Imprimendi Facultas.  
Librum hunc inscriptum Osteologia Nova, &c. planè dignum censemus qui Imprimatur.  
Gualt. Charleton Praeses Coll. Reg. Medic. land. 

Censores. 

Thomas Burwell,  
J. Gordon,  
Will. daws,  
Tho. Gill.     Datum ex aedibus Collegii nostri Augusti 29. A. D. 1690.   

OSTEOLOGIA NOVA, OR SOME New OBSERVATIONS OF THE BONES, AND THE PARTS belonging to them, with the manner of their Accretion, and Nutrition, Communicated to the Royal Society in several Discourses.  

I. Of the Membrane, Nature, Constituent parts, and Internal Structure of the Bones.  
II. Of Accretion, and Nutrition, as also of the Affections of the Bones in the Rickets, and of Venereal Nodes.  
III. Of the Medulla, or Marrow.  
IV. Of the Mucilaginous Glands, with the Etiology or Explication of the Causes of a Rheumatism, and the Gout, and the manner how they are produced.   
To which is added A Fifth Discourse of the CARTILAGES.  
By CLOPTON HAVERS, M. D. Fellow of the Royal Society.  
LONDON: Printed for Samuel Smith, at the Princes Arms in St. Paul's Church-Yard. 1691.   

To the Right Honourable THOMAS EARL of Pembroke, PRESIDENT OF THE Royal Society.  
MY LORD,  
THough Ambition is one thing, that carries me to address myself to a Person of your Honour, and Ingenuity; yet there is a more common Principle of self-preservation, which concurs, and directs me to seek that Patronage, which will bespeak not only the Justice, but the Candour of every Reader. And seeing the Royal Society have so great a sense of their happiness, when they are to act under the influence, and conduct of so Wise, and Honourable a President, I cannot question my own safety under the name of so great a Patron. When I reflect upon myself, that am a tender, and an infantile Author, I find nothing but fear, and discouragement, as I am in danger of being Overlaid by every little Censure; but when I consider myself under the Umbrage of a Person, whose Example, and Authority may prevail with the World to be generous, and to imitate those virtues, which they so much admire in your Lordship, this frees me from that diffidence, and timorous concern, which the censorious temper of the Age, and the sense of my own weakness are apt to create.  
But although it may reasonably be thought, and I have confessed, that I now design my own safety, that this Treatise carries your Lordships name as an Amulet against those censures, which I expose it to; yet it will at the same time appear to be my duty to present to your Lordship, that, which the Relation you bear to the Royal Society, gives you a Title to. I do therefore humbly offer, and dedicate these Discourses to your Lordship as a testimony of that profound respect, which is due to a Person of your Quality, and extraordinary Character, and it is certain, that every Member of the Society speaks the Sense of the whole, when he expresses the greatest deference to your Honour.  
Having therefore consulted my Duty, as well as my Interest in this thing, I hope there is no one will think my addresses a rude transgression of the Laws of Decency. I must confess, that these Discourses are too mean, and unpolished to deserve your Lordships Patronage, but since the desires of the Society did encourage my design to publish them, this seems not only to make them capable of it, but to bless them with a Title to it. I do therefore presume humbly to beg they may not offer themselves to the World without the advantage of your Favour, which will render them more acceptable, and gratify to the utmost the ambitious desires of,  
My Lord, Your Lordships most humble, and most obedient Servant, Clopton Havers.   

To the most Worthy Dr. RICHARD MORTON, FELLOW OF THE college of Physicians.  
SIR,  
I Have been a long time obliged by a continued series of your Favours, and such as would naturally, and irresistibly suggest the thoughts of gratitude to any one, that has not debauched those Principles of Reason, and Justice, which are common to all Men; and I cannot with any satisfaction live involved in so great a Debt without an attempt to make some grateful returns. And when I have this opportunity to make a public acknowledgement of those Obligations, by which I have plainly lost the Title I had to myself, and come under your commands, I dare not be guilty of that silence, by which I must seem either insensible, and no Man, or ungrateful, and the worst of Men. I must own it as one of the kindest Providences of Heaven, that I had the happiness, Sir, not only to be directed in my Studies by you, but by your particular favour to enjoy many other great, and extraordinary advantages, to all which under the Almighty God I owe what I may pretend to in physic. I do therefore as an expression of that Respect, and Gratitude, which are due from me, humbly present you with these Discourses, and although I shall never be able to satisfy that Debt, which I have contracted, yet this will be a demonstration of my inclinations to be Just, and Grateful. And there is no one can be insensible, how far I I am in Justice bound to render to you that, which is an account of the Talent, which you, Sir, have entrusted me with, and so far as I am capable taught me to improve.  
What entertainment these Discourses will find in the World I know not. I cannot have so foolish an opinion of myself, or them, as to think they are free from those imperfections, which will betray the weakness of their Author, and perhaps there are some things, which candour itself cannot overlook. However the security I shall have from your Patronage, gives me the prospect of a more kind, and candid reception, than they can deserve. Which I must ingenuously acknowledge carries so much of an Obligation in it, that whilst I am endeavouring to discharge one Duty, I am sensible I contract a fresh Debt. Thus in the very expressions of my Devotion to your service I meet with Arguments, which confirm my resolutions to be,  
Sir, Your most humble, and faithful Servant, Clopton Havers.   

THE INDEX.  

The first Discourse of the Membrane, the Nature, Constituent Parts, and Internal Structure of the Bones. red Aug. 7. and Octob. 23. 1689.  
THE Introduction Pag. 1  
Of the manner of Generation p. 6  
Of the Periosteum p. 14  
Of the Design of the Periosteum p. 25  
Of the Nature of the Bones p. 30  
Of the Constituent parts of a Bone p. 31  
Of two sorts of Pores formed in the Bones for the dispensation of the Medullary Oil to their Substance p. 43  
Of the Superficies of the Bones p. 49  
Of the Pores of the as Frontis, &c. p. 52  
Of the passages of the Medullary Vessels into the Cavities of the Bones p. 57  
Of the large Cavities, and Latice-work of the Bones p. 60  
Of the smaller Cavities of the Bones p. 71  
Of the Blood Vessels of the Bones p. 74  
Some observations of the Teeth p. 78   

The Second Discourse of Accretion, and Nutrition. red Octob. 30. and Nov. 13. 1689.  
OF Accretion p. 91  
Of Glandular Secretion p. 99  
Of the general agreement of the Glands, or those Colatory Organs, which consist of many small Glandules, and serve for the separation of any matter from the Mass of Blood p. 100  
The manner of Glandular Secretion p. 109  
Of the Nutritious Glandules p. 112  
Of the manner of Accretion p. 117  
Of the limitation of an Animals growth p. 126  
Of Nutrition p. 133  
Of the Accretion, and Nutrition particularly of the Bones p. 142  
Of the Incurvation of the Bones in the Rickets p. 148  
Of the knottiness of the ends of some of the Bones in the Rickets p. 156  
Of the Nodes in the Bones from the Lues Venerea p. 157   

The Third Discourse of the Marrow. red January 29. 1689.  
OF the Medullary Blood-Vessels p. 162  
Of the Membrane of the Marrow p. 163  
Of the Bags, and Vesicles or Glandules of the Marrow p. 166  
The passages of the Medullary Oil into the Interstices of the joints p. 172  
Of the different colour, and consistence of several parts of the Marrow p. 175  
Of the Use of the Marrow, or Medull. Oil p. 178   

The Fourth Discourse of the Mucilaginous Glands. red Nov. 20. and 27. 1689.  
OF the Mucilaginous Glands of the joints p. 187  
The Sorts of them p. 190  
Of the Structure, and particular situation of them, which are considerable p. 192  
Of the Mucilaginous Glands serving to the Muscles, and Tendons p. 199  
Of the Nature, and Use of the Mucilage p. 201  
The use of the Fat, which is separated amongst the Muscles, and the reason, why it is wasted upon continued, and hard labour, or exercise p. 205  
Of the manner, how the Mucilage is made, and of the use of the Spleen p. 210  
Several Experiments made with the Mucil. p. 217  
Of a Rheumatism p. 223  
Some general Rules in the Cure of a Rheumatism p. 242  
Of the Gout p. 249  
The manner how the Tophi are produced in a Nodose Gout p. 262   

The Fifth Discourse of the Cartilages. red August 13. 1690.  
OF the nature, and flexibility of the Cartilages p. 270  
The reason of their flexibility explained p. 271  
The cause of their restitution, or endeavour to return to their natural figure when they are bent. 274  
The difference between a Bone and a cartilege p. 279  
Of the Membrane of the Cartilages p. 280  
Of their Blood-Vessels p. 282  
Of the use of the Cartilages belonging to the true Ribs p. 284  
How they contribute to the enlargement of the Cavity of the Thorax in Inspiration p. 288  
How they conspire in the Contraction of the Breast in expiration p. 291   
 diagram of knee joint bones and other glands and membranes 
TAB: II.  

Fig: 1. The Mucilaginous glad, in one of the Sinuses of the as Humeri at the flexure of the Cubit, taken out of a Human Body   

Fig: 2.  


AAAA The fore part of the knee taken off.  
aaa The large Mucilaginous Glands  
bbbb The Membrane which lies immediately over the Interstice of the joint.  
c The Patella.     

Fig: 3. Represents the Figure of the particles, and the order, in which they ly in the Cartilages, and other flexible Bodys, that have a Rigidity.   

Fig: 4.    

TAB: I.  
Fig: 1  
Fig: 2.  
Fig: 3. One of the Bags of the Marrow consisting of the small Vesicles or Glandules.    

The FIRST DISCOURSE Concerning the MEMBRANE, THE NATURE, Constituent Parts, AND INTERNAL STRUCTURE Of the BONES.  

INTRODUCTION.  
AS no Faculty has received greater Additions to its Improvement in this last Age than physic, so no part of that has been more tempting, or more successfully pursued than Anatomy. The Dissections of many preceding Ages turned to a small account; so that many of the most admirable Contrivances of Nature, and of the greatest Wonders in the lesser World were inobserv'd, till the Curiosity of some ingenious Men, animated with the hopes of some new Discoveries, put them upon farther inquiries, in which their Industry, and Felicity carried them so far, that the Existence of some parts before unknown, the Nature, Structure, and Use of others began to appear. But although the Scrutiny, and Observations of our Age about some of the Parts have been very accurate, we have been only coasting about others; particularly, about the internal fabric, and some other things of the Bones, our Searches have been careless, our Notice slight and transient; not but that they deserve our strictest Enquiry, and serious Remarks: for I do not see, but the Almighty Architect has equally demonstrated his Divine Skill in the whole structure of these Parts, which he has made of grosser Matter, as in the Formation of those, which consist of sifted, and more refined Particles. And how curious the Hand of Heaven has been in the Framing, and Ordering of this Timber-work of our Bodies, may perhaps appear a little from this Discourse; a little, I say, because I am too sensible, that after all my endeavours to act both the Philosopher, and the Anatomist, I am infinitely unjust to my Argument; however, what I have observed, it is both my Duty, and my present Design to communicate to this honourable Society; and as there are several things will occur, which deserve and require a Philosophical Solution; so I shall endeavour to account for them, by explaining the manner, in which they are produced, or considering the Reasons, why Nature has ordained them, as I shall have occasion.  
In speaking to this Argument, I shall purposely omit the notice of the different Figures of the Bones, the divers manner of their Conjunction, and what has been commonly observed; and that I may present you with a Scheme of those general Heads, which I design to treat of, they shall be these which follow:  
First, The Periosteum, or that Membrane, which invests the Bones, which being inservient to several ends, I shall consider the Use of.  
Secondly, The Bones themselves, where I shall endeavour to give an account of their Nature, their Constituent Parts, Internal Structure, and the Pores, and Passages, which are formed in them; as also of those Blood-Vessels, which serve for their Accretion, and Nutrition: And as the Teeth are a sort of Bones different from all others, I shall add some particular Remarks concerning them.  
Thirdly, I intend to explain the manner how Accretion and Nutrition are performed, first in general, and then particularly, with respect to those Parts, which are our present Subject. And in treating of these great Affairs of Nature, I shall take occasion to make some digression about the manner of Glandular Secretion, concluding this Head with the Etiology of those symptoms in the Rickets, wherein the Bones are concerned, and Venereal Nodes.  
Fourthly, I am to give an account of the Observations, which I have made of the Marrow, and to describe the Blood-Vessels thereunto belonging, which when I have done, I design to consider the Use of this Oleaginous Substance.  
Fifthly, I have a particular sort of Glands to give an account of, which I have observed in all the joints. I shall describe the Structure, and Situation of the most considerable of them, and then inquire into the Nature, and Use of that liquour, which is separated by them. And because the Observation of these Glands will be very serviceable to us in explaining the Cause of a Distemper, or two, that affect the Parts, in which they are seated: I shall say something concerning those Distempers, which will be first a Rheumatism, and secondly the Gout.  
Sixthly, and lastly, I shall conclude my Discourses with an account of the Cartilages; explaining their Nature, describing their Membrane, and their Structure, and inquiring into the Use, particularly of those which are united to the true Ribs.   

The Manner of GENERATION.  
IT may perhaps be thought reasonable, and methodical by some, to begin my Discourse with the Original of my Argument, and to offer something concerning the manner, how the parts, of which I am to Treat, are first formed, and although the manner of an Animal's formation, whether it be generated in the Womb, or out of it, is one of the great Arcana's of Nature, and that which neither our Senses can observe, nor any thing of Art or Mechanism imitate; yet we may make our conjectures, and find out some probable, and rational Hypothesis for our satisfaction.  
The ancients for want of those discoveries, which since their time have been made, had a Notion that the seemen of the Man was a part of the Conception: that the Woman had a true Seed, and a composition arising from the mixture of the Seed of the Male, and Female, was the material cause of the Bones, as of all other parts, which they termed spermatic. But de Graef has better informed us, and taught us to explode that Opinion, so that it neither admits of a Defence, nor needs a Refutation, since he has discovered to us Nests of Eggs in Viviparous Animals, and that in the Bellies of Women.  
The Origine therefore even of the highest Animal being from an Egg, it may perhaps, if duly considered, seem most probable that the Bones, and all other parts are by the admirable Stenography of Divine Providence delineated in the Egg, whilst it is in the Ovarium, and before the Female is impregnated. Neither can it seem improbable, that so many parts should be described within the circumference of so small a Body, when we consider the minuteness of some Animalcula, and that notwithstanding they consist of Spirits, Humours, and a multiplicity of Organical parts. And if we suppose an analogy between these Eggs, and the Seeds of Plants, which it is reasonable to do; the Observations which are to be made of the one, may direct us in our Hypothesis concerning the other, and favours our Notion, when we see the Rudiments, the Leaves, the Stem, and Radicle of a Plant, are to be found in the Seed before it falls into the Womb of the Earth, and under the generating influences of the Heavens. It is true the parts of an Animal, whilst they ly within the compass of an Egg, are indistinguishable unto us, and must necessary be so until, and for some time after the Vivifick Spirit of the seemen has put the fluid, and volatile Particles into motion, after the first, and efficacious impressions of which the affair of Generation seems to be carried on in this manner: to wit the Particles, which are the first Principles of the Humours, and all those, which are disposed for an activity, being by this motion put into a Fermentation, are rarifyed, and expanded, and thereupon requiring a larger space, than that, which was capable of containing them, whilst they were more quiet, and by Nature disposed in such an order, as to ly within those bounds, which the convenient magnitude of the Egg could not allow them to exceed before an Impregnation, they begin to dilate the Cavities, and Vessels, which contain them. Being put into motion, though at first it be languid, and proportionate to the tone of those parts, which are afterwards solid, they naturally endeavour to persist in it. And although their first, and natural tendency, after they are moved, cannot be thought to be the same in all the parts, that are thus agitated, yet by the contraction, and pulse of the Heart, it comes to be directed in all of them to the same general terminus ad quem, that is the Veins. For whether this Fermentation be excited in all those Particles at the same time, which afterwards appear in the form of a Humour, or are exalted into Spirits; or be first begun in the Punctum saliens, or that which is afterwards the great Elater of the Blood, the Heart, 'twill come to the same thing.  
If the Fermentation be excited in all that matter contained in the Ventricles of the Heart, and all the Arterial Channels at the same time, though there follows a great variety in the tendency of the motion of these Particles, so that some fly one way, at least endeavour it, and others another, yet still the Heart has the ascendant over all of them, so that the pulse of this Machine, and the power and motion of those Particles, which are immediately propelled by it, direct the course, and order the tendency of all the rest, so that at last they come to be all moving towards the extremities of the Arteries, and to the Veins, which succeed to them.  
If we suppose the Fermentation in the beginning to be partial, and excited only in that matter, which lies within the Cavities of the Heart; as I am apt to think, that the Vessel, which afterwards appears to be the Umbilical Vein, has its course always towards, and terminates in the Membrane of the Ovarium, where there is a poor, by which the spirituous Vapour, or fermentative Particles of the Seed entering the small dust, is conveyed to the Heart, and that to both Ventricles in a manner at the same time; so that whilst one part of them actuates that matter, which lay in the right Ventricle, the other with their full vigour and virtue, communicate a motion to that, which is contained in the lest: and to this end Nature seems to have formed the Foramen oval in a Foetus, by which there is a passage from the Vena Cava, into the Vena Pulmonaris, and so into the left Ventricle, without ever coming into the right, that some part of the Seminal Spirit may be immediately dispensed to the left Ventricle, and agitate the Particles contained in it, before it has spent, or weakened its force by acting upon other matter. I say if the Fermentation be thus partial, we may conceive how the Particles in both Ventricles being rarifyed, and expanded, dilate them, and oblige the Fibres of the Heart to a renitency, and contraction, and so give them the occasion of beginning to make a Pulse, by which contraction, and the expulsion of some part of that matter, which was lodged within the Cavities, they not only communicate a motion successively to those parts, which are contained in the Aorta, and all the Vessels, which are propagated from it, but direct and determine their motion towards the Veins; and thus the fluid parts begin their Circulation. And as by the motion and expansion of these Particles the Arteries are distended; so partly by this expansion, partly by the more direct pressure of that matter, which is in Circulation, the extremities of these Vessels, and the passages into the Veins, which begin where they terminate, will be opened, and so the circulatory course of the Blood will be continued into the venose Channels. And because the putting the Blood into a due, and certain course of Circulation is a business of great importance, absolutely necessary to the Life, and regular increase of the Foetus, as well as in the whole course of our lives after the Birth; therefore there seems to be a particular contrivance for the more effectual accomplishing of this design in the Canalis Arteriosus, by which the Blood, that after the Foetus is excluded, is driven out of one Ventricle into the other through the Lungs, at this time passes directly out of the right into the Aorta, and this Ventricle, which after the Birth neither adds to, nor determines the motion of the Blood in the great Artery, does evidently, whilst the Foetus is in the Womb conspire with the lest in the agitation of that matter, which is in the Aorta, and by the mediation of the Particles, which it immediately propels, makes a pressure upon it to drive it on in the Arterial Channels, as well as the left Ventricle does. The reason why the course of the Blood is diverted from the Lungs, I know, is commonly supposed to be, because the Foetus does not respire in the Womb. But this does not seem to me a sufficient reason; for though it is not necessary that the Blood should Circulate through the Lungs, upon the account of respiration, yet I do not see it would be either impossible, or inconvenient for it to have its course through them, before the Foetus is excluded, and comes to breath. There are the same passages or Pneumonick Vessels before, as after the Birth. And what though the Lungs do always subside, do they not the same in expiration? Nay does not the passage through these Vessels seem more free and easy, whilst the Lungs subside, than when they are inflated, and all the Bronchia, and Vesicles distended, at which time the Blood-Vessels must necessary be more compressed and straightened? But supposing the Blood could not have a free passage through the Lungs of a Foetus, and the defect of respiration forbade it; yet this is no reason, why the right Ventricle should propel the matter it contains, into the Aorta, and not throw it into the left by some contrivance like the Foramen oval. So that we may reasonably think there was this design, to bring both Ventricles into a Conspiracy to determine the motion of the Particles, which are yet to be settled in a due course, to the Veins, and to drive them on through all the Stages of Circulation.  
In the same manner, as the extremities of the Arteries are opened, that is both by the expansion, and direct pressure of the Particles, which move in them, the Pores of the Glandules, whether seated in the sides, or at the extremities of the Arterial Channels, which before were closed, will be dilated, whereby they become fit for, and begin to perform secretions, then are the Spirits separated by the Brain, and when this habitation of the Soul is furnished, and as soon as a sufficient quantity of Spirits are supplied to irradiate the Systema Nervosum, then may probably be the time, when the Soul of a human Foetus is infused, and takes possession. The Nutritious Glandules amongst others beginning to perform their Office, do give the Bones, and all the solid parts a continual supply of such Particles, as are of their own nature, and fit to be apponed to them, whereby they increase, and as the vigour, and pressure of the Spirits grows stronger, and as it were knocks these Particles nearer to one another, the parts begin to show some solidity, to discover their nature, and become visibly distinct. And this Hypothesis, how strange so ever it may seem to some, does give us a clearer, and more intelligible Notion of the manner of Generation, and the effects of the seemen upon the Egg, than what has been said of that plastic power, which has been supposed to be in the Seed of the Male, and to form the parts of an Animal from a rude and indigested Chaos. But I pass off from these conjectures to the consideration of that Subject, I have proposed to Treat of, which does in many things offer itself to our Senses, and encourages us with fairer promises of certainty, and satisfaction, and I begin with that part, which first presents itself to our view, and observation, the Periosteum.   

Of the PERIOSTEUM.  
THIS is a thin transparent Membrane, made up of most minute, and curious threads, endowed with an acute sense, and expanded over the Bones. The Fibres, of which it consists, are not interwoven one within another, but disposed in several Series one over the other. It is in some parts thicker than in others, and consequently less transparent. In some places it offers its superficies fairly to our view, that is where no Muscles have their origination, nor are immediately inserted by their Tendons,( though it is true every where else there are some Filaments inserted into it from the Membrane of the Muscles) and where it may be observed, though it is not exactly smooth, it is more equal, than on that side, which lies next to the Bone; for on this part it has every where inequalities, some whereof are in the form of ridges, others are small Protuberances of divers other figures, some round like little Mole-hills, some Oval, &c. to speak briefly of which, they are correspondent to some superficial Cavities formed upon the Bones, which I shall afterwards have occasion to speak of. It has Blood-Vessels, both Veins and Arteries, which are visible enough in the Periosteum of large Beasts, but they have nothing particular, that is worthy of our remark.  
About the Origine of this Membrane, I do not find that Anatomical Authors seem much to concern themselves, not so much as generally they do about that of the Pleura, and Peritonaeum. The account, that may be gathered from some few of them, is, that the Periosteum of the Skull is from the Dura matter, and that of other Bones from the Fibres of the Muscles. But since it is a Membrane common to the Bones, it does not seem so reasonable to suppose, that in one place it has an original so different from itself in another, especially considering that there are Muscles about the Head, as well as in other parts, from which it might be produced. And the best account of it, that I could gather from a strict examination of this Membrane, is, that the Fibres which constitute it, are every where of two sorts, some of them are propagated from the Dura matter, others from the Fibres of the Muscles. That the Periosteum of the Skull, which lies next to the Cranium, is derived from the Brain, appears not only from what has been commonly observed, that they are united, and the one continued from the other through the Sutures in a Foetus, and Infants newly born; but besides this, the Dura matter passes out of the Skull at other places, as between the as Sphaenoides, and the as Petrosum, so between the as Petrosum and the as Occipitis, which is the reason why it adheres so firmly to that part of the Cranium. When it is got out beyond the Bones, between which it is double, it spreads its self both ways over the Bones, one part running one way, and the other another. And as the Pericranium, which I cannot conceive to be any other than the Periosteum of the Skull, owes the original of one Series of its Fibres to the Dura matter, so does the Periosteum in all other parts; therefore in that part of this Membrane, which lies next to the Bone, there are every where a Set of Fibres, whose tendency is direct from one end of the Bone towards the other, and without that Variety in their Position, which is often to be observed in those Threads, which are derived from the Muscles. This may seem improbable; for though we may easily conceive how those Filaments, which are propagated from the Dura matter, may be continued from one Bone to another in the Pericranium, so far as the Bones are joined by Sutures, or Harmony; yet where the Bones are articulated, and distinguished by visible Interstices, and when the Membrane, which lies over those Interstices, is no part or continuation of the Periosteum, the course of those Fibres, which proceed from the outward Membrane of the Brain, must be interrupted, and after their termination, the Periosteum must necessary be wholly derived from something else. But this difficulty I soon got over, when I came strictly to examine the Ligaments of the Bones, where I observed a continuation of these Threads running upon those Ligaments, by which means they proceed from one articulated Bone to another.  
Besides the Filaments, which arise from the Dura matter, and make that part of the Periosteum, which lies next to the Bone, there are another Set of Fibres, which are propagated from the Muscles, and Tendons, which accede to it in every part as it proceeds; The Original of these in some parts, especially upon the Bones of large Animals, is easy to be discovered; for by taking one of the exterior Fibres of a Muscle, and separating of it gently, it not only leads us to the Periosteum, but I have traced some of them a good way upon this Membrane, where its superficies has been clear of the fleshy Fibres.  
The order, and course of the Fibres in this Membrane, is not the same in all of them: Those indeed, which are propagated from the Dura matter, are every where parallel, and their Tendency, as I have already observed, is from one end of the Bone to the other: But for them, which are derived from the muscular, or tendinous Fibres, they are not constantly agreeable in their course and position, but as they differ sometimes from those, which proceed from the Dura matter, so those, which are propagated from one Muscle, have in some places a tendency different from them, which are derived from another; so that I have in the Periosteum of one of the Bones of the Leg, observed three several series of Fibres lying one over another; the interior, or those next the Bone were streight, the rest arising from two several Muscles, whose different situation gave their Fibres in their elongation a different tendency; those that were derived from one Muscle, proceeded obliquely one way, and they that were from the other, obliquely the other; that they decussated one another in the same manner, as the Fibres of the obliquely descending, and ascending Muscles of the Abdomen do. And according to the position of the muscular Fibres, with respect to those Threads of the Periosteum, which have their Origine from the Dura matter, the Filaments, which are derived from those Muscles, are sometimes parallel, in some places transverse or obliqne to them, which proceed from that Membrane of the Brain. Therefore I have in tearing of this Membrane of the Bones observed, that in some parts it has been more easily rent directly, that is where the Filaments were all parallel, and observed the same tendency; and in others, where some of them were obliqne, or transverse, it was not so very difficult to pull it asunder that way.  
However the Tendons of many Muscles do propagate their Fibres to make some part of the Periosteum; yet, I have observed that some of them, which have often a great stress or dependence upon them, when they act, have not been so kind, but penetrated this Membrane, and were immediately inserted into the Bone, so that I could distinguish the Periosteum, which lay like a circled round them; and this has given me an occasion to think, that all those Threads of the Periosteum, which are propagated from the muscular, or tendinous Fibres, after they have run so far as to make up their part of this Membrane, are inserted into the Bone, and that they are particularly these, which as I shall hereafter show, penetrate into it.  
From the account that I have given of the Periosteum, it may appear, how little reason we have to make the Pericranium a distinct Membrane from the Periosteum of the Skull: For although it be divided at the temporal Muscles; this is no more than what the several series of Fibres do make the Periosteum capable of in the Leg, or any other part; and I have upon the Shin-bone of an Ox divided it into four or five several Membranes, if I may so call them, when it has been dried.  
The Adhesion of the Periosteum to the Bone is firm, and intimate, partly by contiguity, partly by continuity, or the insertion of some of the Filaments of the Periosteum into it, and by the Blood-Vessels, which are propagated out of one, and ramified in the other, and like so many small Ligaments hold them together.  
By continguous Adhesion I mean that union, which arises from the immediate Coadjacence or Contact of two Bodies of a fixed Nature, where no matter either Volatile, or Elastick intervenes, so as to concur with that force, which endeavours to separate them, and is a manner of Conjunction, which some Experiments, that I need not here mention, do demonstrate to us. That part of the Periosteum, which is thus united to the Bone must be the Fibres, which are propagated from the Dura matter, as being those, which lye next to it. To add to the strength of this part of their union Nature has wisely contrived; for all Adhesion, and Union of this kind being so much the more firm, as the Superficies is larger, in which the two Bodies, that are contiguous, do touch one another, the Surface both of the Bones, and their Membrane on that side, which is next to them, is so formed as to receive a considerable enlargement by incisions, and small superficial Cavities formed on the outside of the Bone, and by ridges, and other protuberances on that side of the Periosteum, which is immediately applied to it. And I need not stand to show how these inequalities enlarge their superficies beyond what it would be, if it were smooth and plain, since it is evident.  
But to explain this Adhesion of the Periosteum by something, that is more familiar, and a Notion more intelligible, I conceive that the Bones obtain very much the nature of a Gluten. When their Generation has proceeded so far, that they have made some advancement towards their natural Temper, they are like melted Glue, to which the Periosteum being applied, whilst they are soft and viscous, does adhere, though not so firmly at first, but as this Glue, I mean the Bones are indurated, and their parts more fixed, the union between them, and their Membrane is more and more confirmed, until at last they are not easily separable. And as the Periosteum at first cleaves to the Bone, whilst it is soft, so afterwards in all the growth of it, that matter, which gives an increase to the Bones being, when it is first supplied and apponed to them, viscous like the substance of a new formed Bone, is as apt to stick to any addition made to the Periosteum in its growth, as the Bone itself was to cleave to its Membrane at its first Formation. Neither is this Notion of the Adhesion of the Periosteum to the Bone in such a manner, as if they were joined by Glue merely conjectural, but grounded upon a small Experiment I made: I took a piece of a fresh Bone, and dissolved it in Aqua Portis, then I set it over the Fire in a glazed Vessel, and evaporated so much of the liquid part, that I reduced the Solution near to the consistence of a Jelly, then I set it to cool; after it was could, it not only resumed its hardness,( though it was more brittle) but adhered to the Vessel as intimately, and firmly as ever I have observed Glue itself to do to a Vessel of the same kind. Besides, the Bones in a Foetus are plainly gelatinous, and viscous at one time, and in a Calf, which I had taken out of a Cow sometime before it was to be excluded, where the greatest part of the Bone was in some measure indurated, I observed such a gelatinous matter between that part, which was more solid, and the Periosteum.  
Besides this manner of Adhesion, the Periosteum is united to the Bone by little Fibrillae or Threads continued from the one, and penetrating into the substance of the other, which may be observed in a perfect Bone, especially in some places. But I discovered it more plainly in the Bones of a Calf, which were tender and imperfect, where I found the Threads penetrating that gelatinous Matter, which lay under the Periosteum, and beyond it were inserted into that part, which was indurated, out of which I could draw some of them.  
By these Fibres, and the mediation of the Periosteum, it is probable that the Bones have some internal sense, so that they may be said to be sensible not only in their Membrane, but even in their substance. When we consider how the Teeth, which are at least in the stony Cortex of that part, which stands out of the Gums, more solid than any other Bones, will be affencted by injuries, which make no immediate impression upon the Nerve, which lies in their Cavities, as to instance only in that particular sort of sense they have upon the application of Acids, when their Mucus is scoured off, which we term setting them on edge, what is this but a sensibility of Bones? Considering that this sense must be by the Fibrillae of the Nerve inserted into them, that these Nerves answer for the defect of the Periosteum in that part of every Tooth, which stands out of the Gums; and that this sensible Membrane does propagate Threads into all the Bones, how can we think but that any irregular, and tumultuous motion in the Spirits of these solid parts is communicable to the Brain by the mediation of those Fibres, which are derived from the Periosteum into any Bone, as well as by the Nervous Fibres, which are dispersed in the substance of the Teeth. And to confirm what I now say, there is an observation of Nicolaus Massa, which Diemerbroek mentions, of a Man, that had an ulcerated Leg, where the Bone, which was deprived of its Membrane, was so sensible, that it could not be touched without pain; nay the Bone was Perforated, and he found it had a sense in the internal part, which gave him the suspicion of Nerves, but he has left it to others to find them, and as I could never with the strictest enquiry observe any such thing, so I have shown how the want of Nerves is supplied, and we may be able to account for the sensibility of the Bones without their proper Nerves.  
I come now to consider the Design and Use of the Periosteum; and first, it is to be a Tegument to the Bones: for Nature in the Formation of all the parts is found to be Elegant, as well as Provident, and though it could be granted, that this Membrane serves to no necessary use, yet it is for decency.  
Secondly, It conveys Spirits into the substance of the Bones for maintaining their Heat, for preserving their Sensibility, and to assist in the Work of their Accretion, and Nutrition. How this Membrane immits minute Fibres into the Bones I have already observed, and I do suppose they are continued so far as to be Infundibula, and disembogue themselves into the Interstices of the bony Strings, in which the Spirits afterwards move as their Channels, and therefore some of these Fibres insinuate themselves farther into the Bone than others, as the Interstices which they serve to, are more remote from, or nearer to the Superficies.  
Thirdly, It seems to be one thing, which checks, and helps to set limits to the growth, and extension of the Bones. Whilst this Membrane is growing, and capable of being farther expanded, so long it allows the Bones the liberty of enlarging their dimensions, but when it ceases to be extended, and cannot admit of their increase without a rapture, then there is some stop put to their growth. Therefore we shall find, that the Periosteum is stretched upon the Bone to its utmost extent, so that when it is divided in any part either directly, or piteously, and raised from the Bone, it is so streight, and correspondent to that part, which it was applied to, that the Labia, where it is divided, cannot fairly, and without tearing of it, be extended so as to be brought to lye one over the other. Neither will it seem improbable that so thin a Membrane should hinder the increase of the Bones, if we consider the strength of it, and how we have instances that seem very like it in Trees, where the Bark is often observed to bind them when they are young, so that it is necessary to open it before they can have the liberty of thriving. And even amongst Animals it is not unknown how the Skin of a Horse, which is naturally more Tensile, when he is Hidebound, as they term it, checks and hinders his growing. Not that I think this is the only, or principal thing, that determines the measure of the Bones Accretion, I only suppose it conspires with another Cause, which I shall explain, when I come to speak of Accretion, and to show the reason, why it ceases in full-grown Animals.  
Fourthly, The Periosteum is serviceable in the Conjunction of the Bones and their Epiphyses, whilst the substance of the Epiphyses is cartilaginous; of those Bones, which are joined by Sutures or Harmony, and in the connexion of the Bones and their Cartilages. For being a strong Membrane, and firmly adhering to any of these parts, which are to be united, and not being Tensile like some other Membranes, it does not suffer them easily to recede from each other, or to be displaced, which cannot be without a disruption, or a disengagement from one of those two parts, which it holds together. This, though it be not the same thing as the continuation of the same Body; yet it does in a great measure answer to it, and is a manner of Conjunction, which Art does often imitate. And I not only suppose this to be one use of the Periosteum, but it is very evident where the Cartilages are joined to any Bones; for if we take the Scapula, or any of the Ribs, and divide this Membrane round that part, where their cartilege is united to them, though there is another contrivance for their Conjunction; yet they will be easily separated.  
Fifthly, It serves for another considerable design, and that is to join the Heads, and Tendons of the Muscles fast to the Bones: for although, as I have already observed, the Tendons of some Muscles do penetrate this Membrane directly, and are immediately inserted into the Bone; yet the Origination, and Tendons of a great many Muscles have their immediate dependence upon the Periosteum, by whose mediation they are fastened to the Bone. And for this Reason it seems to be, that Nature has made the Adhesion of of this Membrane to the Bone so firm by that contrivance, which I have taken notice of.  
Sixthly, and lastly, If the sense that this Membrane is endowed with, was intended with a particular respect to the Bones themselves, as it seems to be, and not merely a Consequence, as the Periosteum is propagated from such parts, as are acutely sensible, it was designed for the safety, and security of the Bones from external injuries, for the discovering to us the part affencted, when they are distempered, and directing us in the application of external Remedies. As for other inconveniencies and injuries, which follow upon any external violence, excepting the pain, which they threaten, they are not so suddenly thought of, but this evil of pain we have a natural, and an immediate abhorrence of, without any deliberate thought or consideration, and as the apprehensions of it, so our endeavours to prevent it are quick, and as this obliges us to watch over them; so it makes us withdraw them hastily from any sudden dangers, or appearance of Mischief. Thus for the security of the Eye, which in the Tunica Cornea, has no sense; Nature has given it one, which is acutely sensible, and the design certainly is that the pain, which the Tunica adnata is obnoxious to, should give us the occasion of shutting our Eyes against any thing that may excite it, and consequently serve for the security of the whole Eye: And thus much of the Periosteum.   

Of the Nature, and Constituent Parts of the BONES.  
NOW I have laid aside the Periosteum, the next thing, which comes in view, and under our examination, is the Bone itself, and I shall inquire  
First, Into the Nature of the Bones, which like other products of Nature have their infancy, or first beginning, their improvement, and tendency to maturity, and their perfection. At their first beginning they are soft and gelatinous, that is, whilst their proper parts not only are disunited, but have a mixture of such moist and loose Particles, which intervene, as are neither apt themselves to be fixed, nor will suffer those, which are fit to make a Bone, to unite, as we see water insinuating itself between the Particles of Gum arabic, or any Body of that Nature destroys its hardness. and rigidity, and renders it soft and gelatinous. When they advance near the temper of a Bone they are cartilaginous; as those Particles, which are fit to make a Bone, are driven nearer to one another by the power of the Spirits, and the pressure of that Nutritious Juice, which they drive to, and crowd against them, they express, and begin to free themselves from those parts, which lay between them, and hindered their mutual access, and that unition, which was requisite to make a solid Body of them; but still these Particles are not united at their extremities, which makes the parts, which they constitute, remain as yet less solid, and more flexible than a perfect Bone. But when the Bones are grown to that perfection to obtain their proper Nature, they are solid, and consist wholly of Parts, which are naturally fixed, and voided of motion, which being united, do all Conspire to resist a Pressure, and any endeavours to disturb, and disunite them, so that they can neither be agitated by Subtle, and Volatile Particles within; nor be moved, and disordered but by some great and extraordinary violence from without. These parts are of two sorts, to wit, Terrestrial, and Saline. It is true, if we come to torture a Bone with the Fire, it seems to confess that it consists of all the five chemical Principles; it affords us a Spirit, and Phlegm, a Volatile Salt, and an Oily or Sulphureous Substance, in which there is the same difference to be observed as in the Medulla, one part is soft and liquid, the other is more indurated like a Sebum, and the hard part of the Marrow; after these parts are abstracted, we have the Earthy, and some fixed Saline parts remaining behind. But these several parts are found in a great disproportion, the Terrestrial only are, after a through and perfect Distillation, above two parts of three, which I take to be the truest account of their quantity. I have after a long Calcination of Human Bones, found them to be five parts of nine, but by the continuation of the Fire, they still lose of their weight, so that I could not here tell where to fix the quantity of them: The fixed Salt is very little, and indeed but just so much, as that we may say they have some. The Volatile Salt was about a thirtieth part: the Spirit, and Phlegm, are not so plentiful as in Harts-Horn, being about an eighth, whereas in Harts-Horn they are above a fourth part; the fluid Oil a twenty fourth, besides a good quantity of that oily Matter, which was indurated, and stuck to the upper part, and sides of the Retort. But to speak truly, these cannot all be properly said to be the parts of a Bone: the Spirits, and Phlegm, are drawn from the Blood-Vessels, and the Interstices of the bony Strings, in which the Spirits flow whilst the Man is alive, and the Oil is plainly what had been supplied from the Medulla, and insinuated into the substance of the Bone by Pores, which I shall hereafter describe, so that none of all these can be said to be the parts of a Bone any more, than the blood may be said to be the part of a Vein, or an Artery. That which we call the Volatile Salt, at least the greatest part of it, I take to be a Constituent part of a Bone, and however it is raised, and brought over by the Fire; yet the Particles of it are solid, and sit to be one ingredient in these hard and rigid parts, in which whilst they are lodged, they are fixed, as we find after Distillation they will be Chrystallized, and resume a solidity; besides, this Salt does show much of a fixed Nature upon the Tongue, when it is tasted, having such a kind of sensible coldness as Sal Prunellae has.  
The Particles of which the Bones consist, when we consider how they form Strings, seem to be of a long Figure, and their position streight, so that one end lies towards one, and the other towards the other extremity of a Bone in the sides of it. I say in the sides, because where the Strings alter their course, and run Obliquely, or piteously, as in the Cancelli, and small Caverns of the Bones, and at the extremities, where they lye over, and shut up the Cavities, the position of these Particles must be different. Perhaps I may seem to contradict myself, when I say the bony Particles are of a long Figure, and yet make the Bones to consist of two different Principles, which may be thought to be an implicit Assertion that their Particles are diversely figurated. But it is very consistent with the Notion, I have of the Particles of all at least solid Bodies, which is, that none of them have the true and distinct Nature of any one pure Principle; but are a composition of two, or more, and from the proportion of the Principles, and the manner of their mixture or union, arise the Figure and Nature of the Particles, which they produce. So that though there is certainly a difference in the Figure of the Particles of every Principle; yet those which are formed from the Union of two, or more of them, may all be a like figurated in a Body, which contains several Principles.  
The bony Particles are in every Series united at their extremities, and by this Union they form continued Threads or Strings, which continuity gives the Bones a rigidity. The course or tendency of all these Strings in the sides of a Bone, is as the position of the Particles, from one end towards the other, and wherever the Laminae, which they make, are contiguous, they are Parallel, and so far streight as the Figure of the Bone will admit. Their course is no where more easily to be discovered in the Bones either of Men, or Brutes, than in the Ribs, where some of them may be separated, and run in the form of a String sometimes for some way together. And if we suppose, as we must do, the Horns of Beasts to be of the Nature of Bones, there are some of them, which plainly discover thus much to us, that the Bones consist of several small Strings, as particularly in the Rhinoceros Horns in the Repository their Strings are actually divided, and their course visible at their Basis. Or if we may make a judgement of our own Bones, and those of Birds and Beasts by Animals of another Element, the Whale-bone does sufficiently demonstrate, both that they consist of such Strings, and that the course of them is from one end towards the other. In short, in all the Bones, even those, which are not to us divisible into stringy parts, their tendency does evidently appear in the Fissures, which are many times to be observed in them, when they have lain in the Sun, or are any ways dried so as to crack.  
These Strings, though some of them run to the very extremities of the Bones, and others approach near to them, do not terminate there, so as to have distinct ends, but they are, where they may be thought to terminate, still continued, and run piteously, and as it were Arched, that the Strings of one side of the Bone proceed so as to meet, and be united to those, which are propagated from the opposite; and this at both extremities, that they are a continuation, though not of the Figure; yet in the manner of a Ring. Therefore they are not all of a length, but in every Plate they fall one shorter than another. Those which make the external Plate run from one end quiter up to the other, and are the full length of the Bone, and in some few other Laminae, which lye nearest to this, they want no more than the thickness of what is above them, and do every where, as well where they proceed piteously, as where they are streight keep a sociable course, but in all the other Plates they come more short of the length of the Bone, and run off from them, which close up or make the extremity of it, only by some Corrugations and Apophyses, which form the small Cavities they come to meet, and to be united in some certain places. The Strings of the first internal Plate in those Bones, which have a large Cavity, do plainly first divert from the side, or rest of the Plates into the interstice; after these the Strings of the next Lamina, and thus they run off one after another till we come to the extremity, where those of some few of the external Plates, which remain running piteously without any irregularities, or Plicae, and being contiguous, as on the sides, make a thinner, but compact part, which covers and shuts up the ends of the Bones. And as the bony substance of which the Cancelli, and the small Cavities are formed, is a continuation of the Strings from all sides of the Bones in those, which have the large Cavities; so from the first appearance of these Cancelli, or the first formation of the small Caverns, where there is nothing of that reticular texture, as the Strings of every Lamina strike off to make them, the side or Wall of the Bone grows gradually thinner towards the extremity, so that by that time we come to the end of it, we have not above a fifth, or sixth part, and it may be less, remaining to make the thickness of that part. Thus in the as femoris of a human Skeleton I have observed the thickness of the side before any of the Strings ran off from it to be five times more, than that of the Head. So that if we suppose the side to consist of five and thirty Plates, then has the Head but seven which lye contiguous to one another, and enclose the Cavity.  
Perhaps it may not be so easily understood how the Strings of the exterior Plates are continued at the ends of the articulated Bones, which are covered with a cartilaginous substance supposed to be distinct from the Bone, but the parts, of which these Cartilages consist, are the same as those, which make the Strings in the more solid part, disposed in the same order, so that the Series of the Particles of so many Strings, as answer to the thickness of the cartilege, run through it, and would be continued in the Nature of a solid bony String, but that the liquour, which is continually supplied to the joints, will not suffer the Particles to be so intimately united, as to render that substance of that part equally hard.  
The Bones in their firm, and solid part, and where the small Cavities are distinct consist of several Laminae, or thin Plates lying one within, or under another. So that there is this subordination, in the Constituent parts of a Bone, a proportionate quantity of Earth, and Salt duly mixed, produce the Particles; the Particles regularly disposed, and united at their extremities in every Series form the Strings; the Strings laid in a convenient Order, and Number, and so united form the Plates; and these Plates make up the Bone. I say the Bones in their solid part, and where the small Cavities are distinct are formed thus of Plates, because where any part of their Structure is like Network, or Cancelli, which are to be found in many of the Bones of a Human Skeleton, and more than in other Animals, the Strings are not so ordered, and united as to make any Plates, but run into several Fasciculi of those smaller Strings. Now since the Strings of which these Laminae consist are, as I have already shown, after the perfection of the Bone so continued from one side to the other as to have no distinct extremities, every one of these Plates excepting those, which have their Strings at any end running into Fasciculi, could they be divided entire, would be like a Tube imperforated at both ends. Yet I did in two Oxes Bones, which were fresh, meet with a small Lamell, which lay next to the Periosteum, that fell much short of the length of the Bone, and did not lye round the Cavity so as to be Tubular, but I looked upon it to be extraordinary, and not agreeable to the common method of Nature.  
There is some difference in the manner, wherein the Lamells in several Bones are disposed; where there is a large Cavity they are on every side contiguous, and closely united, and the small Caverns, and Cancelli, which are at the extremities, are produced from Plates, and Strings propagated from the sides: But in the Bones, which have not any great Cavity, but are altogether spongeous within, many of the internal Laminae are placed at some distance from one another in all their length, excepting in those several places, where the flexure of their Strings this way, or that, and their Apophyses bring them to meet, and being thus modified all along just as they are at the extremities only of the Bones, which have a large Cavity, they produce in the whole internal part the same sort of small bony Cells. And because many of the Plates within stand thus distant from one another, they fill up the whole space within the Wall or solid part, with such a cavernous substance, and therefore the sides in these Bones are thinner, and the Plates which are contiguous, and are their solid part, are fewer than in those, which obtain a large Cavity.  
On the inside of the as Humeri of a human Skeleton, I have sometime found the first Plate, from one end of the Cavity to the other, puffed up in several places, so as to form conspicuous Cavities under it, but round every one of those Cavities it was depressed, and remained united to the next Lamina, and where it was thus elevated, I took notice of a great many Pores, by which I do suppose the Medullary Oil did pass out of the large Cavity into those, which were under this Plate, and were some of those transerse Pores, by which the Marrow is conveyed in order to diffuse itself between the Laminae, and which I shall presently give an account of.  
Of these Plates I have in one Bone with a Microscope numbered sixteen together, and by computing the number of those, which I could not so well distinguish, by the thickness of them, which were discernible, I reckoned them all to be three or four and thirty. In another Oxe's Bone I counted one and forty together, which I could plainly discover, the rest I could not so well, because they did not lye so streight, and regular on that side next the Cavity, as that I could be certain as to their number, but yet I discerned they were distinct Plates, and I numbered them so well as I could, which were by that account fourteen, so that they were in all five and fifty.  
That the Bones do thus consist of several thin Plates lying one over another we have presumptive evidence from their exfoliation, and considering how much the Horns of Beasts participate of the Nature of Bones, and how many of them may be actually divided into several thinner Lamells, this may induce us to think that the Bones are in the same manner made up of Laminae. But we have further evidence of it, as they may be distinguished with a Microscope, and not only so, but I have actually separated them in several Bones, particularly I have taken some of the thin, and fine Laminae off from a piece of a human Skull, and in one Bone I had, I could divide the whole Wall from the Cavity to the external superficies into Plates, though some of them I must confess were thicker than others; but when I viewed any of the Plates with a Glass, and numbered sixteen, or more together, whilst they were yet united I could not discern any such difference in their crassitude, so that I am confident, that those, which I found upon separating of them to be thicker than others, and which I could not divide into such thin and curious Plates, as I did some, did consist of thinner, and finer Laminae.  
The manner how the Bones consist of several Plates included one within the other, and how the small Caverns, and Latice-Work are produced, I have endeavoured to express in the first Figure, Tab. I. where a, a, a. are the Plates in the sides of a Bone, which must be supposed to be contiguous, although I have made them distant to represent them distinct, the four exterior of which are parallel and contiguous at the extremities b, b. as well as in the sides a, a, a. c, c. is the Latice-Work produced from the Strings propagated from the Plates d, d, d, d, e, e. are the Caverns formed of the Plates f, f, f, f, f, f. which run off from the side successively, where the crassitude of the solid part appears gradually diminished, G. is the large Cavity, and h, h. the passage of the Medullary Vein, and Artery.  
In the Bones through, and between the Plates are formed Pores besides those, which are made for the passage of the Blood-Vessels, which are of two sorts, some penetrate the Laminae, and are transverse looking from the Cavity to the external superficies of the Bone. The second sort are formed between the Plates, which are longitudinal, and streight, tending from one end of the Bone towards the other, and observing the course of the bony Strings. And that I may not be thought to pretend to the discovery of what no other mens Eyes can discern, because they are generally very difficult to be observed, unless it be the transverse Pores in the internal Lamell, I have the pieces of two Bones, which I have brought along with me, in one of which, the transverse, in the other the longitudinal Pores are very visible with the help of an ordinary magnifying Glass.  
The first kind of passages are formed not only in the first internal Lamina, but in every one, even to that which includes all the rest, and I have not only seen them sometimes in those parts of a Plate, which in the Cavity have been naturally puffed up, and raised from the side of the Bone, and in the next Lamell to that, but I had the satisfaction in that Bone, which I resolved into Plates, to observe some of them in all the Plates. Though so far as I have observed the nearer they are to the Cavity the greater is the number of these Pores, which in the first internal Plate are very numerous. Now this difference in the number of the transverse Pores, besides what I gather from what I have observed, we may suppose for these two Reasons, first because the quantity of Marrow, which is to pass through them is less, and less, as it approaches nearer to the outside of the Bone; for the Marrow being supplied from the Cavity, every Plate transmits so much as is necessary for its own use, and all the Plates, that lye above it, so that every one as it approaches nearer to the superficies, having a Plate less than another to transmit the Medullary Oil to, there is occasion for a smaller number of these Pores in one than in another. Secondly, because it was necessary the Bone should be very solid towards the superficies, where it is exposed to external injuries. About these passages I was particularly strict in my enquiry, whether they were not formed for Blood-Vessels tending either to, or from the Marrow, and although some of the Medullary Veins have Pores by which they penetrate into the substance of the Bone, yet I made myself certain that these Pores for the generality of them, which I examined, had no Vessels, which passed into them. These transverse Pores do not observe any such order as to lye directly one under another to form one continued passage from the Cavity to the external Plate. This could not be, but Nature must either have been frustrated of her end in making them, or injurious to the solidity of the part. If they had been continued through the whole thickness of a Bone, and limited to their present number, without the other Pores which are formed between the Plates, it had been but a small part of the substance of a Bone, that could ever have been touched, and had the benefit of that oily matter, which they serve for the dispensation of. If they had been so thick, and numerous, as that all the substance of a Bone could have been oiled by the insinuating Marrow without the longitudinal Pores, this had been as injurious another way, and such a porosity would have destroyed that solidity, and firmitude, that were necessary in these parts, which are the Timber-Work, and Supporters of all the rest. For the transverse Pores, which interrupt the continuity of the Strings, that constitute the Plates, would have detracted much more from the strength, and rigidity of the Bones, then those, which are formed in the length of the Strings, and between the Laminae, which is easily demonstrable. But ●●y the contrivance, which appears, Nature ●●rains one end in such a method as does not disappoint her of another, but both makes her Bone firm, and in the dispensation of the Marrow is just, and kind to the whole substance of it.  
As the transverse Pores are differently placed in the several Plates so as not to receive the Medullary Oil immediately one from another, so those in the same Lamell are disposed with a seeming irregularity, and scattered, not being digested into such an order as to form Circles, or exact series of Pores round it, which thing is yet regular, and reasonable, and without doubt is done ex proposito, that the Plates might not be weaker, and more apt to be broken in one place, than in another. For although they had not exceeded their present number, yet supposing they had been set in several series round a Plate so as to delineate Circles about it, this would have made it more infirm and apt to be broken in those than in other places, or than now it is in any part.  
Besides these there are longitudinal Pores formed between the Plates, which in the sides of the Bone have a tendency from one end towards the other, and where the Strings alter their course, and are transverse to the Cavity that is at the extremities, they still run along between the Plates, and change their Position, as the Strings do. These are not very commonly to be observed, nor without a strict inquiry, and good Glasses, unless it be now and then in some particular Bones. There are none in which they are oftener capable of being observed than in the Ribs. Though I have in the firmest part of a Scapula, where the Plates were immediately united plainly discerned them, and even seen the Marrow, which had insinuated itself into them, sticking to their sides in the shape of an Oil. I have likewise had the satisfaction to observe them in a human Bone, and that between eleven, or twelve several Plates. By these it is that the Medullary Oil diffuses itself, and is immediately beneficial to the Plates; the transverse Pores are subordinate to these, and rather designed for the passage of the Marrow into them, than for the immediate communication of it to the substance of the Bone. The manner therefore, in which the Medullary Oil insinuates itself through a Bone, and is dispensed to all the parts of it, is this; it first passes being liquid, as it all is whilst the Animal is alive, out of the Cavity through the transverse Pores of the first internal Lamina, and not having Pores of the same kind directly subjacent in the next Plate to transmit it towards the outside of the Bone, it flows into the longitudinal Pores formed between these two, the first, and second Plates, and being carried along in them till it finds some transverse Pores in the second Plate, it passes through these, which when it has done it is again obliged to alter its course to run into, and flow along in the streight Pores between the second, and third Laminae, thus it passes through and between the Plates successively, till it has made its way through the solid part to the external Plate. Thus the Medullary Oil is dispensed in all the Bones to those Plates, which are contiguous, and have no intermediate Cavities to entertain any Medullary Glands of their own, but where any part of the Plates stand at some distance, being only united by intervals as their Corrugations bring them to meet in some certain places, there we have the small Caverns, which are capable of containing some Medullary Glands, so that here the Plates have more immediately, and without the former method of conveyance the benefit of the Marrow.   

Of the Superficies of the Bones, their Passages formed for the Medullary Vessels, and their Cavities.  
NOW I have considered the Constituent parts of a Bone, I proceed to examine it entire, and to take notice of the structure, which arises from the composition of its parts, and the order, in which Nature has disposed the Plates, and the first thing, which falls under our observation is the superficies, which in all the Bones excepting only at the ends of those, which are articulated, where it was necessary that they should be smother to make them more fit to be moved, and managed by the Muscles, is remarkably unequal( though more in some than in others) from Cavities, whereof some are superficial, others are passages, which penetrate farther into their substance, the most conspicuous of which are those, through which the Blood-Vessels of the Marrow, and the Arteries, which are designed for the nourishment of the Bones, do enter.  
The superficial Cavities, which some may think to be accidental, are not the careless stroke, but the design of Nature, and are those inequalities, which I have already in speaking of the Periosteum observed to be a contrivance to enlarge the superficies of the Bones, and to strengthen the adhesion of that Membrane to them. They are of two sorts, some are long, and these we may call Sulci or Furrows, others are more contracted in their length and of a different Figure, which may be distinguished from the former by the name of superficial Pits or depressions.  
Of the Sulci some are larger and broader, some longer, and some more superficial than others. But they all generally agree in this, that they observe the position of the Particles, and the course of the Strings in the Plate, in which they are formed, so as to run directly the same way as they lye, though in the as Hyoides I observed some few of them to be different, some were of the figure of an S, and others were plainly obliqne to the course of the Strings.  
Of the superficial Pits some are broader, and larger, others, and much the greatest number of them, are smaller. Many of these last are round, those which are larger are irregular in their Figure, and seem to be a sort of confluentes, or several of the little Pits run one into another. I have in some of these larger depressions observed others that were small, that there were Pits within a Pit. I have though rarely seen of these superficial Cavities running a little way under the Plate, in which they were formed, into which the Periosteum by a Protuberance answering to it, did insinuate itself.  
These inequalities of the S●l●i, and superficial depressions do not observe the same proportion in their number in all the Bones, some have more Furrows, some more Pits than others. The as Humeri, and the Tibiae, and especially the Thigh Bone have a great number of the Furrows, some of which are deep and considerably long, three inches and more. Besides these they have the superficial depressions, and that some of them in the very Furrows themselves, which are large. The Ulna, and Radius have Furrows too as well as Pits, though the first has the greatest number of them. The Fibula has considerable Furrows in some places, though it has not so many to show us, but abounds chiefly with the other superficial Cavities. Some of them are likewise to be observed in the Bones of the Metacarpus, and Metatarsus. Thus they have appeared in those Bones, where I did industriously observe them, but I see little reason why they should be constantly alike in all Skeletons, so that it is probable Nature does here change her hand in some Subjects, and form more superficial depressions, or more Furrows in the same Bones of several individuals. In short many of the Bones have some of both sorts, and all have the superficial depressions. But in the upper part of the as Frontis, and in the Bones of the Sinciput at those Angles, which meet in the Coronal Suture, and all along on both sides the Sutura Sagittalis I have observed in several human Skulls, not so much this contrivance of superficial Cavities for enlarging their superficies, and strengthening the adhesion of the Periosteum, as numerous Pores penetrating into the substance of those Bones, particularly in one of the Skeletons in the Repository they are very numerous, exactly representing the transverse Pores of the internal Lamina in the large Cavities of the great Bones of the joints, and in one Skull I found many of them planted more backward down the middle of the as Occipitis. The same I have met withal in the as Frontis of an Ape, and in a tiger where I suppose the Tendons of the Temporal Muscles reached to the Sagittal Sature, I found them only in the Bone of the Forehead; and I observed the like in the Ossa Sincipitis of one Rhinoceros, on both sides of the Sagittal Suture. The reason of which difference to me seems to be this, because where these Pores are to be observed in the Bones of the Sinciput there are the Tendons of no Muscles inserted, so that there was no reason to contrive for so firm an adhesion of the Pericranium to these parts, and indeed not much more in the as Frontis, for though there are Muscles, which have their Origination from it, yet they are no more than the Musculi Frontales, which only Corrugate the Forehead, and help to raise the upper Eye-lids, when we would open them very wide, and so have no great stress, or weight depending upon them when they act. Since therefore there was no great occasion for these superficial Cavities, Nature in those parts of the Bones I now mentioned has formed Pores to another end, and may here be thought to be upon a design for the preservation of our Health, and the greater security of our Lives. As it was requisite that the upper Region of our Bodies, where the Soul, that actuates, the Sun, that irradiates the lesser World, is seated, should be clear, free from Clouds, and Vapours, so these Pores seem to be formed as one way to expel, and scatter those moist, and misty Particles, which may be apt to eclipse, or weaken the influences of that Principle, which animates us. I do therefore conceive that they are Perspiracula by which the offensive Vapours, which arise, and gather within the Cranium do perspire. And it may seem more probable if we consider how Sweats do easily, and frequently arise in the Forehead, even when they are not discernible in other parts, to account for which we may reasonably suppose that there is some other way of evacuation besides what is made from the Mass of Blood by the Cutaneous Glands, which are to be found in any part of the Skin as well as there. I know the practise both of ancient and modern Physicians have in taking off the Hair, and the application of plasters as well for clearing, as strengthening of the Brain, directed to have them done upon the crown of the Head, not that they did as I can find ever take notice of these Pores, though Anatomists do suggest that the substance of the Bones of the Synciput are therefore thinner, and more rare than that of the other Bones, that there may be a more free, and easy exhalation of Vapours, which implies a supposition that there are such Pores. I must confess I have not met with them in all the Skulls, that I have examined, and perhaps the difference may make some variation in the state of the Brain, the want of them may be the occasion of a natural dullness, and cloudiness, it may render us obnoxious to a frequent headache not only upon the accident of a could, or any other evident occasion, but even where the Crasis of the Blood is good, and no accountable cause has fallen under our Observation.  
Whilst I suppose some of the serous Particles, which are evaporated in these parts, to come from the Brain immediately, or without the mediation of the Blood-Vessels conveying them to the Cutaneous Glands, some will be apt to think I speak as if I had never heard of those Glands, and did not understand the manner, in which the Serum is commonly excerned when we Sweat. But that there are subtle Vapours continually arising within the Cranium I think cannot be denied, and that they are successively excluded as they arise is as certain, whether they pass through the Skin by the Cutaneous Glands, or some distinct Pores is not material, but the question is whether the Cavity of the Cranium be freed from them mediant sanguine, as they are resorbed by the Blood-Vessels, and carried in the Mass of Blood to the Cutaneous Glands, or whether there be not a more immediate way by Pores and Interstices in the parts guiding, and carrying them, though perhaps meandrically to the external part of the Head. This I am sure we all seem to grant, that there are such immediate passages, by which not only the tenuious Vapours, but more gross, and weal-public Particles may be evacuated out of the Cavity of the Skull, when we prescribe Issues in the Neck, and upon the crown of the Head in any cephalic Distempers: for if they were not conveyed some other way than by their return into the Mass of Blood, and their Circulation through the Sanguiserous Vessels to these artificial Emunctories, I do not apprehended why an Issue in the Heel, or any other part should not be as proper and beneficial in those cases, as in that part, where we so precisely order them. Some that perhaps would allow such a Perspiration as I speak of, if the including parts were only membranous, will object the thickness, and solidity of the Bones, through which these Vapours must pass, but if they do consider those two sorts of Pores formed in the most solid part of a Bone, which I have before given an account of, they may be satisfied that even these solid parts are permeable to a thin, and tenuious matter.  
Besides their superficial Cavities the Bones have all of them deeper impressions, Foramina, which not only renders their superficies unequal, but penetrate far into their substance, where the most remarkable, and they that deserve or admit of our particular notice, are those by which the Blood Vessels pass through the side of the Bone to the Medulla. The Foramina, by which the nutritious Arteries enter the substance of the Bones, are in some places very visible, but not so conspicuous as the other, nor so constantly agreeable in all things that they can well be particularly described, in general many of them are at one end of the Bone, and the contrary to that where the Veins pass out, and there are some planted in the intermediate parts between the two extremities, which are but small. The passages of the Veins excepting them, which accompany the Medullary Arteries, are very numerous and minute, but there is nothing particular in them to be observed excepting their number.  
As for the passages of the Medullary Arteries, and the Veins, which accompany them as they are but few so they are considerable. This is to be remarked that they do not penetrate the side of the Bones, especially those, which are articulated directly into their Cavities, but with an obliquity like the passage out of the Ureters running for some way between the Coats of the Bladder, before it opens into the Cavity, so that I have found this passage sometime to be an Inch, and half, when the thickness of the Bone was little more than the eighth part of an Inch. In this manner they are generally formed in Beasts, and Fowls, as well as Men. But more obliquely in Men, and some sort of Beasts, than in others. In two Rhinoceroses some past almost directly through, and none of them so obliquely as in Men, and some other Creatures: the reason of which seems to be because the Bones of the joints in them are very short; so that the same obliquity of the passages, which seems to be for this cause, that they may not detract too much from the strength of the Bone in that part, was not so necessary here. There is no Membrane invests the sides of these passages, neither is the Periosteum on the outside, nor the Membrane of the Marrow within so kind as to communicate any part as a covering to them. They are most observable in the Bones of the joints, the Ileum, Clavicles, and the lower Jaw. The as Humeri, and as Femoris have sometimes two or three, the Radius and Ulna, the Focile Majus, and Minus, the Bones of the Metarcarp, and Metatarse, the Ossa Sesamoidea, and almost all the Bones of the Fingers and Toes have commonly one, the Ileum has three, two on the inside, and one external. But I must confess I have observed that Nature so little confines herself either as to their number, or the particular place in the Bone where she forms these Foramina, that I can hardly say I have found them all alike in these respects in any two Skeletons, that I have made the subjects of my enquiry. In their tendency these passages are more constant, and I have found that the Skeletons both of Men and Beasts do generally agree, so that where a passage runs upwards, or downward the same Foramen, or that, which answers to it, does in the same Bones of all such Skeletons commonly tend the same way, especially in the lower Jaw, the Clavicles, the Ribs, and the large Bones of the joints. In the as Humeri, the Tibia, and Fibula they run downward, in the as Femoris, the Radius, and Ulna, they pass upwards, so that we may observe that in those Bones, which answer to one another in the upper, and lower joints, they have a contrary tendency, which there seems to be some reason for, because it is generally so, though it seems difficult to give one, that may be satisfactory: that, which I have been thinking of, is the difference there often is in the position of these several parts with respect to the Trunk of the Body, and the Aorta, the posture of the Cubit is frequently transverse to them, and the Thigh-Bones when we sit lye at Angles with the spin, and the great Artery, so that the reflection of the Medullary Arteries is better admitted here than in the Shoulder, which is more parallel, or in the Bones of the Leg, whose position is direct to the Aorta, where their course must have been perfectly contrary to it, though it must be confessed that the Cubit, and the Thigh-Bones are frequently posited in the same manner with respect to the Trunk of the great Artery. But I shall shorten my account of these observations, which it is hardly worth our time to insist upon. In the Lion, the Goat, the Antilope, the Rhinoceros, and the Bones of all other Beasts that I have examined, they ordinarily observe the same tendency as in Men, though in the Bone of the right Thigh, and the Fibula of one Rhinoceros they did differ, but in another they did exactly agree with what I had commonly observed in human Skeletons. In the ostrich, and generally in all Fowls these passages in all the large Bones of the joints tend downward.  
From the superficies of the Bones by the guidance of these passages we come next into their Cavities,( for the Laminae, which make the side or wall of the Bone, I have already given an account of) and we will first take a view of their internal or concave superficies, where the Cavity is large, and the internal Lamina lies fair to be seen. Here we have no streight Furrows, nor superficial depressions, as there are on the outside, and that because there was not the same, nor any reason to exact them, though on the inside of the Cranium,( which yet speaking strictly is not the internal part, which indeed is between the Tables) there are Furrows, but they are accidental, formed by the turgescence, and pressure of the Blood-Vessels, which therefore are not streight, and parallel like those on the outside of the Bones, but represent the branches of those Vessels, that made the impressions. I have likewise, though rarely, observed the like on the inside of the large Bones of the joints.  
The Cavities are not all alike, but variously formed, obtaining a difference both in their figure, and capacity, besides what the particular figure, and magnitude of the Bones, in which they are formed, do oblige them to: they are of two sorts, the one are large, and they are single in every Bone, where such a Cavity is formed, the other are little bony Cells, which are numerous, and make the spongeous part.  
The Bones, which have the large Cavities, are the as Humeri, and Femoris, the Ulna, Radius, Tibia, and Fibula, the Bones of the Metacarpus, Metatarsus, of the Fingers, and Toes, and those of the as Hyoides. To which we may add the lower Jaw, though the Cavity compared with the magnitude of the Bone hardly deserves to be styled large, neither does it serve to entertain a Medulla, but only the Nerve and the Blood-Vessels. And the Bones of an Oxe's heart I have observed to have very large Cavities, that is in proportion to their bigness, and when I ascribe large Cavities to any small Bones, as some of the Fingers and Toes, it is to be so understood; for there are some of those, which I reckon amongst the small Cavities in some large Bones, will be found to be more capacious than those, which I style large in these.  
In the as Humeri, the Thigh-Bone, the Tibia, and Fibula, so in those of the Metacarpus, and Metatarsus, the large Cavity after it approaches towards their extremities often begins to be divided by bony partitions, and to be occupied by some of the bony Strings, shooting from the Plates in the sides of the Bones in Fasciculi, and forming larger Strings, which do not produce any enclosed Caverns, but the partitions are open, so that they cannot be called distinct Cavities, therefore I make all that part so far as they appear, to be a part of the large Cavity. The Fasciculi proceeding from one side till they meet with others, which are propagated from the opposite side, are united so as to be so many continued Strings as I have already shown, and shooting forth laterally as they proceed, by a sort of Apophyses they are joined to those Fasciculi, which are parallel, and do in the same manner shoot out on their sides to meet them, from whence arises a texture, which represents a sort of Cancelli or Lattices. Where these Cancelli begin first to be formed the Fasciculi are very small, and fine, when they approach near to the small Cavities they grow larger. Here we may observe with what caution Nature proceeds in detracting any thing from the side, and solid part of the Bone, for the danger of a Fracture in these Bones being less as the violence is offered nearer to the extremity, and so some parts of the Laminae accordingly can better be spared from the sides, therefore they are gradually diverted from it, we have not a whole Plate run off together at first, but only some minute Fasciculi, afterwards larger and larger as they can be spared, till at last they are so large as to meet, and be contiguous, and so are continued in the form of an entire Plate. The Interstices between the Fasciculi are many of them of a quadrangular figure, though there are abundance of them, which have divers other figures.  
Amongst these Cancelli are sometimes broad Plates, which are produced from the same Strings as that texture is formed of, when several of them run together in that order, in which they lay before they ran off from the side of the Bone. These Plates are sometimes to be observed in the very middle of these Cancelli at some distance from the side of the Bone, sometimes they are contiguous to it, where they recede from the Wall of the Bone in their proper form, and afterwards are divided into such Fasciculi of the Strings, as that texture is made of. Sometimes after the large Cavity comes to be thus divided, and occupied by the bony partitions of these Latices, it opens again into a large Cavity, which is free from any such kind of texture, only there is something of it round about on the sides, and at the end of it the Strings run into this form again, but there is not much of this Lattice Work before the Cavernous part, or small distinct Cavities begin to be formed. But commonly when the large Cavities come once to have the Fasciculi divert into them, and to be divided by them into little Interstices, this Lattice-Work is continued to the lesser Cavities, and when it approaches near to them the Fasciculi grow gradually broader, and broader, till they all meet in such a manner as to run together in the form of irregular Plates, and when they are thus met, and united they begin to make the little distinct Cavities, which first appear next the sides of the Bone with some of the Cancelli still continuing in the middle. In the Tibia of a Horse I have observed this texture as fine, and curious, as in any Bones that I have examined, and I do not question but there is much of the same texture in Camels, and other Beasts that are designed for burden, and where the reason, that required some particular care, and contrivance to make them strong, did make it necessary to be cautious, and sparing in detracting from the solid part, and dividing that strength, which was united in the sides before. In Cows there is little of this Lattice-Work, and that very coarse. In the Bones of those Fowles, which I have examined, which have been of several sorts, I find nothing comparable to this texture: in those of the joints, which are large, and where it might be expected; there are indeed some large bony Strings, or Fasciculi of the small ones running out from the sides into the Cavity, but they are commonly distinct, and single, passing from one side to the other sometimes obliquely, sometimes directly transverse, that they appear like little bony beams lying across, though sometimes some few of them run into the form of a Lattice. And without doubt these Trabes in Fowles answer to the Lattice-Work in some other Animals, and the use and design of both is the same, which I proceed to say something of.  
The design therefore of these Cancelli is in the upper part of the Bone to sustain that part of the Marrow, which fills the large Cavity, which in those Bones, that are large, has a considerable bulk, but is suspended partly by the ramifications of the Blood-Vessels, and their continuation from the larger Mass of Marrow into that which is lodged in the Cancelli, so running over, and winding about the Fasciculi; partly by the Membrane of the Medulla, which is one continued Membrane through all the large Cavity, the Lattice-Work, and the small bony Caverns; so that though the Marrow in such a quantity is ponderous, though the Medullary Bags, and Glands are tender, and as well as the Blood-Vessels easily compressed; yet by this Providence the Superior part having a dependence upon the Strings in the Cancelli, cannot make a pressure upon that part, which lies under it, so as to injure it. And therefore in the Bones of an Ox, where there has not been this contrivance, or but little of this texture, I have observed another thing almost equivalent to it, that is a jetting out of some Plates like ledges or shelves lying transverse, for the Marrow to rest upon in several places, sometimes in the middle, but mostly towards the extremities, where this Lattice-Work should be planted. At the lower end of the Cavity this texture is no less serviceable, where it bears off the pressure of the superior, and incumbent part of the Marrow from that, which is lodged in its Interstices, and preserves it inviolated.  
Before I proceed to give an account of the lesser Cavities. I shall inquire into the reasons why the Bones of the joints( excepting those of the Wrist, the Tarsus, the Ossa Sesamoidea, and the Scapulae) and one or two more have a large Cavity, and they seem to be two. First the largeness of the Cavities was a consequence from what was necessary to be done in order to make the Bones firm, and solid. It is plain that the Bones, which are of any length, are in the greatest danger of being either fractured by any violent blow inflicted laterally, or distorted by too great a pressure made at their extremities, in those parts, which are distant from their extremities, and therefore it was necessary that the structure of these parts should be such as would procure them the greatest solidity, and firmitude, which was not consistent with those distances of their parts, from which the smaller Cavities arise, and therefore the Plates are so disposed there as to be contiguous, from which close application of one to another in the sides of these Bones there follows a large Cavity within them, which is more than equivalent to those lesser Caverns, which any other order, or disposition of the Laminae might produce.  
Secondly, They were designed for some end, to wit, that these Bones might be capable of containing a greater quantity of the Medullary Oil. For being Bones, which are frequently in motion they require, and expend greater quantities of that oily matter, than any of those, which are not articulated, as they employ it not only for preserving themselves in a due temperament, and their security against that dryness, which would render them more fragil, and does as we find by experience make them apt to crack; but likewise with the help, and mixture of a mucilage to lubricate their extremities, when they are moved, and to maintain them in a condition fit for their motions upon all occasions. For this reason it is, that the Bones of the as Hyoides have their large Cavities; because they are as frequently moved as we speak, or swallow. And how evidently does the same reason appear in the Bones of an Ox's Heart,( which, as often as I have observed them, have been two, and articulated) when they are continually in motion upon every Systole, and Diastole of the Heart? There are, it is true, some Bones of the joints, which have not such large Cavities; as the Scapula, the Rotula, the Bones of the Wrist, and some others. Now for the Scapula, it cannot be said to be moved at the articulation; for though its situation is sometimes altered by its proper Muscles, yet at that end, which only is articulated, it has the place of a quiescent Body, upon which the as Humeri moves; so that unless the Scapula had a joint at its other extremity so as itself to move upon another Bone, there was not this reason for the forming of a large Cavity in it. The Rotula is placed in a joint, where there is an Oil supplied from the large Cavities of three Bones, the Thigh, the Tibia, and Fibula, so that it cannot want a sufficient supply of it. For the Bones of the Wrist, and Tarsus, they lie between such as have a considerable Cavity. Another thing, which may be objected against what I now offer as one reason of these Cavities, is, that neither the as Occipitis, nor the Atlas, which have a sensible motion, have such a Cavity; nor yet the Ribs, which are moved so much in respiration: For the two first their motion is neither so frequent, nor ever so long continued as that of the Bones of the Limbs sometimes is, the Head being only now and then turned towards one side, or moved backward or forward, and commonly it does no more than onee incline to one of these postures, and afterwards returns into its more natural situation, so that the expense of the Medullary Oil cannot be there so extraordinary. The Ribs are joined to the Vertebres by a Synarthrosis, or such an articulation as is designed for an obscure motion. And to demonstrate the difference in their expense of this Oil in their motions, or the alteration of their position, let us consider how much the posture of the Bones of the joints may be, and sometimes is altered, and how little the Ribs in Respiration change their position. When any of the Bones from an extension are inflected, or from an inflection they are extended, that extremity, which is remote from its centre or the quiescent Bone is sensibly moved circularly, or so as to describe part of a circled: now by considering how much of a circled this extremity makes in the joints, and how little in the Ribs, we shall easily discover a difference in the quantity of Oil, that they expend. I shall instance only in two, to wit the Tibia, and the Cubit; the first may be, and is sometimes so inflected, as to make above the fourth part of a circled, and in ordinary incession about a twelfth, the Cubit so as to make about a third part. Whereas the Ribs, so far as I can perceive, in ordinary Respiration are not moved above the fourth part of an Inch in that extremity, which is remote from the Vertobres. Now some of the Ribs without their cartilege are twelve Inches in length, but we must allow for their obliquity, and we will suppose the distance between the two extremities of a Rib to be, what it is in some of them, eight Inches, the Diameter of the circled, in which the extremity distant from the Vertebres moves, must be sixteen Inches; now suppose the Periphery of a circled to the Diameter to be but as three to one,( though it is something more) then is the Rib in that part, which is most remote from its centre, moved but the 192d. part of its circled; how insensible then must its motion be supposed to be at its Axis, or the quiescent Bone? Only I must confess they are more constantly in motion than any of the Bones of the joints, and therefore the Caverns in these Bones are many of them of a long figure, and large for the simplo sort, and at that end next the Vertebres they have sometimes a considerable Cavity.  
Besides these large, and more capacious Cavities, there are lesser Cells, and they are found in all the Bones, even those, which have a large Cavity, have some of them at both extremities, which where the Laminae lye near to one another are small, and as they approach nearer to a contiguity grow less, and less, till the Plates being plainly contiguous, and united, they disappear. There are many of the Bones, which have no other Cavities, as the Vertebres, Clavicles, the Ribs, the Ossa innominata, sesamoidea and some others.  
I have observed three sorts of these Cavities. First there are some of them especially in human Bones, which have the Cancelli; others are simplo, or single distinct Cavities, which have none of that Texture; and a third sort likewise have no Cancelli, but are like two or three, or more of this second or simplo sort broken into one. These three sorts are generally different in their capacities, such as have the Lattice-Work being the largest, and the second kind the smallest of the three. Neither is there a difference in their capacity between those of a divers sort only, but of those, which are of the same kind, some are larger than others. Nor do they differ less as to their figure than their magnitude. The first, and last are altogether of an irregular figure. Of the simplo small Cavities some are exactly round, some oval, others a flat oval, some quadrangular, others especially in the Ribs, and Clavicles are of a long figure, and in truth to describe the variety, would be to give an account of all the figures that occur in the mathematics.  
The small Cavities have all of them Pores, or passages of communication, whereby the Blood-Vessels are propagated, and the Membrane of the Marrow is continued from one to another, and by which the Medullary Oil has the liberty of slowing out of the large Cavity into the lesser, and out of one small Cavity into another. But there is a great variety in the number of the Pores belonging to every such Cavity, even the second or smallest sort; in some there are only two, one for receiving, the other for transmitting, some of the Cavities have three or four, or more; in which there is this difference that some have several into one and the same, others have a passage into several, or all the small Cavities, that are next to them, by so many single Pores.  
Where these small Cavities, and the porosity, which arises from them, were consistent with the security of the Bones, that is, where there was no necessity to contrive in their structure that order, which would give the greatest strength and solidity, they were capable of, either because they have not so great a stress put upon them at any time, or because they are so thick and short, that they are in no great danger of being broken, and where the quantity of Marrow, which these small Caverns are capable of receiving, answers to the exigence of the part, as in those Bones, which are not articulated; in all these Nature could without any danger or prejudice make their substance within all spongeous, and has choose so to do, so by lodging the Marrow in the small Cavities formed between the Plates, does intermix with all that part of the substance of the Bones that Medullary Oil, which was necessary to preserve them from growing too dry, and fragil, which was a more easy, and immediate way to answer this end, than first to separate, and deposit the Marrow in one large Cavity, and afterwards to supply it to the substance of the Bones by Pores in that manner, in which it is dispensed to those Plates, whose contiguity, and union renders a Bone solid.   

Of the BLOOD-VESSELS of the BONES.  
I Proceed now to give an account of the Blood-Vessels of the Bones, which are, as in other parts of the Body, of two sorts, to wit, Arteries, which convey the Blood into them, and Veins, which serve in the reduction of it to the Heart, after it has paid a Tribute of some certain Particles to those Glands, which it touches upon in its circulation. And both these may be said to be of two sorts, that is they are assigned to two several parts, some to the Medulla, and others to the substance of the Bones in order to their Accretion, and Nutrition.  
The Medullary Blood-Vessels will fall more properly under our consideration, when I come to treat of the Marrow, I shall therefore defer the particular notice of them till I come to speak of that. As for the nutritious Arteries, there are several of them belonging to a Bone, and every one of them, that I have observed, enters the substance of a Bone at a distinct Foramen, only I once met with two, which made their entry by the same passage. The most considerable of them enter at one end of the Bone, and the contrary to that where great numbers of the Veins have their exit, and in the large Bones of the joints, where they are most obvious to our observation, they plainly enter at that end, which is next the Trunk of the Body excepting in the Scapula; and because they are Arteries, they do not alter the colour of that part of the Bone, which therefore is whither than the other extremity, or where ever the Veins, which are read, and more numerous, do pass out. From that end of the Bone, at which they enter, they have a tendency towards the other extremity. Some of these I have seen running amongst the Laminae in the most solid part, and where the Plates have been contiguous, and traced them a considerable way together, observing them to be sometimes conspicuous, and indeed large considering the close unition of the Plates, and the solidity of the part, that they passed through, and in any part of a Bone, whilst it is Cartilaginous, they are plainly to be observed, and more easily followed. Now though in some parts of the Bones there is little, and in some no appearance of Blood-Vessels, yet that they are in the whitest part of a Bone does evidently appear in the examination of any part of one that is yet Cartilaginous, and that they are very numerous, I have found some reason to believe from a considerable Ecchymosis I have met with in a solid and perfect Bone, in that part, which seemed to have been naturally white, and to have given as little suspicion of such a thing, as any part of it.  
The Nutritious Veins, if I may so call them, that is those, which convey the Blood back from the Nutritious Arteries of a Bone are very Numerous, not throughout the whole or in every part of it, but where the Arteries terminate. For as they do not pass through the same Foramen, so neither do they keep such a sociable course as to run one by another in the substance of a Bone, as they often do in other parts. This was neither necessary, nor convenient: Not necessary because the design of the Veins being to carry back the Blood to the Heart, so long as they conveniently answer that end, it is sufficient, let the course in which they proceed be either this way, or that. It was not convenient, for as there appears in the structure of these parts a providence studiously contriving what was necessary for their firmitude, and ordering whatever was requisite to be done, and might be injurious to it, in such a manner, as to make one consistent with the other, so here that the passages, by which the Nutritious Blood-Vessels are disseminated, might not be too large( which we may reasonably suppose they would have been, if they had been so capacious as to give a passage to the Vein, and Artery together) where ever any of the Nutritious Arteries terminate, be it about the contrary extremity to that, where they enter, or in some intermediate part, the Veins, which succeed to them, instead of running along by the Arterial Channels, and continuing their course within the substance of these solid parts, pass out immediately at their superficies, and their passage in the solid part of a Bone is so short, that vast numbers of them, if not all, seem to be at their exit out of the bony substance, single Veins continuing distinct from the extremity of those small Arteries they serve to, that they never come to fall into any common Channel before they arrive upon the surface of the Bone, which I do suppose from their Number, and the minuteness of them.   

Some Observations of the TEETH.  
ALthough the Teeth are of the Classis of Bones, yet having some things particular, I shall give a distinct account of some few observations I have made of them, and they consist of two different parts of a divers substance, the one is of the nature of a ston, the other is truly bony.  
The first may well be said to be ston, when it has the hardness of Stones, the solidity of Flints themselves, so as in the same manner to resist the impressions of the Saw, and has besides something of a shining, or glistering brightness, as the hardest of Stones have, though after all it must be confessed that it is often eaten away, and will be dissolved in Aqua fortis, which Flints will not; which, as it shows us how injurious strong acids are to this part, may direct us to the use of better means for whitening the Teeth, than Spirit, or Oil of Vitriol, or any thing of that nature. This I call the Cortex of a Tooth, and is plainly, and easily to be distinguished from the other part. The several parts or striae of which it consists, differ in their position from the Strings in the bony part, not lying streight in the length of the Tooth, but on the sides obliqne, near to a transverse position in some Animals, and upon the upper part of the Dentes Molares where the bony strings are transverse, and at the very point, or extremity of the sharp Teeth they are in a manner erect. The figure of these striae in the Teeth of some Animals is streight, in some a little, and in others more obliqne as in those of Men, in which I have observed them to have the similitude of a Bow, the convex part of whose Arch on the sides lies obliquely downward, and the concave upwards, with the lower end planted, and fixed upon the side of the internal or bony part, which gives them a Basis to rest upon, so that when any thing presses upon the other extremity, they are in no danger of being protruded out of their place, having so firm a Foundation to stand upon, and being so disposed, that all impressions are made not laterally, but at one end of them, and so as to make the greatest advantage of their Basis, in resisting that force, which might move, and disorder them.  
Considering the Teeth are designed for the breaking, and dissolving the parts of our solid sood, the reason does appear why that part, which stands out of the Gums, and is the immediate instrument of Mastication, should at least be cased with a hard and stony Cortex, otherwise they would be more easily injured by their action, and sensibly worn away. It is true some other Bones are rubbed one against another at their articulations, where they are of a more soft and tender nature, without any sensible injury; but then there is a continual supply of an oily, and a mucilaginous Matter, which prevents their attrition, which neither the position, nor the Office of the Teeth does admit.  
When a Tooth is broken, and this stony part is viewed with a Microscope, it represents almost a Saw, or rather the inequalities, and notches of such a Grater as is made to some Steel Tobacco Stoppers, excepting only the obliquity of the striae. So that the parts, or( which I am apt to think it consists of) the Laminae of it are formed with such inequalities, that they are applied, and joined together by the way, and in the manner of a Suture, the Teeth, or ridges of one lying into the notches of the other.  
This part does not seem to be allowed any share of that medullary, and oily substance, which is supplied to other Bones, and is not wholly wanting to that part of a Tooth, which is truly bony. For besides that I could never discover any thing of a moist or oily nature insinuated into it, nor observe any thing of an Oil to sweat out of it, either in a Skeleton, or when it has been extracted from one living, it would be so far from doing any service here, and preserving the natural temperament of this part, that it would be more apt to destroy it, as it is, and ought to be extremely dry, and hard, and seems to have something peculiar in its nature, and constitution, which preserves it from being fragil, or friable without the assistance of any oily matter. And whether that Mucus, which is found sticking upon the Teeth, is supplied from within, and passes out of it, is to be much questioned, and it seems rather to be some viscous, or gummous, and terrestrial parts supplied from the Saliva. And however a Tooth is thought to grow beyond its natural length, when its opposite is wanting, yet this is not so certain as not to admit a dispute. I have observed that in some Teeth, when those which stood against them have been gone, there has been no elongation. And if it were so that a Tooth took an occasion to increase its length from the want of that, which was opposed to it, and of that pressure, which it made upon it; why do not the Teeth continually protrude their lateral parts, and acquire an extraordinary thickness in that part of the Cortex, where there is not the pressure, and opposition of another Tooth to hinder it? That therefore, which seems to be an elongation, may rather be thought to be the protrusion of a Tooth from an extravasation, and the pressure of some nutritious juice flowing into the Socket, as we find after a Tooth is extracted, the succus nutritius of the Jaw is thrust forth into the Cavity, and fills the Alveolus with a bony substance. Or if the Tooth does afterwards grow, and exceed its ordinary length, the addition, that is made to it, does not seem to be in the Cortical part. It is true, we cannot well imagine that so thin a substance, as hard as it is, should serve a Man his whole life time without a reparation, so that we must suppose as some of the parts are worn off, they are renewed. But when the Teeth as well as other parts, have a certain and convenient magnitude prescribed to them, and the solidity especially of this Cortical part fixes the limits of its increase more firmly, and makes them more immovable than they seem to be in any other part of the Body; I cannot think that the stony Cortex has any preternatural increase after the opposite Tooth is gone.  
This stony Case or Cortex in Men, the Lion, and other Carnivorous Animals covers all that part of every Tooth, which stands out of the Gums, but when the Teeth come to be protected by them, it grows thinner, and quickly terminates: neither was it necessary that it should be so thick, and strong where it is covered so as not to be exposed to that violence, and those impressions, which the naked part so often meets with. In the Dentes incisores, and Canini both of Men, and Beasts all that part, which stands out of the Gums, is covered with such a Cortex; but in the Dentes Molares there is a great difference. For in Horses, Sheep, Goats, the Antilope, the Rhinoceros, and such Beasts as live upon Grass, and Corn, the basis or that extremity, which lies out of the Gums, is not covered with it, but only the sides, and it runs to that extremity, where it ends in a sharp edge, but sometimes there grows over it a bony crust, and whereas in Men, and Carnivorous Animals there is none of this stony substance within the bony part, it is otherwise in these Animals, in whose Grinders there is the same sort of substance within mixed with that part, which is bony, and that in several places, which rises up likewise with an edge above the bony part, and is often continued to the extremity of the Roots: and there does evidently appear a contrivance of Providence in the formation of these parts in several Animals, accommodating them to the nature of the Food, which the Animal lives upon. In Men, whose Food is generally soft, and more fit to be broken into pieces by compression, than to be ground, they are obtuse. In the Lion, Tiger, Dogs, and such Creatures as eat Flesh, but are frequently entertained with no tenderer Food than Bones, though they are covered with a stony Cortex, they are sharp with several points. In those Beasts, which are maintained by Grass, Hay, and Corn, this stony part rises up in several places in ridges, with a kind of edge, and does answer to the inequalities of a Millstone In Hogs, that eat Flesh, as well as Grass and Corn, they are covered with a stony Cortex, but formed in such a manner as makes them of a middle nature, and fit for the mastication of both.  
Underneath the Cortex in human Teeth, and other Carnivorous Animals,( and within the same stony substance in other Beasts) and within the Gums is another part of the Tooth, which is truly bony. And this Bone( for so I may lawfully call it) consists of Laminae as other Bones do, which I have plainly observed and distinguished in a Horses Tooth.  
From the different nature, and solidity of these two parts of the Teeth is the reason evident, why they are often so hasty in their decay, when the external or stony part is once broken off, that they quickly grow rotten, and hollow, when the Cortex, which is much the thinner part endures so many years, and is daily employed without any sensible detriment, and upon this account it is, that when the Gums are eaten away, so that some part of a Tooth, which is not defended with a stony Cortex is laid bare, it is croded, when that part that naturally stands out of the Gums, and is by such a solid substance secured, suffers no such injury.  
The Teeth have all of them in that part, which lies within the Gums a Periosteum, but not that Membrane, which is common to the other Bones. For that, which immediately invests so much of them as is covered with a Membrane, is not a continuation of the Periosteum of the Jaw-bone, but is united to, or rather propagated from that Membrane, which covers the Gums, and is common to the whole Mouth, which does not terminate with the Gums, but when it comes to their extreme edge, turns in, and is reflected between the other side of the Gum, and the Tooth, then it descends into the Alveolus, and adheres immediately to those parts of the Teeth, which lye within. With the Membrane in some Teeth is communicated to their Roots, especially in the upper Jaw, some part of the hard, and fleshly substance of the Gums, by which the Teeth are fastened more firmly in their Sockets. And because they are parts, which ought to be firmly fixed, there is the same contrivance for the strong adhesion of their Membrane, as in other Bones, to wit inequalities, or superficial Cavities, which in large their superficies. In Men they are often depressions or Pits of an irregular figure, though in some human Teeth there are circular Furrows, which are considerably wide. In the Teeth of the Rhinoceros I likewise find broad and circular Furrows. In the Teeth of a Tiger these inequalities are also Furrows, which are remarkable, and numerous, but they are streight, and run from one end of the Tooth towards the other.  
But though the Teeth themselves have no part of the common Periosteum, yet it comes very near them, for the Sockets, in which they stand, have it. The Periosteum, which ceivers the Jaw bones running to the edges of the Alveoli, or Sockets, turns into those Cavities being on one side contiguous to the Bone, and on the other to that fleshy substance, which helps to fasten the Teeth more firmly, and where none of that hard flesh intervenes, it does coalesce with the Membrane, which does immediately cover that part of the Tooth, that lies within the Gums, and they make as it were but one Membrane.  
There is one thing particularly remarkable in the Teeth, which other Bones do not seem to pretend to, and that is Nerves. The reason of the difference seems to be chiefly, if not solely for the sake of that part, which is destitute of a Membrane: and to answer for the want of the Periosteum. Though the design, and use of the Teeth would not admit of a Membrane in that part, which is immediately employed, and do act in Mastication, yet it was necessary that should have an influx of spirits to assist in its accretion, and nutrition, whereupon the Teeth have every one of them a Nerve, that supplies them to this part. The Nerve, which runs along in the Jaw, and from whence the Nerve of every particular Tooth is propagated, is plainly a fasciculus of other lesser Nerves, which I have found to be more in some than in others. Sometimes they have been sixteen, sometimes twelve, and in a human Jaw I once observed no more than seven. But all these smaller Nerves are divisible into less, till at last they resolve into minute Filaments. The Foramina, by which these Nerves pass into the Tooth, are visible with the help of a magnifying Glass, and many times without it, and there is always one to every Root, and in a Tooth which has had only a single Root I have met with two passages, one on each side, and the Foramen where it is single is not always formed at the very extremity of the Root, but very often a little on one side.    

The SECOND DISCOURSE OF ACCRETION, AND NUTRITION.  
THE next thing, which I am to speak of is the manner of the Bones Accretion, and Nutrition, which as indeed the growth, and nourishment of all the parts of the Body, are hard to be understood, and explained. That Accretion is by the addition or apposition of new matter, and that Nutrition is a reparation of those parts, which are continually expended, are accounts, that are easily given, and as easily understood. But how the nutritious Particles are separated, and supplied; how they are proportionally dispensed to all the solid parts of the Body, and regularly disposed of; how Accretion is performed in young Animals till they grow to a convenient, and the ordinary magnitude of their own Kind, and comes to cease after the dimensions of the Animal are carried to the common and natural limits set to every Species, are not so easy to be explicated. However I have made some essays, and although some unlucky objection or other has made some thoughts I have had about this Argument miscarry, yet I have formed and considered of one Hypothesis, which gives me some satisfaction, and even the confidence to expose it to the objections, and to submit it to the censure of greater Philosophers, and better Judges.  
To complete an account of Accretion, and Nutrition, there are three things to be considered, and explained, the first is the manner how the nutritious matter is supplied, and apponed to the parts of younger Animals so as to give an increase to their dimensions. The second is what it is, that puts a stop to this in a convenient time, or how it comes to pass that Accretion ceases when the Animal is grown to a due magnitude, and the ordinary limits, that are prescribed by Nature to the Species, which it is of. The third, and last thing to be inquired into is, what Nutrition taken strictly is, and how it is performed: all which I shall do at large as it concerns all the parts in general, and then I design to give an account of the growth, and nourishment of the Bones in particular from the general Hypothesis, which will led me to the consideration of some morbid affections of the separts, where their nourishment is particularly concerned.  
I shall not go about to mention, or object against the Philosophy of others about these appearances, but only offer my own thoughts, and take my own method to explain them, only where any thing, that is plausible, and stands in competition with my Hypothesis, occurs, I shall be so natural as to endeavour the defence of what my own Thoughts have brought forth.  
I shall begin first, and explain the manner how the parts in young Animals are nourished so as to be extended in all their dimensions. And first the nutritious Particles are supplied from our daily Aliment, assuming after Concoction, and a due separation of the purer from the more gross, and feculent parts the form of Chyle, which through the Lacteal Vessels passes into the Blood, taking in in its way a juice from the Lympheducts, in which there seem to be many of the luxuriant Particles of the Succus nutritius of the Glands, from whence they arise, which communicates some nutritive parts, and improves the nature of those in the Chyle, which are designed for nourishment, and after this milky juice comes into the Blood, and arrives at the Heart, the parts, which are to make the nutritious juice, and are as yet imperfectly Concocted, are there so broken and attenuated, as to be adapted to the Pores, which are to separate them from the Mass of Blood; and disposed for a separation, after which they are conveyed by the Arteries to all the parts. That the nutritious juice is supplied from the Mass of Blood is supposed, and granted by the greatest part both of Speculative Philosophers, and Physicians, and therefore I need not trouble myself much to prove it, or argue for it, only I mention this to give a more perfect account of what we are now concerned about, and to trace our nourishment from its first original. I know there are some would cast this thing upon the Nerves, who pled the observation of an Atrophy, which often attends the parts, that are paralytic, to prove it. And I confess they have a plausible Argument from it for their Opinion, and it may seem to press hard upon that, which is more commonly received, when they argue thus, that the part, which is affencted with a palsy is often imminished, though there be a Pulse, and an influx of Blood into it. Now if the nutritious Juice be supplied from the Mass of Blood, how should a part, that is paralytic want it, and decrease in any of its dimensions, when the Blood, in which we conceive the Succus nutritius is contained, continues its influx into it. But an obstruction of the Nerves we all allow in this case, and as the influx, and supply of the nutritious Juice is rationally to be supposed to be cut off by those obstructions, so we must conclude, that it naturally flows in those Channels, where the obstruction is made, that is in the Nerves. I shall not stand now to answer this Objection, but when I have offered my thoughts concerning the manner of Nutrition, I shall show how according to my hypothesis an Atrophy may be the consequence of a palsy, though the nutritious Juice be naturally conveyed by the Arteries to the several parts, and with the other sanguineous parts continues its circulatory course in the arterial Channels of that part, which is paralytic, and labours at the same time with the symptom of an Atrophy.  
Secondly, Though the nutritious Juice be contained in the Blood, and supplied from it, it is not the whole Mass of Blood, nor any portion of it indifferently that is fit to be united to, and to give an increase to any parts of the Body; but they are a peculiar sort of Particles, that are every where dispensed for this end, such as will form a substance of the same nature, which the part, that they augment is of. And this Juice not only is different from other humours, both those that are excrementitious, and such as are otherways useful, but we have some reason to think that there is a difference even in the succus nutritius itself. For where the Nature, and Constitution of one part are remarkably divers from them of another, as in the Bones, and Fibres, there the nutritious Particles seem likewise to be different.  
How far the difference lies between the muscular, membranous, and vascular parts I leave to others to inquire, to better, and nicer judgments to determine. Though I cannot but say I do conceive that there is no difference in the succus nutritius of these parts, only in the manner or order, in which the Particles of it are disposed in their apposition, since, as it is commonly known, in Issues and about the edges of them, the nutritious Juice of the Skin does often produce fleshy Excrescencies, such a Flesh as is different from the nature of the part, which it is to nourish. And although the Excrescence from thence made be different from the Skin, yet it is certain that it is from the succus nutritius of the cutis, since the solutio continui is made in that part, upon which the nourishment after it is separated by the nutritious Glandules extravasates, and by sticking round the edges of those Foramina, by which it issues out lays the Foundation, and by the gradual addition of itself raises the Structure of those Excrescencies. It cannot be thought to be the nourishment of the fleshy parts distinct from that of the cutis, for the wound inflicted does not reach so deep as to set open the Canaliculi of the fleshy Fibres, and to give a preternatural passage to their nutritious parts; but in Men there intervenes the Membrana adiposa between the cutis, and any thing of Flesh, excepting in the Lips, and two or three placs more.  
Be there a difference, or not it is always gelatinous, and this not only our reason persuades us, as it is requisite it should be so to dispose it to adhere and unite to the parts, but there is that sometimes, which seems to demonstrate it to our very senses, I mean in Ganglions, where the material cause of the tumour is rather the nutritious Juice of the nervous or tendinous parts extravasated than any preternatural humour, or matter. For although I do not suppose that the succus nutritius of the Body is from the Nerves; yet they have as other parts a supply of it for their own nourishment, which I take to be all the succus nervosus that they have. Now the matter, which is collected in these swellings is always a sort of jelly, which may help to inform us what the nature of the nutritious Juice is.  
Thirdly, The Particles, which serve for nourishment are separated from the rest of the Mass of Blood before they can assume the distinct, and propet form of a nutritious Juice, or be employed in the augmentation of the parts. For if we suppose that they are supplied and cast upon the parts immediately by the Blood circulating through them, if we imagine, according to Diemerbroek's notion, that the nutritious Particles as being a part of the sanguineous Mass and circulating through the whole Body, are by the power of their motion driven against the sides of the Vessels, which contain that Mass of Blood, and striking into the Pores stick there, and as one end of the Particles thus driven in fills them, so the other extremity, which stands out forms another Series of new Pores for the infixation, and unition of new parts: I say, if we take up with this Hypothesis, then we must make the Blood immediately to wash every part that is nourished, so that either Nutrition must be monopolised by the Veins and Arteries, or we must grant an extravasation of the Blood so as to touch upon every single fiber, that is nourished, in its circulation, which will be to make the whole Body to consist of nothing but sanguiferous ducts, besides other Objections, which I shall not stand to mention.  
Fourthly, This separation of the nutritious Juice is made by Glandules or glandular Pores, which may properly enough be termed Glandules, as they serve for the same Office, to wit, Secretion. These nutritious Glandules we cannot suppose to be generally placed at the extremities of the Arteries. For, besides that we cannot upon this supposition conceive how every fiber, and every part of that fiber can have the nutritious parts supplied to it, it is impossible it should be so in the Glands, where the extremities of the Arteries are occupied by Glandules of another nature, that separate another kind of liquour, and such as is evidently not designed for the nourishment of those parts, as to instance only in the Kidneys, it is plain that at the extremities of the arterial Vessels in these Glands are placed the Glandules, which serve for the separation of the urinary Serum, so that there is no convenience for the situation of other distinct Glandules, and those which are there seated being the colatory parts, that separate an excrementitious humour, cannot be thought to be the Organs, that separate and supply the matter, that nourishes them. Therefore I do conceive, and I think not without very good reason, that there are Glandules, or particular Pores adapted to the figure of the nutritious parts, which are to pass through them formed in the sides of the Arteries, every where as they proceed, almost in the same manner as the Glandules are seated in the small Intestines, by which the Chyle is separated from the Faeces, and penetrates the Guts into the lacteal Vessels, only there is this difference that the lacteal Glandules are planted along the small Guts but on one side of the canal, whereas those, that serve for Accretion, and Nutrition are seated on every side of the arterial Channel, and supply a succus nutritius to all the Fibres and other parts which lye immediately round about, or very nigh to them. Now as we cannot suppose that any of these Glandules are seated at the extremities of the Arteries in any of the Glands of the Body, so the situation I ascribe to them, makes them consistent with other Glandules in the same Artery, so that we may easily apprehended how the same Arteries which serve to the Glandules, that separate the particular humour of that glad, serve also for the supply of that Juice, which nourishes it, as it is made no matter of doubt but they are the same. And not only so, but this situation is more convenient for the separation, and supply of the succus nutritius to the whole Body, if it be not that, which only can answer this design of Nature.  
And now I am speaking of the separation of these Particles, pardon the digression, if I suffer myself to be lead a little by this occasion out of the proposed method of my Discourse to consider the manner, in which glandular Secretion is performed, which being explained, will help us to understand how not only this, but all the humours, which Nature extracts from the Mass of Blood, are separated.  
It is true there is a diversity in all Glands, that separate a different liquour, but yet there are several general things, in which they all agree, so far as their Office is Secretion without a respect to the particular liquours, which they secern.  
To what I am going to say concerning this great affair of Nature, I must premise that natural Law of Motion, that all Motion in its own Nature, or proper tendency is direct from its Centre, or terminus à quo, or to use the great Philosopher Des-Cartes's own words speaking of Motion, Altera lex Naturae est; unamquamque partem materiae seorsim spectatam non tendere unquam, ut secundum ulias lineas obliquas pergat moveri, said tantummodo secundum rectas; and that it never does but from some opposition, and the occurrence of another Body either fixed, or differently moving incline to an obliquity, and even every Body that is moved circularly, does endeavour to recede from the Centre of that circled, which it describes. And although when a solid Body being in motion meets with another, which has a greater power to stop it, than that has to persist, it is reverberated; yet there are some Bodies, which are not in their own Nature so fit, and ready to be reflected, as those, which are viscous, soft, or fluid, and be they solid or not, yet when there is a continuation of matter, which from the terminus à quo presses them on with a greater force than what they have to recede with, so long they will not be reflected, though there lies a resistent Body in the way of their direct Motion, but if there are any lateral and obliqne passages they will continue to move on that way, which offers itself fairest for, and comes nearest to the line of their direct motion.  
Now for the particulars, wherein the general agreement between all Glands lies they may be reduced to these Heads.  
First, All Glands have their Vasa Adferentia, or Vessels to convey to them that Mass from which the Particles, or that particular humour, which they separate, is extracted. These Vessels in those Glands, which separate any humour from the sanguincous Mass, are commonly Arteries, though it cannot be affirmed that they are always so. For in the Liver it is known that the bilious Juice is conveyed in the Mass of Blood to the hepatic Glandules by Veins, the Vena Portae, and the branches of it, which belong( to use the old term) to the Parenchyma of that large Viscus. But generally they are of the arterial kind, and such are the Vessels, which carry the Blood and the nourishing parts contained in it to the nutritious Glandules, only in the part I now mentioned, as the Vena Portae does perform the Office of an Artery to the hepatic Glandules, so I do conceive it has the same sort of nutritious Glandules, as the Arteries every where have, formed in the sides of it.  
Secondly, To these Vessels, be they Veins, or Arteries, belong small Glandules or secretory Organs, which seem to be formed from the exterior Tunicle of the Vasa adferentia expanded, and in a peculiar manner modified, and that the Vena Portae might have a Tunicle to spare for this end, it has a Coat extraordinary, immediately communicated from the Membrane, which clothes the Liver. From hence we may have the reason, why the Veins have fewer Coats than an Artery, because, where the one terminates, and the other arise, there is one Tunicle taken off for the formation of the Glandules, which for the most part are placed at the extremities of the Vasa adferentia, whether they are Arteries or Veins, yet not so universally but that where it is more convenient, or rather necessary for accomplishing the ends, for which the Juice is designed, they are seated on the sides of these Vessels, as those that serve for Accretion, and Nutrition. They are always so seated as to be exposed to the appulse of the Blood, that like a shore they have the Waves of this read Sea continually beating upon them, and they stand so as to favour the motion of the Particles, that they are to secern, and their tendency in a right line, at least more than the Vessels, which the residuous Mass continues its course into. This is evidently so in those Glands, in which the Glandules are seated at the extremities of the Vasa adserentia. For as soon as the Blood is arrived at those extremities it is reflected, the Vessels, through which it is afterwards to continue its motion, run commonly directly contrary to the course, which it held in the Vessels, that convey it to the Glandules. So that when the Blood is come to the extremities of the Vasa adferentia, the motion of it afterwards, and its progression into the venose Vessels, which convey it back to the Heart, do not answer to its naturai tendency; whereas the Glandules are conveniently situated for favouring the direct motion of the Particles, which they are to separate, and thereupon the Particles of the liquour, which they secern, do naturally or in obedience to that Law of Motion, respecting its tendency, which I first mentioned, press upon them, and endeavour to proceed into them. And how this assertion, that the situation of the Glandules is so contrived, and ordered as to favour the tendency of that matter, which they secern, more than the Vessels, which carry the Blood back to the Heart, I say how this holds true in the Glandulae Nutritiae, I shall presently show.  
Thirdly, These Glandules have Pores or Passages, by which they receive the Particles, which they are appointed to separate. In this all Glands do necessary agree that their Glandules are perforated on that side where the Blood beats directly upon them, which Perforation is their secretory poor. Besides which they have another, whereby they discharge and empty themselves commonly into Ducts, which meet in one common Receptacle. Tho there are some Glandules, that seem to evacuate themselves by their exoneratory poor into the Mass of Blood.  
Fourthly, at the termination of those glandular Pores, by which the parts of the liquour produced by every glad are separated, or on that side, which lies next to the small Cavity of the Glandules there seem to be Valves or such a Formation as is equivalent to them. For although the Glandules themselves are so seated, that the Particles, which are separated by them, when they strike against them and the passages are clear, and obtain their natural figure, cannot but in obedience to that natural Law of Motion, I have taken notice of, advance into them; yet we find that the particular Ducts leading from the Glandules, to the Receptacles, or any large conveyances, run in several Glands plainly contrary to the course of the Arteries, so as sometimes to make a sociable progress with the Veins, at least for some way: so that the course of these Ducts is as contrary to the natural tendency of the Particles, which they convey, as that of the Veins is, as to instance again in the Kidneys, there autopsie itself does tell us that the Tubuli urinarii, which carry the Urine to the Pelvis, after it is separated by the Glandulae Renales, run as contrary to course of the Arteries, and the tendency of the urinary serum, whilst it is moving through those Arteries with the other parts of the tanguineous Mass, as the Venose Vessels do. And therefore when the Particles that are admitted, and separated by the glandular Pores, are once entered into the Glandules, they have no farther to go in a line more direct, and agreeable to their tendency, than if they were carried into the Veins; but the tendency of their motion must necessary be altered by the variation in the course of those Ducts, and being obliged to a reflection some of them might regurgitate into the Artery, if there were not Valves, or such a contrivance in the secretory Pores as not only makes them capable of giving the Particles they are to separate leave to enter, but denies them likewise the liberty of returning.  
I know there is one thing may be objected against it, to prove that it is not necessary there should be Valves or any thing like them, and that is that the continual succession, and impulse of new matter is a sufficient provision against the regurgitation of any liquour or Particles of it into the Blood by those glandular Pores, which had before separated them. For the Particles which are already separated, seem to be obliged to proceed from the Glandule into the dust, from the continual pressure, and protrusion of those parts, which come immediately after them.  
But Secretion being the grand affair of Nature, upon which not only our Health, and Wellbeing as we are Animals, but our very Lives do depend, it must be thought in a business of so much importance she has taken care for carrying on that great and necessary Work by giving the part, in which it is to be performed, all the advantages in its Structure, which it is capable of: especially when we consider that though there is in the Veins, and lymphatic Vessels the same reason to make such a contrivance unnecessary, though there is the continual influx, and succession of the humours, which they convey, to propel any parts of that matter, which had before entered into, and are moving in the Channels of those Vessels; yet we find that they have their Valves to hinder the regurgitation, or reflux of the Blood, and Lympha in them, and to promote their progressive Motion or Circulation, and that even where they are streight, and there is nothing in their course to alter the tendency of the humours, and to dispose them to a reflection. Nay, even in the Heart at those passages into the Arteria Pulmonaris, and the Aorta, where the pressure of the subsequent Blood upon that, which flows immediately before it, is more violent than in any other part of the Body: Nature has not thought the succession of one part of it to another, and the power, which one has to propel the other, an infallible remedy against the reflux of that, which is already thrown into those Vessels; but to make the progression of it more certain, and necessary, has planted at the passage out of the Ventricles those strong, and remarkable Valves which we call Semilunares. How then can we think that the Glands, which serve( especially some of them) for great, and necessary uses, that stand at a greater distance from the Heart, and consequently have a less violent appulse of the Blood, and where one part of the liquour, which they separate, make a more languid pressure upon another, should be destitute of this advantage?  
Fifthly, and lastly, To the Glands belong also Blood-Vessels designed for carrying off, and conveying back to the Heart that part of the Blood, which had not the liberty to enter into their Glandules.  
The impediment, which hinders the progress of those parts of the Blood, that return by these Vessels, into the Glandules, is twofold, one is necessary, the other contingent. That which is necessary lies against those Particles, which are not in their figure adapted to the glandular Pores, or are of such a magnitude as renders them uncapable of entering into them: That which is accidental prevents the ingress of many of those Particles into the Glandules, which are both in figure and magnitude adapted to their Pores, and of the same nature as those, which at the same time are separated by them. Where it is not because the Glandules in themselves are uncapable of admitting them, that they pass by them into the reducent Vessels, but from the anticipation of other Particles of the same kind occupying the mouths or Pores of the Glandules in that instant, when they are ready to enter. For the Blood being naturally in the hurry of a rapid motion there is no such thing as stoping or expectation in the Artery. So that it is impossible but some Particles should slip by the Glandules, which ought to separate them, whilst others are in the passages. And hence partly it comes to pass that the Blood after so many Circulations, and the Secretions performed in those Circulations does still supply to all the Glands those Particles, which they naturally secern without a continued succession of Chyle; as partly from the comminution of some parts, whose magnitude before they are farther attenuated by the Heart and Spirits, renders them uncapable of penetrating the glandular Pores.  
The Vessels, which carry off the residuous Blood in the Viscera, and other Glands, after it has paid a Tribute to them, are the Veins, and the same kind of Vessels do perform this Office to the nutritious Glandules, but not so immediately. For they not being seated at the extremities; but in the sides of the Arteries, the Blood does not so soon as it has supplied some of the nutritious Particles to the Glandules, presently shift its Vessels, and flow into the Veins, but continues its course in the Artery afterwards. So that it is the Artery, that does immediately convey the Blood from these Glands, unless there are any of them placed at the extremities of the Arteries in some parts, as it is probable there are in the Nerves, and Muscular parts, and in the substance of the Bones, where those extremities do not seem to be occupied by other Glandules. But yet at last the Blood, when it has passed by all the nutritious Glandules in an Artery, is received, and carried away by the Veins.  
From what I have said concerning the general agreement of all Glands in their Structure, and the Vessels belonging to them, and the Law whereby all Bodies, that are moved, are directed in their natural tendency, we shall find it no difficult thing to conceive how all the humours of the several Glands are separated, and to explain the manner of glandular Secretion. As for that separation, which is made by the Glandules of the Viscera, and wherever they are seated at the extremities of the Vasa Adferentia, there is this account may be given of it, to wit, that the Blood being carried with a quick, and violent motion to the extremities of those Vessels, which supply it to the Glands, all the parts of it are there endeavouring to proceed in a right line, and with this endeavour they necessary press upon the secretory Organs, which are there placed, which being seated in the way of their motion, and so as to favour their tendency in a more streight line than the Veins, which run contrary to it, they are continually importuned by their pressure to entertain them, and all the Particles of the Blood, if they could have the liberty of continuing their motion in that line, which they endeavour to proceed in, would more readily proceed into the Pores of the Glandules, than be reflected into the Veins. But although there is an appulse, and a pressure of all sorts of Particles in the Blood against these Glandules, it is not possible they should all of them continue their motion into them, so long as the Glandules enjoy their natural tone, and their Pores obtain their proper sigure; they are only those, which have such a figure, as adapts them to the secretory Pores, and are of such a magnitude as makes them capable of penetrating them, that can be admitted, and these are the Particles, of which the humour that is naturally separated by every particular glad, does consist, whilst others, that are differently figurated, and some of those, which are capable of entering the glandular Pores, being hindered by more forward Particles are hurried into the Veins.  
When I make the adaptation of the figure, and magnitude of the parts, which are to be separated, to those Pores of the Glandules, which secern them, to be the great reason why they have a free passage into them, when some others are necessary excluded, and why every glad is so constant in the separation of its proper, and natural humour, some may be ready to object that there are Particles of a different figure separated by every glad, so through the glandular Pores in the Kidneys do pass both aqueous, and saline, and through those of the Liver, besides salt, and aqueous Particles, some, which are of a sulphureous nature, and so in others. And since it must be granted that the Particles of all these Principles are of a different figure, we cannot suppose the adaptation of their figure to that of the Pores to be the reason why every glad does secern such or such a humour, when it is impossible that the figure of more than one should correspond to it; and therefore we must allow something of a ferment to precipitate it, and to give it its peculiar Nature. To this it may be answered that it is not here supposed that the Pores of the Glandules are agreeable in their figure to the Particles of any one pure Principle, whether it be Salt, Sulphur, or any of the rest, since there are none of these to be found sincere, but the Particles separable through the Pores of any particular Glandules, are, as I have already said of the Constituent parts of a Bone, a composition of two, or more of those, which we call Principles, and from their proportion, and the manner of their union in a Particle does arise the form, which accommodates it to the figure of the poor, which it is to penetrate. And do we not find that there is such an agreement, and such an aptitude in some of them, which we call Principles( and which perhaps may be yet more simplo, and fewer, than we suppose them) to unite, that all the power of the Fire, and the tricks of the chemists could never separate any one of them so that they could pretend to exhibit it sincere.  
But to come to the nutritious Glandules, which it does more properly concern us to speak of at this time, I have supposed that in their situation they are different from all others, that separate any Juice or humour from the Mass of Blood, that whereas others are placed at the extremities of the Vessels, which convey the Blood to them, these are seated on the sides of those Vessels. I did likewise observe that there is something like their situation in the Lacteal Glands of the small Intestines, where all the Pulpe of our digested Food, especially in the Jejunum, and the Ileon passes from one Glandule to another successively, and yields the same sort of liquour to several Glandules in the same canal, as it is reasonable to think that the Blood supplies the nutritious Juice to several glandular Pores in every single twig of an Artery.  
Though this situation of the nutritious Glandules be different from almost all others, yet is it not irregular. For if we consider how ready they stand in this position for receiving those Particles, which they are to separate, and for the continuation of their direct motion, I do not see if their use would have admitted of it, and they had been disposed in the manner and order of the Glandules of the Viscera, that they would have been placed more conveniently for the performance of their Office of Secretion, than now they are. Neither is that proposition I laid down that the Glandules are so seated as to favour the tendency of the Particles, which they secern, and their direct motion, at least more than the Veins contradicted by the situation of these. Nay, it is so far from this, that it is demonstrable they are more advantageously placed, and so seated as to give the Particles, which they are to entertain, leave to move forward in a more streight line than those, which are seated at the extremities of the Vasa Adferentia do. For the motion into them is from some part of the arterial Channel, though we suppose it to be a single streight twig, more direct than to the extremity of that Artery. This will evidently appear to be so, if we consider how the Arteries as they proceed are contracted, and grow less, and less, for if a streight line were to be drawn from some part of the arterial Channel, where it is large, to begin at a little distance from any one side of it, and to run that way, which the Artery tends, it would, after it was carried a little way, run through the Coats, or that side of the Artery, which it is next to. So that whatever moves forward near the side of the Artery, where it is more large, must necessary, when it advances forward to that part, where the Artery is so contracted, that the side of it is drawn into the place, where the streight line of that matters motion runs, there I say it must necessary strike upon, and press against that part of it. So that if it meets there with a free and convenient passage, it does more naturally proceed into that poor, than pass on farther in the arterial Channel, where it is put somewhat out of its direct Road, and obliged to an obliqne motion. As suppose in the second figure Tab. 1. a, a, a. to be an Artery gradually contracted, as it proceeds towards b. and the Particles of the Blood c, c. to be moving in it from the contrary extremity, when any of these Particles are advanced in the Artery as far as d, d. the line of their direct motion does not run towards b. but on in the lines e, e. towards f. so that their endeavour will be to proceed in those lines, and they will necessary make a pressure upon the sides of the Artery at d, d. Besides, that the Blood does thus strike against the sides of the Arteries, and that with a force sufficient to carry any Particles of it through, and beyond the Coats of those Vessels, if there only be passages agreeable to the figure, and magnitude of any of them, is evident to our Senses in the Pulse, and the violent eruption of the Blood, when any one of them is pricked.  
The Particles therefore, which are designed for nourishment, being carried by the motion impressed upon them, and their natural tendency whilst they are in motion, with the other parts of the Blood against the sides of the Arteries, pressing upon them, and finding Pores convenient particularly for their passage, and the continuation of their motion in a right line, do proceed into them, leaving the rest of the Mass of Blood to continue its course in the Artery, and out of that into the Venose Channel. And having entred the nutritious Glandules they are pressed forward by every systole of the Artery as the contraction or subsidence of it renders the glandular Cavities placed in the sides of it more narrow, and perhaps by a power of contraction, which may be in the Glandules themselves; and they are propelled by Particles of the same nature coming behind them in every Diastole of the same Vessel, till they are driven into the Interstices of the Fibres, of the bony Strings, and every other part, where the Spirits move, where it is evident that they will lye in the way of the Spirits motion, and then they come to be more immediately employed in the Accretion of young Animals.  
From the supposition of these nutritious Glandules, and the manner in which the succus nutritius is supplied to all the parts, as I have explained it, I might give some probable account of an Anasarca, and the manner how it is produced, but I must consider I have been already a transgressor, and deviated too much from my Argument, so that I must expect some other opportunity to speak of that.  
For the better understanding how the nutritious Particles are managed, when they are separated by these Glandules, and thrown into the way of the Spirits motion, I shall lay down these following propositions.  
First, That as the Spirits have a direct motion à termino ad terminum, so have they a circular or rotatory motion turning round their own Centers. Neither do I suppose a rotatory as well as a direct motion in the Spirits merely to serve my present purpose, and without any other reason, than that I may accommodate their motion to my Hypothesis, but if we consider the Spirits simply in themselves, and without any respect to the part, that they act in our nourishment, we cannot think otherwise than that they do rotare in the line of their direct motion, when we find in the projection of a ston out of our hands, or out of a Sling that it turns round as it moves forward. And to instance in some things, to which the nature of the Spirits seems to have a very near access, as Fire and the Rays of the Sun, do not the Scintillulae struck off from a Flint plainly move round their own Centers? Do not some effects of Fire, and the Rays of the Sun discover more than one single, or a direct motion in their Particles? For how can we conceive that they should enkindle combustible Bodies, that are solid, and melt the most obdurate Metals, disunite their parts, and dissolve their texture merely by a direct pressure, which without such a violent rotation of the fiery Particles as distracts, and moves the Particles of the Body, which is melted or set on fire, some one way, and some another, would propel or elevate the whole Moles of the solid Body at the same time without disturbing the order, or altering the situation of those parts of it, which are fixed, and united. But I think I need not insist upon any argument to prove a twofold motion in fiery Particles, when the notion, which Philosophers now generally have of the nature of Fire, may save me the trouble of arguing for that, which I would here suppose. Which being granted may go very far to persuade us, that there is the same variety of motion in the Spirits.  
Secondly, The Spirits will endeavour to remove whatever lies in the way of their motion. What Body so ever is moved, as it has a natural conatus to persist, so it will offer violence to any thing, that lies as an obstacle before it, proportionable to the power of its motion, endeavouring either to drive it forward, and to make it comply with its own streight tendency, when the impression is direct, or to divert, and cast it off to one side of that line, in which it moves, which is done when the impression is more lateral, or the Body moving acts upon that, which is moved, by a rotatory motion.  
Thirdly, The Spirits by the power of their circulatory Motion or Rotation will carry the nutritious Particles to one side of that line, in which they move, if there either actually are spaces to entertain them, or any can be forcibly obtained by the power of that motion, which determines them thither; I say the Spirits will rather carry them thus laterally, than give them a direct tendency, since the succus nutritius is liquid, and gelatinous, and the parts of it not so fit to maintain a direct motion, but apt to adhere, that when the Spirits impinge against them, and when the nutritious Particles apply themselves to the Spirits, they will certainly move circularly with that part, which they stick to. But the Interstices of the nervous Fibres, and of the Strings of other parts being repleted with Spirits, it is plain that the nutritious parts, when they are by the Spirits Rotation carried to any side of those Interstices, between which and the Spirits there is no distance or vacuity, will have some stop, so that they adhere there, and are not able to proceed any farther in that circled, in which they were moving. Suppose a Bowl running upon the ground, and the most forward part as it is in motion meets with, and strikes upon any matter, that is viscous, the matter adhering to it will turn with it, and so that, and the part, which it sticks to, will be both in their Circulation brought to the ground at the same time, and the Bowl running close to the ground, though it has nothing to confine it, and necessary to keep it down on the other side, does not carry all the matter quiter round, but pressing it against the Earth leaves some part of it sticking behind, whilst the Bowl itself proceeds. Suppose it were a Body, that were not viscous, only it is not so solid as to be reverberated by it, as a piece of Cotton, Wool, Cloath, or any such thing, we find it does not receive so much a direct motion from that of the Bowl, which is so, as a lateral from its Rotation, so that if any thing of their nature occurs, the Bowl in turning will drive it towards the Ground, which is to one side of its direct motion. And indeed when the power of a rotatory motion in one Body acts upon another, that is truly solid, the natural tendency of that, which receives the impression, is not directly forward from that part of the Body, from which it received it, but lateral.  
Fourthly, Whilst the Animal is young, and tender, the tone of the parts is more lax, the Fibres are more tensile, so that in any intermediate part between their extremities they are capable of yielding to a pressure, and receding laterally, and whilst the Particles are not yet united they are in a capacity of being removed and set at some distance one from the other by the insinuation of any new matter between them: And thus the bony parts, whilst they are soft, and cartilaginous, are in such a state, that the Particles of one series can be moved laterally from them of another, and those of the same series are capable of receding from one another at their extremities.  
Fifthly, the same power of the Spirits Rotation, that carries the nutritious matter to the sides of the Fibrils, of the Strings of the Bones, or any other part, will by crowding this matter against them, oblige their Particles to recede laterally, and by driving it into the Interstices between the extremities of the Particles set their extremities at a greater distance from one another.  
I shall now see how far, and fairly we may be able with these propositions to solve the Phaenomenon of Accretion, and give a particular, and summary account of the manner, how it is performed. The nutritious Particles therefore being separated from the Mass of Blood by their proper Glandules, and carried into the Interstices of the fibrous Threads, and of the Strings of the Bones, come under the disposal of the Spirits, and the power and influence of their motion. And were there not such an active Principle to give a motion to the Particles of the nutritious Juice, and to dispose of them, to preserve the Interstices, into which they flow, free from those obstructions, which a matter of such a gelatinous, and viscous nature as renders it uncapable of diffusing itself freely, and being otherwise equally distributed to all the parts of a Fibril, or bony String, would be apt to create, how soon would they clog, and obstruct the Interstices, and intercept the nourishment, which is necessary for the increase of that part, which lies beyond the obstruction, and ought to have a supply of the succus nutritius from that Glandule, whose secreted Juice did first produce the obstruction? So then the Spirits in their passage meeting with the nutritious Particles lying in the way of their motion, will naturally endeavour to remove them by a pressure arising from that, which is natural to all Bodies, that are put into motion, a disposition, and a conatus to persist in it.  
There seem to be two ways, which the Spirits have, as they have a twofold motion, to clear their Road, and to prevent the interruption of their flux, and the alteration of their tendency, one is by communicating a direct motion to the Particles, which lye in their way, and such a degree of it as shall make them move with an equal velocity, which must be done by that, which in themselves has a direct tendency, or else by driving them laterally, by working, and winding them to one side of that line, in which they move, which is done by their Rotation. But whilst the Fibrils, and bony Strings are capable of receding, and giving way to the pressure of the nutritious Juice, the Spirits must necessary act upon it by their Rotation, as it is gelatinous, and of an adhering quality, so that they must carry it to the sides of the Interstices, in which they move, and drive it upon the minute Fibres, between which those Interstices are formed. But supposing the Spirits could at this time act upon it by their direct as well as their rotatory motion, this would not necessary divert, or keep off the nutritious Juice from the Fibres, which lye on one side the line of their direct motion. For although a Body moving in a streight line will make such an impression upon another, that lies in the way of its tendency, as shall transfer a direct motion to it; yet the incidence of one may be such, and it may in such a manner impinge against the other, as to communicate a lateral motion to it by that, which in itself is direct.  
But then there must be room to lodge this nutritious matter in, that the Rotation of the Spirits may be able to carry, and fix it on one side of the line of their direct motion. For if it could not do this, but the nourishing Juice lay always under the power and pressure of their direct motion, it must necessary be disturbed, and driven along in the Interstices, in which they move, so that it could never have leave to fix upon their sides, and unite. As for the space therefore, or vacuity, which is requisite to this end, though there is no place actually voided before the succus nutritius is driven upon the fibrous Threads, and bony Strings, because the Spirits fill the small Channels, in which they are moving, yet it is obtained both in the Bones, and Fibres, as in all other parts by that force, with which the nutritious Particles are driven upon them. For whilst the Animal is young the Bones are soft, the fibrous parts are very tender, and the Particles of which they consist not so entirely, and firmly united, as they afterwards appear to be. So that the nutritious matter crowded against them by the Rotation of the Spirits does extrude them laterally, and taking possession of that room, which the pressure of it makes, does adhere to the sides of them, and so makes an addition to their crassitude. And as it thrusts them out laterally, so that part of the nutritious matter, which is carried by the same Rotation of the Spirits to the Interstices, which are between the extremities of the Particles, of which the parts consist, being driven in like a wedge, it causes them insensibly to recede, and sets the extremity of one Particle at a greater distance from another,( yet by such insensible degrees, and in such a manner that the continuity of the part is still preserved) so that the line, which they lye in, will be extended, and every Series of them elongated, where the nutritious matter sixing, being united, and becoming a substance of the same nature as the part is of, which it gives an increase to, adds to the length of it. Thus the Spirits so long as the Particles of the Bones, and other parts are capable of receding, and will make room to entertain the nutritive parts out of the way of their direct motion, will drive them upon the sides of the bony, and fibrous Strings, and by that pressure oblige them to recede, where the succus nutritius not only has time, and liberty to adhere to them, but by the Spirits Rotation as they continually pass by is kept close and continguous to the parts, until it is more firmly united, and as the nourishing Particles, that are once lodged there, are crowded nearer to one another by those, which are afterwards supplied, and as it were knocked closer together by the rotatory motion of the Spirits, the matter contracts a solidity, and at last assumes the nature of the part, which it nourishes.  
Thus are performed the separation, the dispensation, and disposal, and lastly the unition of the nutritive parts to those of the Body, which they augment. So that I have finished that part of this Discourse, which concerns Accretion so long as it proceeds, I shall only observe how reasonable it is to think that the gelatinous nature, the viscosity of the succus nutritius, and its coming in the way of the Spirits motion do retund the violence, and quickness of it, and consequently temper that heat, which the Spirits continually maintain, and that the Hectical heats, which attend Consumptions, and often follow upon great evacuations, are from the want of this gelatinous Matter to lye in their way, to check, and balance that violence, and velocity, with which they move.  
But I pass on to the second thing to be considered, which is the reason of the limits of an Animal's growth, and what it is that puts a stop to it, when the Animal is increased to the convenient and ordinary magnitude of the Species. This is either from a defect of the succus nutritius, and because the nature of the Ferments, which serve for Concoction, and Chylification, and the Crasis of the Blood at that time, when Accretion ceases, undergo such an alteration, that the one does not produce, nor the other contain such nutritive parts as are fit to be separated by the nutritious Glandules: or else these Particles are still supplied; but when they are separated, and carried into the Interstices of the fibrous, and bony Strings, or any other part, they have not leave to fix, and are not united to the part, which they are fit to give an increase to. That the first is not the Reason is evident. For although the Blood, and Ferments like other fermenting liquours may undergo some alteration from time, though the Blood may be thought to amit much of its first sweetness, and balsamic nature, and to grow sharper, or more acrious with age, and tho we see it is so altered after some certain time as to contain, and supply a liquour, which was not before to be separated, or observed as that, which in Men serves for propagation, and we might reasonably suppose that an alteration in the Blood on the other hand renders it uncapable of affording such a succus, as it had yielded before, that as Nature produces one, when it is necessary, so she puts an end to the other, when it is not. I say notwithstanding all this we cannot suppose such an alteration and such a defect to be the thing, which puts a stop to an Animal's growth, I mean naturally, and where the Animal is in a healthful State. For it plainly appears that there is a succus nutritius, which is fit to be apponed, and to give an increase to the parts after the Animal ceases to grow, in that there is a reparation, and that not only of the fleshy parts, but even of the Bones, when they have lost some part of their substance, as Diemerbroek tells us of an adult person, who had a part of the Tibia sawed off, that afterwards the Leg was extended to its former length, and after it was Set, was kept quiet, and streight in a wooden Cradle, and by a Callus, which we cannot suppose to be any other than the succus nutritius of the Bones, shooting from the ends of both those pieces, where the Fracture was made, the loss of that part, which had been taken off was repaired, and the broken pieces again united, and the same is more commonly seen in the Skull, when it has been trepanned.  
The reason therefore of this limitation I take to be because the nutritious Particles, when they are separated by the Glandules, and carried into the Interstices of the fibrous Threads, of the bony Strings, and the other parts, are not suffered to lodge, and unite to the parts, which they were wont to nourish, and the reason of their disturbance is, because the Fibres are so tense, their proper parts so contiguous, and the extremities of the bony Particles so firmly united, that they will no longer recede, and make room to entertain them, where they may be out of the way of the Spirits direct motion. For although the nutritive parts, when they are driven by the Rotation of the Spirits against the Fibres, and the Strings of the Bones, can oblige them, so long as they are more lax, and tender, and their Particles more weakly and not universally united, to give way, and so thrust themselves into, and fix in a place, where they are out of the way of the Spirits direct motion, and although so long as the Spirits have a power either to force them laterally, or to remove the extremity of one from another, and to make an Interstice between them, they will by their circular motion carry the nutritious Particles to one side, and fix them upon the filaments; yet when the Strings, or fibrils are so streight, and their Particles so entirely united, that they can no longer give way to the pressure made by the Spirits Rotation, or the nutritious Particles acted by them, so that there is now no possibility of obtaining any place, by which convenience the Spirits may make use, and have the benefit of their rotatory motion to carry the nutritious Particles to one side of that Line, in which they move, the succus nutritius though it continues to be afterwards supplied, cannot have the liberty to lodge, and unite as it did before. For still the Spirits naturally endeavour to remove them, that they may neither stop their motion, nor alter their tendency, and now they begin to act upon, and to agitate them with their direct motion, which instead of driving them to, and fixing them upon the Fibres, and Strings of the solid parts, will carry them along in the small passages or Interstices, in which they move to the extremities of those Interstices, to the habit of the Body, and to several Glands, by some of which they are excerned, and continually spent. And though the incidence of one Body moving in a streight line upon another may be such, as will communicate a lateral motion to it; yet where there is no space for the Body agitated to move laterally, or obliquely into, it will necessary lye under the pressure of that Body, which moves it, which pressure will drive it along in that passage, wherein they are both moving. So the Spirits, though they have a rotatory motion; yet as they fill the small Cavities in the fibrous parts, and the Channels, through which they move in the Bones, especially when the Blood is in the best condition, and most capable of supplying a Nourishment, they can no longer fasten any of the nutritious Juice upon the sides of the Interstices, in which they flow, or suffer it to lodge quietly, and fix there, then the parts will recede, and allow so much space as will receive the nutritious matter to one side of the line of their direct motion. As supposing a Ball exactly fitted to the Cavity of a Tube to be moving from one end towards the other, and that it likewise turns round its own Axis, supposing any matter, that is viscous, lies in the way of its direct motion, so that the one impinges against the other, and the viscous Body adheres to that, which is in motion, it is true the circular motion of the Ball will carry it to the side of the Tube, but it cannot fix it there, so as to leave it behind, and proceed without it, because no manner of incidence, no Rotation can carry the matter beyond the extension, and from under the power of the direct pressure of the Ball, so that it must necessary, when it has by its Rotation carried it to the side, drive it on by its direct motion to that extremity of the Tube, towards which it tends.  
The account, which I have now given of the limitation of Accretion may not only satisfy us how there comes to be such a diversity in the size of Animals of a different kind, and the time, which they are allowed to grow in, but when daily observation tells us, that all the Individuals of the same Species are not strictly limited to the same degree of magnitude, some carry out their dimensions farther than others, and some cease to grow sooner, than some, this Hypothesis will serve to explicate the cause of the difference, and the reason of it is because the Fibres are sooner tense, and their proper Particles more contiguous to one another, and inseparable to that power, which they have to resist; because the Particles, which constitute the bony Strings, are sooner entirely united at their extremities in some, than in others, after which be it earlier, or later, the Spirits come to act upon the nutritious Particles by their direct motion, upon which the growth of the Animal necessary ceases. Though for the different magnitude of some Individuals it must be granted that a more copious supply of the nutritious matter, and a greater plenty, and more vigorous activity of the Spirits to dispose of it, and to make a greater pressure upon the parts, whilst they are capable of giving way both laterally, and at their extremities, are sometimes the cause, why some are larger than others. And I do not question but the Bones may contribute something in their increase to the elongation of the fibrous Threads, as their growth does insensibly stretch the Fibres, which are annexed to them.  
As for the defect of Accretion, which is the Symptom of any Distemper in Children, or any persons not adult, it seems commonly to be from the want of a succus nutritius, and a deficience in the quantity, and vigour of the Spirits, besides that their Appetite is languid, their Diet sparing, and the motion of their Spirits too slow, and weak to attenuate the nutritive parts, the Ferments, which serve for Concoction, and Chylification, are so depraved, that either they do not extract, or they do not form such Particles as are adapted to the figure of the Pores of the nutritious Glandules, according as the use, and design of these Ferments are either to work upon the nutritious Particles so as to give them a convenient figure, or only to dispose them being already conveniently figurated, for a separation.  
And thus much shall serve for the business of Accretion, that, which comes next to be considered, is Nutrition, and this I take to be rather a supply of the fluid parts, and the maintenance of a plenitude in all the Pipes, and Vessels of the Body, such a continual reparation of Spirits, nutritious Particles, and of all the humours, in the Vessels, Nerves, and Fibres, as keeps their Interstices, and Cavities replenished, and the parts themselves in a due temperament, I say it is rather this, than the apposition of new Matter to the solid parts. Tho I will not deny but some Particles, which were joined to, and become a portion of a fiber or any other solid part, may be sometimes rubbed off, and separated, from the translation of which there will follow a vacancy, or voided space for entertaining some fresh nutritious Matter, and wherever it happens, so long as there are Spirits, they will by their Rotation immediately determine some new Particles to those vacuities to supply the place of those, which are removed. When the fibrous parts are eroded by Ulcers, and the Interstices, in which the Spirits move, and to which the nutritious Particles are supplied, are set open so that the Spirits can by their rotatory motion act upon them, and carry them to one side of their direct motion, we find such a supply of Nourishment, as repairs the loss, and creates a new Flesh. Or when a Bone is broken, it being impossible so exactly to set it, and to bring the two pieces so close together, that there shall be no preternatural Interstices, where the Fracture was made, there will be some little spaces found, which will be lateral to those Interstices, in which the Spirits move, and the nutritious Juice flows, and convenient for entertaining that part of the succus nutritius, which the Arteries, that serve for their Nourishment, and the nutritious Glandules supply, and which the Rotation of the Spirits will determine to those vacuities, where being lodged out of the way of the Spirits direct motion, and of that disturbance, which their direct pressure must give it, it quietly fixes there, and is united to the part, and this is that, which we call a Callus. I say there may be, and is all this, but we cannot reasonably think that the substance of the solid parts is always in such a flux, as ordinarily to secede, and to give way for the succession, and apposition of new Nourishment, no not so as to be once universally renewed in the whole interval between the Womb, and the Grave, nor that the imminution, which appears in the solid parts in an Atrophy, is from the loss of their proper substance; but rather from a subsidence of the Vessels, the dryness of the Fibres or the exinanition of their Interstices, and the emptiness of other Cavous, and containing parts, all which for want of a plenitude to keep them distended, and their Cavities enlarged are contracted, so that the sides of the Vessels, and the Filaments, between which the Interstices are formed, which before by a fullness of volatile, and fluid Matter were preserved larger, and distended, come nearer to one another, or fall together, and the part, whereunto those Vessels, and Interstices belong, must lose so much of its breadth, and crassitude as proceeded from their fullness and distension.  
To make ourselves sensible how the fleshy parts are capable of such a subsidence, as will detract from their thickness, and latitude even to a Marasmus, we need only consider how the whole Body is vascular. This the most ingenious Dr. Tyson has in some Lectures of his publicly asserted, and besides the Authority of so curious an Anatomist, those that will be at the pains of making an enquiry may make a great step towards their satisfaction in this matter by their own observation. For when any of the Viscera, even those, which seem most compact, and free from Pores and Cavities, are strictly examined, that, which was formerly taken to be only a Parenchyma, or Mass of congealed Matter, appears to be nothing but Vessels for the Motion, and Conveyance, and Vesicles, or cavous Glandules for the separation, with Cavities in some for the reception of some fluid Matter, which the indefatigable, and sagacious Malpighi has discovered, and sufficiently convinced us of. And wherever our Senses leave us wholly to the conduct of our Reason, we may rationally think that the structure of the parts is Vascular. For how certain is it that the Arteries are continued where we cannot discover their Cavities? Who questions but that the Nerves have their Canaliculi? They that maintain the motion of the Spirits, or a succus nervosus through them do implicitly grant it. And if they have their small Pipes, whilst they are Nerves, there is no reason to think their Caniculi terminate when their Fibres are expanded in a Muscle, seeing the Fibres themselves are continued. The whole Body therefore being Vascular we need not suppose any thing more than a subsidence of the Vessels to explain the immediate cause of that imminution of the fibrous parts, which is seen in an Atrophy. The Voins, and Arteries not being distended as they ought to be, the nervous, and fibrous Channels not being replenished, the vesiculous parts, such as the Fat is contained in, being empty, and contracted, the consequence of all this must necessary be a remarkable alteration in some dimensions of the part, which they constitute.  
The nature of the humours, and Spirits, it is plain enough, is such that they may be easily evaporated, or some other way excerned out of the Body. What quantities of them are sometimes lost by Sweats, and other ways of evacuation. And in Ulcers, where the fibrillae are eroded, and the Pipes, in which the Spirits move, and to which the succus nutritius is supplied by the nutritious Glandules, are set open, so that both may extravasate, what an expense of the nutritious parts, and consequently what a notorious defect may we observe in Nutrition, when the Ulcers are large; so that we have often an Atrophy not only of that particulart part, where the Ulcer is, but even of the whole Body. Besides, the nature of the Fat, and oily parts, which make a considerable addition to the extension of the parts, to which they are supplied, not only is such that they are capable of being put into a flux or made fluid, but they are actually liquid, whilst the natural heat of the Body remains, so that they are easily divided from one another, and separable from the parts, which they lye contiguous to, and so excernible out of the Body. And unless there be a fresh supply to repair the loss, of that, which is evacuated, and did before fill their small bags, these Vesiculae will contract themselves, or subside, which is natural to parts of their Texture, and fabric, when they are empty, and their subsidence will detract so much from any dimension, as the Matter, which before distended them, added to it.  
But the substance of the solid parts is such, that it can neither be exhaled, nor melted down by any heat of the Body, so that if they do indeed suffer an imminution in their proper substance, it must be by the way of an erosion, and be the injurious effect of such a corrosive Matter, as will dissolve them, and eat off the Particles, the consequence of which would be Ulcers in all those parts, which are thus imminished, and such a Corrosive could not so affect the Fibres without the conjunction of an intolerable pain, and the torments of the ston, and Gout would be moderate and easy to them, which in a Consumption would be universal, whereas in a Tabes we have no such Symptom. To which may be added another Argument, which seems to prove against all contradiction, that the imminution is not in the solid parts, which is from what we cannot but observe in the Bones in the greatest Consumptions, that whilst other parts are sinking, and tabid, they are not found to lose any thing of their magnitude. And why so? Were there a corrosive humour, that eats away the very substance of the Flesh, where it is affencted with an Atrophy, it would prey as certainly, and more voraciously upon the Bones. For upon trial it appears that a Corrosive, as Aqua fortis, will sooner perfectly dissolve a piece of a Bone, than the same quantity, or weight of the muscular Fibres. The reason therefore is because the Strings of the Bones are more rigid, so that though the Bones may be equal sufferers with the Fibres, that is their Spirits, and nutritious Juice may be subtracted in a Consumption, as they are in other parts; yet still they keep the same posture, that they were in before, and being uncapable of a subsidence, they are not attended with the same symptom of an evident imminution.  
The loss therefore of what is expended being in the Spirituous, the Humorose, and Fluid parts, and Nutrition being only the reparation of those parts, which Nature continually suffers the expense of, it follows that it is no such thing ordinarily as the repairing of dilapidations, or the filling up of breaches in the solid or containing parts, but only a supply of such Matter as continues in a Flux, which keeps them full, and maintains the natural circumference of every part.  
There is one thing, which I promised to do under this Head, and it is to answer that objection, which is leveled against the Opinion that the nutritious Particles are derived from the Mass of Blood, and is urged as an Argument to prove they are supplied from the Nerves, which is taken from the observation of an Atrophy in some Palsies. The strength of this objection is wholly depending upon a false Notion about Nutrition, to wit, that the substance of the solid parts is in some measure daily expended, and lost, and that the succus nutritius is apponed, and united to the parts in the whole course of a Man's life, as in the time of Accretion, otherways it has not the strength either of an Objection one way, or of an Argument the other. For if Nutrition be only maintaining the fullness of the Vessels, which contain the several humours, and oily parts, and that of the Cavities of the Fibres, and an Atrophy be only a subsidence of all, or some of these, the subsidence, if it were only of the Nerves and muscular Fibres shows only a defect of something to fill their Cavities, and does not prove it to be the want particularly of a nutritious Juice, when it may be a deficience of Spirits only. But we may safely grant the very Notion, upon which the Objection is grounded, to be true, that nutrition is, what they would suppose a reparation of the solid parts, without the least prejudice to that Opinion that the nutritive parts are supplied from the Mass of Blood, though they do not answer the end, which they are designed for, in a palsy. For although the Mass of Blood, in which we suppose the nutritive parts reside, continues to Circulate through any part, that is paralytic; yet the want of Spirits will have this effect to hinder the separation of the nourishment, when the evil spreads itself so far as to affect the Fibres of the nutritious Glandules. For without the Spirits the Fibres of these parts lose their tone, and can never be kept tense, nor the natural figure of the glandular Pores be preserved, which being altered by the relaxation of the Fibres of the Glandules become uncapable of separating those Particles, which are adapted to the natural, but disagreeing from the present figure of their Pores. And by that account which I have given of Nutrition, it will be no difficult thing to explain the reason of an evident abatement in the natural magnitude of any part, when it is the consequence of a palsy. For the Fibres being obstructed, and the influx of the Spirits, which ought to fill, and inflate them, and the supply of their succus nutritius, which as I have already shown is naturally supplied though not apponed to the solid parts after Accretion ceases, being hindered, there will necessary follow the loss of so much of the magnitude of any parts as proceeded from that measure of Spirits, and their proper nutritious Juice, which is now denied to them. And besides the subsidence in the nervous Pipes, there is also a contraction, or falling of the Blood Vessels. For the expansion of the Particles of the Blood, and the turgescence of those Vessels in every part depending much upon the motion, and energy of the Spirits flowing into it, it cannot be thought, though the Blood continues its influx into any paralytic part, that the sanguiferous Vessels will be so much dilated, when the obstruction, and defect of the Spirits are so great that they cease to flow into, and give an activity to the Blood that circulates through them, as when it was rarefied, and expanded. And this difference we may find especially in persons, that are lean, from Heat, and could, that when the Hands are very warm, the Vessels are more turgid, and the parts are plumper, and more large, but when the could weakens the activity of the volatile Particles, and resists the expansion of those, which are agitated by them, the parts seem as if they had some degree of a sudden Atrophy, and the Skin becomes flaccid.  
What I have said of Accretion in general might be sufficient to explain the manner, how the Bones do increase, and how a Callus is supplied to a broken Bone; but because I entered upon the consideration of Accretion upon the account of these parts, I cannot but say something particularly of the manner of their increase. That they have many Arteries bestowed even upon their most solid part, and designed for their Nourishment I have already observed, and given some description of them. By these Vessels is conveyed into them the Mass of Blood, from which the Particles, that nourish them, are separated by Glandules seated in the sides of the arterial Channels, which being carried into the Interstices of the Strings of the Bones, in which their Spirits move, will lye in the way of the Spirits motion, and thereupon are in the manner, which I have already explained, by their Rotation, or circular motion carried to the sides of the Strings, so as to make a pressure upon their Particles, by this pressure made upon the sides of them, so long as the extremities of the bony Particles are not united, they force them to recede laterally, and insinuating themselves between their extremities enlarge the distance between them, and oblige them to give way, and so they obtain a space, which entertains them out of the way of the Spirits direct motion, and where they are contiguous to the bony Particles, to which they adhere, and unite.  
Neither are we at a loss for Spirits in the Bones to act their part in this business, since they receive a continual and plentiful supply of them from the Periosteum, by the Fibres of which they flow into the Interstices of their Strings, and move in them as their Channels, as they did in those of the Fibres in the Nerves, and all the fibrous parts.  
That we may the better understand how the Particles of the Bones are capable of receding both laterally, and at their extremities, we must consider that the Bones of a Foetus are soft, and their parts at one time easily divisible, so that they will sensibly yield to the pressure of the Finger, when an Infant is Born they have very much of a cartilaginous Nature, and it is a considerable time before they arrive at the perfect solidity of a Bone. Now a cartilege, as I shall farther show, when I come to discourse of those parts, is nothing but an imperfect Bone, or a Bone, in which the extremities of the Particles are not united to form continued Threads, but there are small Interstices between them, though they are so disposed as to preserve the continuity of the whole cartilege, and although when it advances nearer to the true, and perfect Nature of a Bone many of them are united; yet they are not all so until the Bone obtains its due solidity. So that whilst the Bones are cartilaginous, or bordering upon the nature of a cartilege, their Particles are capable of receding both to one side, and at their extremities, which being moved by the pressure of the nutritious Juice driven against them by the Rotation of the Spirits, they make room for lodging of the Nourishment out of the way of the Spirits direct motion; Those Particles, which are driven against, and apponed to the sides of the several parts of the bony Strings increase the thickness, and enlarge the circumference of a Bone, those which are forced in between their extremities, widen the Interstices, and sticking there, elongate every series of the bony Particles, and consequently the whole Bone.  
But when these Particles come to be united at their extremities, that will be the boundary of their recedure, and limit the growth of a Bone. Though I suppose likewise a lateral unition, yet the first only will necessary prevent the farther increase of their crassitude as well as of their length, where the Strings are continued in the manner of a Ring, as they are in all the Bones. For unless the Spirits have a power of breaking this continuity they can neither protrude, nor elongate these Strings either on one side, or the other, after their Particles are firmly united. And as they cannot protrude the parts of a String, so neither can they fix any part of the nutritious Juice upon them, because so long as it is in the Interstices it must be disturbed and propelled by their direct motion, which may probably drive it on till it comes into some way, which leads it to an evacuation. I do think too that the Periosteum, which I have already discoursed of, does, as I then supposed, help to prescribe limits to the increase of these solid parts, when its growth, and extension cease. But suppose that none of the bony Strings were so united as to become annular, I mean to be continued in the manner, though not in the figure of a Ring, nor any opposition made to their recedure by the Periosteum; yet the Bones, and the parts, which they consist of, being of a fixed, and quiet nature contrary to that of the Spirits, and all active Particles, so long indeed as the pressure of the succus nutritius from the Rotatory motion of the Spirits is so strong and violent as to exceed, and overpower the quietude, and fixity in those parts, it will oblige them to recede, but when they come to an aequilibrium, that the degree of quiescence in these solid parts answers exactly the power of the Spirits motion, much more if it exceeds it, the fixed Particles of the Bones will begin to stand their ground, and none can without absurdity suppose they should be moved, and protruded by that force, which they are able to resist.  
What I have said of Nutrition in general, I may confidently affirm of that of the Bones, that it is not ordinarily a reparation of their substance or solid part, or the succession of new Particles to any that are destroyed, and expended after they are assimilated. For the Particles of these solid parts are so fixed, and firmly united after the time of their Accretion, that their Nature will not give us leave to think they are capable of such a flux as is necessary to such a change, and succession of Matter. So that their Nutrition is no more than a constant supply of Blood to their sanguiferous Vessels, of Spirits to the Interstices of their Strings, and of their nutritious Juice, which when a Bone is broken, or deprived of part of any of its Laminae, though it be after the time of Accretion, is upon these occasions employed, and apponed in the same manner as it was, when it gave an increase to these parts; it is carried by the Rotation of the Spirits to those Interstices, and defective parts, where a Callus or bony substance is necessary to knit the pieces, which are fractured, or to supply what is lost by Trepaning, or Exfoliation.  
From that Hypothesis, by which I have endeavoured to explain the manner of the Bones Accretion, we may, as I humbly conceive, be able rationally to account for the Symptoms, which we observe in these parts in the Rickets, and for the Gummata, which often appear in the French Disease.  
The Symptoms, which attend some of the Bones in the Rickets, are an Incurvation, a knottiness, and protuberance at their ends. The ingenious Dr. Mayo has endeavoured to give us the reasons of the obliquity of some of the Bones in this Distemper, by supposing a disproportionate growth in the Bones, and the Muscles, which are affixed to them, that the nervous, and muscular parts for want of a sufficient quantity of a succus nervosus, which he conceives to be necessary to their Accretion, have not that addition made to their dimensions in this case, which they ought to have, whereby they fall short of that length, which should give them a proportion to the rest of the parts, and which a natural Accretion would have procured; but all this while he would have the Bones to be nourished, and to increase no less in Rickety, than in Healthful and thriving Children. But as it does not appear that there is any such reason for this affection of the Bones; so if we should suppose the inequality, which is in the distribution of the nourishment in this case, to be between the Bones, and the Muscles, and not between several parts of the same Bone; yet it would do us but little service in explaining the reason of the Bones obliquity, neither would their Incurvation follow upon what he supposes. The ingenious Author's Notion is this, that the Muscles, as I have said, from a defect of a nervous Juice necessary to their Nutrition are not nourished, and extended as they ought to be, but the Bones, from whence they have their origination, and which their Tendons are inserted into, enlarge their dimensions: Now the origination, and termination of the Muscles hindering those bony parts, which lye within these bounds, from extending their length in a right Line, that growth, and addition, which make them exceed the length of their Muscles, will alter their figure and incline them to that of a Bow, as it is certain if any Line be elongated, whilst the extremities are fixed within the same bounds, it will necessary of a streight Line become obliqne. This indeed might solve the Phaenomenon, if the origination of a Muscle were from, and the insertion of it into the same Bone. But this is evident, that as the Muscles are designed for Motion, so between their beginning and the insertion of their Tendon Nature has to make the part movable formed an Articulation, so that the brevity, and straightness of the Muscles would bend the joint, and not produce an obliquity in the two Bones, which are articulated, or in any one of them. So long as there is an Articulation, between those two extreme parts, which he would suppose to be fixed by the beginning, and Tendon of a Muscle, and that part, where the insertion is, being not only capable, but apt to be attracted towards the other, where the origination is, upon the preternatural shortness of the Muscles, just as it is in muscular Motion, where there is a contraction of the muscular Fibres, and their length is not equal to the distance, which is between their beginning, and insertion, when the Bone, which they move is extended, there will follow an alteration in their posture, but no one of them will be obliged to alter its figure. Are not the Muscles, when they move any part, so shortened as to put a stress upon the Bones, and to bring that part of a Bone, which they are inserted into, towards their origination; and what do we find is the effect of this abbreviation, have we an obliquity following in the Bones themselves? No such thing, but only a flexure at the joint. The example he gives us of a young and thrifty three, that has whilst it is growing the ends of a Chord fixed to it, the one in the superior part, and the other below, so that the String is extended to its full length, but the three at first not at all inclined, is not Parallel. There is no doubt of this, and it is demonstrable, that the T●●●, which receives its Nourishment, and is extended in its length, when it cannot carry either of those extreme parts, to which the Chord, that is not equally elongated, is fixed, beyond those limits, which were set before it had this increase, that is, it is uncapable of an elongation in a direct Line, what ever is added to the length of it must be out of a streight Line, and give the three the obliquity, and figure of a Bow. But we must consider, that this is one Stick, one continued Body, which has no Articulation, which if we supposed it to have, the slexure would be only at that joint, and so all the other parts between the Ligatures would preserve their rectitude, and first figure.  
Dr. Glisson's Hypothesis, methinks, seems to be more rational, that the inequality and disproportion of Nourishment lies between several parts of the Bone, which is thus affencted, that the nutritious Particles are plentifully supplied on one side, whilst on the opposite side the Bone wants its due Nourishment, the necessary consequence of which will be an Incurvation, and the Bone will be reduced to the figure of a Bow, whose Convex will be on that part which is duly nourished, and the Concave on that side, where the nutritious Juice is not proportionably apponed. This he proves will be the effect of an unequal Nourishment in the Bone itself; by an instance he gives, Let there be a Pillar, says he, raised with three Stones, lying one upon another, let us suppose it to be such as is perpendicularly streight on every side, and of the same height, if therefore we put in a wedge on the right side between the uppermost and the middle Stones, the highest ston will be inclined towards the left hand, and the Pillar will be raised higher on that side where the Wedge is driven in, than it is on the opposite part, likewise if we drive in a Wedge between the middle ston and that, which is the Basis on the same side, the Pillar will yet be more inclined, and stand bending towards the left hand, and the more Stones it consists of, if a Wedge be put in between every two of them on the same side, so much the greater will the obliquity be in the whole, so that the Stones will no longer make an erect Pillar, but represent part of an Arch, as he has expressed it by a Figure. It is true every ston that is thus raised will with that, which it immediately rests upon, make an Angle on that part towards which it inclines, whereas there are no such Angles in these incurvated Bones. But the reason of the difference will appear, if we consider what he farther says, that the Nutrition, which on one side is most considerable, is there in a manner equally performed in all the length of it, and from this equal Nutrition, the Incurvation of the Bone will make exactly a part of a circled without any Angles.  
We will see how this notion may be farther explained by that account, which I have given of the manner of the Bones Accretion. Much of the difference between a Bone, and a cartilege I then observed to consist in this, that in one, to wit, the Bone, the Particles are at their extremities, which lye opposite to one another in every series, united in the whole length of it, so as to form continued Strings, whereas in the other the Particles are so far from this, that there are minute Interstices between their extremities. Whilst therefore the Bones border upon the Nature and Constitution of a cartilege, as they do in young Children, the extremities of their Particles are capable of being removed, and set at a greater distance from one another, and will admit between them the nutritious Particles like so many Wedges driven in between the the Stones of a Pillar, and where the supply of the nutritious Juice is most plentiful, and the quantity of the Spirits, which forces the nourishing Particles into them, is greatest, and their pressure strongest, there the Particles of the Bone will be obliged to recede farthest, the consequence of which will be a more considerable elongation of every series on that side, when on the other, if there be any defect of the nutritious Juice, and the activity of the Spirits be more languid, the extremities of the bony Particles will not recede to the same degree, nor the Accretion of that part proceed with an equal place, and thus one side comes to be shorter than the other, and that part, which is most extended in its length, will incline the Bone towards the contrary side, and reduce it to the figure of a Bow.  
But although this account does fairly explain the reason of the Incurvation of the Bones in the Rickets, yet I do not think that the disproportionate quantity of the Nourishment, which is supplied, and the unequal influence of the Spirits are the true causes, why one part of a Bone is nourished more than another, but I take it to be rather from some difference in the nature of several parts of a Bone, in one it puts off the form and temper of a cartilege more, and sooner, than it does in another, and if the Particles happen to be united, and to form continued Strings, that they are not so capable of receding, and ready to make room for the entertaining of the nutritious Particles out of the way of the Spirits direct motion, sooner on one side than on the other, that is, the part is there more hasty in its tendency towards the perfect nature and solidity of a Bone, so that the Spirits, and nutritious Juice, though their quantity, and pressure be equal on every side, cannot oblige the Particles equally to recede, then will the Accretion of the Bone cease on one side, or proceed slowly if some of the Particles remain disunited at their extremities, whilst it is carried on more effectually, and evidently on the other, which may be more fully explained and understood by what I have said of the reason, why Accretion ceases in grown Animals. I must confess I never had an opportunity to examine the Bones of any rickety Children, however I am strongly persuaded if an enquiry be made into them, which are incurvated, the Concave part will be found to be more solid, and like the perfect Bone of an adult person, and the nature of the Convex, more agreeable to the age of the Child to whom it did belong. And this we may conclude from the nature of those Oils, which we make use of externally to the part affencted in this distemper, which are emollient, and relaxing, such as are apt to loosen the extremities of the Particles, to dissolve that union, that continuity of them, which makes the Strings more firm and rigid, at least to weaken it so, that the power of the Spirits, and the pressure of the nutritious Juice acted by them, may be able to dissolve it, and make the Particles capable of receding at their extremities, which is necessary in the elongation of a Bone. And so the reason is obvious why these external remedies are to be applied to the Concave part of the Bone, when it is incurvated, which is where the extremities of the Particles are united, and not disposed to recede, and to receive any part of the nutritious Juice out of the way of the Spirits direct motion, which every good Woman, that pretends to cure the Rickets, observes to do.  
From this supposition that the Interstices between the extremities of the bony particles, and the liberty, they have to recede upon the pressure of the succus nutritius are that, which makes the Bones capable of an increase, we may account for the preternatural increase, and knottiness of the ends of some Bones. For in Children at first the extremities of the articulated Bones are but tender Cartilages, and some of them, as those of the Wrist, wholly Cartilaginous, and not only so, but that medullary Oil, and mucilage, which are supplied to, which lubricate and moisten those parts, that are found to be thus nodous, keep their Particles lax, and prevent their natural tendency to a union, as we see this mixture even in grown persons has so far the same effect upon these parts, that they never obtain so great a solidity, as is in those parts of the articulated Bones, which are never moistened with the mucilage. In young Children therefore, where these parts of the Bones are naturally soft, and the extremities of the Particles are kept more lax, and longer disunited by a moist, and mucilaginous Matter, than the other parts of them, there is sometimes, as in these rickety cases, a preternatural laxness, and a greater indisposition in the Particles to unite, and consequently a weaker opposition to the pressure of the nutritious Juice, whereupon they are protruded in an extraordinary manner, and give way for the entertainment of a greater quantity of the succus nutritius, than what is necessary for their regular, and natural increase.  
For the Gummata or Nodes, which appear upon the Bones in the Lues Venerea, since by a long continuance, and their induration they take upon them the nature of a bony substance, it is not to be doubted, but that they are produced from the succus nutritius of the Bones, as their material cause, which is extravasated, and cast out upon their superficies, where it adheres, and produces a preternatural excrescence. The nutritious Juice, after it is separated from the Mass of Blood, comes to flow in the Interstices of the bony Strings. So long as these Channels are entire, and have no breach in all their course, the nutritious Particles are as it were kept within their Banks, but when the continuity of the Strings is broken by the least preternatural foramen, then the nutritious Juice finds a passage to flow out at, and when any parts of it come to be opposite to it, the Rotation of the Spirits will carry them into it, and by the succession, and pressure of one Particle upon another they are driven out of the Bone, where lying out from the Line of the Spirits direct motion, their viscous nature disposes them to adhere, and they generate a substance like that of the part, which they are fit to nourish. So we find when the Fibres lose their continuity, and the small Channels, in which the Spirits move, and where their nutritious Juice flows, have any preternatural avenues, whether it be by the Knife, as in Issues, that are cut, or by the Corrosion of some sharp, and ulcerous Matter, that the nutritious parts contained in them are thrown into those foramina, and Cavities, to repair the loss of what is destroyed, and to restore the natural continuity of the Strings, which are corroded, and even where the case is so ill, that there is no disposition to heal, yet often we are sensible of the extravasation of the succus nutritius from the fungous Flesh, that arises. Now the venenose Particles, which affect the Blood in the French Disease, are both subtle, and acrious, which, when they are scattered through the whole sanguineous Mass, will be apt to attend any humour, that is separated from it, being by reason of their subtlety capable of entering the Glandules of any part. For although the Pores of divers Glandules are differently figurated, yet this will not necessitate these Particles to be separated by those of one sort, because they are so minute, and subtle as to penetrate those Pores, which are of a different figure. And thus subtle we find the malignant Particles in the Lues Venerea to be, when they are discharged by several Glands, sometimes they insinuate themselves into the Salivatory, the Urinary, the Pulmonary, the nutritious Glandules of the Fibrous parts, and raise several Symptoms, where they are separated and deposited. And as the nervous Threads are sometimes corroded, and the nutritious Juice extravasated out of their Interstices produces Caruncles in the fibrous parts, so the same weal-public Particles, when they penetrate the Pores of the nutritious Glandules in the Bones, are mingled, and confounded with the Nourishment in the Interstices, where by the means of their subtlety being arrived, by their acrimony they corrode some of the Strings, so as to eat small passages in the sides of their Interstices, which when they reach the superficies, are a way for the efflux of the nourishing parts, which by the power of the Spirits rotatory motion are carried into them, and by the pressure of such as succeed them are driven to the superficies, where they concrete, and produce an excrescence, which represents the nature of the part, which they are proper for the Nourishment of.   

The THIRD DISCOURSE OF THE MARROW.  
THE Cavities, which Nature has formed within the Bones, are neither empty, and useless vacancies, nor filled with Lumber, and contemptible matter, but convenient Repositories for a curious, and refined substance necessary for the service of those parts, that contain it, which is called the Marrow. The nature of the Matter, which is here separated, and deposited, and immediately serviceable to the Bones, is wholly oleaginous. However the whole Mass, or Body of the Medulla consists of several parts, to wit, of Blood Vessels both Veins and Arteries, of Glandules, and containing parts, and the oily Matter, which is contained in them.  
It has Blood-Vessels, proper to itself. The Artery is sometimes single, sometimes there are two, or three, and in some Bones as particularly in some of the Ribs, they exceed that number, having every one of them a distinct Foramen formed in the side of the Bone for their passage into the Cavities. It passes through these Foramina without any division, or ramification, for I could never observe that any of them sent forth any Twigs into the substance of the Bone for its Nourishment, but were designed solely for the Marrow. After it comes into the large Cavity, or into the lesser Caverns, when the Bones are spongeous, it is commonly divided into two, one ascending towards one extremity, and the other descending towards the other, both of which in their whole tendency are so ramified as to give a Twig to every Vesicle, that performs the office of a Glandule. Though I have with a Glass discerned several minute Blood-Vessels belonging to a single Bag; yet I cannot say I have been able to observe, that every Vesicle has a Blood-Vessel, neither do I think it has. For there being a communication between the Vesicles by Pores, as I shall afterwards show, there may be a supply of the medullary Oil to fill those, which have not Blood Vessels of their own in order to supply such oily parts, and do not separate them themselves.  
As for the Veins, they run from the termination of the Arteries, some all along within the Marrow to the Foramen, through which the Artery enters, and fall into one large Channel, which passes through the same Foramen, others tend to the superficies of the Marrow, whereof some, which are minute, I have observed to pass immediately through the Membrane, and to penetrate into the side of the Bone, which we must suppose to discharge themselves either into some Vein of the Periosteum, if they proceed so far, or into some of them, which are in the substance of the Bone, and belong to the nutritious Arteries; others run upon the superficies of the Marrow, between that, and the Membrane, which fall at last into that larger Vessel, which passes out by the Foramen of the Artery. Where there are two, or more conspicuous passages it is probable that sometimes the Vein may pass singly through one, and the Artery through the other, though I have not yet observed it to be so.  
The Secretory Organs are small vesiculous Glandules, which I take to be likewise containing parts, and continually kept full by the Oil, which they themselves separate, which before I give an account of, I shall take notice of a common containing part investing the whole Medulla. The oily therefore, the vesiculous, and vascular parts of the Marrow are all contained in one common, most thin, and tender Membrane, transparent as Glass, which invests that part, which lies in the bony Cells, as well as that, which fills the larger Cavities. The origine of this Membrane is certainly from the Blood-Vessels. For here we have nothing else, no other Membrane, no Nerves, no tendinous, or muscular Fibres, from whence we can suppose it to be derived. Neither do I think it is from all the Blood-Vessels, but only from the Arteries, nor from all the Coats of an Artery, but from the exterior only, that it is an expansion, and an elongation of the Fibres of this Coat. It is so thin, that it does not seem to be made of the Fibres of more, neither have I been able to observe that it is divisible like the several Coats of an Artery, or that it has the least resemblance to any other, than that I mentioned, but it is plainly a Reticulum, or fine Ner like the Texture of that. It seems in many places to be read, as if it had a great number of Blood-Vessels, but this is not occasioned by Vessels, or Blood of its own, but some of the medullary Veins running upon the superficies of the Marrow, which lies under it, by reason of its transparency make it seem to retain that colour, which it only transmits. I do confess I have not been always able, when I have endeavoured it, to separate the Membrane from the Vessels, which communicated that colour to it. For especially where the Marrow is soft, they will rise with the Membrane, when it is separated from the Medulla, and it is no wonder when it is propagated from some of the Blood-Vessels, so that there is a connexion, and the implication of these with others, will make them rise together; and it is so tender, that it is almost impossible to divide them afterwards. But I have so often separated them in that part of the Marrow, which has been more indurated, and afterwards viewed the Vessels upon the superficies of the Marrow, as to be certain that they are not a part of the Membrane, but only subjacent, and so give it their own colour, as any Opace Body will do to that, which is diaphanous, when it lies behind it.  
This Membrane adheres to the Bone, not only by those small Veins, which are continued from one into the other, but likewise by insinuating itself into the transverse Pores of the first internal Lamell, and that as I suppose, for the better passage of the medullary Oil through one into the other. This is certain, that it has Pores, by which the Oil flows through it into the Bone itself, which it is reasonable to think are formed in those parts of the Membrane, which lye into the Pores of the first Plate, by which one does more conveniently, and certainly receive it from the other. Neither can it seem strange that the Oil should have its egress, after it is separated by the Glands, through Pores formed in this Membrane, when we consider that it is not an unparalleled case, but the Sweat after it is separated by the cutaneous Glands passes through the Cuticula by such Pores. By the elevation, or protrusion of this Membrane in several places to insinuate itself some little way into the transverse Pores on the inside of the Bone are formed little round protuberances, which render the surface of the Marrow unequal.  
The medullary Oil, which is contained in this Membrane, does not lye all confused, and indistinguished in that space, which the common Membrane circumscribes, but there are Divisions, and Subdivisions, in the Membrane are immediately contained membranaceous Bags, and in these Bags are Vesiculae or little Bladders: both which I have observed where the Marrow has been soft, and the Oil continued liquid after it was could. And when I came to inquire into that part of the Medulla, which was indurated, I found by examining of it when it was made hot, and liquid, that the structure of the containing parts was exactly the same, only I could not distinguish the tender Bags so well.  
The Bags, or Lobules made up of several Vesiculae are not all of the same Figure, nor of the same capacity, even in a large Mass of Marrow, and for those which fill the small Cavities, it is plain they are variously figurated, and different in their extension, as the Cavities themselves are so, and in some of the simplo Caverns, which are very small, that which fills them hardly deserves the name of a Bag, for in some there cannot be more than two or three Vesiculae, and in some I cannot tell how to think there is more than a single Vesicle.  
The Vesiculae are small glandular Bladders designed for the separation of the medullary Oil from the Mass of Blood, and for the reception of it. These are as far as I can observe all of the same figure, being round, neither do they differ in their capacity. In that part of the Marrow where the Oil is fluid, and clear they are to look to, very much like the vesiculous substance of the Lungs, when they are blown up, but that the Vesiculae are not so large. In a small piece of the Medulla, where the Oil is indurated, they represent, when they are viewed with a magnifying Glass, a cluster of small Pearl sticking one to another. In a human Bone, which I had preserved till the Oil was wholly evaporated, I found these Vesiculae remaining dry but entire, and their substance representing in a manner a Sponge. The medullary Oil being contained in several small Vesicles, from hence it comes to pass that if any one of the Bags be opened, it does not presently empty itself, the medullary Oil does not all gush out together, but Stills forth in such small quantities, that it is some time before it flows all out, nay if the Bag be gently prest, so as not to break the Vesiculae, it empties itself but gradually, and that because after the Membrane of the larger Bag is broken, the medullary Oil is still contained within the Vesiculae, out of which, whilst they are entire, but such a quantity of it flows forth at a time, as their Pores will permit to pass through them.  
They seem to have Pores or immediate passages out of one into another,( and so do the Bags) by which the Oil has a free course to the joints, and substance of the Bone, for whose benefit it was designed, even from the middle part of that Mass, which fills the large Cavities, and lies at some distance from the side of the Bone as well as from the lesser Cells; and therefore in melting of a large piece of the hardest Marrow over the Fire, the Oil will by degrees all drop away, and leave the Bags, and Vesiculae empty, which shows some passages from the internal part to the superficies. And if we consider the distance of the Bags, and Vesiculae in the Centre of the Marrow in the large Bones, as suppose in that of the Thigh, from the substance of the Bone, and the Articulations, which it is to be supplied to, we must conclude that that there is some contrivance for the conveyance of it to those parts, otherwise all the medullary Oil, besides that, which is contained in those Vesiculae, which lye next the common Membrane, would be of no use to those parts, for whose benefit it is intended. It being certain therefore that there is a motion, and passage of the Oil in the Medulla from one part to another, this must be either by proper Ducts designed for this end, or else by Pores formed in the Vesicles, by which the Oil flows immediately out of one into another, and so successively, till it arrives either at the joint, or the substance of the Bone. By the strictest inquiries I have made I could never discover any thing like Ducts, neither have I indeed been able to observe the Pores, by which I make the medullary Oil to have its passage. So that thus far one may seem as probable as the other. But I say no. For if there were any Ducts leading from the several Glandules, we should have them, as in other Glands, meet in larger Channels, which would be visible, but the Pores are every where very small, and there is no reason they should be larger in one place than in another, so as to offer themselves to our sight. Besides, let us consider, that the Oil is not carried from the Vesicles, or Glandules to one large Receptacle, which would require the convenience of Ducts to convey it thither, but flows out of the superficies of the Marrow in as many places as there are transverse Pores in the internal Lamell. So that we must suppose these Ducts not only to be almost innumerable in their first rise from the Glandules, but even in their termination, which it is hard to conceive, as it is unnecessary, and is not agreeable to the wise methods of Providence, when there may be a more easy, and simplo way for the conveyance of the medullary Oil, as the Vesicles in every Bag, and the Bags in the common Membrane do lye contiguous to one another, which affords the convenience of forming such immediate passages out of one into another, as I have supposed.  
The Bags, and glandular Vesicles are without doubt propagated from the Blood-Vessels, since as I said of the common Membrane, there are no other parts within the Cavities, from whence they can be derived, and they seem to be not only particularly from the Arteries, but from their exterior Coat. Their membranous substance is in the same manner like the common Membrane, transparent, and their texture seems to be every way the same. So that I conceive that the exterior Coat of the Artery expanded, and conveniently modified makes the Vesicles, and being afterwards farther expanded, it produces the Bags, and from the expansion of it beyond all these arises the Membrane, which includes the whole.  
Besides the pressure of the medullary Oil, which is continually supplied, upon that, which was before separated, and deposited in the Vesicles, to drive it on towards the substance of the Bones, and towards the joints in some of them, we have some reason to think, that when the Vesiculae, and the larger Bags are filled to a convenient distension, they contract themselves, as the Fibres of the Bladder, and such membranous Cavities evidently do upon the same occasion, whereby being like a Sponge compressed, the Oil is squeezed and forced out of one Vesicle, and out of one Bag into another successively, whereby that part, which is contained in the Vesicles, that lye next the Membrane, is driven through it, and into the transverse Pores of the first internal Plate, and that, which was more remote, is carried on towards it, and supplies the place of what is removed. And how it is dispensed after it comes into the substance of the Bone I have already shown, when I gave an account of two sorts of Pores formed in, and between the Plates.  
But I have one thing here to give an accout of, and that is the passage of the medullary Oil to the joints. The manner, in which it passes, whilst it is within the Bags, and Vesicles I have explained, but what contrivance there is for its exit out of the Bone, and its flowing into the Interstices of the joints I am now to consider, as it is evident, that it has a passage into them. For if any joint be preserved entire till all the mucilage is wasted, there is to be found even in the Fingers, where I have not been yet able to discover any large passages, for a long time after an Oil transuded and sticking to the ends of the Bones, which is supplied from their Cavities after a Man is dead, where even Death itself leaves a stock to maintain the current of it into the joints, whereas the separation, and supply of the Mucilage ceases as soon as the Circulation of the Blood is stopped, and that, which is left in the joint is quickly evaporated, or some other way disappears. For this end there are Pores or passages formed both at the extremity of the Bone, and in the Sinuses of it, which are on one side. Those, which are at the very end, which seems cartilaginous, are very small, but numerous, which in most Bones it is very difficult to discover; but I have a Bone of a Horse, where they are very plain. And here I take the passage of the medullary Oil to be in the same manner as where the Plates lye contiguous in the sides of the Bone, by transverse, and longitudinal Pores. Some of the passages in some Sinuses are very conspicuous, particularly in the Cavity on the hinder part of the as Femoris, at the Ham there is one, which I opened, and traced for some way up into the cavernous part of the Bone, and in the large Cavity on the hinder part of the Trochlea of the Shoulder-bone there are in most Skeletons several, sometimes six or seven, one whereof is larger than all the rest, and I did particularly examine one, that was considerable, first with a Bristle, whereby I found there was a clear passage down a great way into the Bone, which when I opened, appeared to be a bony dust, that ran for some way into the cavernous part, which besides what it had at its termination, had on every side several Pores, by which it opened into so many of the Caverns. And in the same Cavity in the as Humeri of a Horse I have found eight or nine of these passages pretty large, with several others, which were visible to the naked Eye. Now by these Pores the medullary Oil separated in the Cavities flows into the dust, and by that into the Interstice of the joint. The passage of this dust, where it opens into the joint, is in some Animals very large, in a Calf where it was single, I observed it to be larger than that, through which the medullary Vessels passed into the Cavity. And in fatted Beasts, so without doubt in some Men, who are very Corpulent, there lies often over it something like a Fat glad fixed as it were by a Root into this passage, which at first I was apt to think was indeed such a glad, till I came to make a stricter enquiry, and found from whence that Fat was supplied. For as the adipose Glands between the Muscles, so the Vesicles of the Marrow may often supply a greater quantity of Oil, than is expended, and where the Animal is fatted, and little exercised in motion, as those, which are designed for slaughter, are excused from Labour, there is more supplied, and less made use of than in some others, so that it is not strange to find some of it sticking, upon the Bone, and a superfluity of it even in the joint.  
I shall not here stay to give any account of the nature of that matter, which is contained in the Bags, and Vesicles, which I have described, when every one knows it to be an Oil: nor is it necessary I should say any thing concerning the manner how it is separated, since what I have said of glandular Secretion in general, is sufficient to explain it.  
There is one thing or two, which I shall take notice of, before I proceed to speak of the uses of the medullary Oil; the first is the difference there is between the colour of that part of the Marrow, which is in the large Cavities, and that which is in the bony Cells especially in some Animals, the one being where it is indurated of a whitish colour mixed with a read; the other plainly read. This diversity in their colour proceeds from a difference in the number of their Blood-Vessels. For in that part of the Marrow, which is lodged in the large Cavities I do suppose, that every Vesicle has not an Artery to convey the Blood, which supplies the oily Particles, to it, nor a Vein to carry it back, but there are some, which by Pores have that Oil, that fills them, supplied from other Vesicles, that serve for the separation of it, but those Vesicles, which are in the smaller Cells, have every one of them their Blood-Vessels for this end, which makes them proportionably more numerous, and that part consequently more read. The second thing is the different consistence of several parts of the Marrow, when they are could. In the large Cavities of some Bones, we shall have some, which after it is could is indurated, and of the nature of a sure, some of it remaining liquid, even in the same Cavity. Now Oil in its proper and natural consistence is liquid as well when it is could as hot: So that that part of the medullary Oil, which remains so, shows itself to be more pure, and unmixed; the other, which is congealed, has the addition of something to it, which alters its consistence, and what parts these are we can learn from nothing better than an experiment, in which such a change is effected in common Oil; and this I have borrowed from the most ingenious Dr. Grew, who in his Discourse of the power of Mixture tells us how the Fat of an Animal Body may be imitated: Which, says he, may be made thus, Take Oil Olive, and pour it upon high Spirit of Nitre, then digest them for some days. By degrees the Oil becomes of the colour of Marrow, and at last is congealed or hardened into a white Fat, or Butter, which dissolveth only by the Fire, as that of Animals. In converting Oil thus into Fat, it is to be noted that it hardens most upon the exhalation of some of the more Sulphureous parts of the Spirit of Nitre.— Hence the true congealing Principle is a Spirit of Nitre.  
— And The making of Fat is but the durable congelation of Oil.  
Hence also it appears that Animal Fat itself is but the curdling of the Oily parts of the Blood; either by some of its own Saline parts, or by the Nitrous parts of the Air mingled therewith.  
The reason therefore of the difference in the consistence of some parts of the Marrow, and of the congelation of that, which is found indurated, when it is could, is the mixture, and combination of the Nitrous parts of the Air with it, fixing the Particles of it; which do it so effectually, that if any of the indurated Marrow be distilled per se, it will after it is brought over, and could, return to its former consistence. Though afterward, by setting of it long in the Sun, I brought some of it to the nature of a true Oil, which remained liquid when it was could.  

Of the USES of the MARROW.  
I Shall in the next place give some account of the uses of the Marrow: the uses of it I say, because it serves for more than one, though that can be none of them, which Authors seem to ascribe to it, when they make the medullary substance, which lies between the two Tables of the Skull to serve for the Nourishment of it. For besides that the Bones have evidently Blood-Vessels designed for their Accretion, which properly belong to their substance, and are no ways concerned with the Marrow; to any one that considers the nature of the Medulla, that it is an Oil, it will plainly appear, how uncapable it is of being converted into so solid a substance as that of a Bone. Yet if they will suppose Nutrition to be only a supply of Volatile, and Fluid Matter to maintain the fullness, and to preserve the Tone, and temperament of the containing parts, the medullary Oil may be said to be concerned in their Nutrition, as it is continually supplied to repair the loss of that Oil, which is expended.  
The use of it is in the first place general, and common to all the Bones, and to the whole of every one of them, and secondly more particular to some parts of some of them. It oils the whole substance of every Bone, and by its unctuosity preserves them in a due temperament. Their parts are naturally dry in themselves, and when they obtain too great a degree of siccity they are more fragil, and apt to be broken by any violence, and not only so, but we find how soon the thin part of the Scapula, where there is no Medulla, will without any violence crack, merely by its own dryness, when it is exposed to the Air▪ So that it was necessary for their security against Fissures, and Fractures, that they should be defended by such a Matter, as may help to retund the violence of those accidents, which are apt to injure them, and so mollify their parts as to make them capable of yielding a little to those pressures, and that force, which would otherwise be more easily, more inevitably, and more sensibly injurious.  
Besides this general use of the Marrow, the service of it is more particular to the extremities of those Bones, which are articulated. First, for their lubrication, to fit them for the great, and necessary business of Motion, to preserve them always in a condition fit for it, and to make them more ready to alter their Position, when there is occasion. It is true the ends of these Bones, which are articulated are very smooth, but yet if they were dry, they would not with that readiness and facility obey the commands of those Muscles, which move them. Wherefore Nature has taken care to lubricate them with a slippery Oil, to which, when it flows into the joint, is added a mucilaginous liquour separated by peculiar Glands seated in the articulations, and from the mixture of these two, an Oil, and a Mucilage, is made a composition so fit for this design, that nothing taken from the vast stock of Nature seems comparable to it, as I shall show, when I come to speak of the Glands, which separate the Mucilage.  
Secondly, The medullary Oil in conjunction with a Mucilage preserves the ends of the Bones, which are articulated, from an Incalescence, from contracting an inordinate heat by their Motions, which would otherwise be the effect of them, especially when they are very quick, and violent, and long continued. It is impossible that two Bodies so solid as the Bones in some parts are, and the extremities of those, which are articulated, would be without the benefit of such a Matter, as both mollisies them, and intervenes so as to keep them from an immediate contact, should be violently moved, and rubbed one against another without creating a great heat. This every Coach-man, every Car-man is sensible of, and therefore they have their Oil, and Mucilage, a Composition, in which they imitate this of Nature, that is a mixture of Grease, and Tar, with which they besemar the inside of the Naves of their Wheels, and the extremities of the Axis, upon which they move, without the benefit of which the 〈◇〉 Rotation of one about the other produces a heat, and that sometimes so intense as to let them on fire. And if there had not been a provision in the joints against such a preternatural Incalescence upon their violent Motion, this would have made a slothful World, and have confined us to slow, and deliberate movements, even when there were the most urgent, and hasty occasions to quicken us.  
Thirdly, It was farther necessary that the Bones should be oiled, and moistened with something of this nature in their joints to prevent their Attrition, or wearing by rubbing one upon another. For without it we cannot but be sensible, and certain of this, that two Bodies of the nature, which the Bones are of, being frequently, and as some of them often are, violently moved one upon another, must inevitably be mutually injurious, and some of the parts must be worn off on both sides. So that the contrivance of Nature to adapt one Bone to another in all the articulations, to fit them for an easy motion and that variation of their position, which is requisite in every joint, how admirable soever it might seem at first, would not be long useful, but the stirring part of Mankind would soon find themselves fitter for an Hospital, than for Action, and the pursuit of Business.  
Thus it appears how beneficial, and absolutely necessary the medullary Oil is to the Bones, but the use of it extends itself beyond these parts first to the Ligaments, which tie them, that are articulated, together, these it preserves from dryness, and rigidity, it keeps them pliable, and ready to comform to all the motions and postures of that movable part, to which they appertain. Were they not thus oiled, we may easily be sensible how different their temper would be from what it now is, from the rigidity, which they contract, when they are laid in the Sun, and dried. And why may we not also suppose, that it is as useful, and for the same reason necessary to these parts, as Oil to Fiddle strings, which the Musicians make use of to preserve them from that aptitude to break, which otherways they will have, when they are much extended. So to secure these Ligaments from a disruption, which as strong as they seem to be, they would be in danger of upon a great, and sudden stretch, or contortion, if they were dry, they are oiled and moistened with this mixture of the medullary Oil, and the Mucilage.  
And as it preserves the temperament of the Ligaments as well as that of the Bones, so it serves likewise for their lubrication. Some of them are fastened to the Bone at some little distance from the extreme part of it, that they are distinct, and separate from some part of the side of it, which they lye upon, so that in all the motions of the joint they not only are inflected or extended, but they slide backward, and forward upon the Bone. Now being contiguous to it, and slipping upon it, there does appear a reason for, and a necessity of something, which may lubricate them, which might make their motion upon that part of the Bone, where they slide, more ready, and facile. And from the supposition of a defect of that, which should make them slippery, we may account for the cracking of the joints, which is frequently to be observed in some Scorbutical Persons, where I do think that the Ligaments more than the Bones are to be accused. For if they are not sufficiently lubricated, they will not be so ready to slip that way, which the motion of the joint commands them, and whem they do not slide proportionably, and by a continued motion answer to that variation, which is made in the position of the part, they must needs, if they make any stop, when the joint persists in its motion, be extraordinarily extended, which seems to be the occasion of that pain, which is then often felt, and is one thing that makes me think, that the Ligaments have some sense. But being uncapable of such an extension, as will without their motion give the part the liberty of being extended, or inflected to that degree, to which the Muscles by their contraction oblige them to move,( which would be inconsistent with the due conjunction of the Bones) when they can give way no farther by their extension, they are forced at last to slip, and that with such a quickness, as makes the ends of the Bones strike one against the other with a sudden violence, which impresses such a motion upon the Sonorifick Particles of the Air, as affects our sense of hearing. Although it is probable that there may be another reason for this cracking of the Bones sometimes, and a different affection of the Ligaments to occasion it, that is too great, and a preternatural laxness in them, whereby being more capable of an extension, they do not tie the Bones so close, and strictly together, as to keep down the process or end of one firmly into the Sinus or Cavity of the other, though the relaxation be not near so considerable as to dispose the Bone to any thing like a Luxation. Now supposing one to rise from the bottom of the Sinus in the other, in the motion of the joint the end of one Bone may be pitched against some lateral part of the Cavity, and move upon that as its Axis, and every little irregularity in the position of it, makes it uncapable of moving so as at the other extremity to describe so much of a circled as the contraction of the Muscles will oblige it to do, without a restitution to its natural place, which not being done without some force, it falls down with a violence, and velocity into the bottom of the Sinus of the other Bone, where they strike one against the other in such a manner, as to make a sound.  
The medullary Oil seems to be serviceable to some other parts, besides those, for whose benefit it is evidently employed, and where I have shown the uses of it, and I cannot but think, that it is communicated from the Bones, in which it is deposited, to those Cartilages, which are joined to them, and that for some necessary end. Besides that the Bones are there softer, than where the Plates are contiguous in their sides, and there is nothing intervenes to prevent the passage of this Oil out of one into the other, there are Pores both in that end of the one and of the other, where they are joined together, which allow the passage of it, and seem designed for this purpose. And I have, when they have been relaxed with the heat of the Fire, observed on Oil, which had insinuated itself, and stuck to the end both of the Bone, and of the cartilege. These parts it preserves from growing dry, and maintains their flexibility, and how necessary it is, that they should be moistened with something of this nature, appears from the hardness, and rigidity, which follow upon their being dried.    

The FOURTH DISCOURSE OF THE Mucilaginous Glands.  
I Proceed in the next place to give an account of a particular sort of Glands seated in the joints, which, whilst I was making some observations of the several parts, which belong to and make an articulation, I came to take notice of, which separate a mucilaginous kind of liquour, and are no where described, nor have ever, that I know of, been observed by any one, only some time after I had made my Observations of them, I met at Surgeons Hall with an indefatigable, and curious Anatomist, one Mr. Cooper, an ingenious Surgeon of this Town, who had taken particular notice of the larger sort of these Glands.  
After I had considered the nature of that liquour, which presents itself to our Observation in the Interstices of the joints, which I always found to be mucilaginous. I began to think with myself, that as it was vastly different in its Nature from the Marrow or an Oil per se, though it might have the accession of an Oil, it could not be all supplied from the Cavities of the Bones, but must have some distinct and peculiar parts to separate, and supply it, which gave me the first occasion of inquiring, whether there were no Secretory Organs particularly designed for the separation of it, and upon a strict examination of the Interstice, and the Membrane, which does immediately cover the Articulation, I first found in the Sinuses of the Bones within the joint some soft parts, which to the touch seemed Vesicular, and spongeous, and observed, that the Membrane not only was lax, but also unequal with protuberances of a different Figure and Magnitude. As it was loose and easily extended, where the Ligaments would not suffer the ends of the Bones to recede from each other, it was evident that it was not inservient to their Conjunction, nor was this use of it consistent with an Articulation. For did the Membrane, which lies round the joint tie the Bones together, this must have fixed the part, which is to be moved, on every side, and have made it uncapable of a flexure, or any natural alteration of its position. The inequalities I observed presently gave me the surpicion of Glands, and when I came to make a farther enquiry, I found that the Membrane was truly glandulous, and that those soft Bodies, which were in any of the Sinuses, were Glands, and besides the reason I had from the observation of them to think, that the Mucilage was separated by them, I was fully convinced of the truth of this, when I expressed some of it out of them.  
Now because they have not been taken notice of, nor obtained any name, and I shall have frequent occasion to mention them, it will be convenient to impose upon them one, which may be proper, and distinguishing, and the parts, in which these are seated, and to which they are serviceable, suggest such a denomination as Glandulae Articulares, but because I have observed the same sort of Glands in some other parts, to wit between the Muscles, and about the Tendons, and there are Glands seated in the Throat, which separate a mucilage for the lubrication of our Food, and to make the descent of it into the Stomach more quick, and facile, I shall give them a more comprehensive name, such as Glandulae Mucilaginosae, or the mucilaginous Glands. In Treating of which I shall first give some description of them, and an account of the Structure, and particular situation of those, which are most considerable. Secondly, I shall consider the nature, and design of the liquour, which they separate, and show how so great a quantity of it, as is necessary for the use of so many parts, as it is employed in, is continually generated. Thirdly, I shall give an account of some Experiments I made with it, and of a Distemper or two, which owe their Original very much to the Mucilaginous Glands.  
These Glands are of two sorts Some are small and numerous in every joint, which are set thick all over the Membrane excepting where there are any large Glands, and they are all of an equal magnitude, so as to render it every where glandulous, which is not extraordinary in a Membrane, when we have Tunicles, which are evidently so, and the sagacious Malpighi has discovered to us, that the Tunica Vaginalis of the Testes, the Membrane or Capsula of the Heart, the Peritonaeum, and Pleura are all so. But in some parts of the Membrane, and in the Sinuses of the Bones in the joints these Glandules are so Conglomerated as to form remarkable Glands, and these I am now to describe. In some of the large joints there is only one, as in the Acetabulum or the Thigh-bone, which is a very considerable one. In some, as in the Knee there are four, or five. They have something of a transparency, when they are not discoloured with Blood-Vessels. This they have from their Basis for some way up towards their other extremity in Horses, and such large Animals, where they rise any considerable height above the superficies of the Membrane, but near to the upper part, and so to the very end they receive a read colour from their numerous Blood Vessels. But in Men they are generally every where of a read colour, which is more intense about their termination. They are soft, and pappy, but not tender and friable like the glandulous substance of the Liver, and some other Glands of the Body, so that they are not easily broken by a compression, against which injury it was necessary in their Nature to fortify, and secure them, because they are seated amongst such parts as are obdurate, and press upon them in their motion, though it be so lightly as not plainly to compress them. Neither are the parts of these Glands very easily pulled asunder, and perhaps the mucilaginous quality of the humour, which they separate, may both make their parts flexible, and give them a disposition to adhere to one another, all which opposes their friability. As for their Stucture I had a very good opportunity to inquire into it in some of them, which I took out of the joints of a Horse, that were Hydropical, and filled with a preternatural humour, which distended their Glandules, and made them appear very fair with the help of a Microscope, one whereof was as large as a Man's Hand. They are, as I have said before, Conglomerate, though they do not consist of several Lobules, or Bags of lesser Glandules, as some other Glands do, but of several Membranes superstrated one over another, set thick with small round Bladders, which not only lye contiguous, but tenaciously adhere one to another, as the several Membranes likewise do. And by examining the Mucilaginous glad in the Acetabulum of the Coxendix of a Man, after it was dried, I found,( though I did not question it before) that the Structure of these Glands is the same in Men as in Beasts; for I could discern several distinct Membranes, and divide them, which were six or seven in number. So that though the Glandules are here conformed to those of the Marrow, the Lungs, and of some other Glands so far, as to be of the nature of Vesicles; yet the order, in which they are disposed, is very different. By the Pores of these little Bladders the mucilaginous liquour, is percolated and distinguished from the rest of the Mass of Blood, which is conveyed to them by the Arteries, and from them it flows into the Interstices of the joints by the Excretory passages, which all these Glands have. Blood-Vessels they have a sufficient number of, which, as I observed before, towards the Apex, or termination of them are more numerous, and make them look of a redder colour, than at their Basis. Their Veins have not a direct course, but proceed obliquely with windings, and it is a pleasant sight to see the Anastomoses of several of these small Vessels and their various flexures as they run along in the glad. There seems to be a particular reason for the obliquity of the Veins in these Glands, from the nature of the liquour, which they secern: For the liquour, which these Glands separate, obtaining a mucilaginous quality, the Particles of it do not seem to pass through the glandular Pores with any great expedition, and therefore these Vessels are formed with such windings, that the return of the Blood by them may be somewhat retarded, and the Particles, which are to be separated, may have more time to penetrate the Pores of the Glandules. The figure of the mucilaginous Glands is various, and accommodated to the Sinus, or Cavity, in which they are seated. Some are not only long but broad at their Basis, and grow narrow towards the top so as to terminate in an edge; some have a broad Basis, and rise into a sort of a Cone; some are like little Ridges, some like a Fimbria, some are broad, and pretty flat.  
As for their situation, they are differently seated in the several joints; in some they stand over against the very Interstice of the Bones, and run in a little way between them, where the ends of the Bones towards that side are not contiguous, but so formed as in their Conjunction to make an Interstice, and these are commonly in the manner of a Fimbria; some are seated in some Sinus or Cavity, others planted upon the Membrane, which immediately covers the Articulation. In general they are so seated, that they cannot be injured by a compression from the Bones, and yet there is this contrivance, that the Bone does either in the inflection, or extension of the joint lightly press upon them, so as to promote the Excretion of the Humour, which they separate, into the joints, when they are moved and stand most in need of it. And by this means it seems to be most plentifully supplied, when there is occasion for the greatest quantity of it, and to be proportionated to the present exigence, according to the quiescence, or several degrees of Motion in the part, when it is moved. And it is no small security to these Glands against the obstructions, which the mucilaginous quality of the liquour, that they separate, does naturally dispose them to, that they are solicitated, and the liquour expressed out of them by the motion of the parts, where they are seated.  
But I shall give a more particular account of the situation of the large, and considerable mucilaginous Glands in the several Articulations. I begin with that of the as Occipitis and the Atlas, where there are some of these Glands planted round the Tooth-like process of the Epistropheus the second Vertebre of the Neck, and one on each side. In both the Articulations of the Ribs with the Vertebres they are likewise to be found, but the largest is in the lower Articulation, and on that side, which is next the Cavity of the Thorax. These are but small Glands absolutely, though they are of the larger sort, that is, they are formed of several Glandules conglomerated, and lying one upon another in several Membranes, and so to be distinguished from those that are but single Glandules, which only stand one by another in the Membrane of the joints, and make no conspicuous inequalities in it. In the joint of the Shoulder there is a considerable one joining to the upper brim of the Acetabulum of the Scapula just by the tendinous Origination of the Musculus Biceps on the foreside of it, which runs downward upon the Membrane for some way towards the Arm-pit. And on the other side of that Origination there is another at a little distance from it. In the Cubit there is one glad seated in the Cavity, which is on the hinder part of the Trochlea of the as Humeri, and another large and fair one, in one of those Sinuses, which are on the foreside of the same Trochlea, which I have given a figure of Fig. I. Tab. II. And upon the Radius, and Ulna there are some of them, which lye like a Ridge. At the Articulation of the Bones of the Cubit and the Wrist there are a row of these Glands, or one of them lying like a Ridge of little Hills from one side to the other on the back part. On the inside there are some, but not so considerable. At the Bones of the Carpus there are some, which are like a Fimbria. The Acetabulum of the Coxendix has one of the largest of this sort of Glands in the whole Body. Where, because the Cavity is deep, and the Supercilium, which goes round the brims of it, runs so far over the head of the Thigh-bone, and lies so close to it, that the Mucilage could not have plentifully insinuated itself into the Cavity, nor readily have been diffused for the Lubrication of the head of the Bone, which is received into it, if the glad had been seated, and the Mucilage separated out of that Cavity; therefore the glad, which supplies it to this joint, is placed within it, and lies between the extremity of the head of the as Femoris, and the Coxendix. But as this was necessary, so on the other hand there was a difficulty, and an inconvenience, which without the Providence of Nature, would have attended this situation of it: For if the Cavity had been every where fitted to the head of the Thigh-bone, which it receives, without a particular regard to this glad, and the glad had been placed within it, as now it is, it would necessary especially in a standing posture have been compressed to the destruction of the tone of its Glandules, and so have been rendered uncapable of performing its Office; therefore there is a Sinus or Cavity at the bottom of the Acetabulum formed on purpose to receive, and secure it beyond the injurious pressure of the Thigh-bone. This Cavity is in a human Skeleton almost of an Oval figure which I have found an Inch and five eighths in length, and in the widest place very near one Inch one eighth in breadth, and about three eighths of an Inch deep, occupying at one end, and on both sides only the bottom of the Acetabulum, but at the other end it runs up by the Ligament, which is insterted into the tip of the head of the as Femoris to the brim of the Cavity. In the Knee there are of these Glands both before, and behind, above the Rotula there is one, and at the bottom of it another, which is a very considerable one, and on one side another, that is less, all which I have given a figure of Fig. II. Tab. II. where A, A, A, A, are the fore part of the Knee taken off with the Patella, and the inside turned up, and laid in view: a, a, a, are the large mucilaginous Glands: b, b, b, b, the Membrane which immediately covers the Interstice of the joint, and c, is the Patella. As for the Glands of the Fingers and Toes they are seated on the inside, or bending part, where they are like a Fimbria, and in every joint there are two of these glandulous Fimbriae, one belongs to the remotest or that which is the moving Bone, when the posture of that joint is altered, and is seated just at the edge of its extremity; the other is planted upon the Bone, with which the other is articulated at a little distance from the extreme part of it, up in a Sinus, formed as well for the reception of that glad, as to give the other Bone, when it moves that way, the liberty of sliding towards it, and of being inflected, at which time it makes some little pressure upon it. And now let any one consider the situation of all these Glands, and he will be sensible, how they are seated, as I said, so as to be lightly prest, either when the Bone is extended, or inflected, to promote the Evacuation of the Mucilage out of them into the Interstice of the joint.  
And here I cannot but take notice, that I have observed the same sort of Glandules in the Membrana communis Musculorum, as those, which occupy the Membrane, that lies over the joints in all that part, which has none of the large Glands; and amongst many of the Tendons, there are several of the larger Glands, or the lesser Glandules conglomerated into the form of Glands. So that I dare be positive in this assertion, that the common Membrane of the Muscles is every where glandulous. For in that Subject, where I had some hydropical mucilaginous Glands, I found several parts of the Membrane of the Muscles in the same manner hydropical, where it not only upon an ordinary view appeared like the hydropical mucilaginous Glands, which I took out of the joints of the same Subject; but when I came more strictly to examine the Structure of it with the help of Glasses, which the fullness, and distension of the Glands gave me a fair opportunity of doing, I found, that as it had small Vesicles or Glandules, so were they exactly like those of the mucilaginous Glands of the joints; there was only this difference, that the Glands consisted of more Membranes.  
From the observation of these Glandules, and that hydropical fullness, and swelling of them, which I met withal, I cannot but conclude, that when we have a dropsy about the carnous parts the common Membrane does sometimes contribute to it, and that there is now and then a particular dropsy between the Muscles, where the water is supplied by these Glands only, part of which flows out of them into the Interstices, and part is retained in the Vesicles, which distends them in an extraordinary manner, and by making a great, and preternatural addition to the thickness of the Membrane, produces a sensible swelling in the part.  
The larger sort of these Glands about the Tendinous parts are very easy to be discovered, and remarkable in those Beasts, which are of a considerable magnitude, especially where there are any long Tendons, which slide backward, and forward in a Sinus upon the contraction and extension of their Muscles.  

Of the Nature and Use of the MUCILAGE.  
THE use of the Glands, which I have now described, in general is the same as that of all Glands, that is, they serve for the percolation, and separation of some Matter, and they do particularly supply a liquour, which is necessary for facilitating the actions of those parts, where they are seated.  
The liquour separated by them is a Mucilage, which is almost like the white of an Egg, though it is not always so clear, and limpid; yet when it is pure, it has the resemblance of it; in some Beasts I have observed it to have a yellowish colour, as if there were a portion of boil in it. It is evidently saltish to the taste, and consists of Aqueous, Saline, and Gummous, or such Terrestrial parts, as have no rugosities or inequalities, nor hamous extremities, so that they are apt to slip one upon another, but withal they have so much of an immediate contiguity, as makes them in some degree adhere, which gives them something of a Viscosity, or mucilaginous quality. The Salt, and Terrestrial parts I have found to be about a two and thirtieth part of the Composition, which is more than such a proportion as that must be of Gum arabic, or Tragacanth, which with fair water will make a Mucilage of the same consistence. The nature of the Mucilage seems to be very much like that of the serous part of the Blood, which shows itself distinct from the fibrous parts or Coagulum, after it has stood some time exposed to the Air, and several mixtures will produce the same effect, in both. And it is not strange, that one has so much of the nature of the other, when the Mucilage is supplied from the Blood, and is without doubt a part of the Serum. But yet that there is a difference appears in that the Serum is not so mucilaginous, and from some experiments, for the Serum of the Blood will be more remarkably coagulated with Spirit, and Oil of Vitriol, with Spirit of Salt, and Oil of Sulphur, and when they are held over the Fire in a Spoon the effect is very different, the Serum, as it is known, will in a manner turn wholly to a thick Jelly or Size, which is friable, insomuch that of a Dram I have had, after it had lost its fluidity, two Scruples, and sixteen Grains, and after it was thoroughly dried five Grains and a half, which is very near the eleventh part, whereas the Mucilage with the heat of the Fire turns for the greatest part into a liquour more tenuious, than it is itself naturally, and produces only a thin film upon the top with some little white Coagulum, and what remains after the aqueous parts are all perfectly evaporated is not a thirtieth part.  
The use of this Mucilage is principally to lubricate the joints, to render and preserve the ends of the articulated Bones so slippery, that the Animal may move, and manage those parts, as there shall be occasion with the greatest facility. This seems to be the great, but it is not the only thing, that lubricates the articulated extremities of any Bones. For besides the liquour, which is supplied by the mucilaginous Glands, which I am now speaking of, there is an oily substance transmitted from the Cavities of these Bones into the same Receptacles or Interstices by passages formed for this end, as I have shown in my Discourse of the Marrow. These two meeting in the joint are mixed together, especially upon the motion of the part. And certainly there is no liquour, nor any mixture can be thought of more proper for this end, than this is, where not only both the Ingredients are of a lubricating nature; but there is this advantage from the Composition, that they do mutually improve one another: for the Mucilage adds to the lubricity of the Oil, and the Oil preserves the Mucilage from inspissation, and contracting the consistence of a Jelly. And here we cannot avoid the notice of the visible footsteps of an infinite Reason, which as they are deeply impressed upon the Universe, so more especially upon the sensible parts of it in those rational contrivances, which are found in Animals, and we can never sufficiently admire the Wisdom, and Providence of our great Creator, who has given all the parts in these animated Beings not only such a Structure, as renders them fit for their necessary Motions and designed Functions, but withal the benefit and advantage of whatever may preserve them, or facilitate their Actions.  
There are some other ends, which this Mucilage is inservient to, as the preservation of the extremities of the articulated Bones from Attrition, and an incalescence, but because neither of them seems to be the first intention of Nature, in the Generation, and supply of this liquour, and I have taken occasion to speak of these uses, and how it serves to them in Conjunction with the medullary Oil in the preceding Discourse concerning the Medulla, I shall take no farther notice of them, than to mention them.  
As I have observed the mucilaginous Glands seated between the Muscles, and about the Tendons, and a liquour of that nature supplied to those parts by them, so it is not to be doubted but the design, and principal use of it is the same as in the joints, to wit, to lubricate them. And when we consider how the contraction of the Muscles not only obliges their Tendons to approach towards their Origination, but draws up some part of every fiber towards their beginning, so that they must necessary move or slide backward or forward upon the part, which lies contiguous to them,( which is the Membrana communis Musculorum) as they are contracted, or relaxed, and extended, we shall soon be sensible how necessary it is that the Muscles should be lubricated. And for some of the Tendons, which slip up and down in Sinuses, as those of the Musculi perforantes, which are inserted into the third or last joint of the four Fingers, and into the same joint of so many of the Toes, some of the flexors of the Leg, and some others, the Mucilage does appear as useful, and necessary to them, as in the joints, so that I need not go about to prove it.  
Allowing therefore this liquour, when it is supplied to the Muscles, and Tendons, to be employed in their Lubrication, as it is at the extremities of the Bones, which are articulated, it will be no unreasonable supposition to think, that there is the same kind of mixture in these parts, that there is the addition of an Oil to the Mucilage to preserve it from inspissation; since the nature of the liquour is the same in both, there is the same reason in one as in the other, and the matter of Fact does in a manner appear, when we find such vast numbers of adipose Glands, and such quantities of Fat between the Muscles in some Bodies, and in fatted Beasts there are some of the adipose Glands to be observed about the Tendons, which move in a Sinus. Though such a collection of Fat does not occur in all Bodies, yet that there are the same Glands in those, that are Lean, does not admit of any dispute, nor is it less certain, that they perform their Office and separate a Fat so long as there are oily parts in the Blood, which in the Circulation of it, will offer themselves to those Glands. And although the reason of leanness in some Men may be, because the quantity of Oil, which is separated by these Glands, is not so great as in those, that are obese, which seems to be the reason in old Men, in sickly persons, and in those, that feed high, and use but little exercise, yet are of a thin habit of Body: yet that which makes the variation between fat, and lean Bodies, is often a difference in the expense of this Oil. The design of which being to assist in the Lubrication of the Muscles, and Tendons, it follows, that it wust be more profusely expended, where their motions are frequently repeated, or long continued. Therefore there are many in the World, as those, whose Fortune condemns them to hard Labour, and have little Rest but the Repose of the Night, that cannot show such larded Muscles as some others can( as I do not know that ever I saw a Country Labourer Fat) who notwithstanding have better Appetites, enjoy such a perfect state of Health, and carry all the signs of the good Crasis of their Blood, that we have no reason to question, but the Mass of their Blood supplies that proportion of Fat, which would make them as Corpulent as some of their Neighbours, but that the laborious manner of their life makes them have some other occasion for it, and the motion of their Muscles is a way, by which it is continually expended, so that there is no overplus to be reserved in the adipose Cells. And how often do we find an alteration in the plight of these Men, when they can indulge their ease, and allow themselves in a more idle way of living? How evident is this in Horses, which, whilst they rest, and are well fed, grow Fat, but when they come to be rid, or to work hard long together, spend all that stock, and lose their Flesh, as it is termed, so as to be almost a shane to a Market? That there is a greater expense therefore of the Fat upon great motions, and exercise is plain, the question then will lye here, how this Oil is employed. Dr. Mayo supposes these sulphureous parts to be separated from the Mass of Blood by the Parenchyma of the Muscles, and by a congress with some Nitro-aereous Particles or the Spirits conveyed to them by the Nerves, mutually axagitating each other, and producing an effervescence to serve for the contraction of the muscular Fibres, and in case the Muscles are not frequently exercised, and contracted, so as to employ all those sulphureous, or as he makes them salino-sulphureous parts, in their motion, and so to destroy them, that then they are conveyed by peculiar Ducts from the interior part of the Muscle to convenient Receptacles, in which we afterwards find them collected in the form of Fat. And to strengthen the probability of this Hypothesis he urges this as an Argument that these parts are separated in the Parenchyma of the Muscle, that the Blood-Vessels, which are disseminated through the Body of a Muscle are never propagated so far, as the Fat, so that the parts, which constitute it, cannot be immediately supplied from them to those parts, in which we find it. But this Argument may be easily invalidated. For although it is true the Blood-Vessels in the Fat are not so numerous, as in some other parts, yet there are some, which are visible, and Glandules, which serve for the separation of those oily Particies. Besides, I have observed some adipose Glands about the Tendons at a great distance from the freshy Fibres. And we find in the Cavities of the Bones a substance of the same nature, where it certainly is neither separated by the Parenchyma of any Muscles, nor concurring with the Spirits in their contraction, but some part of it is asigned to the joints, where it meets with the Mucilage, which necessary requires something of this nature to preserve it from inspissation. Which if it be requisite for this end in the joints, is no less in any other part, where the Mucilage is employed. But if these sulphureous parts are expended, and destroyed in the contraction of the muscular Fibres, then must they be wanting to this liquour, when it is most plentifully supplied, and there is the greatest occasion for them upon the external part of the Muscle. So that I rather think, that the first intention of this Fat is to make such a Composition, as is fit to lubricate the parts, and all the uses of it are in Conjunction with the Mucilage.  
Besides the intention of Lubrication, the Mucilage with the addition of an Oil is farther necessary to the Muscles, and Tendons, to preserve them from shrinking, from growing dry, and rigid. Therefore in Rheumatisms, when the nature of it is altered, and it contracts such a viscosity, and thick consistence, as render it unfit to moisten these parts, we have a stiffness, and Stupor, which I shall take farther notice of, when I come to speak of that Distemper.   

Of the Generation of the MUCILAGE.  
HEre some may be so curious, and inquisitive as to ask me, how the Mucilage is continually generated, and how the sanguineous Mass comes to be capable of supplying such large quantities of it, as are necessary to lubricate so many parts, as it is constantly, though not always in the same measure supplied to. I answer, that the matter, of which it is made, is originally from our Food, and the Chyle, which is daily added to the Mass of Blood, as all other Juices are; but yet it is a great alteration, which those parts of which it is generated, do undergo, before they are reduced to the true nature of a Mucilage. The change therefore, which that part of Blood from which it is produced, undergoes in order thereunto, seems to be made by some glad, and there is none, that I can think of, which seems so fit, and likely to be concerned in this affair, as the Spleen, which I suppose to be the Officina, where Nature ptoduces, and elaborates the Mucilage, from whence it is administered to the Blood, and by that dispensed in its Circulation to all the parts, about which it is necessary it should be employed. This I have been thinking, that this large Viscus is designed for such an Office, that it is not absolutely necessary to the life of Animals, since we find not only, that the privation of it is consistent with Life, but that the Animal has seemed little concerned for the want of it. And this not only has been observed in Dogs, which are the ordinary Subjects of this experiment, but there are some, that tell us, if we may give credit to what they say, that it has been found wanting in some Men, and taken out of others, who have been restored to their Health by a happy Cure. Thus far this glad, and the use, which I assign to it, agree, since the Office, which I suppose it does perform, is not so requisite to the being, as the convenience, and well being of an Animal. For although the Mucilage did wholly depend upon the Function of this part, we may easily satisfy ourselves, how it comes to pass; that the Animal is no more injured by the want of it. For since the use, and design of it is to lubricate the parts, and there are no parts, about which it is employed, but have an Oil, that answers the same end supplied to them, the inconvenience, which we may suppose should follow upon the want of the one, is very much taken off by the other, which is likewise of a slippery and lubricating nature. Though I am apt to think if the Animal, after it is deprived of the Spleen, were put upon great, and frequent motions, there would appear a more sensible injury from the want of it, and because the Subjects, in which this Experiment is commonly made, have not been afterwards put upon stirring, but being fit for no farther use, or reserved only for dissection, have been allowed to lye at home, and to live a lazy, and soporose life, therefore they have had less occasion for the Mucilage, and so have seemed unconcerned for the want of that part, which supplies it. And, as I make this an Argument for my Hypothesis, that as the Spleen, so the Mucilage is not absolutely necessary to the conservation of life, so the quality of that matter or Juice, which is always found in the Parenchyma of the Spleen, does give us some reason to suspect, that it is designed for the generation of this mucilaginous liquour. For that it contains, and exhibits such a kind of Juice there is no Man, that has his Senses, and examines it, can deny. And why does it produce such a liquour, if not for the service, and benefit of those parts, which do stand in need of it, and are evidently supplied with a liquour of such a nature as the Juice, which is found in the Spleen is of? Besides, considering of how great, and public use the Mucilage is to most parts of the Body, it is not strange, that a Viscus should be formed, and designed particularly for the Generation, and Elaboration of it. Moreover from this supposition, as this glad has no common Receptacle to entertain, nor proper Ducts to convey the humour, which it separates, to other parts, we may easily see the reason, why it has neither; one was inconvenient, and the other in a manner impossible. It was not convenient, that this liquour should be carried into, and reserved in any Receptacle in or about the Spleen, because it stands at a great distance from most of the parts, to which the Mucilage is necessary, so that if it were deposited in any such large Cavity, it could not be immediately supplied upon any occasions, that are extraordinary, or sudden, as our motions oftentimes are. And for Ducts it seems next to an impossibility, that the Spleen should have so many, as would be necessary to convey the Mucilage to all those parts, which stand in need of it; whereas by what I suppose the thing is done without them, for by the Communication of it to the Mass of Blood it is brought into a method, in which it is dispensable to all the joints, the Muscles, and Tendons, and whatever parts can be thought to require it, since the Blood, with which it afterwards Circulates, has its motion through all the parts of the Body, and in its Circulation flows to all the Glands, by which the Mucilage is separated in every part.  
I will go farther yet, and now I have endeavoured to prove, that the use of the Spleen is to generate this mucilaginous liquour, I will attempt to explain the manner, how it does it, which was a thought suggested to me from what I accidentally observed, when I was about making one Experiment with the Mucilage. Designing to try what alteration an acidaustere would make in it, I mixed some Spirit of Vitriol with some of the Decoction of Galls, and I found, that the mixture produced a soft, and perfect Gum. Now as there are evidently gummous parts in the Mucilage, so in the Spleen there seem to be supplied from the Blood two Principles of the same nature as those were of, of which I made that Gum, that is an acid and an austere to produce it. The Spleen having a sub-acid taste when it is boiled as Diemerbroek has observed, does discover an acid in it. I do therefore suppose, that the Splenick Glandules being formed with two colatory Pores, do by one separate an acid, and by the other an austere Juice, which meeting in their small Cavities the one does precipitate the other in the same manner as the Spirit of Vitriol did the Decoction of Galls, not into a plain, and perfect Gum, but as the degree both of the acidity, and austerity is low, only into a more thin Mucilage.  
The nature, and use of that liquour, which is naturally separated by the mucilaginous Glands, however it is first generated, are such as I have described. But as other Glands of the Body, so these do sometimes, separate, and take off from the Mass of Blood a weal-public Matter, which because it is not excerned out of the Body, but is thrown, upon, and lodged in some parts, which are affencted, and injured by it, does excite some particular Symptoms, wherever it is deposited. Therefore all the parts, where any of these Glands are seated, must be obnoxious to Catarrhs, when ever they are disposed for the separation of that Matter, which is Heterogeneous, and weal-public, and Nature makes an attempt to depurate the Mass of Blood by them. Now as these Glands, as I have shown, are seated both between the Muscles, and about their Tendons; and in the Interstices of the joints, so this defluxion of Matter happens sometimes to one, sometimes to the other, and sometimes to all of them: which when it is excluded from the Mass of Blood by those mucilaginous Glands, which are seated between the muscular parts, produces a Rheumatism; when by those, which serve to the joints only, and the Tendons, which are inserted near them, procures the Gout. I shall therefore say something of both these Distempers. But before, and in order to the explaining of the Nature, and Cause of them I think it necessary to give an account of some Experiments, which I made with the Mucilage, which is the liquour naturally supplied to, and always entertained in those parts, which are affencted in these Distempers. This I proposed to myself, that as the humour, which is the cause of them, is weal-public, and mingles with the Mucilage, when it is thrown into the same Interstices, so the alterations, which I might observe from several mixtures made with the Mucilage, where they agreed with what we often observe in these cases, would discover both the nature of that humour, which is then the cause of these Distempers, and the reason of some Symptoms, which accompany them.  
The trials, which I made with this liquour by mixture, have been many, and more than I shall here take notice of, because there were several, which did not succeed so as to make any sensible alteration in it. The Mucilage which I made use of, I had from the joints of Oxen, and of a Horse, which being large Animals, did afford sufficient quantities for my purpose. I made most of the trials both when it was hot, and when it was could. Vinegar dropped into it, when it was hot, made a considerable Coagulation with a Serum, to all which I afterwards added the powder of Coral, both because it is esteemed a specific in a Rheumatism, and I thought the effervescence, which would follow might dissolve some part of the cured, which the acid had produced, but I found no such effect from it, nor from Antimonium Diaphoreticum, Crabs Eyes, nor any thing of a testaceous nature, that I tried. All the following Experiments I made with it, when it was could: I made the same, when it was hot, but because to give a distinct account of both of them would be little better than a Tautology, I shall only observe, that those, which were made with it could, did produce the same effect when it was warmed, to wit, a Coagulation, with Acids, and Stipticks, only in a higher degree; and whereas the Coagulations, which were made, when it was in one state did only change it into a thick Jelly without any Serum, after the manner of a Cheese, when it it is newly set, as they term it, which over the Fire afterwards exhibited two distinct parts, a Coagulum, and a Whey; in the other, that is, when the Mucilage was hot, the mixtures, which coagulated it, produced a harder cured, and a Serum distinct from it. By dropping in some of the Decoction of Galls to some of it I turned the whole into a gelatinous Mass, and it was all a sort of Coagulum like a skin, of a whitish colour, and so tough as to hang all together, when I took it up with a Needle. This Coagulum, or Jelly, being laid in the Sun, and dried, the parts of it stuck all together in one piece, but was very friable, and easily rubbed to a powder, which was very much like fine flower. The same effect had the strong infusion of Balaustia, read Roses, Pomegranate-Pills, and the Peruvian Bark, although there was some difference in the Coagulation according to the different degrees o● their adstringency. With a few drops of Aqua Fortis distilled upon it the Mucilage was immediately coagulated, though the Coagulum, which was white, was so tender, that it would by agitation be dissolved in fair water, and make it of the same colour almost like Milk. Spirit of Nitre made exactly the same alteration in it, as Aqua Fortis did, a Coagulum, which was of a white colour. From which Phaenomenon I shall afterwards endeavour to give the reason, why the injuries of the Air, and taking could are so frequently the occasion of the Gout, and a Rheumatism. Vinegar, Spirit of Salt, of Vitriol, Oil of Vitriol, and of Sulphur in some Mucilage, which I tried it with, did not make any considerable alteration, when it was could, but in some other it did more, when Aqua Fortis, and Spirit of Nitre did produce in all the same effects in the same degree. And I could not but admire to see, that so strong an acid as Oil of Vitriol should have no greater effect upon it to alter it, not so considerable as that of Vinegar, which makes me think, that it is not always the high degree of acidity, that works this change, but there seems to be something particular in Wines, which disposes them to coagulate this liquour, when any of them are made use of, and those parts of them, which are apt to act thus upon it, are cast into those Interstices, where they have the Mucilage singly to work upon. And therefore we find how readily any Wines do procure the Paroxysms of the Gout, where the tone of the Glands is weakened, and the Patient has a disposition to this Distemper, which agrees with those trials, I made with some of them. For Claret, White-Wine, and even Sack, but the Claret especially did make a Coagulum in the Mucilage like a Jelly. And it was not strange, that Claret, which has both an Acid, and a Stipticity in it, should produce the greatest Coagulation. A mercurial water made of Sublimate, and Aqua Calcis made a very considerable whitish Coagulation, and rendered it all a thick Jelly, which being held over the Fire turned to a cured, and a Serum. A Solution of Roman Vitriol produced a Coagulation likewise, so did Alum dissolved in water, but it made a greater alteration in some, than it did in others, though the Mucilages were taken from Subjects of the same Species. Saccharum Saturni did inspissate it, which appeared to be a true Coagulation, because with the Fire they would turn to a distinct Coagulum, and Serum. Salt of Wormwood made no sensible alteration, only it seemed a little thicker, to which I put some of the Decoction of Galls, which immediately produced a Coagulation. Then I dropped in some Spirit of Vitriol to see what would be the effect of the Colluctation of the Salt, and Spirit, and I found after it was over, that the Coagulum, and serous part were distinguished, and the Serum limpid like water. I took some of the Decoction of Galls, and added to it Spirit of Vitriol intending to make a strong acid-austere, where I observed, that these two by themselves produced a Coagulation, and stirring of them together, to see, if the whole might not be brought to mix by that means, I found the Coagulum turned into a viscous Body, and a perfect soft Gum. Then I took out the Gum, and poured some Mucilage to the residuous liquour, by which it was changed so, as to assume a whitish colour, but was not considerably coagulated, which it was the less, because the austere parts were most of them with some of the acid precipitated into the Gum, which I had separated from the serous part. But if the Spirit of Vitriol, and the Mucilage are first mixed, and the austere liquour be afterwards added, they make a considerable, and plentiful Coagulum, which will only be broken into smaller parts, and not be dissolved in water. Aqua Fortis, and the Decoction of Galls being both dropped into some of the Mucilage made a white Coagulum, which likewise was not dissolvable in water, although with Oleum Tartari per deliquium, and so with Spirit of Salt Armoniack dropped upon it, I presently dissolved it. I found likewise, that the Coagulum made with the infusion of Pomegranate-Pills, read Roses, and Balaustia, being mixed with some of the Mucilage, to which an acid had been put, made the Coagulum more firm, so that it would not dissolve in fair water, but yet the Oleum Tartari per deliquium, and the Spirit of Salt Armoniack did the business in all of them. The Coagulum of the Mucilage made with an acid, and the infusion of the Peruvian Bark, and several other Astringents I kept, and dried, which when they were first put to the Teeth seemed a little gritty, though after they were moist, they were of a softer nature: I cannot but take particular notice, that all the mixtures made of the Mucilage with an acid, and an austere, produced not only a plentiful Coagulation of a white colour, but such a one as was of a thicker consistence, and not dissolvable in fair water, as that was, which was made with an acid only, because I shall have occasion to make use of this observation, when I come to explain the manner, how the Tophi are produced in a nodose Gout.  
And now I come to give an account of some ill Offices, which the mucilaginous Glands sometimes perform to those parts, where they are seated, which being, as I said before, either about the Muscles, or in the Interstices of the joint, do in the one conspire with other causes to procure a Rheumatism, and in the other the Gout. And first   

Of a RHEUMATISM.  
I Must own, that this Distemper having its seat in the Muscular parts, may seem to lye out of the compass of my Argument, as my Discourse has a respect to the Bones, but as I am now concerned with the mucilaginous Glands, it lies so in my way, that I should think myself guilty of the neglect of some part of my business, if I should not take this occasion to offer something concerning it. And what I shall say of it, is to be understood of a true Humorose Rheumatism: For that, which is Scorbutical, being nervous, and these Glands seeming to be innocent, and to have no hand in it, my Discourse concerning them does not led me to consider it.  
That a true Rheumatism is caused by a flux of humours to the parts affencted is universally received, and understood by Physicians, and this Notion agrees not only with the Sense, which they have of it, but with the Name too, which they have given it, though the manner, in which the weal-public Matter is thrown upon the parts affencted, has never been truly explained, nor could it be known without the observation of these mucilaginous Glands seated amongst them. My business therefore shall be to inquire both what the nature of the Humour is, which causes it, and what way it is conveyed to the parts, which it affects, from both which considered I shall endeavour to account for the Symptoms of this Distemper.  
The Humour cannot be thought to be the Mucilage itself in its proper, and natural State, for it is too mildred and inoffensive to the tenderest, and most sensible Fibres, otherwise we should be naturally, and continually afflicted with this Distemper in some degree or other. Nor can we suppose, that the Mucilage does at that time, when a Rheumatism happens, degenerate in the Blood into any such quality, as makes it acrious, or pungent to the parts, for then all the parts of the Body, that have Glands, which separate the Mucilage, must necessary be affencted at the same time. It is therefore a preternatural, a weal-public Matter distinct from the Mucilage lurking first in the Mass of Blood, which being dangerous, and uneasy to Nature irritates the powers of it to purge the Mass of Blood from it. But yet it does not seem to be the same in all Rheumatisms, but that difference, which may be conceived to be in the Humours, that are capable of exciting such pains, may rationally be supposed to be in that, which is the cause of this Distemper, which I therefore judge to be of three sorts. Sometimes it is acrious, and more subtle, and of such a nature, that though it procures an acute pain, and is almost intolerable to the sensible Fibres, yet it does not coagulate, nor inspissate the Mucilage, with which it is mixed, when it comes into the Interstices of the Muscles, as things of that nature will not do it out of the Body. But because it is hot, and volatile, and so not only distends the parts by its influx, but disorders the Spirits, and agitates the Particles of the Blood, which by its quantity, and the compression of the extremities of the Vessels it obstructs, there arises a heat, and a greater inflammation in the parts, which swell. This matter is easily, and quickly translated from one part to another, so that the swellings, especially before the inflammation arises, are not so permanent, nor the pain so firmly fixed in any one part, but wherever it is, it gives the sense of a burning, and fiery quality.  
Sometimes the matter is Saline, where though the fixed Salt, as I observed of Salt of Wormwood, may a little inspissate the mucilaginous liquour, yet it does not give it such a consistence, as makes it certainly, and pertinaciously fix, though it moves up and down with less quickness, and the pain does not so frequently shift its seat, as when the matter is acrious, and more subtle: besides which the sense of it is different, as it is pungent, and lancinating.  
But then thirdly it is sometimes, and most commonly an Acid, or kind of Corrosive. In which case though the matter, whilst it is in the Mass of Blood, be not thick, and gelatinous, yet when it comes to be separated from the sanguincous Mass, and to be mixed with the Mucilage in those parts, where the Mucilage is deposited, it coagulates it, and makes it a sort of a Jelly in the same manner, as it will be altered by Spirit of Nitre, and other Acids. And it not only appears from most of those Experiments, which I have mentioned, that the mucilaginous liquour may be thus coagulated in the Body, but in some Rheumatical cases it is evident, that it is so. I will not insist upon what may be frequently observed from the application of Vesicatories in this Distmeper, how there appears, when the Blister is raised, and taken off, under the Cuticula a tough Jelly like a thick skin, which I have afterwards dissolved, because this may not pass for demonstration. But I have met with the account of one case, which does undeniably prove it; it is in a college of practise red by Dr. Drelincourt at Leyden, where he says he himself in a Person, that died of a Rheumatism, found a Jelly concreted upon the superficies of the Muscles of the thickness of two or three Ducats. And I had lately the opportunity of observing our chirurgical case, and the account of another from Mr. Edward Bulkley, a curious, and observing, and skilful Surgeon of this Town, which confirmed me in my opinion. The Patients were both of them his. They had a large Tumour in one of the Thighs, which he, finding a fluctuation of matter, opened by a caustic, and there ran out a large quantity of matter, some Ounces of which I saw, as it was taken from one of them, and it was not any thing like a Pus, but plainly like Milk turned to a Posset, consisting of some pretty large, and many smaller pieces of white cured mixed with a Serum, and was lodged in the Interstices of the Muscles, where the Mucilage is separated, and deposited. Now as my observation of the mucilaginous Glands about the Muscles may inform us, what way the weal-public humour was brought thither, and my Hypothesis does explain the manner, how the matter, which was found, was generated there: So these observations do seem to me clearly to prove, what I would argue for, that the Mucilage is sometimes coagulated in the Body, whilst it is animated, especially, when I consider how exactly it agreed with some alterations, I found in the mucilaginous liquour from some mixtures, I made with it, when I had made it hot.  
When the quality of the weal-public matter is acid, and the Mucilage is coagulated, the pains are more fixed, so that, though they arise in some other parts, yet those, which were the first Fruits of the Patients misery, continue immoved, the pains are corroding, so that we have these Patients complaining of a gnawing( so they are pleased to compare it) as if Dogs were tearing of their Flesh, and this is that Stubborn and Chronical Case, which sometimes persists for half a year, or longer, and it may be is never overcome by all the Art, and Instruments of physic. But yet as there is a difference in the nature of the acid, and the degree of acidity, so the degree of the Coagulation is sometimes less, and sometimes greater, and consequently the Distemper is with more, or less difficulty vanquished.  
It is very probable, that sometimes there is the addition of an austere, which conspires with the acid to coagulate the Mucilage, and then as the consistence of it is rendered thicker, so it is more tough and difficult to be dissolved, which makes the case more Stubborn, and Chronical. However I do not think it is at any time an austere only, when the pains are acute.  
The way of conveyance, by which this humour, whatever the nature of it is, is derived to the muscular parts, is by the mucilaginous Glands, and that in the manner of a Crisis, so that the preternatural Humour, and the Mucilage are cast into the same Receptacles, into the Interstices of the Muscles, where they will come to be mixed together, and if the weal-public matter be an Acid, Experiments tell us, that the consequence will be a Coagulation.  
The first occasion of this Distemper is known to be generally the taking of could, and then it seems to be from a nitrous acidity, and such a kind of Spirit in the Air, as destroys the due mixture of the parts of the Blood, fixing the Spirits, and those Volatile parts, whose motion, and activity do naturally so agitate all the rest, as to confounded one with the other, and to preserve those, which are of the same nature, from running together, which is the mixture of the sanguineous Particles. And when the Air is in an extraordinary degree impregnated with such a Spirit, then is this Disease more frequent, and Epidemical.  
That the Air does consist partly of a Nitre, or nitrous spirit is of late an Opinion so generally received, and so strenuously defended, that he is almost thought a heretic in Philosophy, that denies it. Now that this nitrous spirit may be admitted into the Body even by the Pores of the Skin, I do not see how any one can question, who considers, how the parts of Mercury, how those of oily lineaments, and Ointments, which are more gross, will insinuate themselves this way. Being therefore received in such a quantity as to precipitate the Blood, and to produce a serosity in it, it Communicates, as coagulating liquours will do, its own quality especially to the Serum, which being thus altered, becomes apt to coagulate the Mucilage, when they meet together in the same Cavity. Though I do think, that when any rheumatic pain seizes any part upon the immediate influence of the Air, as when it does affect that place particularly, upon which the could Air strikes in an unusual manner, it does more immediately affect the Mucilage, by penetrating through the Pores of the parts into the very Cavities, or Interstices, where the Mucilage is deposited. And that such a nitrous spirit of the Air will coagulate this liquour, when it either mingles with it per se, or Communicates an acidity to the Serum of the Blood, and is conveyed to it in that Vehiculum, we may be sensible from that Experiment, which I made with the Mucilage, and Spirit of Nitre.  
The taking of could, as is evident, does alter the Crasis of the Blood so, that some parts of it lose their due mixture, and degenerate so far as to become unfit ever to be intimately, and amicably mixed with the sanguineous Mass again, and thereupon Nature uses her endeavours to exclude them, that they may neither destroy the Diathesis of the Blood, nor continue to disturb its Circulation. Therefore it is obvious to our Observation, that there follows either a Fever, which is only an attempt to overcome, and exclude that Heterogeneous Matter; which endeavour is more sensible and protracted, because the matter is not excluded by any Glands, which perhaps may therefore be retained in the Blood, because the Particles of it are not yet accommodated to the Pores of any Glandules, and as the violent commotion in the Mass of Blood at that time is in order to expel them, so we may suppose it is no less to break, and so figurate them, that they may be capable of being excerned by some Glands, which when it is once done, there follows a Crists. I say there follows either such a Fever, or some Evacuation. Sometimes Nature is so intent upon this affair, and so violent in her attempts to throw off this matter, as to sustain the loss of her own Treasure, and the purer parts of the Blood in the exclusion of those, which are Incongruous, and Morbisick, as when the Crisis is made, or endeavoured by a Hemorrhage: but commonly this is done without that expense, and then it is by the glandular Sluices, but not always by the same, sometimes by those of one sort, and sometimes by those of another, according as they are disposed to receive, and separate the weal-public Particles. Therefore upon a could we have sometimes a Crisis by the Glands of the Nose, as in a Coryza; or by the salivatory Glands; at another time by them of the Trachea, and Bronchia, as in a Cough, or Catarrh upon those parts; sometimes by the cutaneous Glands, and sweeting; sometimes by those of the Intestines, and a diarrhea. Neither are the mucilaginous Glands always excused; but the Mass of Blood exonerates itself by them, by which the weal-public humour being separated it is necessary cast upon the Muscles and Tendons, where the nitrous Spirit, Communicated from the Air, and the matter depraved by it coming to act upon the Mucilage singly do inspissate it, and produce that Distemper, which we call a Rheumatism.  
Although this Distemper does often owe its Original to the preception of could, yet it is sometimes contracted from other causes, and occasioned from the liberal drinking of Rhenish-Wine, and those liquours, which are in the same manner acid. Neither have we any reason to wonder at it, when we consider the nature of the Blood, and the Chyle, which does daily feed the Vessels, and repairs the sanguineous Mass. I need not go about to prove, that the Chyle is of the nature of Milk, since the Opinion has generally prevailed, that Milk is the very Chyle conveyed to the Breasts, either by the Arteries, before it is assimilated to the Blood; or by more immediate Ducts. And Experiments do tell us, that they both undergo the same alteration from the mixture of an Acid. What must we then think of the Blood, which is every day renewed, and maintained by it, but that it borders upon the nature of it? So that since sour liquours do produce a serosity, and a Coagulation in one, we must expect it will make an alteration in the Blood, which is somewhat like it, though not in the same degree, especially if we drink plentifully of liquours, that have much of an acidity in them, whilst the Chyle retains its lacteal nature, and before it is assimilated to the Blood. And I knew one, in whose cure I was concerned, who was Scorbutical, that upon the drinking of sharp Wines, such as White-Wine, and Rhenish, especially at that time, when some of the Chyle was yet in the lacteal Vessels, and whilst that, which was newly supplied to the Blood-Vessels, was milky, would find the same effect, as from the injuries of the Air, to wit, plainly a could, for so I must call it, in his Head, and a Coryza. And when we find these Wines so diuretic, it argues something like a Coagulation, which causes many of the serous parts to lose their mixture, and disposes them to a separation.  
When these parts are so altered, and once deprived of their due mixture, as they are never again, or not easily to be reduced to their natural state, nor in that, which they are in, consistent with the good Crasis, and regular motion of the Blood, they become a peccant, and an offensive humour. So that the business of Nature then is, as in a could, to extrude them from the sanguineous Mass. And what is that plentiful excretion of Urine, which commonly attends, or follows the liberal drinking of such liquours, but a kind of critical Evacuation of Serum, or a depuration of the Mass of Blood from some parts of it, which, when they are precipitated, and have lost their due mixture, agree better with a Chamber-pot than the sanguiferous Vessels.  
As the serous parts altered by the nitrous Spirit of the Air, so neither the acid liquours, which we drink, nor the Serum precipitated by them, are always separated by the same Glands. Though this separation is often by the Kidneys, yet sometimes it is made by those, which supply the Saliva, especially in some Scorbutical Persons, which I have often observed; sometimes these liquours not only increase a Cough, and heighten the Symptoms of it, which experience tells us will be the effect of our ordinary drink, but they sometimes produce a Catarrh upon the Lungs; and sometimes it so happens, that the weal-public Matter is thrown upon the mucilaginous Glands, which having the convenience of exonerating themselves, cast it off into the Interstices of the Muscles, and Tendons. Being deposited in the Receptacles, if I may so call them, of the Mucilage, it mixes with it, and as we see that the Acid, which produces a Coagulum, and a Serum in any liquour, Communicates its own quality more especially to the Serum, so these Wines, which cause a kind of Coagulation in the Blood or Chyle, will impregnate those serous parts, whose due mixture they destroy, with an acid quality, and render them of such a nature, as that they will coagulate the Mucilage, when they come to mingle with it, as I have shown that these Wines themselves will do it.  
Although the humour thus separated does produce a new Distemper, it is no more improper to call it a Crisis, than Buboes, and the swellings of the Parotides in Pestilential Fevers. For though it be not so in respect to the whole Body, yet in respect to the Mass of Blood it is. And I have observed, where a Rheumatism has been evidently critical, as particularly in one Patient I had, who laboured with a Fever, in the Declension of which there came on a Rheumatism in her Arms, which without doubt, was one thing, that solved it, as Nature excluded from the Mass of Blood part of that Matter, which before had disordered it, by the mucilaginous Glands of those parts.  
The Symptoms of this Distemper may be easily, and fairly accounted for from the nature of the Matter, and the causes of it, as I have explained them, and the manner, in which I have supposed it is produced. They are generally a swelling of the parts affencted, sometimes with a redness; severe and acute pains, there is commonly a Fever, a rigidity in the parts, and sometimes in the declension a Stupor, and stiffness.  
For the first the Tumours, they must necessary attend this Disease, if it be caused in that manner, in which I have endeavoured to prove it is. For when the weal-public Matter is plentifully separated by the mucilaginous Glands of the Muscles, and cast into the Interstices, it cannot but distend, and raise those parts, which lye above it. And besides what is lodged in those Cavities between the Muscles, the Catarrh, or vast influx of the Humour will in an extraordinary manner fill, and distend the Glands themselves, and so far increase the thickness of the Membrana communis Musculorum as to cause a sensible elevation of the parts, which lye over it. Thus we see the Glands on the inside of the Nose in a Coryza are sometimes so distended, the Membrane of the Nostrils so tumified, that the passages are stopped, and we are obliged to find another way for the inspiration, and expiration of the Air. And such a swelling, and thickness I observed in those parts of the common Membrane of the Muscles, which I found Hydropical.  
With the influx, and plenitude of the weal-public Matter conspires that, which follows upon it, an obstruction in the Blood-Vessels. This is evident, that a small compression upon the Vessels, where they are minute, will force one side of them to be contiguous to the other, and where the compression is great, as it must be where there is such a preternatural fullness, and swelling of the adjacent parts, we may well suppose the Vessels to be so obstructed, that the Blood can at best but with difficulty Circulate through them: so that the continual appulse of it flowing more plentifully and freely into them, than it can proceed into the Veins, will swell and distend the Vessels, in which it is obstructed, as we see the Veins will be tumified below a Ligature, and in an Ophthalmia we find the obstruction of the Blood will so enlarge the Vessels as to make them appear visible, which were before indiscernible.  
The reason of the pains we may be able easily to understand from the Nature, which I suppose the weal-public Matter to be of. When it is either Saline and pungent, acrious and urent, or acid and akin to a Corrosive, it is sufficient to excite such pains, and we can expect no better treatment from it, when it falls upon such sensible parts as the Muscles, and Tendons, and the Membrana commums Musculorum. Besides the sense, which arises merely from the quality of the Matter, the copious influx of it into the parts affencted, stretching the Fibres beyond their natural tone, does affect them with a dolorifick sense, at least by making them tense it renders them more sensible of the pain excited by the Salt, the acidity or acrimony of the humour, which is more intense or moderate as the quantity of the matter, and the degree of its quality are greater or less.  
The Fever, which is another Symptom, that commonly attends this Distemper, does first arise from the Heterogeneous nature of the weal-public Particles, and their unfitness to be mixed with the Mass of Blood, at which time it is mostly an effort of Nature to expel them, but afterwards it is continued by the acuteness, and severity of the pains exagitating the Spirits, and producing a disorder and a tumultuous violence in their motion, which they Communicate to the Blood as they have a continual influx into it, to invigorate it, to promote its Circulation, and to preserve the mixture of its parts. And to this Fever something may be added from the compression, and obstruction of the Blood-Vessels. For when the free Circulation of the Blood is hindered in one part, it seems obliged to move quicker in others: As we see in a River dividing itself into two Channels, if one of them be stopped up, the motion of the Water will be more rapid in the other.  
Besides the rigidity, which necessary follows the swelling, and preternatural fullness of the parts, there is both a stiffness, and Stupor, which the Patient has commonly the sense of after the rheumatic pains are in a manner gone off. Both of them I conceive to be from an alteration in the nature, and consistence of the Mucilage, and the effects particularly of such a Rheumatism, as is caused by an Acid. To preserve the Fibres flexible and tensile it is necessary, that they be lubricated, and moistened; and for the continual motion, and influx of the Spirits into them, it is requisite not only, that they be supplied in a sufficient quantity, but their passages the Canaliculi in the Nerves, and fibrous parts must be clear too. Now when the Mucilage is coagulated, it becomes unfit to lubricate the Muscles, and Tendons, or to moisten, and preserve their Fibres so pliable and tensile as naturally they were. Whereupon they cannot be so easily contracted, nor those parts of them, which approach nearer to their Origination, when they act, slide so readily, as they ought to do. And there may be some opposition in the Tendons of the Antagonist Muscles to their own extension, as they must be extended when the others are contracted. I did not long ago in the tendinous Fibres of a Horse observe transverse, and circular wrinkles or Corrugations, which if we suppose to be in our own Tendons, and muscular Fibres, when they are not extended, which we have great reason to do, then we may reasonably think that the coagulated Mucilage insinuating it seft into, and sticking in the small Foveae, or Furrows, hinders the free and easy extension of those parts.  
So the Stupor or numbness, which sometimes affects the parts after a Rheumatism, proceeds from the same alteration in the consistence of the Mucilage. For although the obstruction, and defect of the Spirits be the immediate cause, yet this obstruction arises from such an alteration in the Nature of that liquour, as renders it unfit to perform its office, and to moisten the nervous Fibres, for want of which they will become more dry, than they ought to be, and consequently their small Pipes will be contracted. So that this Distemper, where there has been such a Coagulation, leaving sometimes such an alteration in their temper, as contracts, and streightens their Canaliculi, or small Cavities, impedes the plentiful influx of the Spirits into them, and their course through them. And where we have such a Stupor, I am apt to think, there remains some part of the inspissated Mucilage after the pains are ceased, and when the swelling in a manner disappears, and that it is thicker, than it is during the height of the Distemper, though because it has lost that quality, which made it dolorifick, it does not affect the Fibres in the same manner, as it did before. This angustation of the Canaliculi of the Fibres, if it proceeds to a total obstruction, produces a palsy, as sometimes we do observe, that this Distemper succeeds to a Rheumatism.  
From what I have said concerning the matter, which is often the cause of this Distemper, how it is an Acid, and coagulates the Mucilage, we may understand the reason, why a Rheumatism continues sometimes so long, and stubborn. And when it is so protracted, I take this to be a true diagnostic of the nature of the weal-public Humour.  
If I may have leave here to make a little incursion into the Physicians Province, I would add something concerning the Cure. And from what I have said of the diversity of the Humours, which may be the cause of a Rheumatism, we may discover some reason for altering the means, and method of Cure at some times. And as the difference of the Humour does indicate the use of different Medicines, and shows the unreasonableness of one common and constant method in all even true, and humorose Rheumatisms, so by attending to the signs, which discover the quality of the Humour, and whether it has coagulated the Mucilage or not, we may be directed both in our prognostics, and the choice of Means.  
This I may lay down as a general Rule, that since a Rheumatism, as I have shown, is a Crisis, or depuration of the Blood by the mucilaginous Glands, we must endeavour to put Nature into another method, and to procure the exclusion of the matter by some other Glands, which may free not only the Mass of Blood, but the whole Body from it; where it is to be considered, what excretory Glands do seem most apt to separate, and carry off that weal-public Matter, which is to be excerned. For as there is sometimes a difference in the nature of the matter, so every sort without doubt will pass off more readily by one particular way of Evacuation, than by any other.  
When the weal-public Humour is acrious, and of such a nature that it does not upon its mixture coagulate nor inspissate the Mucilage, the most convenient Evacuation after bleeding seems to be by the cutaneous Glands, and however diaphoretic Medicines may malè audire before the declension of a Rheumatism, yet in this case they may be certainly used not only with safety, but with benefit provided they are temperate, and free from an acrimony, such as Pulvis é Chel. compositus, Lapis Contrayervae, Antimonium Diaphoreticum, a Decoction of Sarsa, and things of the like nature.  
Besides Evacuation, there must be an endeavour to temper the heat, and to correct the Acrimony, in order whereunto some sorts of Emulsions will be convenient, and this is the case, in which the Tincture of Roses, which is used without any distinction in humorose Rheumatisms, is truly a specific. For where the humour is acid, and the Mucilage coagulated the use of it does seem neither reconcilable to Reason, nor to be defended against, what Experiments dictate to us. Our Reason will tell us, that astringents as read Roses, are not proper to attenuate, nor an acid as Oil of Sulphur, or of Vitriol to prevent or dissolve a Coagulum. By Experiments we shall find, as I have already shown, that both Roses, and Oil of Sulphur, or Oil of Vitriol, with which this Tincture is made, do produce the same alteration in the Mucilage, that the weal-public Matter in this case does induce, so that they cannot be proper means to Cure it, nor effectual Remedies to prevent the farther degrees of the inspissation.  
Where the humour is Saline, or Briny, though I will not wholly condemn diaphoretics, because such a humour seems in some measure apt to be excerned by the cutaneous Glands, as the sweat is naturally salt, yet the most convenient way of Evacuation is by a Diuresis: So that as I proposed diaphoretics in the first case, so I conceive diuretics to be most proper in this. For tempering the fixed Salt it seems reasonable and necessary to dilute it, and in order to correct it we may allow such light acids as will alter the nature of it in the Blood, and not coagulate the Mucilage, if they proceed so far as to change the nature of that salt humour, which is lodged in the Interstices of the Muscles. So that here it is, where the Conserve of Fructus Cynosbati seems to be a specific. And in this case I do not see, why we may not both with safety, and benefit make use of stronger Acids, seeing the fixed Salt, and the Acid will mutually alter, and correct each other, that the latter may not have a power to coagulate the Mucilage, if it should not only act upon the weal-public Matter in the Mass of Blood, but also find a way into the Interstices of the Muscles by the mucilaginous Glands. What Coral, which is proposed as a specific in all humorose Rheumatisms without such a distinction, as I have made, is like to do in this case I do not well apprehended.  
The third and last sort of Humour, which I suppose to be most frequently the cause of a Rheumatism is an Acid, such as not only distends the parts, where it is deposited, and affects them with a pain, but likewise makes a considerable alteration in the consistence of the Mucilage. When the Mucilage is thus coagulated diaphoretic Medicines are certainly pernicious, not only in the augment, and height, but through the whole course of the Distemper, unless it can be first so attenuated, as to be capable of being discharged out of those Cavities, in which it is lodged, and the ordinary method of practise, which forbids the use of them till the declension of it, is in this case highly reasonable. Though I say, they are at no time proper, unless the inspissated matter be first dissolved, and attenuated, as a preparatory to the use of such Medicines. However, the effects I found from Spirit of Salt Armoniack poured upon the coagulated Mucilage, and its contrariety to an Acid may led us to the plentiful use of such a diaphoretic as that is, and of all those things, which do in the same manner dissolve a Coagulum. When the matter is thick, and gelatinous, what can other diaphoretic Medicines do? Suppose they raise a sweat, and drive out some parts of the matter, which lies beyond the mucilaginous Glands, we must expect they will be those, which are the moist, and thin, which are necessary to prevent its induration, and to conspire with our endeavours to attenuate it, by which means we have the coagulated Mucilage reduced to a thicker consistence, and rendered more uncapable of being dissipated, and consequently the cure of the Distemper more tedious, and difficult. And as I suppose the more than ordinary toughness, and the very thick consistence of some part of the coagulated Matter remaining after the pains are gone off, does cause some Symptoms, so I am apt to think that an imprudent use of diaphoretics may reduce the matter to that thickness, and be the cause of that rigidity, and Stupor, which are sometimes left behind. There is one thing, which may deservedly be recommended, where the weal-public Humour has coagulated the Mucilage, that is Salt of Tartar, the nature of which we know to be such as will correct an acid, and if Experiments may not be thought to deceive us, will be no less effectual to dissolve the coagulated Mucilage, as appears from, the trials I made with it, which I have given an account of. Here Coral, and testaceous powders may be thought to be proper, and sudorifics. For, though it is true, they will not dissolve the Coagulum; yet by correcting the Acid in the part affencted they will mitigate the pains, and by altering that part of the weal-public Matter, which is not yet excluded from the Mass of Blood, they will cut off that supply, which would feed, if I may so speak, and protract the Disease. Some Physicians for the security of the respiratory Organs do in the Cure of Rheumatisms prescribe mucilaginous, and oily Pectorals, which in this sort of Rheumatism do seem highly reasonable in respect not only to the Lungs, but likewise to those muscular parts, which are affencted. For they standing in need of, and having naturally the supply, and benefit of an Oil, and a mucilaginous liquour, and the nature of the Mucilage being so altered, as to be uncapable of answering its intention, this is imitating Natures Composition, and substituting an artificial mixture, which supplies the defect of that, which the weal-public Matter has vitiated.  
To this kind of Rheumatism there are some Evacuations, which seem more peculiarly agreeable, than any others. By observing the tendency of the Matter to the Salivatory Glands, and the plentiful spitting, which some Patients have in this case, I am inclined to think, that a Salivation may here be very proper. And the tough, and gelatinous Matter, which I have seen gathered under the Cuticula from the application of Vesicatories to the parts affencted, I may say the sensible relief, which I have known from them has been an Argument to persuade me, that the Cantharides are in an especial manner effectual to Evacuate the coagulated Matter.   

Of the GOUT.  
I Proceed now to consider the other Distemper the Gout. And if I should be thought to have made a Digression in what I have said of a Rheumatism, I return now to my Argument. For this Disease, as it has its seat amongst the Bones, does plainly lye within the compass of it.  
A great part of that account, which I have given of a Rheumatism, is applicable to this, the humour, which excites the pains is of the same nature, the Glands, by which it is separated from the Mass of Blood, of the same kind, the parts, upon which it is cast, equally sensible, and some of them, as the Tendons, which are inserted near the joints affencted, in Specie the same: but the seat of it is different, which being in the joints, and about the Tendons, that lye near them, changes the name of a Rheumatism, which may be taken for a more general one, for the particular denomination of an Arthritis or Gout. However, since it has a relation to our Bones, and the Argument I am concerned with, does direct me to a particular consideration of it, I shall say something first of the nature of the Matter, which causes it: Secondly, I shall explain the manner, in which, and the reason, why it is carried to, and lodged in the parts affencted. Thirdly, I will endeavour to give the reason of the Symptoms. In all which I shall as much, as ever I can, avoid the repetition of any thing, that I have said of the first Distemper.  
For the first the nature of the Humour, I conceive, that there is the same difference, which I supposed in a Rheumatism, that it is sometimes Saline, and pungent; sometimes acrious, and urent; and most frequently an Acid or in a manner corrosive. I have this to add, that it is certain, it is not always of the same nature from the different, and sometimes contrary effects of the same remedies, which we find to be so uncertain, and fallacious, that we commonly doubt of the success of one thing in one Patient, which we have found to be efficacious, and beneficial to another.  
Though there be these differences at some times in the weal-public Matter, yet very commonly the humour seems to be an Acid, and I conclude it to be very often so not only from what we may observe in many Patients about the time, when the fit is coming, and whilst it is upon them, as we shall have them complaining of sour belchings, and throwing up acid humours by vomit: but also from the procataretick causes, which frequently give the Patient the first disposition to this Distemper, and afterwards procure the paroxysms of it, when he adventures to make an Experiment of their effects: these are such liquours, as have much of an acid in them, and do easily degenerate, and turn into a sharp Vinegar, as French Wines, Cider, and the like.  
The manner, in which the weal-public humour is cast out from the Mass of Blood, when it is thrown into the Interstices of the joints, and upon the Tendons, which lye near them, is by the way of a Crisis. And this makes the Distemper return by paroxysms, which when the Mass of Blood is depurated, and the weal-public Matter, which Nature had deposited about the parts affencted, is dissipated and spent, go off. But when the Blood comes by degrees, or from some great occasion more suddenly to be again impregnated with such a quantity of these heterogeneous Particles, that the whole Mass is in danger of being depraved, and Nature is irritated to endeavour their exclusion, then they return; there will follow some discharge by those Glands, which are most apt to receive and separate them, which in this Distemper being those, that supply the Mucilage to the joints, the weal-public Particles are cast upon these parts, where they raise such Symptoms as are the genuine effects of their own nature, and such as the parts in which they are deposited, are thereupon subject to.  
That the weal-public Humour is in this manner, that is critically thrown upon the affencted parts, we have reason to conclude from that Febricula, which immediately precedes the paroxysms of the Gout, and shows, that Nature is then disturbed, and making an attack upon the hostile Matter. And, as when the Crisis of an ordinary Fever is once begun, and proceeds by a Sweat, if the sweat be suppressed, that that Crisis is hindered, and no other succeeds to it, the Fever is increased, and all the Symptoms of it often renewed by the retention of the febrile Matter in the Mass of Blood: In the same manner will the interterruption of this Crisis by the mucilaginous Glands of the joints, or the reflux of the Matter into the Blood occasion a Fever, if Nature does not find some other way to depurate the sanguineous Mass: as Forestus in the 21. Observation of his 29. Book, tells us of one, who laboured with the Sciatica, and upon making a Ligature to open a Vein in his Foot he fell into a Swoon, so that they could not bleed him, however he was cured of his pain, but fell into a Fever.  
Upon this supposition, that every fit of the Gout is from a critical exclusion of weal-public Particles from the Mass of Blood, and their separation by the mucilaginous Glands, we may apprehended, how the paroxysms of it may be, as they are commonly esteemed, a preservation of the Patient's Life, and a security against violent Fevers and any other more fatal Distempers, as they depurate the Mass of Blood from those Feculencies, which if Nature had not this ready, and easy way to cast them out of the sanguineous Mass, would produce such a disorder, and excite such a violent fermentation, as makes a Fever. Upon which fermentation if the weal-public Matter happens to be determined to, and thrown upon the Glandules of the more noble parts, then must the consequence be ill, if not fatal, such as an Apoplexy, a Phthisis, an Asthma, or the like. If the Mass of Blood can never be so victorious, as to exclude them by some Glands, there must necessary follow a Cachexy or ill habit of the whole Body, and all the mischiefs, that attend it. And when does this Distemper prove fatal, but when the Matter is translated to, and fixed upon some noble Part, or Nature is tired, and so languid, that she cannot rise up against her Enemy with so much vigour, as to drive it to the extreme parts. Neither do the arthritick paroxysms only give the Patient some security against other Distempers, that might proceed from those impurities, which the Blood insensibly contracts, but as the mucilaginous Glands of the joints, are disposed and ready to take off any incongruous Matter, as the Blood has occasion to make use of them, they often prevent those Diseases, which would otherwise arise from evident occasions.  
The secretory Organs, which serve to this Crisis, and separate the weal-public Humour, that causes the paroxysms of the Gout, are in Specie the same as those, by which the Matter in a Rheumatism flows to the parts affencted, that is the mucilaginous Glands, and I have said so much of them of the Articulations, and Tendons, that it is easy to prove, they are parts, which by reason of these Glands are evidently obnoxious to the afflux of a preternatural Humour.  
Although the weal-public Matter is sometimes obtruded upon, and separated by the mucilaginous Glands of some one particular part, yet it is not very strange that the Symptoms will often shift their seat, and that sometimes very suddenly. For though Nature will bear some lesser quantity of heterogeneous Particles, and they may lurk in the Mass of Blood for some time, when they have a small beginning, and increase insensibly, yet when they come to that fullness, that the whole Mass is in danger of being vitiated, and Nature is irritated to expel them, there arises a sermentation in the Blood in order to exclude them, which being once begun is not easily suppressed, but if the Crisis by the Glands of the joint, where it is first attempted, and begins, be interrupted, then there is a recourse to some other Glands either of the same kind, as when the Matter is translated from one joint to another, or to some other mucilaginous Glands; or of a different sort, as when the weal-public Matter is thrown upon the Lungs, the Brain, or Stomach. And how frequent is this motion of the Peccant Humours from some Glands to others in other Cases? How common, is it for Nature in the Evacuation of any weal-public Matter, when she cannot finish her work by the Glands of one part, to command the service of others? Thus sometimes we shall have a diarrhea succeed to the stoping of sweats, and the suppression of a diarrhea excite a kind of Salivation. In the Small Pox, if the Pustules fall, and the spitting of the Patient unexpectedly stops, how often, and how suddenly does Nature endeavour an excretion of the weal-public Matter by the Glands of the Intestines, and sometimes the Kidneys are observed to undertake the work of the cutaneous, and salivatory Glands, when the excretion of the variolous Matter does not proceed well by them.  
I take notice of this Phaenomenon, and have explained the reason of it, to show that the quick motion of the arthritick pains at some times, and the sudden translation of the Humour do not make it necessary to suppose, that the weal-public Matter, or any part of it is immediately supplied from the Nerves, as some would have it to be. Neither do I see how the Metastasis of the Matter does in the least favour such a supposition, unless it could be proved that the passage and translation of it is more free, and easy by the Nerves, than by the Blood Vessels. And to make it farther evident, that this observation does not make it improbable, that the Matter is derived from the Mass of Blood in the Gout, let us consider how patallel the case lies between an Arthritis, and an Erysipelas in this respect, where the Matter is generally allowed on all hands to be from the Blood. Does the arthritick humour, when it is repelled, or by any occasion suddenly removed from the part affencted, appear with its Symptoms in some other, sometimes showing itself in another joint, sometimes revenging the disturbance upon the more Noble Parts? So in the Erysipelas we sometimes observe a translation of the matter as quick and sudden, as that in the Gout, and in the same manner it sometimes shows itself again by Glandules of the same nature in some external part, sometimes it is cast upon the Brain, the Stomach, or the Lungs. But yet the arthritick pains are often sixth, and immovable, and when the matter so suddenly shifts its seat I take it to be either acrious, or saline, rather than an acid.  
From this supposition, that the weal-public Humour is separated by the mucilaginous Glands of the joints, and the Tendons which lye near them, we may easily satisfy ourselves, why the Gout does invade those parts, which we find to be obnoxious to it. As for the Sciatica, or Hip-Gout, I have taken notice, that the mucilaginous glad of the Acetabulum of the Coxendix is one of the largest of the sort in the whole Body, so that it is no wonder, that the Humour is exeerned, and thrown into the Cavity by it, and excites such Symptoms as we find there. In the Hands, as I have shown, there not only are considerable Glands in all their joints, but the Tendons, which are there inserted, especially those of the Musculi Perforantes have their mucilaginous Glands, so that Nature has a convenience in these parts to depurate the Mass of Blood, and they must receive the weal-public Matter, when the Blood in its Circulation obtrudes it upon them, and the Glands are disposed to separate it. The same thing I might observe of the Shoulder, and of the Knees. But of all the parts none are so frequently afflicted with this Disease, as the Feet, and it is plain, why they are so. For besides that they have many mucilaginous Glands in their joints, and others about the Tendons, which are inserted into their Bones, as the great Chord, or Tendon of the Muscles, which extend the Foot, and those of the Perforantes, I say besides this, they are the infeferior, and pendulous parts, so that as their Glands make them capable of entertaining, so their situation does conspire with the effort of Nature to bring down the weal-public Matter into them.  
I should in the next place consider the reason of the Symptoms, which are an acute Pain, a Tumour, which does most commonly, but not constantly attend the Gout, and the Tophi, which are sometimes generated in this Distemper. In the swellings there is nothing so particular, and different from them in a Rheumatism, that I need add any thing to what I said concerning them of a Rheumatism. So the sense, and Symptom of pain being always found in that Distemper. I have been already obliged to take notice of it, and what I have said concerning it, when it accompanies a Rheumatism, may discover the reason of it here from the nature of the Matter, and so far as it affects the Tendons. But there is one thing here, which deserves our consideration, that is how the joints themselves, or what parts of them are affencted with the pain. I have supposed the Bones themselves to have some sense by the mediation of of those Fibres, which from the Periosteum penetrate, and are inserted into their substance; but yet since the extremity of an articulated Bone has no Membrane, I cannot tell how we shall make this part of them capable of Communicating that impression to the sensitive Faculty, which the quality of the weal-public Matter is apt to make upon it. There are therefore only the Ligaments, and the Membrane, which lies immediately over the Articulations, with the mucilaginous Glands, that can there be the subjects of it. This, as other Membranes are found to be, may reasonably be thought to be acutely sensible. And if I should say, the Ligaments themselves have some sense. I do not think I should speak either absurdly, or erroneously. I know it is a common opinion, that they have none, as being a thing inconsistent with the convenience, and well-being of an Animal, and that, which would entail an uneasiness, and pain upon the motions of it. But supposing they were sensible, I do not see any necessity to conclude, that their motion, and the stress, which is at any time put upon them, would be uneasy, and troublesome, so long as that place of the Bone, upon which any part of the Ligament slides, is polished, and continually lubricated with a soft mucilaginous, and oily substance, and so long as there is no violence offered to them, and they are not extended so as to exceed their bounds prescribed by Nature. Is it not as strange, that the Stomach, which all must acknowledge to be sensible, does daily receive the Nourishment, takes in some matter, that is actually hot, as well as some, that is could, and by that matter is distended; yet feels not the ingress of the Food into its Cavity, perceives not the extension of its Fibres, unless there be something offensive in the quality, or some excess in the quantity of what we eat or drink. The reason of which seems to be very much the continual using, and accustoming of Nature to the thing. So in the Ligaments besides the smoothness, and lubrication of that part of the Bone, which they move upon, their being always contiguous to it, and accustomend to slip upon it, makes them unconcerned, and is the reason, why they perceive no disorder in their Spirits, though they have 〈◇〉 sensibility. And it is evident, that the contiguity of a sensible part to that softer substance of the articulated Bones, which is at their extremities, is consistent with the ease of it from the tendinous origination of the Musculus Biceps of the Arm, which in passing from the brim of the Acetabulum of the Scapula, over the Head of the as Humeri, has no Membrane intervenes between that and the Bone, but is immediately contiguous to it.  
When the weal-public Humour is acid, and flows into the Receptacles, as I may call them, of the Mucilage, or Interstices of the joints, and Sinuses of the Tendons, and comes to be mixed with it, the effect will be the same, or like that, which I observed in the Experiments I made upon it with Aqua Fortis, Spirit of Nitre, &c. that is a Coagulation, as I have shown before, when I treated of a Rheumatism. And this may give us the reason, why the Gout not only is often fixed in one place, but remains so long, and obstinate. For when the matter happens thus to be thick, and gelatinous, it is not to be expected, that it should be easily, and presently discharged out of the Interstices of the joints either by being resorbed, or evaporated, when the consistence of it renders it uncapable of insinuating itself into the minute Pores, and penetrating those narrow avenues, through which it is to pass. And according to the degree, and nature of the acid in the weal-public Humour, it does more or less Coagulate the Mucilage, and the part affencted is sooner, or later, with more or less difficulty freed from it either by the translation of it to another, or by the more happy exclusion of it out of the Body.  
As from the Hypothesis, by which I have endeavoured to explain the nature, and causes of a Rheumatism, and Gout, we may be able to solve the reason of all the Symptoms in an ordinary Arthritis; so from some of the Experiments, which I have given a relation of it seems to be no difficult thing to account for that tophaceous Matter, which is sometimes found concreted in those parts, that have been afflicted with this Distemper. I did then particularly observe, that an Acid, and an Austere being both mixed with the Mucilage did produce a plain, a notable, and white Coagulation, where the Coagulum, though it was made when the Mucilage was could, was not so soft, and tender, nor dissolvable in water like that, which was made with Acids only; but though it would break, remained distinct in it, and being dried was easily reducible to a fine powder like flower, or the fine powder of Chalk. Now therefore I do humbly conceive, that wherever the Gout comes ro be nodose, there is not only an acidity in the preternatural Humour, which is separated by the mucilaginous Glands, and mixed with the Mucilage, but it is an acid-austere, which is no sooner thrown into the Interstices of the joints, and the Sinuses of the Tendons, which are thereabouts, but but it produces a Coagulum in the Mucilage, and that such a one as is not easily attenuated, and dissolved, so that it lies fixed, and imprisoned there, and in time as the aqueous, and moist Particles are by the heat, and Spirits carried off, the Terrestrial and Saline parts concentrated come nearer together, and coming to be immediately contiguous do mutually adhere, and are concreted, so as to produce that Chalk or Tophaceous Matter, which is in some arthritick cases to be observed. And as the Coagulum, which may be made by an acid-austere seems apt to make a Concretion of that nature, so the colour of the Tophaceous Matter does answer to that of this Coagulation, so as to seem generated in this manner.  
I might here from some of those Experiments I gave an account of, observe how proper some preparations from Tartar, Spirit of Salt Armoniack, and those of the like nature appear to be in a Gout, where the Mucilage is coagulated either with an Acid, or an acid-austere, especially when the Coagulum is first made, and before it is plainly Tophaceous. For when it has proceeded thus far, we cannot promise ourselves much service from them, when it seems to defy our Art, and Physicians themselves confess, that Tollere nodosam nescit Medicina Podagram.  
And as Medicines of this nature are internally convenient, when the Mucilage is coagulated, so external Remedies of the same nature are certainly reasonable, and none that I know of seem to carry in them so much efficacy. Therefore I cannot but think that, that, which Dr. Willis prescribes in his Chapter de Arthritide, a Solution of Salt of Tartar, and Salt Armoniack in Spring, or Rain Water is an excellent fomentation in this case. However if it be used as it is prescribed without any distinction, and respect to that particular Humour, which causes the Gout, and the Coagulation, which it produces, it must necessary, as the Humour is not always the same, sometimes deceive our expectations, as no remedy will answer them, but when it is opposed to such weal-public causes, as it is apt to remove.  
It is a common Rule, and Observation in this Distemper, that the cathartics, which are used, ought to be very strong, which especially in case of an Acid, and a Coagulation will hold true. The reason of which will appear, when we consider that the exclusion of the weal-public Humour from the Mass of Blood, and the separation, which is made by the mucilaginous Glands is Critical, so that it is requisite they should be sufficient to alter the manner of the Crisis, and to turn the Humour into another Channel. But the principal reason seems to be, because the matter to be excerned is viscous, such as is not apt to be exagitated, nor easily removed out of the Cavity, in which it is lodged. But it seems reasonable, and necessary to attenuate the matter both by the internal, and external use of such means, as will dissolve a Coagulum, before they are exhibited. And if this be first done, perhaps more moderate Purges may be sufficient, and answer our intention more effectually.  
The Hypothesis of the Great, and Immortal Dr. Willis concerning the cause, and Ratio formalis of the Gout, is indeed very ingenious: But yet, if I may without the suspicion of arrogance discover my dissent from him in this thing, I cannot but say, that as there is no evidence or proof of the accumulation of an Acid from the Nerves to some particulae Salino fixae suggested from the Blood, from the congress of which he supposes there arises a fermentation, so neither could I ever observe by any Experiment such an effervescence, as he supposes, when I have at any time poured an Acid to the Mucilage, though it was sensibly salt. Neither is it necessary to suppose such an Ebullition, or Conflict between the weal-public Particles to make them painfully injurious to such sensible parts, as the Fibres. There is no body will question, but an Acid, an Acrious, or a Saline Matter, unless it be conveniently temperated, will without such a commotion, and only by contact be uneasy to them, and excite such acute pains, as we have in this Distemper. Therefore this supposition, as I conceive, is made rather to explain the Cause of the Tophi, than the reason of the pains. For the Doctor from the observation of a Coagulation made by the mixture, and after the effervescence of Spirit of Vitriol with Oil of Tartar supposes it probable, that from the mixture of an Acid derived from the Nerves, and of a fixed Salt from the Mass of Blood, made in and about the joints, there follows first an effervescence, and at length from various Fermentations, and Coagulations of them there is generated a Tophaceous, and chalky Matter. But what I have offered with a design to explain the manner, how these Tophi are produced seems confirmed by some Experiments, and such as were made with the very liquour, which is actually separated about those parts, and to be found, where the Tophaceous Matter is generated, and so comes nearer to a Demonstration.  
According to that Hypothesis the Matter, which is the cause of the Gout, is to be always the same, to wit an Acid from the Genus Nervosum, and a fixed or Alchalizate Salt from the Mass of Blood, which if it were so, I do not see, how there should be such a difference in the effects of the same Remedies: For if there be at no time a difference in the weal-public Matter, that, which is beneficial to one, would as certainly relieve another, and so every one that labours under this Distemper, allowing only for the various degrees of Concretion in the coagulated Matter, which is contradicted by daily experience: So that we must conclude there is such a difference in it, as I have supposed, at least, that it is not always of the same nature.  
I shall say no more concerning this Subject, only as the nature, and effects of some Remedies, which I have known used in the Gout, have agreed with the Notion I have of the Causes, and Nature of it, and confirmed me in my Opinion, so I have satisfied myself about the Etiology of their effects, and the manner of their operation from my Hypothesis, and perhaps, if it be well considered, it may led us to more rational, and effectual means, and methods of Cure, than are now made use of. Which it is not proper at this time to insist upon, when the design of my Discourses should confine me to Anatomy, and natural Philosophy, and every incursion into the Province of Medicine is a running away from my Argument.    

The FIFTH DISCOURSE OF THE CARTILAGES.  
THus I have pursued the method I at first proposed, as far as the Cartilages, which though I cannot call Bones, yet so nearly are they allied to them, that it is not very strange to find them stepped out of their own form into the Classis of Bones, and therefore it will not be improper, though the Argument be different, to carry on my Discourses, with those Observations I have made of them, and with the account of their Nature. In some Fishes all the Bones, if I may so call them, are no other than Gristles, and there are in Man the most perfect of all Animals some of them, that continue cartilaginous for some considerable time after the Birth, and are in the ordinary course of Nature converted into Bones. The preternatural mutation of them of the Aspera Arteria, of the Cartilago Eusiformis, and some others into Bones is no more, than has been observed. So in Horses, Oxen, and some other Beasts this change is not very rare in the Cartilages of the Thorax.  
But notwithstanding the aptitude there is in the Cartilages to become Bones, yet the difference, when they are one, and when they are the other is considerable. First in their substance, and comformation. The substance of the Cartilages is softer, and the parts of them more easily divided with the Knife, neither have they any large Cavities as some, nor any spongeous part, as all the Bones have. And whereas the Wall, or that, which makes the sides of a Bone is the most solid part of it, I have in several Cartilages observed it to be quiter contrary, to wit, that the exterior part was the softest, and most flexible.  
Secondly, They differ in their flexibility. The Bones are rigid, and more tenacious of their figure, the Cartilages are flexible, and more apt to be conformed to those figures, which the force, that bends them, would oblige them to.  
The reason of this flexibility in one above the other is the difference, there is as to the union of their Particles, which in a Bone are at their extremities so united in every series, as to form a continued and an entire string, and when all inflection obliges the extremities of some Particles either to recede, as where the convex is elongated, or to approach nearer to one another, as when the Concave is shortened, consequently that Body, in which they are so united, that they can do neither, must be rigid, and unapt to be bent.  
The flexibility of the Cartilages arises, as in all other Bodies, that may be bent without injury, from the position, and figure of all, or at least some of their Particles, as well as from the disunion, and distinction of their extremities, which are of a long figure, and have a streight position, so that one extremity looks towards one, and the other towards the other end of the Body, which they are the parts of.  
Besides the long figure, and the streight position of these Particles, there is a certain order observed in the placing, and disposition of them, which is such, that the extremities of those in one Series do not terminate just, where the extremities of the Particles, which are in the Series next to them, do; but they lye beyond them, and reach to some intermediate part between the extremities of those Particles, which lye next to them laterally, as I have expressed in the third Fig. Tab. II. For as the extremities of the Particles in a flexible Body must be distinct and their figure such, that those, which lye in one Series may be capable of moving, and sliding upon them, which are contiguous to them in the next, so must their position, and order be such that they may slip, and the extremities of their Particles may not only approach nearer to but recede from one another without interrupting the continuity of the Body. For want of the first of which the Body would be inflexible, and from a deficience in the other, it would be inevitably broken upon being bent when any part of it is elongated. But upon these suppositions we may easily conceive how a flexible Body may be inflected without a dissolution of the continuity of it, even when the convex part is lengthened, and the extremities of the Particles recede one from another. Where they are driven closer together, it is true, there is no reason to think, that a Fracture should be the consequence of an inflection though the extremities do not lye in this order. But without doubt in the bending almost of all Bodies there is an elongation of one side, even when the other is shortened, and supposing the alteration, which is made in the position of their Particles to be by their recedure, yet still the Body will be as secure against a Fracture, and as capable of being inflected without any injury, whilst the order of its parts is such as I ascribe to them: As suppose in the fourth Fig. Tab. II. a, a, a, a, to be four Series of Particles lying contiguous to one another laterally, and making one Body, suppose those of the first, and third Series, which have their termination about the middle part of them, which lye next to them in the second, and fourth, to be moved, and to slide at one end towards b, and in the other part towards c, so as to elongate the whole Body, we may apprehended, how they may move both ways, and slip upon the Particles, which are laterally contiguous to them, without any injury to the continuity of the whole, and until they come as far as d, or the Interstices between the extremities of the Particles in the second, and fourth Series there will be no Fracture. But when they are forced so far, that one of their extremities is brought to those Interstices, there will necessary follow a solutio Continui. And this is the reason why a Body, when it is too much inflected, breaks, and why it is broken first in the convex part, for on that side is the recedure of the extremities of the Particles, and the nearer they lye to the superficies there, the more considerable it is, and consequently they are first brought to the Interstices between the extremities of those Particles, which lye next to them laterally.  
Not, that I suppose, that all the Particles in every flexible Body obtain such a position, or that every one of them; that lye in the same Series, are capable of receding from, or moving nearer to one another, but there are so many, that are, as answer to the degree of inflection, that the Body is capable of salvâ continuitate. And according to the number and proportion of the Particles, that are of a streight figure, and thus posited, and according to the length of them, and the distance of the extremities of the Particles in one Series from the extremities of those, which are contiguous to them laterally, the Body may be more, or less inflected without a Fracture.  
Besides their flexibility, the Cartilages have some rigidity, and a power of restitution or recoying, when they are bent, which is very evident in the Epiglottis, though it be not so rigid as some other Cartilages, which has no Muscles to pull it up, but does after it has been d●●●est by the descending Food rise by its own innate power of restitution into its natural position, which reflection may be observed in it after the Animal is dead, when it is prest down upon the Rimula of the Larynx.  
This seems to arise from the Air; sometimes from the pressure of the external Air, sometimes from an Aer insitus included in the Interstices of the Body itself, but generally from both. As I have shown, that it is necessary the extremities of the Particles in a flexible Body should be distinct, so we may reasonably think, there are some Spatiola, or Interstices between them,( nay in many Bodies, which are rigid, they are very visible,) in which there is an imprisoned Air, which, as it is evident from innumerable Experiments, is endured with an Elasticity or Spring. So that whatever presses upon its Spring, and as it were winds it up to an extraordinary height, will cause a sensible renitency in it, and an endeavour to expand itself, and this resistance in the Air, when it is crowded into a narrower space, than is convenient to the nature of it, is that which gives a recoiling Body the power of reflection, and obliges it, after it is bent, to return to its former figure, in which the Spatiola within it obtain their natural capacity, and the Air which is compressed recovers the liberty of expanding itself.  
When the concave part of any rigid Body, that is bent, is shortened, and the extremities of the Particles are prest nearer to one another, the Interstices between them will necessary be rendered less, and the Air included in them will be compressed, so that the Spring must be, as it were wound up, and the natural consequence of this compression will be a renitency in the Air, or an endeavour to drive the Particles into that posture, and the whole Body into that figure, that will restore the natural capacity of the Interstices, which was accommodated to the quantity of Air contained in them. The strength, and powerful resistance of the aereal Spring, when the Air is contracted into a narrower space, than what it usually, and naturally expands itself in, is evidently seen in the use of a Wind-Gun, where a greater quantity of Air is crowded into it, than the space, which it is confined to, is capable of containing without a violent compression, and running up the Spring of it to an extraordinary height, and when the Gun is discharged, when the included Air has the liberty of dilating itself, and relaxing its Spring, we find with what a force it exerts its elasticity.  
But when the convex part of a recoiling Body is elongated, when the extremities of the Particles on that side recede from one another in inflection, the pressure is then not upon the Air, which is included in the Interstices of the Body, but upon the external Air. Forasmuch as the Spatiola between the extermities of the Particles are enlarged, so far the Body incroaches upon the Atmosphere, and so long as the external Air is excluded, and has not the liberty of filling up what is added to the capacity of the Interstices, there is nothing to answer for that space which the Atmosphere loses, so that the external Air must necessary be compressed, and the Spring of it heightened Thence follows in it an endeavour to drive back the Particles of the inflected? Body into their natural position, and to reduce the Spatiola of it to their former capacity, which cannot be be done without the restitution of the Body to a more streight figure. An effect of this nature from a pressure upon the external Air we have formerly seen here in an Experiment made by Monsieur Papin before this honourable Society, which was done with the Barrel of a Gun fitted to the Air-Pump. In which Experiment the Air being exhausted out of the Gun, and obtruded upon the external Air, and the external Air being excluded from the Cavity of the Barrel, so that it could not obtain any space to answer for that, which the evacuated Air then occupied, it was compressed, and the Spring of it considerably heightened, which afterwards appeared, when the breech of the Barrel was opened, and the external Air had the liberty of expanding itself; for it rushed in with that violence, and exerted the power of its Spring so much as to shoot the Bullet, with which the Gun was charged, with a great violence.  
I have been the longer insisting upon the nature of flexible Bodies, and made it one part of my busine●s at this time to explain the reason, why those, that have a rigidity, do receil not only to show why the Cartilages may be bent without breaking, and how they endeavour to return, after they are bent, to their natural figure, but because I designed, that what I have said concerning the flexibility, and power of restitution, which are in some Bodies should serve as some account of the nature of these parts, of the Particles, which they consist of, and of the order, in which these Particles are disposed. Now therefore to make a particular application of what I have said of the nature, and parts of a flexible and recoiling Body, to the Cartilages, the figure of their Particles is long, and they are smooth, their position streight, their extremities distinct, between which there are Interstices, and in these Interstices is an included Air, the Particles are disposed in a certain order, so that in every Series they reach with their extremities to some intermediate part, or near to the middle of those, which are next to them laterally, and lye quiter over the Interstices, which are formed between the extremities of those on their sides, whereby the Spatiola are enclosed, and the Air contained in them is strictly imprisoned.  
From hence we may understand, wherein the difference between a Bone and a cartilege does consist, that in one the Particles are united at their extremities so, that every Series makes a continued, and complete string, whereas in the other they are distinct, and there are little distances, or cavities between their ends, so that they are in every Series capable of being driven nearer to, or forced farther from one another. And this is the alteration, that a cartilege undergoes when it becomes a Bone, to wit, the Particles at their extremities are so nourished, and receive such an addition, as to touch one another there, to unite, and acquire a continuity, which makes them in every Series form an entire string, when the implanted Air has a passage out of the Interstices, and gives way to that Nourishment, whose accession it did before resist. By this union of the Particles the temper of it is altered, and it being difficult to disengage, and part them, it grows firm and inflexible.  
The terrestrial parts, and the fixed Salt in the Cartilages, whilst they obtain their proper nature, are much less in proportion to the other parts, than they are in a Bone. For I find there remains after Calcination but about a fifteenth part.  
The Cartilages have a Membrane, as the Bones have, which to speak properly we must call the Perichondrium, though it is in a manner the same, and a continuation of the Periosteum, consisting of the same sort of threads, being of the same texture, and every way so agreeing with it, that I need not stand to give a particular account of it. Neither does the use and design of the Perichondrium differ from them of the Membrane, which immediately covers the Bones, it serves to cloath the parts, and helps to set bounds to their Accretion, it supplies the want of Nerves in them, gives them a sensibility, and affords them those Spirits, which are necessary to assist in their increase; and is a medium, whereby the Tendons of the Muscles are fixed to those Cartilages, which have any of them inserted into them as those of the Larynx, and some others. But in those, that are joined to any of the Bones, it seems to be chiefly serviceable in strengthening their conjunction. For though there be another contrivance for joining of them, yet when this Membrane is taken off, or divided round that part, where they meet, they are easily separated.  
For strengthening the adhesion of the Perichondrium to the Gristles, and consequently to make the conjunction of the Bones, and Cartilages, which are united, and the union of any part, that appertains to them, more firm, they have little Furrows, and superficial Pits, or depressions so to enlarge their superficies, where their Membrane is applied, and adheres to them, which it does partly by an immediate contiguity, which manner of Conjunction, as I observed, when I gave an account of the Periosteum, is so much the more firm, as the surface where two Bodies, so united do immediately touch one another, is larger, and therefore this Membrane has on that side, which lies next to the cartilege, inequalites, and protuberances exactly fitted to, and filling the superficial Cavities, which are formed in the part it adheres to.  
But besides this manner of Conjunction, their Membrane is united to them by small Fibrillae, or threads, which enter some way into their substance, as those of the Periosteum are inserted into the Bones. By these are supplied the Spirits, which serve in their Accretion, and by whose mediation we may reasonably suppose, that the Cartilages have some other sense, than what is external, and merely in their Membrane.  
Though they present us with a whitish colour, they are not destitute of Blood Vessels, but they have abundance of them, so that in the single Cartilago Thyroides I have seen some hundreds of Pores, by some of which some of the Vessels passed into it, as by others some of them had their egress. These all serve only for their Accretion, and Nutrition.  
The Cartilages do not seem to have any medullary Oil separated within them from their Arterial Blood. For though they evidently stand in need of something of that, or the like nature, and when I have traced the Blood-Vessels, which run along commonly in the middle of those Cartilages, which are of a long figure, so far as the part where I thought they had their termination, I have sometime found an oily substance beyond it, yet I could not discover any Vesicles, or Glandules for the separation of it, so that that Oil seemed to be supplied from the Bone, to which it was united. Thus in my account of the Marrow I supposed some part of the medullary Oil to be assigned to the Cartilages, where they are joined to any Bones, and I observed that there are Pores, which I cannot but think are formed for the communication of it from one to the other.  
For the joining of those Cartilages to the Bones, which are united to any of them( besides the service of their Membrane, which I have taken notice of) the Bones are formed in that part, which is applied to them with some conspicuous Protuberances or short and obtuse Roots, and other lesser Radicles, which are numerous, and stand thick together as well in those Protuberances as in the other parts of that end of the Bones, by which they are a little way implanted into the Cartilages.  

Of the USE of the CARTILAGES.  
THE use of the Cartilages in general is no obscure thing. We must consider, that there are some parts of the Body, which require a greater strength and solidity, than was agreeable with the nature of the Fibres, or Ligaments, as they are necessary for the defence of some tender, and noble Parts, or for the Dilatation of some passage, to keep it distended, and to restore it to its natural capacity, when it has been compressed, and straightened; and yet withal it was no less requisite, that they should be more flexible, than the Bones, and so pliable, as to alter their figure, when the motions, and actions of some of the parts, which they either protect, or are united, or adjacent to, do require it. Now to make a Part both solid, and flexible, and so capable of answering both these intentions, Nature has formed the Cartilages, which are of a middle temper between a Bone and a Ligament, that partake of the firmness, and rigidity of one, and the flexibility of the other, and they are made use of wherever a firmer part than a Ligament, and a more pliable substance, than a Bone is required. And it were an easy thing to show, how all parts of this Constitution are necessary, and serviceable in every part, where they are planted: But I think it not needful, since every one, that does but view, and consider the parts, which they are appointed to, may have the prospect of them, and the reason of this contrivance at the same time. I shall only give my thoughts particularly concerning the use of the Cartilages, which are united to the true Ribs, because their use, and the manner, in which they are serviceable in Respiration seems to be imperfectly explained, and not truly understood.  
Any one may be sensible, how improvident Nature had been, if she had made the Walls of the Thorax fibrous, and placed two of the greatest Engines of Life without a solid defence on those sides, which are obnoxious to external pressures, and injuries. But as these parts were to be protected, so there is the necessary action of Respiration, which as it was not to be interrupted, nor the parts inservient thereunto to be injured by external violence; so there must be some contrivance, that it may not be hindered by the structure and nature of the parts, which enclose the Cavity of the Breast. If the Cartilages of the Breast had been Ligaments, or only membranous, the Heart, and Lungs could have had no defence and security against the impressions, which the violence offered to these parts had been apt to make upon them. If they had been plainly Bones, that Bow, which lies between the Sternum, and the Vertebres had not been capable of an Elongation, which is certainly the thing designed in making some part of it cartilaginous, that by the reducing of that part to a more streight figure both the Vertebres, and Breast-Bone may be protruded.  
The learned, and ingenious Dr. Mayo has given us a good account, how the Ribs do contribute to the ampliation of the Breast by the alteration of their position, and being raised from that Plane, which divi●es the Cavity of the Breast into two equal parts, towards which they did before incline, be it the Mediastinum, or be it imaginary, so that whereas before they made acute, they come to form right Angles with that Plane. For the Ribs, as he observes, are not articulated with the spin, and Breast Bone at right Angles, but so as to form acute Angles beneath themselves, and he supposes the Cartilages are joined to them to add to their length, and for augmenting the Concave of their Arch. And this is demonstrable, that if several Bows, or incurvated Bodies as the Ribs are, lying upon, or inclining to a Plane, be so raised as to rest upon their extremities, and to make Right Angles with that Plane, they will form a large Cavity under their Arches. But if this were the design of the Cartilages, the Ribs would have done this as well if every one of them had been a continued Bone from the Sternum to the Vertebres. Therefore I conceive, that they are intended to make the Ribs more capable of altering their figure, and so contribute another way to the dilatation of the Breast. I shall not then be afraid to assert, that the Cartilages do some particular way add to the capacity of the Breast in Inspiration, as I doubt not, but they likewise act a part, and assist in the Contraction of it, when the Air is forced out of the Lungs.  
First I say they help in enlarging the Cavity of the Thorax, not merely by being raised from the Plane, towards which the Ribs incline, when the Air is evacuated, but by altering their figure, when they ascend towards the Clavicles. For if we strictly observe the ampliation of the Breast, when we draw in the Air, we shall find, that there is something more added to the Capacity of it, than what can proceed from the elevation only of the Ribs, it will appear to any one, that takes notice of it, that the Vertebres of the Thorax are driven outwards, and the Sternum though not so sensibly is protruded, when we inspire, which cannot be effected by the elevation of the Ribs, and their forming Right Angles, with that Plane, from which they are raised. For although this does enlarge the Cavity of the Breast in that part, which is under their Arches, yet this elevation alone does make no alteration in their Longitude, without which it is impossible they should protrude both those parts, that are joined to their extremities, at the same time. For so long as the distance between their extremes is the same, when they are pulled up towards the Clavicles, as when they descend, this alteration of their position only can no ways thrust forth the parts, which are fixed to their extremities.  
Therefore to solve this thing of the protrusion of the Vertebres and Sternum in Inspiration, we must suppose, when the Ribs ascend, such a change of their figure in some part of them, as makes an addition to the length of the whole. And we shall see how this is done, if we observe the figure of the Cartilages, that are joined to the true Ribs, how it is a sort of an Angle, so that as this Angle is more or less Obtuse, the extreme part both of the Rib, and cartilege, recede farther from, or come nearer to one another. So that when the Ribs descend, and incline towards their Plane, and their Cartilages obtain their natural figure, this Angle, as it is always obtuse, comes nearer to a Right Angle, but when they are drawn up, it is rendered more Obtuse. And as the alteration of their figure when we draw in the Air, and the restitution of it in expiration require their flexibility, so I have observed these Cartilages to have continued cartilaginous, and flexible, where this Angle has been, when the rest of the cartilege has been of a bony nature, which confirmed me in my Opinion, that this angular part of them is particularly designed for their elongation at that time, when we inspire. Now this is capable of a Demonstration, that as an Angle becomes more Obtuse, and it approaches nearer to a streight Line, the distance between the extremities of the two lateral Lines, which form it, will be increased. So it is here, the Angle of the Cartilages being rendered more Obtuse by the contraction of the Intercostal Muscles, and they being reduced nearer to streight figure, when the Ribs are raised, their extremities do necessary recede from each other, and consequently thrust out the Sternum, to which they are united at one end, and drive back the Ribs, which are joined to the other, by the mediation of which they protrude the Vertebres. And if this were not the design of that angular figure, which these Cartilages obtain, to wit, to add to the Capacity of the Breast by the protrusion of those parts, but only to enlarge the Cavity or Arch under the Ribs in their elevation, I do not see why Nature has made this difference between their figure, and that of the Ribs and did not rather give them both the same obliquity so as to make one exact Bow of them both. Nay why has Nature made any such thing as Cartilages here, and filled up some part of the distance between the Vertebres and Sternum with a substance of a flexible temper, if it were not with this design to make them capable of an elongation, when if every Rib had been a continued Bone to the Sternum, and had had no such thing as a cartilege joined to it, it had with an Articulation at the Breast-Bone been as readily disposed to ascend towards the Clavicle, and would have formed the same Arch, as it does with it, if we suppose no alteration in the figure of this part.  
I have secondly made these Cartilages to conspire in expiration, to prove which we must consider, that they obtain their proper figure, and their parts have their natural position only, when the Breast is contracted, and because there cannot be such a change in the figure of the Cartilages, as renders their Angle more obtuse, than it naturally is, without the same disturbance to their Particles, and the same alteration in their Pores, or the Interstices between the extremities of the Particles, as there are upon the inflection of any rigid Body,( for what inflection is to a Body that is streight, the same is extension to that, which is crooked) therefore there must necessary be a pressure upon the Spring either of an internal, included Air, or of the external Air, as the Convex is shortened, or the Concave is elongated: For in the extension or reducing of an obliqne Body nearer to a streight figure, different from what it is in the bending of one that is streight, when there is an elongation, it is on the Concave, and the abbreviation is on the Convex part.  
These Cartilages therefore having from the Spring of the Air a power of restitution, will, when their figure, and the capacity of their Pores are so altered, as to make a pressure upon it, recoil, and without the help of any Muscles return to their first figure, as we see in the Epiglottis, which is not so rigid. By this power of restitution they are one cause of their own, and of the Ribs subsidence, whereby they contract the Cavity of the Breast, and by making a pressure upon the inflated Lungs contribute to the expiration of the Air, which distended them. And this is one great reason, why the Thorax is contracted in all dead Bodies. This we cannot think proceeds from any action of the Muscles, which serve for expiration, unless we will suppose they are always the last that act, which seems to be improbable, when we have better reasons to conclude that the inspiratory Muscles are the last of all these, that contract themselves. Let them be which they will, this is certain, that after Death neither of them can modify the Cavity of the Breast either by contracting or distending of it, whereas if the Lungs are then inflated, and the Thorax is dilated, still it afterwards contracts itself. And though this is partly to be ascribed to the subsidence of the Vesiculous substance of the Lungs, yet if we consider, that the resilience, or reflection of these Cartilages, when they are extended, arising from the elasticity of the Air, without any dependence upon the Animal Spirits the power of it remains the same, when the Body is dead, as it was before, and that they have still a natural conatus to return to that Figure, which they cannot obtain without the depression of the Ribs, and the contraction of the Breast, we cannot but think, that this is one thing, that determines the posture of the one, the figure, and capacity of the other after Death.   
FINIS.   

ERRATA.  
page. 10. Line 3. red are. p. 42. l. 18. for four r. three. p. 56. l. 20. r. render. p. 87. l. 10. r. does. p. 95. l. 15. r. places. p. 109. l. 5. r. Glandules. p. 146. l. 25. r. exactly to. p. 186. l. 5. r. an. p. 199. l. 21. for Glands r. Glandules. p. 222. l. 24. r. joints. p. 226. l. ult. for our r. one. p. 227. for it r. the matter. p. 233. l. 15. r. they.   

A Catalogue of physic Books lately Printed for Samuel Smith, at the princes Arms in St. Paul's Church-Yard.  
PRaxeos Mayernianae in Morbis internis praecipue Gravioribus& Chronicis Syntagma, ex Adversariis, Consiliis ac Epistolis ejus, summâ Curâ ac Diligentia concinnatum. 1690.  
Phthisiologia seu Exercitationes de Phthisi tribus Libris comprehensae. Totumque Opus variis Historiis illustratum. Autore Richardo Morton, Med. Doct.& Regii Collegii Medicor. land. Socio. 1689.  
De Morbis Acutis Infantum. Autore Gualtero Harris, Med. Doct. Celeberrimi Collegii Medicorum Londinensium Socio, atque Censore. 1690.  
Synopsis Methodica Stirpium Britannicarum, in qua tum Notae Generum Characteristicae traduntur, tum Species singulae breviter describuntur: Ducentae quinquaginta plus minus novae Species partim suis locis inseruntur, partim in Appendice seorsim exhibentur. Cum Indice& Virium Epitome. Auctore Joanne Raio, è Societate Regia. 1690.  
Pharmacopoeia Bateana. In qua, Octingenta circiter Pharmaca, pleráque omnia è Praxi Georgii Batei Regi Carolo Secundo Proto-Medici excerpta, Ordine Alphabetico concisè exhibentur. Quorum Nonnulla in Laboratorio Publico Pharmacopoeano land. fideliter parantur Venalia: Atque in usu sunt hodierno apud Medicos Londinenses. Huic accessit Orthotonia Medicorum observata: Annexa item est in Calce Tabula Posologica Dosibus Pharmacorum quorundam expeditiùs computandis accommodata. Curâ Ja. Shipton Pharmacopoei land. 1688.  
An Essay of the great effects of even Languid and Unheeded Motion. Whereunto is Annexed an Experimental Discourse of some little observed Causes of the Insalubrity and Salubrity of the Air and its Effects. By the Honourable Robert boil, Fellow of the Royal Society. 1690.  
R. Boyle's memoirs for the Natural History of human Blood, especially the Spirit of that liquour. 1684. Octavo.  
— Experiments and Considerations about the porosity of Bodies. 1684. Octavo.  
— Short memoirs for the Natural Experimental History of Mineral Waters. 1685.  
— Of the reconcileableness of specific Medicines to the Corpuscular Philosophy; to which is Annexed a Discourse about the Advantages of the Use of simplo Medicines. 1685. Octavo.  
The Philosophical Transactions, published by the Royal Society Monthly. Quarto.  
Acta Eruditorum ab Anno 1682. ad An. 1690. Lipsiae. Quarto.  
Pharmacopoeiae Collegii Regalis Londini Remedia omnia succinctè descripta; Atque Serie alphabeticâ ita digesta, ut singula promptiùs primo intuitu investigari possint. Editio Altera Priori Castigatior& Auctior. Huic annexus est Catalogus Simplicium, tum locupletior tum Compendiosior, quàm antehac Editus. Accessit in Calce Manuale ad Forum: Nec-non Pinax Posographicus. Curâ Ja. Shipton Pharmacop. land. 1690.