marrow which are sent down directly into the substance of the heart as if the more easily to convey some influence into it No great difference this and yet the cause that induced Nature to make it may be great What it is is difficult to find out It may probably have some respect to the prone posture of Brutes which being horizontal must cause the ponderose machine of the heart to swagg and the cone to point not toward the midrif as in erect man but toward the Sternum and therefore in them there might be need of more auxiliary Nerves to assist the hearts motion in that position But whatever may be the true reason I do not assent to their conjecture who say that because the heads of beasts look downward therefore the providence of Nature hath furnished their hearts with more Nerves lest Animal Spirits should not in sufficient swarms be sent every moment from the prone head into the heart of a Brute that position of the brain forsooth rendring the transmission of these Spirits more difficult and slow And the reason why I do not assent to this witty conjecture is because neither the Authors of it nor any other man whose writings I have read have sufficiently proved that there are such things as Animal Spirits in rerum naturâ In some books indeed whole Common-wealths of them are found so that ye can hardly pass along without meeting crouds of them But till I see their Existence otherwise than precariously asserted I am justly excusable if I doubt thereof The Heart being thus composed of many myriads of strong Fibres of various orders by most dense contexture compact and of various Nerves intersperst it required to be continually cherished with due heat as well without as within Wherefore the Heart having no heat but what it receives from the bloud in which only the true Calidum innatum the lar familiaris resides Nature hath furnished it with two Arteries for its own peculiar use divided almost from their origine into two trunks the Orifices of which open themselves near to the beginning of the aorta immediately without the Valvulae Semilunares They are fitly called Coronary Arteries because their trunks do not presently enter into the parenchyma or substance of the heart but first make their tour or circuit the more commodiously to disperse their branches round the basis of it in manner of a crown or rather a Diadem and though from their very original they divide and recede the one from the other to the opposite regions of the heart yet they meet again in their extream branches and by mutual Anastomóses or inosculations communicate betwixt themselves so that if any liquor be injected into either of them it will in a moment appear to diffuse it self also through the other And this mutual Communication seems to be design'd to a good end For since the necessity of influent heat or life is equal in all parts of the heart that necessity could not be more commodiously satisfied any way than by this Artifice of mutual inosculation betwixt the extremities of these two Arteries No sooner hath the bloud thus imported communicated its vital heat to the substance of the heart than it is thence exported by the two Coronary Veins which in like manner encompassing the heart and by their numerose emissary surcles imbibing the bloud effused out of the Arteries reduce it into the right Ventricle thence to be brought through the Lungs back again into the left So that here is a private circulation in a small circuit instituted for the peculiar benefit of the Heart As the extreme surcles of the Coronary Arteries are mutually inosculated so also are those of the Coronary Veins as is apparent from ocular inspection For if you take the heart of a Calf or any other very young Animal for in such these vessels are most easily discernable and with the back of a pen-knife gently impel the bloud from one side of the heart toward the other you shall see it flow out of the Vein of one side into that of the other and vice versâ Nor is it to be doubted but that in all other parts of the body there is the like mutual communication per anastomôsin betwixt Capillary vessels of the same kind Besides the proper vessels of the heart now described there are annext to its basis also two Subsidiary Muscles hollow and round from thence call'd Auriculae cordis framed with no less art than the Heart it self though of less bulk For they are composed of robust Fibres too and disposed in the same order and as their motion precedes that of the Heart so have they Nerves from surcles of the Eighth pair before they reach to the heart it self Besides their intermediate fleshy Fibres which form little musculose columns are elonged to opposite Tendons For the Tendon at the basis of the Heart is common also to the ears of it and serves them for a fulcrum or prop and on the other part of the right Ear where it respects the Vena Cava it is firmed by a harder and Tendinose circle betwixt which two Tendons the Fibres tending to each are terminated as appears in the right Ear of a human heart inverted Of these Ears the right is always greater than the left Perhaps because the flux of the bloud being less rapid out of the Vena Cava into the right Ventricle of the heart than out of the Arteria Venosa into the left whither it is impell'd by the compression of the Lungs and by the coincident elasticity of the inspired air it was therefore requisite the capacity of the right Ear should be proportionately larger to receive and transfund into the right Ventricle a quantity of bloud sufficient to fill it For evident it is that the office of these Ears is like that of funnels to transmit the bloud into the Ventricles of the heart For the same reason the trunk of the Vena Cava when it approaches to the heart participates somewhat of the nature of a Muscle For there it is furnished with fleshy circular Fibres by which it is constringed and consequently the bloud running through the canale thereof is urged the faster into the right Ear in the same manner as when a gut or bladder is outwardly constringed by the hand the liquor therein contained is expressed and its regress hinder'd We have now survey'd the Structure of this admirable Machine the Heart at least so much thereof as may serve to render more plain and intelligible what I am about to say concerning the Action thereof To which I now pass ¶ ⸫ Evident it is both to the sight and to the touch that in the act of Pulsation the whole fleshy substance of the heart is stretcht and hardned with very great force as all other Muscles are when they act and certainly this tension and induration arises from the very Structure of the heart For the Fibres of the columns of it and their
Actions and Uses of the Ears and Valves of the heart first discover'd by our immortal Dr. Harvey and since confirmed by various experiments of other excellent Anatomists Being then certain of the Phaenomena it remains only that we endeavour to explore the Mechanic causes of them In the first place because the Ears of the heart are Muscles round hollow and composed of fleshy Fibres wound about Spirally and intersecting each the other decussatim and because they end into little columns and trenches in the same manner as the left Ventricle is framed therefore must they operate by the same Mechanic necessity and Artifice by which the heart operates viz. by the force of a Press and by wedges insinuated into the Pores of their Fibres they must be swell'd and so constringed and consequently express the bloud contein'd in them Secondly That the constriction of these Ears ought to precede the contraction of the Ventricles of the heart though both motions seem to be performed at one time may be thus demonstrated For if this be not true then either the Ears and Ventricles of the heart are constringed in one and the same moment of time or the heart is first constringed and then the Ears If the first because the triangular valves have no use before the heart is constringed nor after the constriction of it is complete because the shutting of the Valves would be in vain when the bloud cannot flow back and slow back it cannot before the heart is constringed because then the bloud is not yet in the Ventricles and so cannot be impelled by the Systole of the heart and after the constriction of the heart the expulsate bloud can much less flow back therefore it is necessary that at what time the Ventricles are constringed at the same time the Venose orifices ought to be exactly shut by the Triangular Valves that the bloud may be impelled not backwards but forwards into the Arteries But if at that same time the Ears were constringed they would inevitably vomit out the bloud contein'd in them into the Ventricles and so open the clausure made by the triangular Valves because they are so disposed as to be opened and dilated by the very coming of the bloud Wherefore at the same time the bloud would be impell'd by the Ear into the heart and repell'd by the heart and so these two contrary motions would mutually destroy each the other and both be in vain Besides when two outlets are at the same time open in one Ventricle of the heart the whole compressive force of the heart is divided into two equal parts which impell the two halfs of the bloud one backward the other forward into the Arteries and therefore Nature would foolishly by a double endeavour attain but half her end We may add that the triangular Valves would be wholly useless since they would then urgente necessitate be open when they ought to be shut Wherefore it seems impossible that the Ears of the heart and its Ventricles should be constringed at the same time But if we suppose the natural order to be inverted i. e. that first the Ventricles of the heart are constringed and then the Ears compressed this would be much more absurd for half of the bloud contein'd in the Ventricle would flow back into the Ear on both sides open and thence into the Vein It must therefore be confessed that the constriction of the Ear ought to precede and then immediately ought the constriction of the Ventricle to succede and then all the operations procede regularly and compendiously For the Ear being comprest first the regress of the bloud into the Vein is hindred next the bloud is expressed out of the Ear into the cavity of the heart Thirdly the Orifice of the heart is shut by the constringed Ear Fourthly the Ventricle of the heart being filled with bloud and distended the Membranes of the triangular Valves are expanded These actions being in this order of succession done then in the fifth place follows the swelling of the heart by which all the bloud in the Ventricles which cannot by reason of the double clausure slow back is forced to run forth by the open door of the Artery Thirdly it is observable that the action of the right Ear differs from that of the left because the bloud ought to flow out of the Arteria Venosa or as some call it the Vena Pulmonaria which is very ample into the left Ventricle of the heart with a swift current by reason of its gravity and of the compression of the Lungs For this reason a little Ear is sufficient to transmit the bloud so swiftly running into the left Ventricle and with the help of the mitral Valves also exactly to shut the aperture of the heart On the contrary in the right Ear the slowness of the blouds influx ought to be compensated by the amplitude of the Canale And moreover because the right Ear ought not only to close the Orifice of the heart but also to impel rapidly the slow paced bloud into the right Ventricle therefore Nature hath made the Muscle and cavity of the right Ear stronger and larger than that of the left Fourthly We may farther gratifie our curiosity by considering the manner how the triangular Valves exactly shut the Orifices of the heart which seems to be this Because these Membranose Valves have their bases fastned to one part of the circular Tendon of the Orifice of the heart as flags are fastned to their staves and their other sides are by many Tendinose Filaments or strings fastned to the fleshy teats in the opposite part of the cavity of the Ventricle as Webs of Linnen exposed to the Sun are kept upon the stretch by many small cords tied on each side Hence it comes that by the stream of bloud rushing in the cavities of the Ventricles are dilated and so these Membranose Valves which before were lax and flagged are drawn and expanded transversly so as to spread themselves through the whole space of the Orifice Necessary it is therefore that the points and sides of these Triangular Valves thus drawn by the little cords decussated should be conjoyned and being conjoyned make one Conical superfice greater than the plane of the Orifice or of the circle of the basis of the same Cone After this follows the Systole of the heart when the insides of the Walls of the Ventricles are united and therefore those little cords of the Valves are at the same time relaxed and united also and so the faces of the Triangular Valves themselves must be united and acquire a Sinuose or embowed figure their Superfice not diminish'd because their membranes are not contracted Whence it comes that the bloud filling the Ventricle doth by repelling the membranes and inflating them bow them as the Sails of Ships swell'd by the wind are bowed into a hollowness Again since those membranes thus embowed are transfer'd toward the Tendinose Orifices of the heart the round area of
said that Fibres when they act cannot possibly exercise their force by their contraction and by drawing their extreme terms towards the middle because by a corrugation or shrinking up into wrinkles of their length they must rather be relaxed Therefore as a weight hung on to a lax cord cannot be raised thereby while the cord continues lax So by Fibres lax and corrugate cannot the opposite walls of the Ventricles of the heart be violently drawn together and conjoyned Secondly but if we suppose that the Fibrose Spires of the heart are not wound about tortuosè with turnings and windings quite home to the Ventricles but extended in a direct course into the Ventricles and there bound together into those fasciculi or sheafs which compose many little Cylinders or cords then indeed a man may think that by simple contraction of the Fibres those little Cylinders may be totally shortned and so the opposite walls of the heart be brought to meet together But this is evidently impossible because in such a position there must necessarily be admitted a corrugation of the whole concave superficies of the heart intercepted betwixt the bases of those little columns or cords and therefore innumerable Fibres there contexed must be crouded up together and in like manner corrugated i. e. relaxed and by consequence could not act by their tense contraction which is repugnant to the supposition Besides in the right Ventricle of the heart are found but very few of those little Cylinders or columns and therefore this subterfuge can have no place there Yet farther a total decurtation of those same columns or cords could not be made unless the lengths of the Spires ending in the columns themselves ran out betwixt other Fibres as into sheaths or about pullies neither of which contrivances is to be found in the heart For the Fibres of the heart are with decussated directions contexed and so closely and firmly bound among themselves that they cannot by various and contrary motions start out of their places and run out among other Fibres embracing them In fine that the Tension of the heart cannot be solved by a simple contraction of its Fibres as heretofore hath been commonly imagined may be sufficiently evinced even from this that the bulk of the Muscles of the Limbs which when they act are truly contracted is sensibly diminished rather than augmented but the bulk of the heart while it acts is augmented since the Cavities or Ventricles of it are filled up by the fleshy substance the outward figure of the whole heart being at the same time unchanged and undiminished Wherefore the proper action of the heart is not performed by contraction of its Fibres Quod erat probandum Hence arises this Corollary That the cavities of the Heart are constringed not because the lengths of the Ventricles are shortned but because their side-walls are brought nearer each to the other so as almost to touch This appears from the very position and configuration of the Ventricles of the Heart and from its operation For the left Ventricle dissected from the bottom to the top is ye see extended through the whole length of the heart from the Basis down to the Cone which ends into a sharp pointed and slender wall and since the external figure of the heart while it beats is not shortned therefore neither is the length of this cavity diminished that is to say the Basis of the Cavity is not brought nearer to the Cone of it Besides the Base and Cone of the heart cannot at all be inflated and incrassated because the Base wants Fibres and is intirely destitute of flesh as being wholly occupied by the four ample Orifices of the Veins and Arteries and the wall of the Cone is very thin and slender Therefore the Cavity cannot be filled by inflation of the Fibres of the Basis and Cone of the heart It remains then of absolute necessity that the Cavity be filled by inflation of the side-walls of the heart which are very thick full of Fibres and therefore easily capable of inflation Lastly as was said before if a man put his finger into a hole made by incision in either of the Ventricles of the heart of any Animal yet living he shall perceive a strong constriction of the side-walls but none of the Basis and Cone tending to their approximation one toward the other By this Consectary thus verified we are led to understand The Mechanic reason of this Operation That by Mechanic necessity the Cavity of the heart cannot be shortned may be farther proved thus Because a Contraction of the heart cannot be made but by a Contraction of its Fibres therefore those parts of it that want Fibres will not be capable of Contraction but of that immense multitude of Fibres descending from the Basis of the heart not so much as the thousandth part attains to the Cone because if they should be there connected they would being accumulated stratum super strato make the acuminate and thin wall of huge depth or thickness whereas now that wall is very slender in such a situation and all the rest of the Fibres that are spiral are woven together and reflected into the heart with a transversal Circuit before they reach to the Cone Ergo they will not be able to draw up the Cone of the heart toward the Basis and by consequence the length of the cavity of the heart will not be shortned But the Cause by which the side-walls of the Ventricles are brought to meet is this Because almost all the innumerable Fibres of the heart are wound obliquely and transversly about the sides of it and of them are composed very many Layers one above another like Membranes But when the Fibres of any Layer are inflated or huffed up they touching each the other laterally and lying in one Superfice will of necessity croud and press each the other laterally and so thrust each the other out of their places and urge them farther viz. sideways toward the Basis and toward the Cone Wherefore the interval betwixt the Basis and the Cone ought to be rather augmented But because the other external Fibres obliquely encompassing and closely girding the transverse and intersecting them decussatim hinder their elongation and protuberance it comes to pass that of necessity the inflation of the Fibres ought to cause them to swell inwardly toward the cavities and so the insides of the walls being puft up must be brought nearer together Moreover the septum cordis or partition-wall of the Ventricles consisting for the most part of transverse Fibres will not be shortned by their inflation but the thickness of it is much augmented and the outward walls ought likewise to be inflated inwards towards the internal cavities therefore the insides of the opposite walls ought to meet the Basis remaining always at the same distance from the Cone Quod erat ostendendum Hence we may deduce this genuine Consectary That the meeting of the opposite insides of the walls
of the Ventricles of the heart is the sole and immediate cause of the expression of the bloud that was conteined in them into the Arteries For the swelling or incrassation of these opposite walls being all inward toward the Centre of the heart and withal so great as to fill up the cavities of the Ventricles it is necessary that the bloud contained in the cavities being on all sides vehemently compressed give way and flow forth through the apertures or Orifices by Nature provided for its efflux the resistence of the fluid bloud holding very little proportion to the mighty force of the solid compressing it But so grand an intumescence of the fleshy substance of the heart could not otherwise be made than by a great swelling and turgency of its Fibres and therefore we may infer that the thickness of the Fibres of the heart is in the act of Pulsation doubly greater than in the diastole This being granted I consider that the external Fibres of the heart exercise very great force not by shortning themselves but by resisting distraction as the iron hoops of a hogshead that the perimeter of the heart be not augmented and at the same time they are inflated in their Concave part or under side as we have said the threads of a glome are and in like manner the internal Fibres when they are swell'd and incrassated exercise very great force by making folds and turgid wrinkles so tense and rigid that they do the office of wedges by which not only the cavity of the heart is filled up but the bloud therein conteined is by vehement compression squirted out by a motion very much resembling that by which we spirt Plum-stones with our Thumb and fore-finger compressing them behind But the slender fleshy Columns holding in the opposite walls of the Ventricles of the heart are at the same time also incrassated and withal shortned their Fibres being swell'd and corrugated to help fill up the cavity Yet they exercise greatest force to perform the office of wedges They exercise none towards the drawing together the opposite walls of the Ventricles because themselves are lax by reason of the corrugation and shrinking of the length of their Fibres and besides this they could never exactly conjoyn the opposite walls because being of a musculose constitution they cannot be totally shortned the nature of the Muscles being such as suffers not contraction greater than the third part of their length Yet it cannot be denied but these musculose Columns serve as cords to retain and conserve the due disposition of the internal parts of the heart and to prevent the immoderate distension and distraction of the Ventricles which too great a quantity of bloud rushing into them out of the Veins might otherwise cause Finally the Papillae or little fleshy teats standing up within the Ventricles and to which the membranose filaments of the triangular valves of the heart are fastned do also act their part in this Scene not only by admitting the like inflation of their Fibres but also by firmly erecting themselves ad instar penis All these things are verified in the left Ventricle and in the Ears of the heart but in the right Ventricle where is not found an equal number of Columns the constriction is made by incrassation of the external wall namely by inflation and decurtation of the Fibres thereof so that the hollow crookedness of it by swelling inward comes near to a Plane and the Arch within becomes streight Also the inflation and swelling of the Septum cordis or middle wall of the heart of great thickness naturally contributes not a little to the repletion of the right Ventricle For hence it is that the Convex superfice thereof doth become more prominent and stretched out whence that space resembling the figure of a concave Lens is filled up and the walls mutually touch the circuit of the Lenticular cavity remaining still the same Now this whole operation is exactly conform to the institute of Nature which primarily fills and amplifies the Pores of the Spongy Fibres by the humectation above explained from which she attains to a double effect For in the Muscles of the Limbs that swelling of the Pores of the Fibres produces a secundary effect which is the decurtation of the Muscle and the strong traction of the joynt but in the heart from the very inflation of the Fibres and consequent incrassation of the walls she effects the repletion of the Ventricles But the Machine is the same in both namely the force of a wedge dilating the Pores of the Fibres But that this expression of the Bloud out of the heart is not made by a Spiral contorsion or twisting of the heart such as that by which water is commonly squeez'd out of a wet napkin as some late Writers have thought is easily to be proved I acknowledge it to be most true that the expression of the bloud out of the heart no less than the wringing of water out of a wet cloth is made by constriction of the Cavities and Pores which were filled by the fluid but at the same time I deny that such a constriction is made in the heart and such an expression of the bloud thence by the same cause the same Organs and the same Mechanic action by which water is squeez'd out of wreath'd Linnen For in a Linnen cloth before its Contorsion the threds were all lax and therefore they admitted many Interstices that might be filled with little drops of water Afterward the cloth being strongly twisted the threds are forced to make many circuits about the twist of almost the same altitude and so they must not only be much elonged in those prolix Gyres but also extenuated and stretch'd and consequently their sides being made smooth by extension of their folds and wrinkles will mutually touch and their interstices vanish whence the little drops of water that were in them before will presently be squeez'd out But in the heart the repletion of the Ventricles is performed in a manner far different from this For in the act of Pulsation the bulk of the heart is not extenuated or diminished but rather augmented in a double proportion nor are the Fibres of the heart elonged but rather contracted as the nature of all Muscles requires The same Fibres do not mutually touch nor are their interstices fill'd up by reason of violent traction and extension but of their inflation Notwithstanding this we are not to think that the Spiral disposition of the Fibres of the heart is of no use For they serve to the firm binding or hooping as it were of the walls thereof that the face and configuration of the heart may continue still the same which Nature hath provided for also by Girths of other Fibres wound round about from the external Tendinose Orifices of the Vessels of the heart to the Columns within and with admirable Artifice decussated and woven together And thus we have made good our
Proposition That the proper Action of the heart is the Constriction of its Ventricles and the consequent compression and expression of the bloud contein'd in them not by a Contorsion of its Spiral Fibres but by an inflation and corrugation of them Here some perhaps may be willing to propose to me this question If it be true that in the Systole or act of Pulsation neither the exterior Superfice of the heart is augmented nor the Cone of it drawn up toward the Basis both which we have asserted how then comes it that in every Systole the Cone of the heart knocks against the left side of the breast Which may be thus Answer'd Because the heart is hung in the middle of the Breast by strong Ligaments and yet in every Systole is brought to touch and strike the inside of the Breast therefore it is necessary that this be done either by a dilatation of the heart or by local motion and translation of it or by erection of the whole or by flexion and incurvation of the Cone thereof And as our observation and experience rejects the three former causes of this Phaenomenon so it obliges us to embrace and acquiesce in the last Wherefore it remains only that we investigate the Mechanic reason of this effect Which seems to depend first upon the disposition of the Fibres of the heart For we see that a crooked gut tied about with a thred and not wholly fill'd with water is by the weight of the water extended directly or in a strait line but if the water be impelled toward either end by compression then the gut becomes crooked again as the nature of it exacts and the other pendulous extremity will be erected and strike against your hand held a little over it This plainly follows from the curve figure of the membrane of the gut which is longer in the convex part and shorter in the concave So in the left part of the Ventricle of the heart the left wall is shorter less fleshy and less crooked than the two walls that make the right Ventricle Wherefore in the Systole of the heart the Cone of it ought to be erected toward the left side of the breast and to strike against it more or less strongly according to the degree of violence with which it is erected This may be somewhat helped also partly by the erection of the heart lying obliquely partly by the situation and disposition of the Fibres which are wound about obliquely and spirally from the right side of the Basis of the heart toward the left side of the Cone whence in the act of Pulsation when the Fibres are shortned the Cone may be a little distorted and erected by the fasciculus or combination of Fibres forwards toward the left side and so the Percussion may be made Seneca as ye may remember in epist. 57. most elegantly describes first the inevitable horror that invaded him while he was passing through the dust and darkness a darkness so thick as even to be seen of the Crypta Neapolitana now named the Grot of Pausilype in the way between Naples and Putzole and then the chearfulness he calls it alacritatem incogitatam injussam that returned to his mind upon the first sight of the restored light The same surprising alacrity methink I now feel within my self after my passage through the no less darkness in which Nature had through a long Series of ages involved her great secret of the Motion of the Heart made more obscure by the dust of mens various opinions and my arriving at the light of knowledge both what is the proper Action of the Heart and by what Mechanic necessity that Action is performed In the ardor of this alacrity I proceed to the use and action of the Ears of the Heart and of its Valves The end of the Vena Cava which is conjoyned to the heart is as hath been said before in greater Animals Musculose round about that the trunk of it may be constringed as Sphincters are closed by virtue of their circular Fibres But the end of the Vena Pulmonaris wants the like fulciment and therefore cannot constringe itself Then both these Veins end into the Musculose Ears which are hollow like little bags affixed to the sides of the heart and whose structure much resembles that by which the left Ventricle of the heart is contexed in the hollow part of it For the Ears also consist of fleshy Fibres intersecting each other like a St. Andrews Cross which within are bound together into many little Cylindrical Columns and trenches connecting the sides of the bags To these Ears succede three membranes in the right Ventricle and two in the left which are of a very strong contexture of a triangular figure the bases of which are closely affixed to the whole Circuit of the Tendon of the Orifice of the heart Then the areae or middle spaces of these little membranes are branched within the Ventricles of the heart into many little Tendinose Strings or cords which are fastned to the tops of the papillae or teats that stand pointing upwards placed on the opposite side Now this admirable structure being known let us enquire the design or use of it First the extreme part of the Vena Cava seems not to be made Musculose for strength lest it should be broken by the current of the bloud rushing in but rather by its constriction to protrude the bloud into the oblique Sinus of the right Ear and to render the same turgid Which action is helped by the peristaltic constriction of the whole trunk of the Vena Cava and by the compression of the Muscles and Viscera of the whole body as was yesterday demonstrated when we considered the motion of the Bloud Hence it comes that the bloud impelled through the open aperture of the Ear fills the cavity of it and then runs into the right Ventricle and by the like necessity the bloud flows out of the Vena pulmonaris into the left Ear and thence into the left Ventricle of the Heart No sooner are the Ears filled and distended with bloud but they both at the same time constringe themselves by a contractive and compressive action common to all Muscles resembling that of a Press in this order that first by shutting their apertures they hinder the regress of the bloud into the same Veins out of which it came in then by the great force of compression they squeez it into the Ventricles of the heart until they be filled and made turgid To this action of the Ears immediately succedes the compression of the press of the Heart itself by which the bloud itself by reason of its abundance inflating and distending the triangular and mitral valves exactly shuts the Orifices or mouths of the Veins and so prevents its own recoiling into them Whence it is of absolute necessity that the same bloud be expressed into the Pulmonary Artery or Vena Arterialis and into the aorta These are the
solid meats and together with the drink serve as a fit Menstruum to extract the laudable and alimentary parts of them ad modum tincturae But this liquation of solid meats in the Stomach seems to be effected by motions placid gentle and imperceptible in the state of health not by those violent commotions and irrequiet agitations that always proceed from and accompany Ferments properly so call'd during their working as all men that enjoy good health feed soberly and keep a regular course of diet may easily observe in themselves And therefore this Acid Phlegm cannot properly and in Philosophical strictness be referr'd to the family of Ferments The same may with equal reason be said also of the Bile and Pancreatic juice commixt in the Duodenum They may perhaps conduce somewhat to the farther attenuation and exaltation of the Chyle they may also promote both the separation of the Nutritive from the Excrementitious parts of the same Chyle and the insinuation and permeation of the former through the coats or membranes of the Guts into the milky veins all this they may do and yet not by way of Fermentation whereof there is neither necessity nor sense in statu sanitatis and to argue from a preternatural state to a natural is a Paralogism Now if neither of these two so much celebrated Ferments hath any more right to that denomination than what is precariously derived from some remote and slender analogy or semblance imagined to be betwixt their nature qualities and effects and those observed in genuine and true Ferments as certainly neither of them yet appears to have What ought we to think of all the rest of invisible Ferments supposed to reside in places where hitherto they have never been found Why may we not till they shall be by Anatomical and other convincing experiments shewn to us believe that they have existence no where but in the brains of fancyful men For my part I blush not even in this venerable Assembly of most Learned men where I have as many Judges as Auditors openly to profess my self to be of this belief because de non apparentibus de non existentibus eadem ratio est and because I have heard an eminent Member of this first and more ancient Royal Society a man renowned over all Europe for his Philosophical and Anatomical Writings deliver this judgment of the multiplicity of Natural Ferments fancyed to be in the body of an Animal that they were a new-found asylum ignorantiae I say of Natural Ferments lest what I have said should be detorted to the exclusion of Praeternatural Fermentations which I do not deny to be incident sometimes to the bloud and other humours of the body more signally in Fevers and some other acute diseases though perhaps not so often as vulgar Physicians imagine What I have hitherto said may perchance seem to some of my Auditors to be a digression and they may be apt to think that I have made my first step in a wrong path I am therefore obliged in my own defence to advertise them that having proposed to my self to enquire strictly into the natural necessity or Mechanical reasons of the Motions of the Bloud and finding the aforesaid Comment of Ferments lying like a block in my way I thought it concern'd me rather to remove than to leap over it and leave it for others to stumble at For some there are and those too men whose names are deservedly celebrated for their profound knowledge both in Anatomy and the Mathematicks who in their books have professedly taught that even the bloud it self the seat of life also undergoes a certain natural Fermentation in the heart lungs and greater arteries as necessary to its perfection and vitality A doctrine which to me I profess seems very improbable and inconsistent with the wisdom of Nature Improbable First Because of all the various liquors found in the body of an Animal in statu Naturae the bloud seems of it self least prone to Fermentation which is incident chiefly if not solely to new and musty liquors whereas the greatest part by much of the bloud is old and by repeated Circulations well defaecated in its proper Emunctories and by insensible transpiration and by consequence needs no Fermentation True it is indeed that new Chyle is ever now and then brought into the rivulet of the bloud out of the common cistern thereof by the ductus thoracicus and the Subclavian vein for a recruit but in a quantity so small a few drops perhaps at once for more will not be found to bear a just proportion either to the capacity of the common Receptacle of the Chyle which is but little or to the narrowness of the Pipe leading from thence to the Subclavian vein as cannot in reason be thought sufficient to perturb and excite a fermentation in the bloud with which it is mixt If a greater quantity of Chyle were mixt with the bloud at one time certainly the bloud would soon lose its native purple and put on the white livery of the Chyle especially in the descending part of the Vena cava where the commixture is first made which yet no Anatomist for ought I know hath ever observ'd Secondly When Ferments are commixt with liquors consisting of heterogeneous particles they are generally slow in exerting their power and by degrees insinuate and diffuse their active particles through the whole mass before they can so far prevail as to raise an universal commotion and tumult in them as common experience testifies but the newly commixt Chyle and bloud are in a moment at most in the space of a few pulses of the heart rapt out of the Vena cava first into the right Ear and then into the right Ventricle of the heart so that here is no morula no competent space of time given to excite an actual fermentation Thirdly Here is wanting also convenient place To all Fermentations is required fit room wherein the liquors may have liberty to undergo an impetuose commotion and agitation of all their dissimilar and contrasting particles nor will the Must of Wine it self ever ferment if it be kept in close and strong casks as appears from the making of Stum but the Vena cava the Heart and Arteries are fill'd with bloud even to distention till by their Systole they squirt it forth and then in the next moment they are replenished What room then is left for the bloud to ferment in Seeing therefore that the bloud is by its own constitution unapt to ferment as bearing a greater analogy to the nature of Milk than to that of Wine whatever the Willisians have said to the contrary and seeing that neither the small supplies of Chyle which it daily receives are sufficient to induce nor the shortness of the time in which it passes through the praecordia nor the want of convenient room permit a fermentation what reason have we to assent to their opinion who teach that a fermentation of the bloud
act continually but interruptedly or per vices short and almost isochronic or equal quiets interposed So that the bloud express'd by the heart doth not flow thence in a continued course as rivers and fountains do that are without intermission carried on by the weight of their waters but gush forth and stop alternately though this vicissitude be exactly regular and proceeds in a constant order Now these things considered it may seem consentaneous to conclude that the motion of the bloud cannot be continuus since two pauses or quiets are interposed betwixt every two pulsations or Systoles of the heart during each of which the motion ceases but on the contrary ought to be esteem'd and call'd an interrupted and mixt motion And yet notwithstanding the verisimilitude of this conclusion I doubt not to lay down and expose to your examination this First PROPOSITION That the bloud is carried in a round through the body of an Animal in a truly continued and never interrupted motion This perhaps may sound like a Paradox but that shall not a-whit discourage me from asserting it while I remember that remarkable sentence of Minutius Felix in Octavio Inest in incredibili verum in verisimili mendacium Though it be true and evident that the heart doth not in the time of its pauses express any Bloud into the Arteries yet it is not true that the bloud contain'd in the Arteries in the Viscera in the habit of the body and in the Veins doth at the same time stagnate and stop its course but on the contrary is always carried on in its journey though with unequal velocity First the Verity of this appears in the Arteries For the afflux of bloud from the heart being wholly intercepted either by a Ligature applied to the aorta at its original or by cutting out the heart it self as is commonly done in Frogs and Vipers we see that nevertheless the bloud wherewith the Arteries were fill'd is by degrees squeez'd out so that they are soon after left altogether empty And doubtless this exinanition of the Arteries happens because they by their own spontaneous motion constringe themselves and contracting their Circular Fibres express the bloud into the habit of the parts and are at the same time compress'd also by the contraction and tension or the peristaltick motion of all the Muscles of the Body From the observation of this vulgar Phaenomenon viz. the emptiness of the Arteries in dead bodies the Ancients perhaps took occasion to believe and teach that not bloud but only Vital Spirits are contein'd in the Arteries Secondly this appears also in the Veins For that the bloud doth continually flow on in them likewise not only when it is urged forward by the Arterial Bloud pursuing it but even in the time of the hearts pauses is evinced from this that then the bloud runs on through the trunk of the Vena cava to replenish the right Ventricle of the heart But why do I mis-spend time in alledging reasons to prove a truth that is manifest to sense in Phlebotomy no sooner is a Vein open'd than the Bloud flows forth with a swift stream and while the wound is open continues to flow without pauses or interruption which is a demonstration of the thing proposed viz. of the continual motion of the Bloud in the Veins Being thus assured of the effect let us proceed to investigate the Causes which are not equally evident nor can we hope certainly to solve this Problem without enquiring the Mechanical reason of the continual motion of the Bloud through the Veins This therefore I will now attempt to do That Nature hath instituted no immediate Communication betwixt the Capillary Arteries and the Capillary Veins per anastomôsin is manifest to sense and now acknowledged by all Learned Anatomists and therefore it cannot stand with reason to imagin that the Bloud in its Circular course is emitted immediately out of the Arteries into the Veins these vessels being separate And though we opine that there is some secret communication betwixt the extreme Orifices of the Arteries and those of the Capillary veins by the intermediate Spongy substance of the flesh Viscera and glandules or by the Cribrose substance of the Bones as by the Pores of a Pumice stone yet we are still to seek by what motive force the bloud may be carried on from those intermediate Porosities and insinuated into the veins First because 't is consentaneous that the impulsive force whereby the Systole of the heart squirts the Bloud into the Arteries is by degrees weakned and at length languid in those streights of the extreme vessels and of the intermediate Porosities Secondly Because the Orifices of the Capillary veins cannot continue always open and dilated their consistence being not hard and bony but membranose soft and slippery so that they are apt to be closed by conniving and consequently to hinder the ingress of the bloud newly arrived Thirdly Because here we can have no recourse to the compression of the Viscera and the Muscles whereby the bloud should be squeez'd into the Orifices of the Capillary veins for we see that the bloud is suckt up by the Capillary veins not only when the Muscles are invigorated and upon the stretch but also when they are quiet and relaxed and do not exercise their compressive power as is most evident in sleep when the Circulation proceeds without intermission This is confirm'd from hence that in the Brain in the Medullary substance of the bones where no compression can be admitted the Capillary veins receive the bloud as freely as in the softer flesh it self Seeing then that the effect cannot be denied viz. that all the bloud effused out of the Arteries is after absorpt and carried off by the Veins to be brought back again into the heart and seeing also that this is not effected by way of Attraction there being no such thing as attraction in Nature as I have more than once elsewhere proved we are compell'd to assert that the Bloud is imbibed by the Capillary Veins for the same reason and by the same Mechanick action by which Syphons Sponges Filtres Chords and all Porose bodies are penetrated by water with which they are moistned which power is no other than the gravity of the fluid it self which is augmented by the impetus of its proper motion and by the impulse communicated to it from external force So the motive force of Gravity which the bloud can want no more than water can when it finds the small chanels of the Capillary veins open for they can never be so closely constringed by the flagging and connivency of their thin membranes as to leave no entrance for a fluid as appears in the Pores of Ropes how hard soever twisted must of necessity overcome the weak resistence of the streights in all Filtres and Porose bodies and consequently the bloud may be insinuated into the Capillary veins by a Mechanic action like that of Filtration If this proposition
be true the greatest difficulty occurring in the whole mystery of the Circulation of the bloud is now at length solved The bloud having in this manner passed the aforesaid streights and entred into the Canales of the small veins by the same motive force whereby it was insinuated for such an ingress is not possible without motion may be advanced a little farther in its way by its proper force and by external force and also by the impulse of the new bloud following behind as we see water suckt up by a Filtre to be carried on to the end of the list Afterward because many small veins meeting together make one wider ductus or pipe and because in this larger pipe the former impulsive force of necessity grows more and more languid and faint by degrees and by consequence the motion of the bloud is retarded therefore it stands in need of some auxiliary forces to be carried on the rest of its journey These are First the force by which the Circular Fibres of the Veins that naturally have a peristaltic virtue contract themselves always after they have been stretch'd as all Nervose and other tensile bodies are observ'd to do Secondly The Compression of the Veins by the weight of the Circumambient air or Atmosphear and the Elastic virtue of the air inspired Thirdly The Tonic motion of the Muscles when they act together with the various motions of the Viscera and of humours discurrent through the body all which more or less compress the veins Now that the manner how this compression promotes the continual decurse of the bloud in the Veins may be the more fully and clearly understood I will take liberty to lay down this Second PROPOSITION That by the artifice of the Valves the Compressions of the Veins protrude the Bloud toward the heart with a motion doubly swifter not indeed in a continual flux but with little pauses interpos'd and with unequal velocities We here behold in the Crural vein slit open from end to end certain Valves placed at unequal distances in the inside of the Vein which for demonstration sake are accurately represented in this Figure expos'd to sight These Valves ye see are nothing but half pockets of a membranose substance or little bladders affixt to the sides or walls of the Vein and resembled by AONMP and BONQR They are found sometimes single sometimes in pairs placed one opposite to the other and laterally touching each other as at NO the convex tops of which pair respect the Capillary beginnings of the Veins beyond HL but the Orifices of their cavities PO RO open toward the heart have respect to the parts IK Now I am to demonstrate that from this structure and situation of the Valves it is necessary that the Bloud be protruded toward the heart Imagine then that the same portion of the Vein HMQL is replete with bloud and because by the circular Fibres of the Vein itself and by the ambient Muscles and perhaps also by the gravity of the Atmosphear one part of the Vein is constringed after another all along it must be that the lateral walls ST come nearer to each other toward V and then the Vein so girded will lose its Cylindrical form and be turn'd into two little funnels HVL MVQ which are less capacious than the former Cylinder and therefore the bloud which was contained in the spaces VHS and VLT will be expell'd out of the Orifice HL but the remaining quantity of bloud contained in the spaces VSM and VQT will be squeez'd without the Orifice MQ toward IK It appears then that from the above-mentioned compression of the sides or walls of the Vein the bloud is express'd in equal quantity to the opposite parts and this would certainly happen if the Valves were removed But because to the walls of the Vein within MP QR are fastned two Valves it is necessary that the bloud impuls'd by a compression made in ST be forced through the narrow chink NO because the yielding fluid contain'd in the cavities of the Valves and urged by the advenient bloud is constringed and thrust out of them and then instantly the sides of the Valves that before touched each other NO receding one from another leave an open way by which the flux of bloud coming on from MSTQ may be insinuated and pass forward beyond AB Again after the bloud hath passed the confines of the Valves PO RO there necessarily follows a restriction of the little chink NO For the bloud it self must by reason of its heavy bulk and fluidity fill the little baggs of the Valves and so their soft and pliable sides being dilated till they mutually touch ought closely to shut the rimula NO Moreover because the Vein is not constringed in all its parts at the same time but part after part successively therefore after the bloud is transferr'd beyond the Valves within the little funnel ABCD there follows a constriction of the walls AD BC in the same time in which ST is not constringed And because by reason of the close shutting of the rimula NO half the bloud that was contain'd in the spaces EAG FBG cannot flow back toward AB finding the obstacle AOB fill'd with bloud and retain'd by the Valves it is compell'd with a reflex motion like that of a Tennis-ball rebounding from the wall to flow toward DC and since by the same compression the Bloud that was contain'd in the spaces EDG FCG is protruded beyond DC therefore a double quantity of bloud is in the same time in which the compression is made expelled through that same aperture DC but when a double quantity of a fluid is in the same time emitted at the same Orifice it must run out with a double Velocity Thus is our Proposition verified And as to single Valves from what hath been said of the use of double it may easily and genuinely be inferred that they also help to promote the course of the bloud though but half so much as the double Wherefore Natures wisdom is admirable in placing single Valves both at less distance one above another and for the most part where the Cavity of the Vein is a little narrower or where a less Vein laterally exonerates it self into a greater in both which cases the necessity of this demonstrated acceleration of the motion of the Bloud seems to be less In the trunk of the Vena cava no valves are found as well because of its ample Cavity as because of its contiguity to the trunk of the great Artery by whose pulsations it cannot but be somewhat compress'd and consequently the Bloud flowing through it proportionately promoted In the Iugular veins also none have yet been observed probably because in them the bloud descends swiftly enough from its own weight and fluidity In small veins they are not placed unless in the Coronary veins of the heart just at the place where they empty themselves into the right Ventricle of the heart and of these
too the use is not to promote the course of bloud of which there is no need in so small a circuit but only to prevent the reflux of it out of that Ventricle in the systole of the heart as appears from their situation and from their conformation Nor are any found in the Arteries in which the bloud with mighty force impulst by the constriction of the heart and of the Arteries needs no additional machine to accelerate its motion except those that are placed in the inlet and outlet of the left Ventricle to obviate the regurgitation of the bloud into the arteria venosa and out of the aorta into the left Ventricle and the two very little Valves sited in the two Coronary Arteries at their origine from the aorta to prohibit the regress of the bloud into the aorta ¶ ⸪ If this Artifice of the Valves affixt within the veins be so necessary to promote the reflux of the bloud toward the heart certainly he that first discovered them deserves to be remembred with honour But who was that fortunate man Fabricius ab Aquapendente put in his claim to the glory of the invention as wholly due to himself in these very words De his itaque ostiolis nempe venarum locuturus subit primùm mirari quomodo ostiola haec ad hanc usque aetatem tam priscos quà m recentiores Anatomicos adeo latuerint ut non solùm nulla mentio de ipsis facta sit sed neque aliquis prius haec viderit quà m Anno Domini Septuagesimo quarto supra millesimum quingentesimum quo à me summa cum laetitia inter dissecandum observata fuere But Padre Fulgentio professly ascribes the invention to that prodigy of Wisdom Learning and Virtue Padre Paolo the Venetian at the same time openly accusing Aquapendens of disingenuous arrogance and theft for challenging to himself the honour of having first discovered the Valves to which he had no right and for stealing the glory due only to Father Paul The sence of his impeachment is this The whole Tractate concerning the Eye which passeth under the name of Aquapendens or at least so much of it as contains new and rare Speculations and Experiments is the work of Padre Paolo whereof I have had speech with some that were eye-witnesses and knew that a due part of the praise was not attributed to him that deserv'd it all But much more in another matter of more moment which was the finding out of those Valvulae those inward shuts or folds that are within the Veins Of which argument I do not find that any either ancient or Modern hath made mention because it was a thing unthought of till these times when Aquapendens moved the question in a publick Anatomy But there are still living many eminent and Learned Physicians among whom are Santorio and Pietro Asselineo a Frenchman who certainly know that it was no Speculation nor invention of Aquapendens but of Padre Paolo Who considering the weight of the bloud grew into an opinion that it could not stay in the Veins except there were some bunch to hold it in some folds or shuttings at the opening and closing of which there was given a passage and necessary Aequilibrium to life And upon his own natural judgment he set himself to cutting with more accurate observation and so found out those Valves c. Having thus faithfully recited the Pleas of these two great men I leave it to you to decide the controversie and to fix the Laurel on the head of which of the Competitors you please For my part if my judgment were considerable I should declare my self on Padre Paolo's side as to the invention and allow to Aquapendens the honour of being the first that by writing made the thing known to the world Understand me I beseech you only of the Valves themselves not of the true use of them which neither Aquapendens nor the Father had the happiness to discover Not Aquapendens because of the two uses by him assign'd to these Valves which he most improperly named Ostiola namely the corroboration of the Veins which might otherwise be by the bloud every where distended and broken into varices and the retardation of the bloud in the Veins that so all parts of the body might have time to take in their due shares of bloud for their nourishment and not have their meat forsooth snatcht away before they have fill'd their bellies of these two mighty uses I say neither is true and both are raised upon this Supposition that the course of the bloud is out of the greater and superiour Veins into the smaller and inferiour which is most evidently false even by the testimony of the sight But lest I be thought either not well to understand or to misrepresent his meaning I am obliged to recite his own words Nam cùm in varicibus in quibus aut laxari aut rumpi Ostiola par est plus minusve dilatatas semper venas conspiciamus dicere proculdubiò tutò possumus ad prohibendam quoque venarum distensionem fuisse Ostiola à Summo Opifice fabrefacta c. Thus far then I have done him no wrong He proceeds Erat profectò necessaria Ostiolorum constructio in artuum venis quae non exiguae sed vel magnae vel moderatae sunt magnitudinis ut scilicet sanguis ubique eatenus retardetur quatenus cuique particulae alimento fruendi congruum tempus detur quod alioqui propter artuum declivem situm confertim ac rapidi fluminis instar in artuum extremitates universus conflueret ac colligeretur idque tum harum partium tumore tum super positarum marcore Here also I have faithfully interpreted his words and ye see that he thought the contrivement of the Valves necessary to retard the motion of the bloud because he took it for granted that the bloud descended through the greater Veins into the less grossly erring in both opinions For that the former is false we have seen demonstrated from the construction and situation of the Valves themselves and that the latter also is false and absurd is known to all who understand any thing of the Circulation of the Bloud To these errors he hath in the same Page added a third much more extravagant which is that the bloud is by a flux and reflux perpetually carried forward and backward in the Arteries For attempting to give the reason why Nature hath framed no Valves in the Cavities of the Arteries he saith Arteriis autem ostiola non fuêre necessaria neque ad distensionem prohibendam propter tunicae crassitiem ac robur neque ad sanguinem remorandum quòd sanguinis fluxus refluxusque in Arteriis perpetuò fiat It appears then that this famous Anatomist who in many other things deserved well of the Commonwealth of Physicians had no just title to the honour of having first invented the true and genuine use of the Valves