of the Basis of the Cranium the other at the eighth as aforesaid is their ascent with the Arteries after a quite different manner from the former even to their capillary Extremities a manifest indication that they serve for the reduction of so much Blood from the Dura Mater as the aforesaid sort of Vessels the Arteries have brought thither and although by reason of their smallness Nature seems not to have been so sollicitous in avoiding the Inconvenience supposed to have follow'd upon the Artery's entring the same hole with the Veins taken notice of in the preceding Case where they are very large and consequently the Effect might prove much more injurious yet Nature hath not been wanting in providing a Remedy against it as will plainly appear in the following Pages From this manner of their entring the Brain at the same inlet of the Skull with the Arteries may for ought I know be very rationally accounted for that violent troublesome Noise which many in Distempers arising from the turgescency of the Blood causing a preternatural beating of the Arteries do so much complain of a Symptom happening from the Stricture before mention'd which the unyielding circumference of the Bone occasions upon the different Blood-vessels entring at one and the same Foramen to which effect also the nearness of the Os Petrosum through which the Hearing Nerves do pass to this hole which is in that part of the Wedglike Bone that joyns to or is conterminous with it does not a little contribute To the same cause in some measure doubtless may be ascribed the frequent Headachs happening in Feavers the Artery then so swelling and compressing the Vein against the edges of the Bone that the Blood cannot be returned back through it in a due proportion and consequently by its stagnation the Membrane becomes inflamed and painful So that conformable to what hath already been taken notice of concerning the wise contrivance of Nature in ordering the different distribution of the Blood-vessels so as to avoid the Inconveniencies which might accrew to the Brain by compression of the reductory Vessels occasion'd through their entrance at one and the same hole with the Arteries it seems very much worth our observing that besides the Veins of the Dura Mater which enter the Cranium together with the Arteries as hath before been mention'd there are also several others belonging to this Membrane having their rise at and their descent after a very remarkable manner from a Vein hereafter to be describ'd on each side of the Longitudinal Sinus as you may see in the Figure FIG 4. dd nn c. and consequently must grow capillary in their descent down from it after a quite contrary manner to the other and these do visibly inosculate with some of the Extremities of the aforesaid capillary Arteries after the same manner as those larger Veins belonging to the Pia Mater do with the Arteries belonging to the Brain and it by which means it so falls out that a considerable part of that Blood brought up by the Meninx Arteries is carried back by these Veins to the end that especially in all preternatural swelling of the Blood the inconvenience of Compression and all its ill consequences happening by reason of an overfulness of these Vessels may be in a great measure avoided CHAP. IV. Of the Veins belonging to the Brain it self AFTER this short digression by order of Method the Blood-vessels belonging properly to the Brain it self fall under consideration The curious
dispersed thro' Bourd p. 196. par 2. it so forcible as to create a sensible Systole and Diastole in its outward coverings 'T is worth noting that while the Blood-vessels are all full so as to keep the Dura Mater upon its full stretch the pulsation is not vi sible at all or at least very faintly but after a depletion of the Vessels so as that grows somewhat more lax the beating becomes very visible equally in the Sinus and Membrane too After having made this Experiment I found one Author of the same opinion and that is Falloppius who in vindication of Galen against Vesalius his Contemporary says all I have said upon the foregoing Experiment and all the great Vesalius was able to answer in his own vindication in his ingenious Book call'd Anatomicam Gabr. Falloppi Observat Examen falls very short of its aim As to the Transverse Ligaments which are in some places * Fig. 4. r. round cordal and in others †Ibid. x. broad or membranous in the Longitudinal Sinus chiefly both serving for Strength and in concurrence with the cruciform ligamentous Fibres taken notice of by Vieussenius on the under and outside of this Sinus from whence the Fibres belonging to the falcated Process aforemention'd seem to have their original Elasticity to this part for its more vigorous reduction of the Blood passing through it together with its blind Cavities or Diverticulums serving to moderate the over-swift or violent motion of the Blood seeing I find them so exactly describ'd by Vieussenius to whom the Reader may have recourse I think their description need take up no room here But as to the manner of the Veins entring this Sinus I find it far different from that which is describ'd by Lower first Low fig. 4. h h. Vituss tab 2 D D c. and afterwards by Vieussenius both whom make them enter with their Orifices from behind forwards two or three only excepted by Vieussenius and that for some other useful purposes than what have hitherto been taken notice of And this is as follows Fig. 4. dd c. viz. About one half of them tho' intermixedly but all after having first upon their arival at the Sinus insinuated themselves for some space alter the manner of the Pancreatick Duct or Ureters first taken notice of by Lower Ib. dd c. betwixt the Duplicature of the Dura Mater from behind forwards the other half from before backwards as in the Figure Now by this contrivance 't is plain that first of all there are made two contrary Torrents in one and the same Channel by which means the refluent Blood made poor by the vast quantity of its richest parts drawn off as it were into Animal Spirits thro' a collision of Parts which by this contrivance must needs fall out is preserv'd in its due mixture which when at any time lost through the languishing of its intestine motion or elasticity retards even its circular or progressive motion which when it happens but in some degree is the cause of many Distempers and when altogether of Death it self In the next place the circulation is at all times not only somewhat retarded and the Blood hinder'd together with the help of the bony Cell at which the internal Jugular Veins enter the Sinus's especially in an erect posture from descending with that rapidness and weight it would otherwise have done upon the descending Cava to the Heart but also much more so retarded in a supine position of the Head a posture most natural and ordinary for Mankind to take their rest in through which contrivance in concurrence with that of the Lateral Sinus's whose structure is such that in the aforesaid posture the Blood is forced to climb upwards before it can arrive at the place of its descent into the Jugular Vein there is made a more plentiful generation of Animal Spirits one chief Cause of the great refreshment and vigorous disposition of the whole Body we find after Sleeping As to the other manner of the Veins entring this Sinus viz. from before backwards it from thence happens that in a prone Position of the Brain a posture not uncommon amongst Men the Blood is help'd forward in its circulation through the Sinus the truth and design whereof are at once both evident and pointed at by Nature from the Structure of this part and which therefore shews the great usefulness of Comparative Anatomy in Brutes who by reason of such a Position which the necessity of Feeding almost always keeps them in have always such a disposition of this Part to assist the Blood in its heavy circulation The design of Nature in making these Channels so wide on a sudden in respect to the Branches of Veins lately treated of terminating in them seems to correspond with the conformation of the Parts just now treated of and with that it had in making the Ramifications of Arteries afore taken notice of so large and unproportionable to the Trunks from which they spring which is a flower than ordinary circulation of Blood through the Brain in order to make a still more copious production of the Animal Spirits so called Which profitable Design and End of Nature had nevertheless been attended with a very great Inconvenience viz. an extravasation of too much Serum the usual effect or consequence of a slacken'd Circulation had it not been for another provident Contrivance of Nature in the two Communicant-branches betwixt the Carotid and Vertebral Arteries aforemention'd p. 36. by the narrowness of whose Channel the influent Blood is in some measure represt in its motion and an overcharging the Vessels with Blood prevented These Sinus's differ in structure one from another the Longitudinal and Lateral ones having many transverse Ligaments which the other have not and the Longitudinal having many small Cavities or blind Diverticulums as aforesaid which the Lateral have not the use of them all being for strengthening and defending them from giving way to the violent irruption of Blood into them against which sometimes notwithstanding they are not able to defend themselves as I have seen in many Skulls ni which the Blood hath burst open the sides of the Sinus's and found its way between the Duplicature of it so as even to have made a Fovea or Cavity in the Cranium it self as was before noted one of which I have now by me CHAP. VII Of the Plexus Choroeides THIS Plexus is an aggregate Body made up of Arteries Veins Membrane and Glands double on each side which hath not before been taken notice of and consequently having two Originals The first Original is from the foremost Branch of the Communicant Artery FIG 1. ee which running backward up betwixt the hinder Lobes of the Brain in which for some part of the way it is immerged and to which it gives many large Branches and the Medulla Oblongata at length arrives at the Lateral Ventricles FIG 5. ee and makes one part of
Anatomist Malpighius Malp. de Cereb p. 6. par 2. De Cort. Cereb p 81 par 2. in his Letter to Fracassatus says they bear a third proportion to those of the whole Body and for what reason seeing seeing the part it self bears not the same proportion to the whole it is so it will be worth our while to enquire hereafter These are either Arteries or Veins The former go under the name of Carotid and Vertebral The first of which after a curved passage which is very well expressed in a Fig. Willis p. 29. Fig. 1. of Dr. Willis from the place where it begins to enter the Basis of the Cranium which is from the Styliform Process of the Os Petrosum to the place where on the inside they pass through the Dura Mater and ascend into the Brain which is at the foremost internal Process of the Os Cuneiforme there is very near an inch and an half distance I say after this crooked passage into the Brain they are propagated quite through its substance having first divested themselves of that thick Coat borrowed of the Dura Mater during their stay in the passage aforementioned but not without the mediation or intervention of the Pia Mater which Membrane all the Branches of the aforesaid as well as the Vertebral Artery more or less first prop themselves upon before they enter on and disperse themselves through the substance of the Brain it self and is very finely expressed in a Cut of Placentinus Sig. p. 179 Mol. p. 77. Marchetti p. 191. par 5. at the end of Spigelius insomuch that Molinetti with whom also agrees Marchetti looks upon it as only a production of those numerous Vessels whereas all those little ramifications both of the Carotid and Vertebral Arteries viz. those from the carotid Artery which as soon as it gets through the Dura Mater and parts with its borrowed Coat are sent to the a Vieussen p. 35. par 1. p 34. par 6. Infundibulum b Tab. 17. c c. Olfactory and c Ib. g g. Optick Nerves together with those other of the Vertebral Artery which accompany pany the d Vicussen p. 35. par 1. third e Ibid. fourth f Tab. 17. p p. 35. par 1. fifth g Tab. 17. TT Tab. 4. sixth h h. p. 35. par 1. seventh i Tab. 17. Fig. 2. Tab. 4. h h. eighth k Ib. Fig. 2. ninth and l Tab. 4. h h. tenth pairs of Nerves inasmuch as they enter not the Brain it self are altogether exempt from that Membrane any of which now-mention'd Blood-vessels you either find delineated in Vieussenius's 17th Table or mention'd in some other place of his Book by those Directions here placed in the margin all which tho' existent in Nature are nevertheless there painted too stiff and formal I am afraid by guess inasmuch as that without an injection of Mercury except those two which belong to the Olfactory and Optick Nerves they do rarely come to sight in any form at all Wax being over gross a body to enter such minute Vessels as those are whereas by an injection with Mercury I find scarce any Nerves but what hath some such small ramifications of Blood-vessels in them To go about to describe distinctly the whole ramification of Arteries through this part which as was before noted is here more remarkable for number and size than in any other part of the Body would not only be to do what in a great measure hath been already done by Vieussenius in his sixth Chapter but seem to have also in it much more of oftentation than use I shall therefore only take notice of such propagations of them as are either remarkable for magnitude some curiosity of Structure or useful design of Nature And of this sort may well be esteemed the Vertebral Artery next after the Carotid which hath already been described as entering the Brain at the last and largest Foramen of the Skull contrary to what Dr. Willis Willis p. 29. col 1. par 2. and before him Wepfer affirms coming thither on each side out of the hole in the transverse Process of the first Vertebra of the Neck after a very remarkable curved manner as you see in the Figure Fio. 1. Eâ— and by no means like to the delineation and description given by Dr. Lower and Dr. Willis ascending laterally upon the Medulla Oblongata as far as the beginning of the Processus Annularis where they meet together in one single Trunk continuing so the length thereof Vieussen Tab. 4. bb by Vieussenius call'd Arteria Cervicalis after which they either send forth two Branches or receive two from the carotid Artery by means whereof there is a communication betwixt these two large Blood-vessels and that of great use and benefit to the Brain for by this means it happens that if even three of the four great Arteries which furnish this part with Blood were totally obstructed there would yet be a way left for a competent supply from the other unobstructed fourth These I call the Communicant branches very ill pointed in Bidloo's ninth Table but very well in Vieussenius's fourth as may plainly appear here in the Figure taken exactly from Nature it self FIG I. dd The structure and sinallness of these Arteries seem to suggest two yet further provident Intentions of Nature The first is the same it hath expressed in several other places as in the ascent of the Blood by the Carotid Arteries both which enter the Brain in a crooked line the first at the fourth hole of the Basis of the Skull the second from the hole in the transverse process of the first Vertebra of the Neck after the manner already in both places described So in the like manner here by the narrowness of these Branches the Blood is in a great measure retarded in its motion to the carotid Artery and by consequence to the Brain it self which for Reasons hereafter to be given in describing the Sinus's would otherwise be in great danger of being overflowed with extravasated and restagnant Blood The second is a forcing the Blood more plentifully into the Spinal Artery with which tho' through the conical structure of the Arteries in common it cannot be altogether unfurnish'd yet by its perfectly-reflexed position would have it very scantily were it not that by reason of the narrowness of the aforesaid Communicant-branches betwixt the two great Arteries the Blood was driven back in a sort of a retrograde motion 'T is true there is a conformation of Arteries something like this tho' not altogether in the mammary and epigastrick Branches but 't is worth noting that in both these places the main Artery from which these Branches spring is much more taper or conical Ibid. p. c c and the succeeding exporting Vessels far less both in number and size than those of the carotid Artery here whose foremost and hinder lateral ramifications between the Lobes of the
to make my self a Party on either side at this time seeing the fineness of structure and dignity of functions are sufficient to give preference to one above another and to render it more worthy of a particular consideration And this part I take to be the Brain the delicacy of whose structure is such that with no little resemblance to its divine Author whilst it gives us the greatest and clearest discoveries of other things lies most concealed it self And seeing all that Mystick Knowledge which in ancient times in the eyes especially of the Vulgar appeared meer Necromancy or Witchcraft as well as all the Curious Discoveries of more modern Ages upon the whole subject of Nature now going under the more familiar and proper term of Refined Sence or Philosophy hath been meerly owing to a more acurate knowledge of the parts and modification of Matter I see not any more likely way of conquering the difficulties yet behind upon any particular subject than the endeavouring after a further and more nice scrutiny into it by such means and experiments as serve to bring its most minute parts and texture under the test of Sence which so assisted doth the same office to the discerning faculty at good artificial Glasses do to it bringing the Object and Judgment to such a nearness that even the first Link of the Chain becomes discernable and the mechanical proceedings of Nature so highly instructive to the Understanding in its finding out and assigning proper Causes to Effects much more obvious and intelligible I shall therefore treat this Noble Part after the aforesaid manner with all the Justice I can leaving those invisible and almost divine things called Animal Spirits to be treated of more at large by those more illuminated Philosophers who see best when their Eyes are put and content my self with making an inquiry into and giving a description of whatsoever upon this Subject by Dissection shall offer it self as an Object of our Senses THE ANATOMY OF THE BRAIN CHAP. 1. Of the Anatomy of the Brain THE topmost part or Olla of the Cranium being removed the first part of the Brain that comes in view is the Dura Mater which with the subjacent Pia Mater is accounted only an improper part of the Brain strictly so called however of great use in many respects to it 'T is by Spigelius and other Anatomists reckon'd and I think not undeservedly the thickest and hardest Membrane of the whole Body enclosing the whole Brain properly so called somewhat losely sticking almost inseparably to the Basis of the Cranium and to the top and sides under the Coronal Sagittal and Lamdocid Sutures very fast by the Sinus's whose description will come in another place In some places of the upper part of the Cranium which on each side of the Sagittal Suture or Vertex are called Ossa Bregmatis it adheres not to the Bone notwithstanding the positive Opinion of Van Roonhuyse Roonh p. 149. in his Leiter to Du Foy to the contrary who for that very reason would fain take away in a great measure the use of the Trepan and Trefoyne and altogether the use of the Instrument called Decussorium which skilful Surgeons do often make use of to make room for the discharge of subsided matter below the fractur'd place in many Accidents of the Brain 'T is very discernably double as Columbus and several others formerly Col. p. 348 and Vieussenius lately have observed having very strong and large Fibres on the inside but very small Vienss p. 3. and hardly visible on that side next the Skull as appeared to me after having first let it lye a little time in bolling or at least very scalding Water But as to the distribution of the double sort of Fibres on each side this Membrane I could not by any means find them agreeing with the description Vieussenius hath given of them as running in an oblique semicircular manner externally from before backwards and in the same figure internally from behind forwards but far otherwise on the inside where they are very strong they seem manifestly to have three originals from the top part of the Processus Falcatus before behind and in its middle those before running in a curved manner backwards half the length and a great width of the Dura Mater and those behind running after the same manner forwardly with this difference that a great number of them bend soon after their rise from that process in a kind of a semilunary way to it again a little on this side the rise of the middle Series of Fibres others of them making a bigger arch after having stretched themselves wider upon the Dura Mater bend back again to and terminate in the Falx a little beyond the rise of the aforesaid middle Series of Fibres Those from the middle part of the Falx run backwardly but less curved than the rest terminating as the Fibres which arise backwardly do at some distance from the Process in the inward Superficies of the Dura Mater As to those belonging to the exernal side or second Lamina of the Dura Mater they are extream small and obscure running from behind forwards Besides these there are no less remarkable ones belonging to the Falx it self of two sorts of Orders the one running streight about half the length of it on its upper part from before backwards the other transverse from the inferiour or fifth Sinus to the superiour or third on the hinder part of the Process and are most conspicuous there as the other are towards its foremost part As to the Use of those Fibres it may be remembred that this Membrane consists of two Lamina's between which the Veins which reduce the Blood from the Arteries which furnish the whole Brain with it run for some space after the manner of the Ureters in the Bladder in large Trunks before they enter the Sinus so that the Fibrous Constitution of this Membrane here where the Blood-vessels are largest together with the curved entrance of them into the Sinus especially in an erect position of the Body do the office of Valves support the weight and promote the ascent of the Blood But that which is most considerable is this That if the inward Lamina of this part which makes the inferiour and lateral part of the Sinus was not in some measure furnish'd with additional strength on this side suitable to that which it hath on the other by reason of its cohesion to the Skull the Blood which is continually running through it with no small rapidity especially in great plenitude of the Vessels or preternatural Ebulitions would frequently burst out or at least cause such distentions as could not but be very injurious to a part so very exquisitely sensible yet notwithstanding tho' Nature seems plainly to have made a double provision against such Accidents by the transverse Ligaments within the Sinus and these strong and numerous Fibres without I have rarely open'd any strangled Body where some
together with almost all the Ancients as Vesalius Columbus c. to the contrary I have never found this Rete wanting or with any difficulty discoverable in Men springing from and lying on the inside of each Carotid Artery in that place of the Circular Sinus chiefly which looks into the four abovemention'd inferiour and superiour Sinus's in the Basis of the Brain and in some measure also the whole length of the Sella Turcica on each side between the Gland and the Carotid Artery And that it is so small in them with respect to what it is in Brutes of several kinds is no way surprizing when consideration is had to the Use and Service of it in those Creatures who by reason of their prone Position would otherwise be in danger of having their Brains deluged as it were with an over-great quantity of the Influent Blood and of a Rupture of the Vessels by its violent ingress and this Danger so much the more threatned by how much the same Cause which brings it into the Brain with that force is equally as great and effectual to hinder its proportionable return for the relief of which Inconveniency Nature hath contriv'd a means of its more easie and safe descent into the Brain by turning that one large Stream of Blood which through its being penn'd in one Channel becomes so rapid into many more by which means the Carotid Trunk above the Dura Mater in those Creatures is very small to what it is beneath whereas that Artery in Men c. hath the same bigness on both sides that Membrane and they not only reticulated and contorted for the more slow and laborious which Contrivance the Ancients thought was only for a more exact preparation of the Blood for Animal Spirits descent of the Blood but also many of them by their insertion into the Glandula Pituitaria attended with small Veins issuing thence to take off some part of the burden too This last contrivance of Nature methinks may be sufficient to render that Controversie of Vieussenius with Willis which before them Vieuss p. 16 pat 2. was bewixt Waleus and Rolfincius the two latter on each side denying this Rete to have any Veins very needless feeing that if the Pituitary Gland have any which I am confident it hath notwithstanding the positive Assertion of Diemerbroeke Diemerbr p. 364. par 3. in order to serve his own most unprobable Hypothesis to the contrary as having seen them plain injected with Wax then this part of the Blood in some of the Branches of the said Rete which are plainly inserted into the Gland is equally capable of being reduced by those Veins without any necessity of having recourse to those remote Branches Vieussenius hath been forced to seek for Vieuss p 45 par 2. as if it had had them of its own And that to the aforesaid Position of different Creatures ought chiefly to be ascrib'd the variety of Magnitude of this Rete in several of them its size in Dogs seems highly to evince in which by reason of their Horizontal Position being neither so prone as several Brutes who seed on Grass nor so erect as Man that Rete is found smaller than in the first and larger than in the last Another Use it hath been thought to have is to carry off a considerable quantity of a dull watery part of the Blood in order to the production of the finer Animal Spirits and this it is thought to effect by means and help of the Pituitary Gland betwixt which and it self there is constantly observ'd a greater affinity the one being either greater or lesser in proportion as the other is so and betwixt which there are in all Creatures but more remarkably in those where they are both large a distribution of several Branches coming from the aforesaid Rete And this is look'd upon by Vieussenius so considerable an office of the Glandula Pituitaria that in those Creatures where it is but small as in Men Horses Dogs c. he hath substituted many Vieus p. 102 par 3. but particularly two Cavities for that use in the Wedglike Bone just under the Sella Turcica in which he supposes that part of the aforesaid Serum which by the smallness of the Rete cannot be return'd that way is remitted by several little Arteries slipt off from the Carotid whilst under the Sella Turcica terminating in the two abovenamed Cavities there either deposing a part of the Serum to be carried off by a strange way he there mentions viz. by two holes into the Nostrils and thence into the Fauces or else by certain Veins meeting them in that place as their proper Reductory Vessels Vieuss p. 9. par 2. to the Heart Now as to this office of the Glandula Pituitaria I cannot easily be perswaded it is either design'd for or capable of it till such time the Abettors of this Opinion can be able to show me it furnish'd with an Excretory Duct for this purpose And if they offer that the Veins are such I reply That besides its being very unprobable that so vast a quantity of Blood as continually is brought by the Carotid Arteries to the Brain should be able to get rid of any considerable quantity of its Serosity by so small a part as the Glandula Pituitaria is 't is not the usual way of Nature to part with any Share of its Juices out of its Vessels when so unactive and unprositable as this is and immediately to receive it in again seeing it is provided of Emunctories enough to convey it away by Moreover granting which by no reasonable means is to be granted it were so as they would have it yet nevertheless in conformity to Nature's proceedings in all such-like case there ought to be an intermediate passage by way of a Secretory Duct which none hath been able hitherto to discover And so far as Vieussenius seems to be of this opinion Vieus p. 102 par 3. which in one place he plainly is making it of so gross and viscid a nature as is only sit to be discharg'd at the Emunctory of the Nose the same Reply is satisfactory But when by way of flat contradiction to himself he comes to make the same gross Humour a perfect fine Lympha the Answer is then Vieuss p. 54. par 1. That there is no need of parting with it beforehand seeing we find that Liquor only separated by the Lymphaeducts of the Brain afterwards Seeing therefore there is such an affinity as before mention'd between the Rete Mirabile and Glandula Pituitaria and taking it for granted that the office of the Glandula Pituitaria is not what it hath generally hitherto been believ'd to the end we may attain a more exact knowledge of what it really is it seemeth not altogether immethodical to take that part into consideration in the next place together with the Infundibulum which last hath not only as near a relation to the Gland as the Gland
is that of Instinct relating to the Sensative Soul or an aptitude of the Nervous Structure to act according to the Impressions made upon the Nerves either from within or from without and so may be said to depend on the presence of such Causes as are supervenient and extraneous to Nature suitable to the impressions whereof the Animal either pursues or avoids the Object obeys or resists the Impulse Now I take it for granted that no body will deny but that the Nerves by vertue whereof these last actions of Instinct are performed whether thâ—y â—râ—se from the Cerebrum of Cerebellum are equally under the command of the Soul or else as I said before the Brain in those Creatures is to no purpose And of this sort I reckon all those actions in rational creatures of Instinct before they have attain'd to the use of their Vnderstanding from any sort of Impressions or inadvertent and inconsulted when he hath the controuling power of Reason allow'd him and makes no use of it such as are called Habitual which at first were produced by command of the Rational Part only but through frequent repetitions at last without any command from that out of a blind obedience to a bare impulse from the Object or lastly such as happen when he hath altogether lost the use of it as in Sleep or Distraction in which last Cases 't will be very difficult to distinguish him from a meer Machine or Automaton Now from what hath been said I cannot but think it plain that many of the Actions before spoken of in Dr. Willis's sence by him called Involuntary as proceeding from the dominion of the Cerebellum only such as he calls the various Configuration of the Face from some Impulse or Provocations in the Viscera or elsewhere erecting the Ears turning the Neck and Eyes about sudden Shrieks and Outcries upon some extraordinary frightful Object surprizingly affecting one Sense or another furnished with either such Nerves as he supposes to be altogether under the command of the Cerebellum as the fifth and seventh or else to have a very near correspondence with that part by vertue of Vicinity as the ninth do more truly proceed from that perceptive faculty or to use his own words that part of the Soul he hath confin'd to that part of the Medullary System called the Cerebrum inasmuch as in reasonable Creatures they may and commonly are suspended as well as the Nerves they slow from sometimes made use of as Instruments of Voluntary Motion by it also and to think the contrary is as much as to say that when any body happens to express any of the aforemention'd involuntary Acts or but hit his Bedfellow a box of the Ear whilst asleep all these must be allow'd to proceed only from the Organ of Involuntary Motions called the Cerebellum And of this kind also in a great measure I reckon Respiration concerning which I cannot easily be brought to think it satisfactorily explain'd by Dr. Willis from the Energy of those Animal Spirits which flow only from the Cerebellum in the Par Vagum after the same manner they do to the Heart by the Intercostal and that Pair for its pulsation and as only under the command of the Soul to be stopt now and then as it pleases by vertue of some Nerves communicated to the Intercostal Muscles and Diaphragm the chief Instruments of breathing from the Spina Dorsi I am therefore rather enclin'd to think this Motion is of the other different kind before spoken of under the Title of Instinct proceeding from an extraneous supervenient Cause acting conformably to the course of Nature in oother Cases of the same kind as in Hunger and Thirst and the like where the obtaining the designed End or Effect renders the part from whence comes the Motion for some time insensible of the impression and where after the ceasing of the Effect or Motion the sense of the impression revives again whence there happens an equal reciprocation between the Sense and Fruition or Sense and Motion To apply this account of the manner and reason of the Spirits acting upon the Stomach and Parâ—â—te in relation to Hunger and Thirst to that of the Systole and Diastole of the Lungs or Respiration 't will be needful to take notice that in an Infant unborn there is no Respiration but yet there is a Cerebellum and that if this sort of Motion called Instinct which I make to differ from purely Natural Motions such as are contemporary with even the first living Rudiments of the Individual was altogether and solely owing to the Cerebellum after the manner of that of the Heart then of necessity the Child in the Womb ought to respire But being satisfied of the contrary it remains that we account for its respiration another way which is as afore noted through the presence or absence of the first moving Cause or Impulse which I make or suppose to be any thing impressing the Nerves propagated through the Organs of Breathing so as to transmit the impression from within to the perceptive Faculty presiding both over the Cerebrum and Cerebellum too to the end the Spirits may from thence forthwith be commanded into such other Nerves as act those Muscles which serve for enlarging the whole Cavity of the Thorax in order to let the Air into the Lungs more plentifully which was the thing aimed at by Nature and these are the Intercostal Muscles and Diaphragm Now 't is easie to conceive that whilst the Child is enclosed in its Mothers Belly there is not that occasion for Respiration as when 't is born the main Stream of Blood all that while finding no passage thro' them and that which does by the Ruyshian Artery made of Juices much more mild and cooler the native heat being little and the Aliment meer Chyle or Milk from whence it falls out that the Pulmoniâ—k Nerves go altogether unprovoked which after birth are continually otherwise impressed or provoked by the hot Effluviums of Blood new bred of stronger Food and by a stronger native heat and wholly flowing through them which heat continually as the Child acquires a greater maturity encreasing may for ought I know not a little contribute by way of natural impulse to its exclusion The truth of this will the more clearly appear to any who will take the pains to consider well of the structure of Parts in Children unborn in whom the usual circuit of Blood through the Lungs which are designed for rarifying and perfecting the mixture of Blood and Chyle is denyed as also through the Liver serving chiefly for separating that gross Excrement the Gall not bred at least in any proportion in an Infant unborn and in lieu of these other Passages which become altogether unnecessary after birth provided by Nature after a shorter and more compendious way viz by the Foramen Ovale betwixt the Vena Cava and Vena Pulmon and Tubulus Arteriosus between the Art Pulm. and Aorta in the Lungs and
the Trunks in the Brain p. 55 The Vse of the narrowness of the Communicant branches p. 56 How the Carotid Artery in Brutes comes to be smaller above the Dura Mater than under it p. 65 Animal Fluid what p. 91 108 155 How it passes out of the Carnous Fibres p. 109 Its effect in glandulous and other parts not serviceable to Muscular Motion ibid. It s production p. 115 Anus p. 124 Aquae emissarium of Vieussenius p. 132 B Brain its Vessels in general p. 20 Their kinds ibid. Blood vessels their different distribution in relation to the Brain it self and its Integuments ibid. 26 The reason of this different distribution p. 27 Blood-vessels belonging to the Brain it self only p. 32 What proportion the Blood-vessels of the Brain bear to the rest of those of the whole Body p. 32 38 The remarkable propagations of its Arteries p. 35 Blood-vessels belonging to the Nerves p. 33 34 Blood in the Sinus's hath two contrary torrents p. 53 The effects thereof ibid. How the circulation of the Blood comes to be retarded in the Brain p. 53 The Bony cell where the Sinus's go out into the internal Jugular p. 53 The effect of its structure ibid. 54 The Brain how distinguish'd p. 87 113 Its two Substances ibid. Their structure p. 89 90 Why of a different colour p. 90 92 Blood why red p. 91 How the Brain is suspended p. 7 8. Its Lobes and particular description p. 113 114 Its hinder Lobes stretched backwardly beyond the Cerebellum ibid. Original of its medullary part p. 115 Bombyces vide Hippocampi Blood-vessels of the Nerves p. 144 Watery Bladders instead of Brain p. 178 179 Brain petrified p. 179 Propriety of the Brain to Nerves often thought under the power of the Cerebellum p. 198 C Consent of Parts p. 19 Carotid Artery vid. Artery The Circular Sinus p. 43 Communicant Branches between the Carotid and Cervical Arteries their Vse p. 55 56. The Cortical or cineritious part of the Brain p. 88 It s medullary part ibid. Corpus Callosum p. 115 It s Striae p. 116 Centrum Ovale of Vieussenius p. 117 Crura Fornicis p. 818 Commissura Crassioris Nervi Aemula of Willis and Vieussenius p. 126 Corpus Callosum p. 115 Centrum Ovale p. 117 Crura Fornicis p. 118 Corpora Striata p. 120 The Cerebellum p. 133 Its dâ—fference from the Brain p. 135 Corpora duo alba pone Infundibulum p. 140 Olivaria ibid. Power of the Cerebellum p. 170 173 D The Dura Mater p. 1 Its manner of adhesion to the Cranium p. 2 Is double ibid. What sort of Fibres and their distribution p. 3 Their Vse p. 4 5 6 How affected in some Distempers particularly in Vapours p. 6 Its Nerves ibid. Its Processes p. 7 9 Their Vses p. 7 8 9 Its Blood vessels apart from the Brain their number and distribution p. 20 22 Two sorts of Dropsies of the Brain observed by Tulpius and Wepter p. 59 Their Solution ibid. 60 E Elasticity of the Blood p. 53 The Effects of that being weakened ibid. Extravasation of the Nutritious Fluids its effect p. 97 Elasticity not competent to the first principles of Bodies p. 100 The Occasion of it in other Bodies ibid. Elasticity it s aequilibrium in the whole compapages of Muscles p. 105 The Effect thereof ibid. 106 Experiments by Injection of what use in Muscular Motion p. 110 F The Falx and its particular uses p. 7 8 9 Is wanting in several Creatures and why p. 9 Fibres of the Dura Mater do the office of Valves p. 5 Fleshy part of the Body what p. 94 Fluids of the Body their different motions p. 96 Fornix p. 117 It s Crura p. 118 The Fornix of Vieussenius p. 115 The Fornix commonly so called p. 117 It s Fimbria according to Vieussenius p. 118 It s Crura ibid. How natural and vital Functions relate to the Cerebellum and with what difference p. 170 171 How they come to be not under the power of the rational Soul p. 174 How performed when the Brain is utterly incapable of acting p. 177 G The Glandula Pituitaria enclosed in strong Membranes p. 46 No Serum can get through its Integument ibid. 75 Glands of the Plexus Choroeides p. 63 63 The Glandula Pituitaria not capable of carrying an Excrementitious humour p. 69 73 The Gland Pit its situation p. 71 Is not suspended in Men as in Brutes ibid. 73 In substance it differs from all other Glands ib. Is of two sorts and why p. 81 In what manner the Lympha gets into it ibid. The Glandula Pinealis its situation and connexion p. 83 Is of the Conglobate kind p. 84 Errors of Des Chartes Lower and others about it p. 84 85 Geminum Centrum Semicirculare of Vieussenius p. 122 H Headach how happening in Feavers p. 29 From the closeness of the Pores in the Cranium p. 42 Two sorts of Hydrocephalus p. 59 Hippocampi Arantii p. 118 Their Striae ibid. I Injection with Mercury makes Blood-vessels appear p. 34 The Infundibulum p. 77 The difference between it in Men and Brutes ibid It s two Ducts in Brutes p. 78 Its Office p. 79 80 Infundibulum the passage into it by three Foramina's p. 124 Isthmus p. 125 Instinct what p. 162 163 The differing effects of some Impressions upon the Soul p. 181 182 183 Transmission of Impressions according to Doctor Willis improbable p. 184 185 Difference between involuntary and inadvertent acts p. 187 Internal Senses their seats p. 190 L Lsgaments of the Sinus's p 51 Their Vses p 52 56 Lateral Sinus's p. 40 Longitudinal Sinus's p. 41 Lymphaeducts of the Brain p. 61 62 Lympha how generated within the Ventricles p. 81 82 To what end ibid. Laughter how made p. 181 Why peculiar to Man p. 182 Libidinous Actions how caused p. 181 182 M Membranes of the Brain vid. Dura and Pia Mater Muscular Motion p. 99 Divers Opinions about it ibid. Muscle its inflation or contraction p. 102 106 Muscle how contracted or swelled by force p. 104 Muscles the effect of their being cut through p. 105 Muscles their hardness and swelling in contraction whence caused p. 106 107 Muscular Motion some particular Phoenomena about it solved p. 110 111 Muscular Motion made by the Nervous Fluid alone without concurrence of the blood p. 177 A Medullary Tract not before observed p. 123 Medulla Oblongata p. 139 It s Crura ibid. Animal Motion p. 158 Motion voluntary and involuntary p. 159 160 Two sorts of Motions in Brutes p. 161 Medullary Tracts of the Brain p. 192 N Noise in the Head how occasion'd p. 29 Nervous Juice p. 88 93 Nutrition p. 88 89 94 Nervous Juice how generated ibid. Nerve its structure p. 93 The effect of its being taper ibid. 102 Nates p. 125 Nerves Olfactory p. 143 Optick p. 144 Motorium or third Pair p. 145 Patheticum or fourth pair p. 146 The fifth pair p. 147 The