ESSAYS OF ANATOMY In which the Construction of the ORGANS AND THEIR MECHANICAL OPERATIONS. Are clearly Explained according to the new HYPOTHESES.  
By ****** Dr. in Medicine.  
Written Originally in French.  
EDINBURGH, Printed by George Mosman, and are to be Sold at his Shop in the Parliament Close, Anno Domini 1691   

TO THE RIGHT HONOURABLE The VISCOUNT of TARBET.  
My LORD,  
THe following Treatise receiving the Approbation of a most Ingenious Peice, it has encouraged the making and publishing this Translation, to supply the scarcity of French Copies, and to satisfy the Curious, who do not understand that Language. And because the Author of the Essays has both the Honour of Your Lordship's Acquaintance, and also the Favour of Your good Opinion: Therefore Your Lordship's Patronage and Protection, is Humbly desired to this Translation, which will be found a just enough Representation of the Author Thoughts and Sentiments. And the Publisher hath presumed to prefix Your Lordship's Name to this, that He may testify his Duty to Your Lordship; and likewise because of Your Lordship's readiness to encourage all Ingenious Studies and Enterprises.   

The STATIONER'S ADVERTISEMENT TO THE READER.  
THose who Judge of a Book by the Title, are Discouraged when a Title is Simple; and on the contrary, believe that a Work is Excellent, when Men have the Art to give a great Idea of it, by an ingeniously invented Title; we might doubt of their acceptance of this little Treatise, if many others which have appeared with the same Modesty, and have nevertheless had a great Success, had not favourably disposed the Reader for the word Essays. Since those of the Famous Montaigne, how many others have appeared in Physic and in Morality, which have been the Admiration of all the Learned? I hope therefore that they will not be prejudiced against this present Treatise, because it promiseth nothing but Essays, and that they will have the Patience to see what it says. After which I am persuaded they will be satisfied. I shall say no more to recommend my Merchandise.   

THE PREFACE.  
THe knowledge of the Living Body is extremely necessary for Physicians. Without it they do nothing but at adventure. This is a Flambeau which gives them Light in the Causes of Diseases, and in the Choice of Remedies. And all they who understand nothing in it, can be reasonably concluded no other than Charletons'.  
The most part of Judicious and Ingenious Men have always acknowledged this Truth. It is for this that they have ever cultivated Anatomy with much application. In the past Ages they thought they knew all that could be Learned of it. And in this, they have found, to the shame of Physicians, that they have made but a very small advance in this Science.  
The preoccupation in which they were in past Ages in favour of the Ancients, was the Cause why they did not apply themselves to Learn but what these had discovered. Hypocrates and Galen only were then studied. They sought in their Writings, all that they were obliged to know to render; them Learned Men. They imagined they knew all, and took those for Visionairs, who pretended to know more than these. Thus the past Ages have been extremely barren in Discoveries.  
But, Thanks to the Penetration of an excellent Philosopher of this Age, it has been discovered that the Living Body is nothing but a Machine. Men have applied their Minds to discover its Springs. In this Harvey and Pecquet have been successful. The Circulation of the Blood has Immortalised the one, and the Reservatory of the Chyle and the Thoracick Conduit, has given the other a Reputation, which will never end.  
Their Example has animated all the Anatomists. They found they had made small progress in the knowledge of this Machine. They were persuaded that they needed but search to make Discoveries. In effect the Bartholin's, the Wharton's, the Steno's, the Willis's, the Glisson's, the Lower's, the des Graaf's, etc. And above all the Malphigis have searched very deep into the Structure of the Living Body. The Discoveries which they have made do give us an Idea of an Animal, altogether different from what the Ancients had of it.  
It might seem that after them, there remained nothing to be Discovered. Nevertheless there are Treatises frequently published, which contain some new thing, and I doubt not but an hundred years hence they may make some new Discovery.  
The Contrivance of the Body, is necessary for explaining the Office and Function of its Parts; and if what we fancy to to be the Contrivance, is not sufficient for the Explication of the Operations of the Body, nor the Effects of its Particular Members and Parts we may therefore conclude that there is something of this Contrivance yet to be Discovered. The best Anatomists do ingenuously acknowledge, that they fail in many Particulars; there are therefore many Discoveries yet to be made.  
Some of them will be found in these Essays; and to me they seem Important enough to make me believe that they will not be unacceptable. I do not conceive the same hopes of my Sentiments, concerning the nature and use of the Liquors which are found in the Living Body. To those who are prejudiced, the Novelty of the most part of them, will make them seem extravagant. But I hope those who do not condemn an Opinion, without having examined it, will do me the favour to believe, that if they find them Erroneous, I was not hastily mistaken without good and probable inducements.  
I shall only beg of them to Read the first Treatise of these Essays, before they read the rest. It gives the Idea which I make to myself of the Elements, and without it, they will not conceive so distinctly what is contained in the rest.  
There is a great Connexion between all the Treatises of these Essays: Those who would understand them well, will not do ill to read them in Order. The Order which I give them will seem Fantastical to those who are accustomed to read Courses of Anatomy written according to the Ordinary Method. But they who shall observe that each Treatise serveth for the understanding of that which followeth, will acknowledge that I have given them a Natural Order.  
Perhaps it may be thought strange, that I make no mention of Authors in the places where I set down their Discoveries. They may even think that I do it on Design, to attribute to myself the Glory of them. In this they would do me a great Injury. I am not so base as to acquire Reputation at the Expense of that of others. But I have not named those who have made the Discoveries, because every Body knows them and it would serve nothing for the understanding of these Essays.  
There is an excellent Anatomist at Montpellier, who is called Monsieur Chirac. The first reason which has made me wave the Names of others, has no place as to him. Nevertheless, I have not Named him any where. But I'll do him Justice here. It is he who has written to me, that all the Glandules were nothing but heaps of Circumvolutions of Vessels; after which I have told him. That by chance I have observed something like to this in the Prostates of a Dog.  
Moreover almost all Authors do place their Names at the Frontispiece of their Works. This probably flows from the good Opinion that every one has of his own Productions. Every Body is fond of them. There is scarce a silly Scribbler, who does not imagine that his Work has something of Transcendent in it. Though for the most part it is nothing but a Multilation of good Authors.  
By this you may know the reason why I do not as others. I have not a good enough Opinion of this Work to imagine that it will do me a great Honour. Besides I Writ but to expose my Thoughts to others, to the end, that if they be wrong, they may Correct them, and if they be just, they may help forward to better.   

ESSAYS OF ANATOMY.  

The first Discourse. Of the Elements of a Living Body.  

SECT. I. Of the first Elements.  
THe Idea that we have of Matter and Motion, leads us to think, that all Bodies are composed of Insensible Corpuscles, of different Magnitude and Figure If it fall out that many of these Corpuscles are united, they compose little Masses, which we call Molecules. And if they continue separated from one another, by reason of great Agitation, they compose a Matter which we shall call the Aethereal Matter.  
Whereas the Molecules are form by the assemblage of parts of the Aethereal Matter; there is amongst them an almost infinite diversity, as well in respect of their Magnitude as their Structure and Figure. This will be evident enough to those who shall consider, that the parts of the Aethereal Matter are very different from one another. It is for this that the Molecules, which are made up of them, have great diversity amongst them. And since we have no reason to deny, but that they are of as many sorts as can be, we may well think that they differ amongst themselves an infinite number of ways, as well in respect of their Magnitude, as of their Structure and their Figure.  
To examine well the differences of their Structure and Figure, all the Molecules, may be conveniently reduced to five kinds. The first shall be of those which have sharp Angles on their Surface with much Solidity. We shall call these kinds of Molecules, Acides. The second shall be of those which have many Pores, great and open. These we shall name Alcalis. The third shall be of those which are branched, we shall call them Sulphurs. The fourth shall be of those which are long, and their Extremities like those of an Oval. We shall name them Phlegm. And in fine, the fifth shall be of those, which have not sharp Angles on their Surface, which are not very Potous, which are not branched, and which are not Cylindrical with Oval ends; but which are either round, or Oval, or rough, etc. and we call them Earth.  
The Aethereal Matter flows without ceasing through the Pores of the Molecules, it fills also all the spaces where there are no Molecules. And the Molecules compose all the Bodies which we call Terrestrial  
A living Body is one of these Terrestrial Bodies which are composed of Molecules. Therefore Acids, Alcalis, Sulphurs, Phlegm or Earth must needs be in it. Being therefore that we have proposed to give a clear Idea of its Elements in this Discourse, we shall examine the nature of Acids, Alcalis, Sulphurs, Phlegm and of Earth.   

SECT. II. Of Acids.  
TO understand well the Nature of Acids, we must examine their Figure, their Stature, and their Magnitude. As to their Figure, when I examine the matter nearly, I remark that there is amongst them almost an infinite difference. There are Conical, Triangular, Regular and Irregular of all sorts: There are of them whose Angles are very sharp, and others of them whose Angles are less sharp. There are who have many Angles, and others who have fewer. And since there may be amongst all this an Infinity of different Modifications, we make no scruple to say, that there is almost an infinite difference amongst Acids, by reason of their Figure; Which makes me think, that it would be a fruitless labour to endeavour to know all the differences which are amongst the Acids, by reason of their Figure The multitude of them being Infinite, we cannot hope to know them all. We shall therefore content ourselves to know in general, that all the Acids have sharp Angles on their Surface, without enquiring whether the Spirit of Sulphur, for example, has its parts Conical, Pyramidal, of many sides, or otherwise.  
As to the Structure of Acids; forasmuch as it consists in the ranging of the Particles of the Aetherial Matter, we need not doubt but that the diversity which is amongst them in this respect, is almost Infinite. In effect, the ranging of these Particles depends upon their Magnitude, as well as on their Figure and their Motion.  
Now there is an Infinite difference in the Magnitude and Figure of the parts of the Aetherial Matter, and they move an infinite number of ways. There must therefore be an Infinite difference in the Structure of Acids.  
Nevertheless, forasmuch as hardness depends on the Structure, because the more hard a Body is, it has the fewer Pores, or its Pores are the smaller, we may suppose that we know in general the Structure of all Acids; in that they being the hardest of all the Molecules, they must have the fewest Pores, or at least such as are the smallest. It shall satisfy us to know this, without troubling ourselves to no purpose, to discover all the Modifications which may be in the Pores of Acids.  
As to the Magnitude of their parts, the difference is also infinite; so that to consider them in this respect, it is impossible to determine all the differences. If we consider in the mean time, that we find Acids whose parts are so subtle and so delicate that they are exhaled by a small Fire; as for example, the parts of the Spirit of Venus, whilst we find others so gross and Massy, that they do not exhale but by the force of a vehement heat, such as the Oil of Vitriol, the Spirit of Alum, etc. We may well reduce, by this means, the Acids under two kinds, by dividing them into Fixed and Volatile. The Fixed, are those which do not exhale, but by the force of a vehement Fire, and the Volatiles on the contrary shall be those which exhale by a moderate heat.   

SECT. III. Of Alcalis.  
SInce Alcalis are nothing but the most porous Molecules, to know them well, we need only examine their Figure, their Pores and their Magnitude.  
We may say here of Alcalis, what we have said of Acids in speaking of their Figure, viz. That they are so many, that it is impossible to know them all The reason is, that their composition depends upon the motion of the Particles of the Aetherial Matter.  
For since these Particles move every way, they may in uniting themselves compose Molecules of all sorts of Figure, as well Regular as Irregular. So that the understanding, finding its self unable to examine them all, and wanting moreover means to accomplish it, must content its self to know that there are Alcalis of all sorts of Figure, without being anxious for the Figure of each Alcali.  
It is good notwithstanding to remark here that some Alcalis have the Figure of Acids, that is, that many Alcalis have sharp Angles on their Surface. But because they have not Solidity, they do not produce the same effect. In speaking of the hardness of Acids, we have insinuated that it depends upon the small number or smallness of their Pores. Seeing then the Alcalis are incomparably more Porous than the Acids, they must of necessity have very little hardness in comparison of the other, so that if some Molecules partake of an Acid because of their sharp Angles, and of an Alcali, because of the great number and wideness of their Pores, they cannot produce the same effect which Acids produce, because they have no solidity, and in certain rencounters they have not the effect of Alcalis, because of the sharp Angles of their Surface. We shall call these sorts of Molecules, Alcaline Acide Particles.  
The Pores of Alcalis are also different from one another an infinite number of ways, which is the cause we cannot determine them; from hence it comes, that not being able to know in particular the Structure of the Pores of Alcalis, we shall content ourselves to say, that they have the wideness and Figure that is needful to produce such an effect, when we are to speak of a Phaenomenon that depends upon them, which will serve on the like occasions  
As to the Magnitude of the Alcaline parts, tho' the diversities that are amongst them be infinite, yet we shall divide them into Fixed and Volatile as we have done the Acids. With this exception, that the Fixed Acids do exhale by the action of a great Fire, whereas the Fixed Alcalis do not exhale at all.  
We distinguish therefore Alcalis into Fixed and Volatile; the Fixed are those which subsist in the Fire, and change rather into Glass, than exhale. And the Volatile are those which exhale by a moderate Fire; as for ex the Spir of Sal. Arm. the Volatile Alcals of Hartshorn.   

SECT. iv Of the mixture of Acids with Alcalis.  
AFter having treated of the Acid and Alcalis, we must mingle them together, to see what will follow; and that we may follow a method that needs not be quarrelled, we shall say nothing in this Chapter, which does not follow from what has been said in the foregoing.  
If we consider that a pure Alcali is composed of nothing but the most porous Molecules, it must needs be granted that a great deal of the Aetherial matter passes through the pores of its parts.  
From hence it follows, that to the end a Body may subsist for a long time in the torrent of the Aetherial matter, the pores which are on its Surface must be no greater than those which are in the middle. The reason is, that if the pores of the Surface were not a little near equal, the parts of the Aetherial matter, which should enter on one side, could not get out on the other with the same freedom as they entered. They would therefore force by their great agitation all that should oppose their passage, and consequently break the union of the parts; the assemblage of which did make the pores too small to permit them to pass through them Here recourse cannot be had to the grosser parts of the Aetherial matter, which remaining on the surface of the Body might keep its parts united, by resisting them uniformly with as much force as the Aetherial matter that passes within: Because all the parts of the Aetherial matter which are less gross than what runs through the parts of the Body, do not enter, and consequently rest on the Surface. But in as much as they have less force than what is within, they are obliged to give way, and let them at this place make all kind of havoc, by disordering all the parts of that Body, and breaking wholly the union of it. So that in that place where the Pores are narrower than in the rest, there will never fail to follow a dissolution of the parts  
This dissolution or disordering of the parts falls out ordinarily by the mixture of some Heterogeneous body; whose parts enter into the pores of its Surface stop them, and consequently render them smaller. So that the Aetherial matter not being able to get out at this place, as freely as it entered, forces the Obstacle, disorders the parts of this Body, and makes its passage, till it can continue its way through all with an equal facility.  
When this motion which disorders the parts of a Body is sensible, it is called Fermentation, and the Body by whose mixture it falls out, is called the Ferment. They distinguish five kinds of Fermentation. The first is called Bubbling. It is when the mixture of Bodies excites sometimes a visible motion of the parts, accompanied with small Bubbles, and sometimes small Bubbles of Air only. These Bubbles are produced by the detachment of some most delicate parts, which mingle with some parts of the Air, which is always to be met with amongst the parts of Liquors. For in separating, they scatter the other parts through which they pass, and make to be gathered together in these places, enough of Air to make up a little Bubble, which by its Lightness ascends to the Surface of the Liquor.  
The second is Elevation, which is when by the mixture of certain Bodies, the Bodies are blown up and swelled, or to speak better ratified. Which is done when the dissolution is not indeed sensible, but when the parts of the Dissolvant are so figured that they cannot associate with others without taking up together more place, than when they were separated.  
The third is Sparkling, which is when the mingled Bodies dissolve with a kind of hissing, accompanied with small and interrupted sounds. Then the parts which are disordered incline and bow by the action of the Ferment. These parts thus bended, make a spring and excite thereby in the Air all those little motions, which may produce in us the Sensation of Sound.  
The fourth is Effervescence, which is done, to speak properly, when by the mixture of bodies there is made a dissolution of parts, accompanied with some degree of heat. For if the dissolution be not made but by a great effort of the Aetherial matter, the motion which the parts acquire becomes great enough to excite in us the sensation of heat.  
In fine, the fifth is Exhalation, which is done when the disordering of the parts is accompanied with Fumes. Which falls out when by the disorder, some subtle parts acquire motion enough to ascend visibly in the Air, whiles the more gross parts remain in the Mass.  
After all these Reflections, it may easily appear that a Fermentation must follow upon the mixture of Acids with Alcalis. For Acids' being pointed and Alcalis porous, if they be mingled together, the points of the Acide will enter into the Pores of the Alcalis, and render them consequently smaller. So that the Aetherial matter cannot get out at that place with the same facility that it enters. It will therefore disorder the parts amongst which the points of the Acids have been received, and this disorder or fermentation will last till the Aetherial matter can pass through all with an equal facility.  
Moreover according as the Pores of the Alcalis are great or small, and the points of the Acids in comparison of the Alcalis great or small, the Fermentation will be a Bubbling, or an Elevation, or a Hissing, an Effervescence or Exhalation. Sometimes two of these kinds of Fermentations will be observed at once, as the Hissing and Bubbling, the Exhalation and Effervescence, etc. Sometimes three of them, whiles four, and sometimes all of them. For according as the pores of the Alcalis are a little more or less stopped by the Angles of the Acids, the Aetherial matter will move with more or less force the parts of the Body which is Fermented. And it is from this greater or lesser Agitation and Commotion that all the kinds of Fermentation derive their Origine.  
From all this may be easily gathered that the Fermentation must last, when it is once begun, till the Aetherial matter can pass without hindrance through the Pores of the Alcalis, which are mingled with the Acids. Which is done when the parts have been so disordered, as that all the pores which were before form, are destroyed, and others form of a near equal wideness. For when things are brought to this State, the subtle matter meets no stop in its passage. Therefore it passes strait forward without moving any part of the Body through whose Pores it passes.  
When the parts of this Alcalis have been disordered thus by Acids, they recover their first calm, and are so united with them, that there results from both a body of a third species, which is neither Acid nor Alcali, but a composure of both, which we shall call a Salt. So that Salts are nothing but porous Bodies, whose Surface is made all rough by the points of the Acids which are fastened to it.  
There is no property remarked in Salt, which is not a Consequent of what we have said, as we could demonstrate, if we did treat here of Salt as it ought to be treated in Physic. But since we speak of it only as a result of the mixture of Alcalies with Acids, we shall say only, that as there is an almost infinite diversity of Alcalies and Acids, so there are so many differences to be found amongst Salts that it is impossible to determine them all. Nevertheless it is fit to remark that the most part of these differences depends upon Acids. For since Salts do not act on Bodies, but by the points of Acids, which are raised on the Surface of the Alcalies; all the difference which is to be met with in these properties, depends upon the Acid points, which act sometimes one way, sometimes another, as they are more or less sharp, in a greater or lesser number.  
There are notwithstanding Salts which differ amongst themselves by their Alcalies, as may easily appear by what we have above said. For if a certain Acid be mingled with a Volatile alcaly, it is not to be doubted, but there results from this mixture a Salt, which will be different from the Salt resulting from the mixture of the same Acid with a Fixed alcaly. For that the Volatile Alcalies have their parts incomparably more delicate than the Fixed Alcalies. From whence it follows, that the parts of the Salts must be also incomparably smaller, which suffices to make a difference between the Salts.  
We may found a division of Salts into fixed and Volatile, from what we have said: The fixed Salts, are those who have their parts so gross, that they do not exhale with any heat, as Sea Salt, Vitriol, Salt petre, etc. And Volatile Salts are those which do exhale by a moderate heat, as the Flowers of Sal Armoniac.   

SECT. V Of Sulphurs.  
WE have said nothing hitherto of the Figure, Structure and Magnitude of Acids and Alcalies, which may not also be understood of the Figure, Structure and Magnitude of Sulphurs. In effect, if it be considered attentively, it will easily appear that there is an infinite diversity of Sulphurs, by reason of their Figure. For if one Sulphur have parts more branched than another. if it have parts whose branches are shorter or longer, or otherwise ranged than another, it will be infallibly different, and consequently capable of producing different effects. And forasmuch as there may be amongst all this an Infinity of Modifications, it seems to me evident enough, that there may be also an Infinity of differences amongst Sulphurs in respect of their Figure.  
There is no less diversity amongst them in respect of their Structure. For since Sulphurs are made by the assemblage of parts of the Aetherial matter, since these parts may be assembled an infinite number of ways, it is clear there may be of Sulphurs an infinite variety as to their Structure.  
If moreover we consider their Magnitude, we perceive there is no less difference amongst them as to this. For since matter is divisible in infinitum, there may be an Infinite difference amongst the parts, some of which are grosser than others, because there is no Magnitude which may not be augmented, without acquiring in the mean time the Magnitude of another which is a little grosser than it.  
We cannot therefore, what tour soever we take, place Sulphurs under certain kinds, by considering simply their Figure, Structure or Grandeur. Nevertheless, since we have reduced Acids and Alcalies under two kinds, by dividing them into Fixed and Volatile; notwithstanding the infinite difference there is amongst their parts, we may do here the same thing as to the Sulphurs. And since there are Sulphurs which do not exhale but very difficultly, and others which exhale by moderate heat; we may be allowed to call the former Fixed Sulphurs, and the later Volatile Sulphurs.  
The Fixed Sulphurs do not exhale but very hardly, for that their parts are gross, and garnished with gross branches. For then as soon as they are agitated, they communicate almost all their motion, to the parts of the Bodies which environ them. So that they cannot acquire as much as were needful to exhale them without an extreme heat. Whereas the Volatile Sulphurs having their parts very delicate, and their Branches most subtle and close, they move easily. Therefore a moderate heat is capable to give them agitation enough to raise them into an Exhalation.   

SECT. VI Of the mixture of Sulphurs with Acids and Alcalis.  
AFter having examined the nature of Sulphurs, it will not be amiss to mingle them with the Elements, whose nature we know, to see what will follow.  
Since Acids are Molecules, which have many sharp Angles on their surface, and Sulphurs are Molecules branched, if we mingle an Acid with a Sulphur, the Acid must coagulate the Sulphur: In effect, when we mingle an Acid with a Sulphur, the Acid engages its points amongst the Branches of the Sulphur; by this means it holds the parts and gathers them so together, that by little and little they lose their motion and co-agulate. So it may well he said in general, that Acids co-agulate Sulphurs.  
If the nature of Alcalies be well considered, it will easily appear that they must act on Sulphurs in a way quite opposite to that of the Acids. For if Acids co-agulate Sulphurs in embarrassing their points in their Branches, the Alcalies which are without points must dissolve them. In effect, when the Alcalies mingle with the Sulphurs, they separate the parts, by placing themselves amongst them. They free them of one another, so that having no more union, the whole becomes more Liquid. And so it may well be said in general, that Alcalies dissolve Sulphurs.   

SECT. VII. Of Phlegm.  
BEsides Acids, Alcalies and Sulphurs, there are also oblong Molecules and Polished, whose two ends are almost blunted, like the extremities of an Egg. These parts compose the Phlegm or Water, when they are assembled in a considerable quantity.  
The difference which may be amongst the Phlegm, as to their Figure, is so small, that it does not merit we should stop at it. For as they are all oblong and polished, the more or less that may be met with in this Figure, is not capable of producing effects, amongst which there can be great difference  
The same thing may be said as to their Magnitude, which is never so different, as upon that head to distinguish them into Fixed and Volatile. On the contrary, for that their parts are polished and oblong, they do never embarrasse so strongly with other Principles, but that a little motion will extricate them, and consequently a very small heat raise them into a Vapour So that to consider them, after this manner all Phlegmes must be Volatile.   

SECT. VIII. Of the mixture of Phlegm with Acids, Alcalies, and Sulphurs.  
SInce Acids are the most solid and most angulous Molecules, all that can befall them by the mixture of Phelgme is dissolution. In effect, when we consider that parts so Figured as to have many angles on their surface, when they are gathered together, do not touch frequently but by the points of their angles; it will easily appear, that having so slender an union, a little force will shake them. And forasmuch as the dissolution of a Body is nothing but the disorder of its parts, the Phlegm having enough of force to disorder the parts, the Acids must be dissolved.  
Besides the dissolution of Acids, which is made by the mixture of Phlegm, their force is extremely weakened, which is not by the division of their angles; but rather for that the Phlegm, which keep the parts of the Acids distant one from another, have not the same force to act upon certain Bodies, that we observe of Acids.  
All that we have said of the mixture of Phlegm with Acids, must also be understood of the mixture of Phlegm with Alcalies. For the same reason which has made us conclude that Phlegms dissolve Acids, must make us think that they dissolve Alcalies, Yet it is true that Phlegm must dissolve Alcalies with some less trouble than they do Acids, for that the Alcalies being only porous parts, they touch them in more places than the Acids So that they require less force to disorder them. Their dissolution must also diminish their activity, for the same reason that the dissolution of Acids by a mixture of Phlegm, does weaken their force For if the parts of water cannot produce the same effect with the parts of Acids, neither can the same parts of water do the office of the Alcalies. The same thing may be freely said of Salts, for that the Saline Particles not being joined together, but by the points of their Acids, they may be disordered by the least force, so that the Phlegm striking against them, shake and separate them one from another with great ease. The Phlegm must also weaken the Salts after the same manner that they diminish the force of the Acids and the Alcalies.  
But the Phlegmes must produce on the Sulphurs an effect quite contrary to what they produce on the Acids, the Alcalies and the Salts. For that the Sulphurs having their parts branched their brances do so engage amongst one another, that they do not leave between them Interstices or Spaces large enough to give way to the parts of the Phlegm. So that the Phlegms not being able to thrust themselves in amongst the parts of the Sulphurs, and moreover not being able to separate the parts which close one upon another, without detaching themselves when they are encountered, instead of dissolving them, they must set them closer together. For the parts of the Phlegm striking on all sides the parts of the Sulphurs, without separating them from one another; and not being able to enter into the pores which they leave between them, they press them, the one against the other, and in some manner increase their union. Hence it comes that Oils cannot mingle with water.   

SECT. IX. Of Earth.  
WE have not only remarked Acids, Alcalies, Sulphur, Phlegm amongst the Molecules, but we have found also a fifth kind of Particles, which is different from the rest. These are they which have not sharp angles on their surface, but are rough and unequal, which have fewer pores than the Alcalies, and are less solid than the Acids, which have not the branches of the Sulphurs, nor the figure of the Phlegm, in a word, which have nothing for their whole share, but a surface very unequal, with a considerable enough solidity, and we have called them Earth.  
When we consider their Figure, Structure, and Magnitude, we can say nothing of them but what we have said already of the Figure, Structure and Magnitude of Acids, Alcalies, and Sulphurs. Which has obliged us to distinguish them into Fixed and Volatile. So we find that there may be parts of Earth gross enough to subsist in the Fire, which we shall call Fixed Earth; and there may be also, which cannot subsist in the Fire, but do exhale by a moderate heat, and we shall name them Volatile Earth.   

SECT. X. Of the mixture of the Earth with the other Elements.  
IF we reflect on the nature of Acids, Alcalies, Sulphurs, Phlegm and Earth, we shall see that there cannot result a great matter from the mixture of Earth with the rest. For it cannot dissolve them, nor Coagulate them, nor excite in them any Fermentation. So that all that it operates, is to trouble the purity of other Elements with which it is, and consequently to diminish their force. Nevertheless, as the most part of Bodies are composed of many of our Elements, and sometimes of them all, the Earth is not entirely useless. Since it finds a place amongst the other Elements, and fills the spaces which they leave between them, and by this means renders the whole body more massy and more firm.   

SECT. XI. Of the manner of knowing the Elements which enter into the Composition of particular Bodies.  
IT is nothing to know that there are Acids, Alcalies, Sulphurs, etc. We must know which of them are in particular Bodies To come to the knowledge of this, we make use of Chymie, because it separates the Elements one from another, and collects them as much as is possible in their Elementary purity.  
It accomplisheth this by the means of Fire, which is an universal Dissolvant The Fire by its great subtlety enters into the pores of Bodies, and by its great agitation moves their parts and breaks their union. So that in continuing to agitate and disunite them, those which are most Volatile separate from the rest, and the more Fixed abide in the Fire. After which we separate them from one another, by the mixture of some other Body; and in fine, collect them in their Elementary purity.  
For example, if I would know of what principles a Plant is composed, I take a great enough quantity of it, beat it in a Mortar, and without any more ado, put it in a Cucurbite. I place my Cucurbite on a Furnace, and afterwards put on the Cucurbite an Alembick, and to the Pipe of this Alembick, I put a Recipient I give it Fire as it ought to have, which acting upon my Cucurbite, makes by Vapour to ascend into the Alembick, all that is Volatile in the Plant. Ordinarily if it be an Odorous Plant, we find some drops of Sulphur which swim upon the Water. We call these Sulphurs Essences. Besides these Sulphurs, which are known for such, not only for that they easily kindle when they are cast into the Fire, but for that Acids co-agulate them, and Alcalies dissolve them. There are some Acids, or some Volatile Alcalies, which are dissolved in the Water. We know them by means of the Fermentation which they excite, either with Acids, or with Alcalies. For if they ferment with Alcalies, we do not fail to conclude, that they are Acids; and if they ferment with Acids, we conclude they are Alcalies. Thus we discover that in the Plant there are Phlegm, Volatile Sulphurs, Volatile Acids or Alcalies.  
After this, that we may know what there is of Fixed; I take what remains in the bottom of my Cucurbite, and expose it to the Fire; if it take flame, I conclude that in the Plant there are fixed Sulphurs, which could not ascend by Distillation. Afterwards I reduce the whole to ashes, and to know of what these ashes are composed, I make a Lee of them. The Water dissolves all that there is of Acid, Alcali and of Earth. I pass my dissolution through Gray-paper, to the end I may have nothing but the Salts, Acids, or Alcalies dissolved in Water. And the Earth being too gross to pass through the pores of the Paper, remains within, and then I see how much Earth enters into the Composition of the Plant. I take after this my dissolution which I set upon the Fire. The Fire by its activity makes all the water to exhale, and what there is of fixed, remains in the bottom of the Vessel. I examine it, and see if it be an Alcali, by mingling it with an Acid; or if it be an Acid, by mingling it with an Alcali, by the Fermentation which it will excite with the one or with the other. But if it do not ferment at all, neither with Acids not with Alcalies, I conclude that it is fixed Salt.  
Thus I know all the Elements which enter into the Composition of a Plant, and how we may operate almost upon all Terrestrial Bodies, to extract their Elements, Chymie is the only Science whereby we may know aright of what Bodies are composed.  
The most part do not grant this, because they imagine that the Fire acting upon Bodies changes all their parts; so that the divers Elements which we extract from Bodies by the means of Chymie, were not there in their opinion, such as they are when we extract them. But I have great reasons to be of another Sentiment. Which are 1. for that the Fire does not change Acids into Alcalies, not Alcalies into Sulphurs. For though the Fire by its great agitation may produce some change into the parts of a Body; yet it is inconceivable that it can change the Principles by spoiling them of their Nature to  them With the nature of another. Thus therefore though it were even true, that the Fire should produce some change in the parts of Bodies upon which we operate to extract their Elements; yet it is certain that what is extracted of Alcali, was there under the form of Alcali; what is extracted of Acid, was there under the form of Acid, etc.  
But that which obliges me chief to think that the Fire makes no change in the Elements of Bodies which are extracted by Chymie, is, that if we take the Spirit of Salt and mingle it with the Fixed Alcali of Tartar, we make a true Salt of it, and if we take the Spirit of Nitre, and mix it with the Salt of Tartar, we make a true Nitre of it. Nevertheless all they who can operate in Chymie, know well enough that the Fire must be blown with an extreme violence to distil the Spirit of Salt and the Spirit of Nitre. So if the Fire should produce any change in the Elements that are drawn from Bodies by its means, it would be chief in the Distillation of the Spirit of Salt and Spirit of Nitre, where it must act with all its force.  
Nevertheless, Experience makes appear that there is no change produced, and that the Spirit of Salt and Spirit of Nitre were such in the Salt and in the Nitre, as they are when the Fire has separated them from the other Element, with which they must be mingled to constitute the Salt and the Nitre; since we make a true Salt and a true Nitre, by mingling them with that other Element, which is the Salt of Tartar.  
We are convinced by true Philosophy, that Odours are nothing but the most subtle parts which get away from Odorous Bodies, and spread in the Air by way of Exhalation. We are not ignorant likewise that it is from the different Magnitude and Figure of the parts, that all the diversity of Odours does proceed. So that there must be a certain Magnitude and Figure in these parts to excite a particular Odour. And if it fall out that this Magnitude or Figure comes to be changed by whatsoever cause, the Odour which these parts should excite after this in us would not be the same. But we extract by Chymie the Odorous parts of Odoriferous Bodies, without making any change in them: Since they excite in us the same Odours which the Bodies do from whence they were extracted: Witness the Essence of Rosemary, Gillyflowers, Cinnamon, etc. from whence we may with reason conclude, that the Fire does not produce any changes in the Elements which are extracted from Bodies by the means of Chymie.  
And since many different Liquors are to be found in Animals, which are composed of divers Elements, we shall make use of the Chymie to separate them from one another, and to examine them apart, that we may know the nature of each in particular After this we shall easily see what may be their uses in the animal Oeconomy, and what effects do depend upon them.    

The second Discourse. Of the Blood.  
WHen I strike a Lance into any outward part of a living Animal, I remark that there comes from the wound I have made a red Liquor, which I call Blood.  
I imagine that it is very important to know the nature of it aright, for I find it so spread through all the Body, that there is no part which is not watered with it. Which obliges me to gather a little of it in a Vessel and to know if it be not some of our Elements, or if it be not a composition of them. I mingle it first with Acids; and I find that they co-agulate it; in such a manner notwithstanding that they co-agulate but a part of it, and that remains another very Liquid and Transparent, which we call Serosity. In the second place I take the Serosity and mingle it with Acids, and I find that there is made by this mixture a little Fermentation.  
From hence I conclude, that there are in the Blood much Sulphur, and some Alcali; that the Sulphurs are that which has been co-agulated by the Acids; and that the Alcalies are that which ferments with the Acids, which we mingled with the Serosity.  
I do not satisfy myself with this, I take Alcalies and mingle them with the Blood, to confirm what I conjecture by some new Experiment. And it falls out that the Blood is extremely dissolved by this mixture. And as I know that the effect of Alcalies on Sulphurs is Dissolution, I am confirmed the more in the opinion I have, that in the Blood there is a great deal of Sulphur.  
The small Fermentation which the Acids have excited in the Serosity, makes me think that there is in the Serosity something more than Alcalies'; and by consequent that there is through all the Blood some other Principle than Sulphurs and Alcalies'. To know therefore the truth of the matter, I take a considerable quantity of Blood, I put it in a Cucurbite, I place my Cucurbite in a Furnace to distil some part of it by Sand. I adapt a Head to my Cucurbite, and to the Pipe of the Head I apply a Recipient. I take care to lute the Junctures well, and give it a little Fire at first, and augmenting it afterwards by degrees, I dry gently all the Blood which I had put in my Cucurbite  
Whilst the Blood is thus drying, there arise some Vapours in the Alembic, which gathering in its concave Surface, run in drops of Water through the Pipe into the Recipient. I take this water and try it, by putting it on my Tongue. A little favour that it excites there, makes me judge that it is not pure Phlegm; I mingle Alcalies with it, and I remark no Fermentation. Which makes me think, that what is in this Water is not Acid. I mingle afterwards Acids with it, and I perceive by the light Fermentation that arises from this mixture, that there are Alcaline parts extremely Volatile mingled with much Phlegm.  
I take out (after this) that which is dried in my Cucurbite, and I put it in a Retort, which I place on a Furnace proper for this. I give it Fire by degrees, and there comes out of my Retort a stinking Oil, which is the Sulphureous part of the Blood. With the stinking Oil there comes out a great quantity of whitish Particles, which stick to the neck of the Cornute, and to the concave Surface of the Recipient, as if it were a most delicate hoar Frost.  
I examine the stinking Oil, by the mixture of Acids and Alcalies. The Acids Co-agulate it, the Alcalies Liquify it, which will not let me doubt that it is a true Sulphur. I do the same with the whitish Particles, which I rub off from the neck of the Cornute, and the sides of the Recipient, and I learn by the great Fermentation they make with Acids, that it is nothing but an alcaly, which rising by a moderate heat, is very Volatile. I have therefore three Volatile Principles which compose the Blood, viz. A most considerable quantity of Phlegm, much of a Volatile Sulphur, and yet more of a Volatile alcaly. That I may know now what remains in the the bottom of the Cornute, I put it in a Crucible, and Calcine it by a wheel Fire. There is some small matter that yet Exhales. And in fine, after the whole have been well Calcined, I make a Lixivium of it, which I filter. I make a part of the Water to evaporate, which makes up the Lixivium. I put the rest in a cool place, and there Chrystallizes somewhat about my Vessel in form of a Salt.  
I take this Salt and mingle it with Alcalies and Acids. The Alcalies do not move it, but the Acids excite a Fermentation, yet less than what they do with the Volatile Alcali of Blood. Which makes me think that it is a Fixed alcaly with which there may be some Acid mingled.  
I perceive after this, that there remains some Terrestreity in the Paper through which I filtered the Lixivium, from whence I had extracted the Fixed alcaly. So that after having examined all, I find that the Blood is a Composure of Volatile alcaly, Fixed alcaly, Volatile Sulphur, Phlegm, Earth, and it may be some little Acid mingled with the Fixed alcaly. So that it abounds more in Sulphur, in Volatile alcaly. and in Phlegm, than in any other Principle. For there is little of Fixed Salt, and almost no Terrestreity.  
We may easily understand by this, the reason why through a Microscop there are to be seen in the Blood many small red Globules which swim in a Crystalline Liquor, while the Blood is put into small Pipes of Glass. The Sulphurs which are more disposed to keep themselves united to one another, because their branches are embarrassed, do swim in a Liquor composed of Phlegmes and Alcalies. The Phlegmes by their motion press those branched Particles one against another, and oblige them to form small Sulphureous Globules, after the same manner that the Air makes the drops of water Spherical. And the Alcalies make the smallness of these Globules, and oblige the Sulphureous parts of the Blood to assemble in small Bodies, by keeping them separated one from another.  
We see also the reason wherefore curdled Blood, after having been washed in cold water, seems all Fibrous: For cold water dissolves the Alcalies and carries them away. Afterwards it assembles the Sulphurs, which fall down to the bottom of the Vessel like a Glairous matter, and composed of small Fibres like Glue.  
It is also for the same reason, that when we receive the Blood amongst hot water, as soon as is comes out of the Vein, there gathers about small Rods which you put into it a Mucilaginous and Glairous substance. For the Alcalies spread through all the water with the Sulphurs, and strike together against the Surface of the small Rods. The Alcalies never fix to them, because they have not proper Particles for this; but the Sulphurs insinuate into the Pores of the Wood, which are opened by the heat of Water, the extremities of their Branches. So that finding themselves engaged, they continue fixed there, and the other Sulphureous parts of the Blood which swim in the Water join to the first, so that in fine, when the Water is become Cold, we find the Sulphurs of the Blood upon the Surface of the Rods, like to a Glaire, or a Mucilage.   

The third Discourse. Of the Glandules.  
WHen we follow the Arteries and the Veins, we find that a great number of their Branches end at certain round Bodies involved in a most delicate Coat; and from which Bodies there comes a Canal, and from thence flows a Liquor quite different from the Blood.  
The Anatomists call these round Bodies, Glandules. There are three considerable things to be remarked in them. The first, that each Glandule receives a Branch of an Artery, which carries the Blood to it, and that there goes from it a Branch of a Vein which carries the Blood away. The second, that there goes a Canal from each Glandule from whence flows a Liquor different from the Blood. And the third, that the Composition of Glandules is of two sorts, some are nothing but a heap of small Vessels contorted, which reuniting, make the Canal through which there flows a particular Liquor. And others, are nothing but an assemblage of little Vesicles. In some places these Vesicles are angular, and there is a Communication between their Cavities. So that they end all into two or three, whose prolongation makes the Canal, from whence flows the Liquor which is different from the Blood. In some others there are separated Vesicles, which send each one in Particular a little Canal. Those, which are nothing but a heap of Contorted Vessels we shall call Vascular Glandules, and those which are composed of nothing but a heap of Vesicles, we shall name Vesicular Glandules.  
If we reason upon these three things, we will easily discover the nature of Glandules. The arteries bring the Blood, which after having watered the Vessels or Vesicles of the Glandules, returns by the Veins which go from them, Now the Glandules are nothing but a Composure of small Vessels or Vesicles, full of a Liquor different from the Blood. But for that we have not hitherto discovered any Vessel which brings any thing to the Glandules, but the Arteries which carries Blood thither, we may well think that this Liquor is a certain portion of Arterial Blood, which has been separated from it by the Vessels or Vesicles, and has been collected into their Cavity, from whence it comes that this Liquor flows always from the Glandule by the little Canal which comes from it, and which we shall call the Excretory Canal.  
The difference that is between this Liquor and the Blood, ought not to keep us from being of this sentiment. For since the Blood is composed of heterogeneous Principles, a certain portion of one, or many of these Principles, may be separated from the Blood into the Cavity of the Vessels or Vesicles of the Glandules. And for that the principles of the Blood are not to be met with there, whether in number or proportion sufficient to make Blood; the Liquor that results from this Assemblage, must be a Liquor quit different from Blood.  
Thus the Liquor that flows from the Glandules by their Excretory Vessels, must come from the Blood. But that which confirms us yet more in this Sentiment, is that we can extract nothing from this Liquor by Chymie, which we do not draw from Blood: which is an evident enough mark, that this Liquor is no other thing, but an Assemblage of certain principles which have been separated from the Blood, by means of the Glandule.  
As to the Liquor which one Glandule separats from the Blood, we observe that it is always the same. Nevertheless, we must not for this imagine that all Glandules separate the same Liquor Experience makes appear to us most considerable differences between the Liquors which proceed from different Glandules. Which abundantly shows, that for the most part, divers Glandules separate different principles from the mass of Blood.  
But as this does not entirely satisfy the mind, it will not perhaps be impertinent to inquire into the manner, how the Glandules do separate from the Blood, the Liquors which flow from them. That we may succeed in this enquiry, I remark that the Arteries bring the Blood into the Body of the Glandule, that the Blood is a Composure of heterogeneous parts, that some of these heterogeneous parts go out of the Cavity of the Arteries, and gather into the Cavity of the Vessels or Vesicles, which compose the Glandule. From whence I conclude, that there are passages from the Cavity of the Arteries into the Cavity of the Vessels or Vesicles of the Glandules, and such Passages as that no other principle of the Blood can pass thither, but these which are absolutely necessary for making up the Liquor which flows from each Glandule in particular. We shall call these sorts of Holes, or Passages, Pores.  
To the end that the thing be thus done, these Pores must be proportioned to the Magnitude and Figure of the parts which are separated from the Blood, that they may be gathered into the Vessels or Vesicles of the Glandules, whiles parts of another Magnitude and Figure cannot pass through them. For then the Blood coming to run in the Arteries, which are spread through the substance of the Vessels or Vesicles of the Glandules, those of its parts which can pass through the Pores, when they come thither are engaged in them. And for that the Blood continues to move in the Arteries, the parts which are engaged in the Pores through which they can pass, are thrust forward, and being followed by others which have the same fate, they are in fine pressed forward into the Cavity of the Vessels or Vesicles of the Glandules There they mingle with many others which are come thither after the same manner, and compose with them the Liquor which flows from the Glandule through its Excretory Vessel.  
But for that the Liquor which runs from one Glandule is made up of Heterogeneous parts, it must needs be that the Pores of each Artery are not all equal. So that according as the Liquor of one Glandule is composed of Sulphurs, Alcalies' or Phlegms, there must be proportionably in the Arteries of that Glandule, Pores fitted to let Alcalies, Sulphurs or Phlegms pass through them.  
We may even affirm, that not only the Pores of the Arteries of Glandules are not all equal amongst themselves; but also that those of the Arteries of one Glandule are sometimes entirely different from those of the Arteries of another. The reason is, that there comes sometimes from one Glandule a Liquor entirely different from that which flows from another.  
After this, it is to be observed, that there are Glandules to be met with alone, without being joined to any other. These are called Conglobated Glandules, because they are considered as little Globes, which separate a Liquor from the Blood. But when there is an assemblage of them, and that they are all folded up within one Coat, and that all their Excretory Vessels are united in one, and so compose one Canal through which the Liquor runs, which they have all with one accord separated from the Blood, they are called Conglomerated. Glandules  
The greatest part of the Conglomerated Glandules are Vascular, and the most part of the Conglobated are Vesicular. As those may see who will give themselves the trouble to make the enquiry. And sometimes there are Conglobated Glandules which are Vascular in some Animals, and Vesicular in others.   

The Fourth Discourse. Of the Nerves.  
THe Surface of the Brain and of the Cerebellum, as well as the inner part of the Marrow of the Backbone, are made up of nothing but a heap of small round Bodies. It is observed that they receive Arteries, they send off Veins, and there goes from them a small white Fiber. The Arteries do bring them Blood, after that it has watered them it returns by the Veins. But since it is not found in the Veins with the same qualities which it had in the Arteries, we may well conjecture that it has left something in these round Bodies, which occasions all this Change.  
In effect, this Change does not befall the Blood, but either by the Addition of some new matter, or the loss of some of its parts. It will easily appear that it is not from the addition of any new matter, if we consider that these little round Bodies receive nothing but from the Arteries.  
For if they made this alteration in the Blood by communicating unto it any new Liquor, they should receive it elsewhere. The reason is, that the Blood passes continually through these round Bodies, and is also continually changed. So they must incessantly Communicate unto it this Liquor, which cannot be, if they do not receive it from some inexhaustible source. Since therefore this source is not known, we may reasonably think that this Change does not befall the Blood by the addition of any new matter.  
It must needs then be occasioned by the loss of some of its parts. And because this change is sensible, it cannot fall out but by the loss of a considerable number of its parts; which since they cannot stay in these round Bodies, because they are perpetually parting from the Blood, they must needs go through some passage to be carried elsewhere.  
When we examine narrowly these round Bodies, we find nothing in each of them, but Arteries, Veins, and a small white Fiber. The parts which are separated from the Blood, do not go by the Artery, since it is by the Artery that the Blood comes to the round Body; neither do they go by the Vein; for if this were, there would be no difference between the Blood of the Artery and that of the Vein. It remains therefore, that they pass through the small white Fiber. And thus we find that the Surface of the Brain, is nothing but a composure of small Glandules, which do receive Blood from the Arteries, which send it off by the Veins, and which have their Excretory Vessels from whence the the Liquor flows which they have separated from the Blood.  
There are two sorts of Substance taken notice of in the Brain, the Cerebellum and the Spinal Marrow. The first is that Glandulous Substance, which making the Surface of the Brain and Cerebellum, is called their Cortical Substance. In the Spinal Marrow, it is found in the middle covered with the other Substance. And the other, which is a white Substance, more firm than it, is nothing but the assemblage of the Excretory Vessels of the Glandulous Substance. They call it in the Brain and Cerebellum, the Callous Body, or the Marrowie Substance. And in the Backbone it has no Name.  
The Vessels which compose the Callous Body of the Brain and Cerebellum, are so interwoven, that they resemble a Net. It has not as yet been discovered, whether they are Inosculated, or if the Nets be made only by their passing one over another.  
In fine, they gather into little Bundles, which are found shut up into Membranous sheaths. According as they advance into the Body of the Animal, they are divided into many small branches, and after this manner spread themselves through all. So that there are very few parts in the Body of an Animal, which does not receive its portion of them.  
In the Nerves the Excretory Vessels of which they are composed have no Communication; even it is not remarked that they are Interwoven. But they extend themselves in length, couched one above another, as if they were small Bundles of little Cords.  
I say, this falls out in the Nerves, that it may be observed that it is quite otherwise in certain tumors fastened to the Nerves, which are called Olive Bodies, or Ganglions. For these Olive Bodies are not form but by the interweaving of the Nervous Vessels. Even as the thread of which a sling is made, seems to take up more room in the Body of the sling where the Stone is placed, than in the strings which are on either side.  
Many Nerves meet together in divers places of the Body of an Animal, and are so interlaced one with another, that the Anatomists call these assemblages Plexus. They part afterwards from these Plexus, and spread round about.  
It must carefully be observed, that when many Nerves meet in one, there is not an Anastomosis of the Vessels that Compose them, but only of their Coats. And when a Nerve is divided into many branches, its particular Vessels are not branched into many, but the division is only in their cover, and the Vessels which are in one Bundle, are parted into many Bundles.  
In fine, the use of the Nerves is to distribute the Liquor which runs into the Fibres, into all the parts where they terminate. As to this Liquor, it must needs be composed of the most subtle and most Volatile parts of the Blood. It is looked upon as a very subtle wind which passes through the Fibres of the Nerves, and that not without reason. For since it escapes our eyes, and that the best Microscopes are not capable to make us see it; we may well think that it is the most subtle of all the Liquors which are separated from the Blood through the Glandules of the Body of an Animal This Liquor is called the Animal Spirits, because of its great subtlety, and because it is the Soul, which makes Animals to live.  
Though nothing of this Liquor can be gathered to examine its nature, by mingling it with Acids and Alcalies, yet we are inclined to think that the Volatile alcaly prevails in it with an extremely Volatile Sulphur. The reason is, that all Volatile Alcalis taken inwardly, do increase the Animal Spirits, the Volatile Sulphurs do almost the same thing, and there is nothing which does so much increase their quantity, as Sulphureous Volatile Alcalies, as all Volatile Alcalies Aromatised are.  
The effect of Alcalies upon Sulphurs, confirms us in this Sentiment For Alcalies do dissolve Sulphurs, by separating their parts one from another, and by this means hinder their branches from grappling together. For this cause the Interstices or Intervals of the branches are replenished with Aetherial matter, as well as the Pores which remain between the Sulphurs and the Alcalies; which being larger than if the Liquor were simply Alcaline or Sulphureous, do also contain within them much more of Aetherial matter. And for as much as this Aetherial matter is highly agitated, it moves with much force all the parts of this Liquor, which contributes not a little to its activity and its subtlety.   

The fifth Discourse. Of the Muscles.  
WHen we follow the Nerves and Arteries, we find that the most part of their branches do lose themselves into Carneous Bodies, which are covered over with a most delicate Membrane, and are called Muscles.  
Three sorts of parts do enter into their Composition. 1. We discover in them a great many Arteries and Veins. 2 Nerves, and in fine, small Fibres, which are neither Arteries, Veins nor Nerves, but which are certain small long Filaments, most delicate, and yet very strong.  
The manner after which they are ranked in the Muscles, has something in it very remarkable. At first we find them all gathered together, and then they resemble a string. Afterwards they separate from one another, and receive amongst them divers branches of Arteries & Veins. In fine they unite together, and make again a Cord The first and the second Cords are called Tendons, or the Head and Tail of the Muscle. And that part which is placed between the Head and the Tail, and which is the place where the Fibres of the Tendons separate from one another, and where they receive the Veins and Arteries amongst them, is called the Belly of the Muscle.  
These Fibres are all parallel, both in the Tendons and in the Belly. In the Tendons some of them are longer than others, and in the Belly all are of the same length. By the order they are placed in, they make an Obliquangular Parallelogram in the Belly of the Muscle. And they are so closely pressed together in the Tendons, that they resemble two Strings, which draw the Obliquangular Parallelogram by its opposite sides, as may be seen in this Figure.  
A. B. represents a Tendon, or the head of a Muscle, B. C. the Belly, and C. D. the other Tendon, or the Tail.  
The Arteries and Veins which are spread through the muscle, are not to be found but in its Belly; if they be found sometimes in the Tendons, they are so few, that they are not to be regarded. So the Tendons are nothing but the Assemblage of the simple Fibres, which for this we shall call the Tendinous Fibres. whereas the Interstices, which are amongst them in the Belly of the muscle, are all replenished with Veins and Arteries.  
From hence comes the difference, which we observe between the colour of the Tendons and that of the Belly of the muscles. The Tendons are Brown and the Belly is Red. And it is this part of Animals composed of Tendinous Fibres and of Veins and Arteries, which we call Flesh.  
Therefore we must not imagine that Flesh is Red of its self, no more than we are to believe that a Glass full of red Wine is red of its self. But rather as the Glass appears Red, because the Liquor that is within it is of that colour, even so Flesh and all the other parts of the Body of an Animal appear Red, only because of the Redness of the Blood which is contained in the Veins and Arteries of these sorts of parts.  
This truth is demonstrated by an Experiment which renders it Incontestable. That is, if you make Injections of warm water into the Arteries, which spread their Banches through the Flesh, after you have repeated frequently the Injection, the Flesh becomes of the colour of the Tendons  
The Muscles are not only composed of Arteries, Veins and Tendinous Fibres, but the Nerves also make one of their parts. They march first upon their Coat and pierce it. When they have pierced it, they divide themselves in most delicate Branches, which are mosculated with the Tendinous Fibres. Sometimes the Nerves enter into the Tendons, and sometimes into the Belly of the Muscles. But in what part soever they enter we find always the extremites of their Branches to end at the Tendinous Fibres.  
All these Tendinons' Fibres have a Cavity that goes through them, like unto a Tube or Pipe. Indeed this Cavity cannot be seen by the eye, but there is an Experiment which abundantly shows the necessity of it, that it cannot be Contradicted by those who will hearken to reason. The Experiment is that always when a Muscle acts, its Fibres are considerably shortened, and in the mean time they swell bigger. Nevertheless we cannot conceive how flexible Fibres can swell bigger, and be shortened, at the same time, but by the means of some Liquor which fills a Cavity that pierces them from one end to the other.  
After this it will not be very hard to discover how all these things must act. Each Tendinous Fiber receives a Branch of a Nerve; and each branch of the Nerve sheds animal Spirits into the Cavity of the Tendinous Fiber. The Animal Spirits are the most subtle and the most agitated parts of the Blood. When they enter into the Cavity of the Tendinous Fibres they blow them up and shorten them. Even as the Air which is blown into a bladder, swells it and shortens it at the same time.  
If we consider after this, that the Belly of the Muscle is stuffed throughout with Arteries and Veins, we will grant that the Tendinous Fibres cannot be blown up without diminishing the Cavities of the Arteries and Veins, from whence if follows that the Blood is driven out of them. It is for this that in some Animals the Muscles become white always when the Animal Spirits do dilate the Tendinous Fibres.  
If in fine, we take notice that when the Blood stops in the Arteries and Veins, the Tendinous Fibres do not receive enough or motion from the Animal Spirits to thrust forward that Blood which stays amongst them. From hence it follows, that in such rencounters they cannot dilate nor become shorter.  
From hence we may conclude, that there are two things absolutely necessary for the blowing up of the Tendinous Fibres of the Muscles. the first is, that the Animal Spirits must have their free course through the Nerve which goes to the Muscle. For since the Tendinous Fibres are not blown up but by them, it is clear, that if their course be●● interrupted that they cannot flow into their Cavity, they cannot dilate them. Experience confirms this, in that if you cut or tie a Nerve with a thread, the Muscle which receives branches from it, becomes flaccid, and do what you will its Fibres do not swell.  
The second thing needful for the blowing up of the Fibres, is the free course of the Blood through the Arteries and Veins of the Muscles. For since the Tendinous Fibres cannot be dilated without straightening the Arteries and Veins, and the Arteries and Veins cannot be straitened without voiding the Blood that fills them, it is visible that if the Blood stop there, it will hinder the Tendinous Fibres from being blown up.  
This is so true, that if you take a living Animal and tie the Aorta four Fingers below the Heart, it becomes paralytic from the ligature even to the Extremities of the feet.  
When the Fibres of a Muscle are blown up by the Animal Spirits, there are two powers which concur to restore them to their first estate. The first is the spring which these Fibres make. For since their Pores acquire an disposition by their being blown up, the Aetherial matter which does incessantly pass through them, makes an effort to restore them to their former estate.  
The second is the Effort of the Arterial Blood, which being poussed by the Heart with Vigour, blows up again the Arteries and Veins, and at the same time straitneth the Tendinous Fibres. And as the Arteries empty themselves of Blood when they are straitened by the swellling of the Fibres, so the Fibres empty themselves of the Animal Spirits, when they are put again into their ordinary state, as well by the force of the Arterial Blood, as by that of their Spunginess.  
As to the rest, the Tendons of the Muscles are ordinarily fastened to some Cartilege, or to some bone. Which is the Cause why the shortening of the Tendinous Fibres makes that part move to which the Tendons are fastened. It is to be remarked likewise, that one of the Tendons is fastened to an immovable part, and the other to a movable part; from whence it follows, that when the Muscle is shortened the movable part is drawn towards the immovable.  
But for as much as there is not almost any motion in one part which has not its opposite motion, so there is not almost any Muscle which has not its opposite Muscle. These Muscles which serve thus to make opposite Motions, are called Antagonists.  
It is to be observed, as to the Antagonist Muscles, that when the one is shortened, the other is extended. For since their action is opposite, and that that of the one cannot subsist at the same time with that of the other, the shortening of the Muscle which acts, must needs produce the extending of its Antagonist.  
But for that the shortening of one Muscle draws the Fibres of its Antagonist beyond their ordinary length, they must needs spring back. It is for this reason that the action of one Muscle which has been lengthened by the contracting of its Antagonist, is done with ease enough. For the Tendinous Fibres can be easily contracted again, however they have been lengthened, though there be few Animal Spirits which flow into their Cavity, because the force of the Spirits is augmented by that of the spunginess of the Fiber.   

The sixth Discourse. Of the Cartilages, Bones and Membranes.  
WE find in the Body of an Animal many parts which seem to partake of the nature of a Bone, and of the nature of Tendons, in that they are not altogether so hard as the former, and are less soft than the other. They call them Cartilages.  
The first thing which makes me conjecture that Cartilages are nothing but a composure of Tendinous Fibres which are hardened by being replenished with Volatile Alcalies, is that there is no Cartilege in which many Tendinous Fibres are not lost. That which makes my conjecture probable, is, that we see by the eye, that the substance of the Cartilages is nothing but a heap of Fibres. And that which puts the thing out of doubt, is, that in young Animals many parts which were Tendinous become at length Cartilaginous; And that we observe frequently in old Animals, that certain Tendons are changed into Cartilages.  
As Tendons are changed at length into Cartilages, the Cartilages are likewise changed into Bones. If therefore we have concluded the Cartilages were nothing but a composure of Tendinous Fibres, for that the Tendons are sometimes changed into Cartilages; we are obliged by the same reason to judge that Bones are nothing but a Composure of Tendinous Fibres, which after having been hardened to become Cartilages, are afterwards so far hardened as to make Bones.  
The Observations which are made upon the Bones of Foetus' do demonstrate this Truth to the Eye. In effect, we observe there a great many Tendinous Fibres, and particularly in the Scull. It appears in the beginning, as if it were nothing but a Membrane composed of Tendinous Fibres. It becomes afterwards Cartilaginous, and in fine is changed entirely into Bone. After which it cannot be doubted, but that Bones are a heap of Tendinous Fibres, which are hardened after such a manner, that they acquire the firmness of Bone.  
Tendinous Fibres are hardened, by being replenished at length with Volatile Alcalies. The Fibres of the Nerves do shed into their Cavity Animal Spirits. That which is more subtle of them, escapes by the Pores, and the grosser remains. So that at first these Fibres are filled with Volatile Alcalies and Volatile Sulphurs. Whilst there are Sulphurs there, they appear under the form of a Cartilege; but when the Sulphurs are consumed, whether by nourishing the Fibres, or by escaping through the Pores, or in splitting themselves, they appear under the form of Bones.  
From hence it comes that there are no parts in the whole Body of an Animal, from whence we extract so much of Volatile calies as from Bones.  
In fine, we remark that Bones are all covered over with a Membrane, which they call the Periostium. This Membrane is so strongly fastened to the Bone, that in certain places it is impossible to separate it, but by cutting or renting of it.  
When we do examine it narrowly, we find three sorts of parts which enter into its composition; to wit, a great many Tendinous Fibres, many branches of Nerves, and some Arteries and Veins. So that after we have duly considered all, we find that the Periostium is nothing else but a Web of Tendinous Fibres of the Bone, Nerves, Veins and Arteries.  
And because all the other Membranes have communication with the Bones and with the Tendons of Muscles, and for that they have Tendinous Fibres, Nerves, Arteries and Veins, we judge that all the Membranes which are observed in a living Body, are nothing but a Texture of Tendinous Fibres, Arteries, Veins and Nerves.   

The seventh Discourse. Of the Lymphatic Vessels, and of the Lympha.  
IT is found that from all the Parts of an Animal, certain small Vessels do proceed, which the Anatomists call Lymphatic, because they are full of a clear and transparent Liquor, which they name Lympha  
The Membranes which compose them are so delicate, that they are invisible when they are not replenished. They are inosculated into one another, and so compose big enough Trunks, which are inserted into the Veins.  
Those which come from the Head, and from the Neck, are inserted in the Subclavian, or in the Jugulars. And the most part of those which derive their Origine from the Inferior parts, and from the Viscera of the lower Belly, do discharge themselves into one Cistern placed upon the Vertebrae of the Loins, from whence there goes a Vessel, which after having passed over the Vertebrae of the Thorax, does void its Lympha into the Subclavian Vein.  
This Cistern is called the Reservatory of the Chyle, because the Chyle which is form in the Stomach by the Digestion of the Meat, comes thither, and the Vessel which goes from this Reservatory is called Canalis Thoracicus, because it is found couched upon the Vertebrae of the Thorax.  
That which is most remarkable in these Vessels, is a great quantity of little Valves, which are placed at very small distances from one another. They are so disposed as that they permit the Lympha easily to run towards the Veins, but they hinder it from coming back again, and from flowing towards the parts from whence the Lymphatic Vessels do proceed.  
From whence we may certainly conclude that the Lympha does not come from the Veins but from the parts from whence the Limphatick Vessels do derive their Origine. Which agrees perfectly with experience; for if you tie with a thread any Lymphatic Vessel, the Limpha does so abound between the Ligature and the part from whence the Vessel comes, that it blows it up prodigiously; and is so emptied between the Ligature and the Veins whether it is going to discharge its self, that there it becomes invisible. From whence it follows that the use of the Lymphatic Vessels, is, to carry into the Veins the Limpha which they have received from all the parts of the living Body.  
We have not hitherto discovered any Vessel which brings any thing to the parts of the living Body, but Arteries and Nerves. The Arteries bring Blood and the Nerves Animal Spirits. It must needs therefore be, that the Lympha comes either from the Arteries alone, or from the Nerves alone, or from the Arteries and Nerves together. It does not seem to come from the Arteries alone; for if you cut the Nerves which go to one part, there does not flow so much Lympha in the beginning, and diminishing by little and little, in fine, it ceases entirely. Neither does it come from the Nerves alone, since if you tie the Arteries which carry the Blood to one part, it ceases by little and little to furnish Lympha. It must needs be therefore that the Lympha come partly from the Arteries, and partly from the Nerves. And consequently it must be composed of a part of the Arterial Blood and of the Animal Spirits.  
The Lymphatic parts which come from the Blood, pass after the same manner, as the particles of the Liquors which flow from the Glandules. For as these pass from the Blood by being engaged in certain Pores of the Arteries, even so the Lymphatic particles finding in the Arteries small Holes through which they may pass, they are engaged in them. But because they are followed by others which press them forwards, they get out and pass into the Fibres of the parts from whence the Lymphatic Vessels come.  
These which come from the Nerves do not get out by this Artifice. The Nerves insert their Filaments into the Tendinous Fibres of one part, and shed the Animal Spirits into their Cavity. The Fibres have Pores through which they escape, and mingle themselves with what runs from the Arteries, to compose the Lympha by their mixture.  
Since we have established in the discourse of Nerves that the Animal Spirits are no thing but a Sulphureous alcaly, we may well think that the Lympha is nothing but a Composure of Volatile Sulphurs, Volatile Alcalies and a little Phlegm. The Volatile Sulphurs, and Volatile Alcalies are the Animal Spirits which enter into its composition; and the Phlegm with the fixed Sulphurs are those of its parts which come from the Blood by the Pores of the Arteries.  
An Experiment which succeeds always, confirms this Sentiment. That is, if you gather of the Lympha in a Silver Spoon, and place the Spoon on the Fire, as soon as it gins to warm, there goes from the Lympha a small Vapour, and then it hardens like the white of an Egg that is boiled.  
I say this Experiment confirms, that the Lympha is nothing but a Composure of a great deal of Fixed Sulphur, a little of Volatile, a little of Phlegm and much Volatile alcaly. For the Lympha is fluid, whilst the Volatile Alcalies keep its Sulphurs dissolved, and it hardens like the white of an Egg, how soon the Fire has exhaled them. For then the Fixed Sulphurs being alone, do so entangle their branches one with another, that they cannot move after the manner that is needful to compose a Liquor. As to the Volatile Sulphur and the Phlegm, it cannot be denied but there is of them in the Lympha; for that the Animal Spirits which compose a part of it, are made up of them, and the Vapours going from the Lympha, when set on the Fire, do sufficiently resemble the Vapours of Water.  
We conclude from this, that the use of the Lympha is to nourish the parts, between the Fibres of which it flows. As will appear plainly enough after what we are going to say of Nutrition.  
It is a truth well enough known, that many Particles of our Bodies are separated and do exhale; and because these parts go out by the Pores of the Skin, as if it were a most subtle Wind, they call this Transpiration.  
The parts which pass from our Bodies by Transpiration, are ordinarily Salts dissolved in Phlegmes, with which there are some Sulphurs mingled. They are separated from the Blood by the means of an infinite number of small Glandules, which are situated under the Skin, and whose excretory Vessels end at small Holes, which are on the Surface of the Body, and which we call Pores.  
These Glandules which we shall call Subcutaneous, do receive Arteries, send forth Veins, and have some Filaments of Nerves. So that judging of them by others, we may well think that their use is, to separate from the Mass of Blood the Saline parts, which are form thereby the Conjunction of the Acids and Alcalies. Which makes us conclude that the parts which pass away by Transpiration, are parts of the Humours of the living Body, and not Particles of its solid parts.  
The Acids which are mingled with the Humours pass away, not only when they are joined with the Alcalies, but also when they are joined to the Sulphurs. The Author of the Animal Oeconomy, has put a considerable number of Glandules in the Membrane, which cover the thin Leaves of Bone in the Nose, which are proper to separate from the Blood the Sulphurs united with Acids. It is for this that there runs from the Nostrils a Glewy and whitish Liquor.  
By this we see after what manner the Alcalies, Sulphurs and Phlegmes of our Humours are consumed. Which makes us think that they would be very soon spent entirely, if they were not repaired. And it is this reparation of the Humours which we call Nutrition  
The Animal Body is never better nourished, than when all its parts are full of Humours which Circulate, or are in motion. And because it is the Lympha which flows amongst the Fibres of the solid parts and fill up their Interstices, it is this also which is that Humour whose abundance makes Nourishment.   

The eight Discourse. Of the Mouth.  
EVery Body knows, that the Mouth is that Cavity which all Animals have in their head; and through which the Aliments do enter into their Body. In it four principal things are taken notice of; which are, the Teeth, the , the Spittle and the Tongue.  
But before we enter to inquire into these things, it will not be impertinent to remark, that the Mouth is made by the upper and the under jaws. The most part of Animals open the Mouth by putting down the nether Jaw, and they shut it by taking it up. The Contrary is observed in Crocodiles, Serpents, and Lizards.  
The sides of the Jaws are pierced with many Holes of a good depth. They receive into their Cavities the roots of those little Bones, which are more polished, more white and hard than others, which adorn the entry of the Mouth like to a Palissade, and are called Teeth.  
That part of the Teeth which enters into the Holes of the Jaws, is called their Root, and that which stands out is chief named the Teeth. The Roots are usually much longer than the Teeth themselves, which is the Cause that they keep firm to the Jaws.  
Some have their Roots with three points, others of them with two, there are many of them also which have but one. When we break the Teeth with a Hammer, we find in the Body of them an empty Cavity, which extends its self even to the Root.  
The Teeth are not only fixed to the Jaws by their Root, but they are likewise fastened to them by a hard and firm Flesh which covers their sides, and whose Fibres are extended from one end of the Jaws to the other. This Flesh is called the Gums.  
Moreover the Teeth are of three sorts. Those which are placed in the entry of the Mouth are broad, and their extremities made with an edge. They are called Dentes Incisivi. The other which are farther within the Mouth, and which the Cheeks cover have a thick, strong and large Body, and their extremities broad and unequal, which makes them fit to break and bruise. It is for this they call them Dentes Molares, or the Grinders. And there are yet others which are very strong, and have their Extremities pointed, and are most fit to hold any thing fast. There is always one of them placed on each side, between the Incisive and the Grinders, and they are called the Dog-teeths or Eye-teeths, because they receive a branch of a Nerve from those which move the eye.  
The number of the Teeth is not always the same. Some men have 14 in each Jaw, some have 15 and others 16. Usually they reckon four Incisive, two Dog-teeths, and eight Grinders, as well in the upper as the nether Jaw.  
From all this we may Conclude, that the Teeth serve to chew the Aliment. The Incisive cut it into little Morsels, and the Grinders break and bruise it into very small pieces, to the end it may pass forwards, and the Dog-teeths cut it in pieces, when the Incisive are not strong enough for this effect.  
The Palate is that part of the Mouth which makes its Roof, and which is extended from the upper Jawbone even to the bottom of the Mouth. The surface of it is unequal, and its Forepart cut into small narrow furrows, placed near one another, from the Incisive Teeth to the middle of the Mouth and its hinder part is of a pretty even surface  
It is furnished outwardly with a very delicate Coat, under which there is another more thick and strong, when this is raised we discover an almost infinite number of small Glandules. These, being formed like the Grapes of Raisins make up the Body of the furrows of the Palate. Their Excretory Vessels do pierce the membrane which covers the membrane which covers the furrows, and shed into the Mouth a pretty clear and somewhat viscuous Liquor. The hinder part of the , whose surface is even, hath under its membranes small Glandules of the bigness of the Grains of Millet. They differ from those which make the furrows of the Forepart in this, that they are not ranked about their Excretory Vessels, as the Grains of Raisins about the stalk of the Grape: but they pierce the Membranes of the Palate by as many Excretory Vessels, as there are Glandules. All these Glandules of the Palate receive Arteries from the Carotides, send Veins to the external Jugulars, and receive Filaments of Nerves from the seventh pair.  
We find at the bottom of the Palate three remarkable Bodies, to wit, two Glandules, on each side one. They call them the Almonds; and between these Glandules a small piece of Flesh of a Conical Figure, which they call the Auula or Pape.  
The Almonds are Vesiculate Glandules of a Yellowish colour. Though they seem two in number, yet they are but one, the middle of which is covered by the Membrane of the Palate, and the Extremities appear like two Lobes. This middle part which makes the Communication of the two Lobes, is both more straight and more delicate, than the two ends of this Glandule.  
Each Lobe has a Sinus or Cavity, which is divided in many Apartments, the Excretory Vessels of these small Vesicles tend thither, and shed a glewy and whitish Humour, which is not unlike to the Snot of the Nose. They receive Arteries from the Vertebrals, they send Veins to the Jugulars, and their Nerves come from the third, fourth, and fifth pair.  
As for the Uuula, it is nothing but a small bag of the Membrane of the Palate. It hangs between the two Lobes, which make the Almonds. This Bag is full of an infinite number of small Vesicular Glandules, which are of the colour of the Flesh, because of the great number of Arteries which they receive from the Vertebrals and the Carotides, and the many Veins which they send to the Jugulars Their Excretory Vessels do pierce on all sides its outward Membrane, and bedew it with a Transparent & somewhat viscuous Liquor.  
The Mouth is not only watered with the Liquor which flows from the Glandules of the Palate and the Uuula, there are likewise four other great streams which empty themselves into it. They discharge themselves of a sweet and Transparent Water, in which there is some Viscosity remarkable. This Liquor is called the Spittie.  
We find within the Mouth two small Holes, the one on the Right, the other on the Left side. They pierce the Checks towards the Molar Teeth, or Grinders: And because we find them always wet, we make no doubt but they are the opening of two streams of Spittle.  
And indeed if we put into them a Bodkin, we find that it goes without difficulty into a small Membranous Pipe, which extends its self alongst the Cheeks, and is divided into many small Branches when it approaches below the Ear. This Vessel is always found full of Spittle, and the small Branches which are at its rise, do lose themselves into a heap of Vascular Glandules. These Glandules are placed about the Inner-part of the Ear, they are called Parotides. So that the small Excretory Vessels which go from each Glandule coming to be inosculated together, make up Vessels somewhat larger. These larger Vessels joining together do compose a greater, which increaseth according as it approacheth the Mouth, where it empties the Spittle which the Parotides have separated from the Blood.  
Moreover the Parotides do receive their Arteries from the Carotides, and send Veins to the External Jugulars; there are amongst them many Branches of Nerves which come from the hard portion of the seventh pair.  
The opening of the two other streams which do discharge the Spittle into the Mouth, is to be seen under the point of the Tongue towards the incisive Teeth. They are so small that they cannot admit a Hogs Bristle. They appear at the end of two fleshy Papillae, which serve them for small Sphincters. They extend themselves alongst the Tongue, and when they come near its root, they are divided into many Branches which lose themselves in a heap of Glandules, which are called the Maxillar Glandules.  
They are placed within the under Jaw, and they extend themselves from the root of the Tongue even to the Chin. The part of this Conglomerated Glandule which comes nearest unto the Parotides, is grosser and more red than the rest. As it advanceth towards the Chin, it diminisheth, so that it becomes by little and little more narrow and slender. There is remarked towards its middle part a little strait, which joins its fore part to the hinder. And afterwards, after having increased considerably, it extends its self even to the Chin, under the Figure of a Quince.  
All the Glandules which compose it are nothing but a Convolution of Vessels, which are Inosculated in one another to make by their Concourse two considerable Canals. These Canals extend themselves on each side, on the side of the Tongue, and end at the two Papillae fastened to the Gums, near the two incisive Teeth, within the Mouth.  
The Maxillar Glandules receive their Arteries from the Carotides, they send Veins to the Jugulars, their Nerves come chiefly from the third, fourth, and seventh pair. They separate from the Blood the spittle, and the Vessels of which we have been speaking do empty it in the Mouth.  
Besides the four streams of spittle, we remark also many small Rivulets of it which are within the under Lip and alongst the Gum on the inside of the Mouth. It comes from some Glandules which are found engaged amongst the Carneous Fibres of these parts, and whose Excretory Vessels pour into the Mouth the Liquor which they have separated from the Blood.  
The little Viscosity that is remarked in the Spittle makes us think that it is composed of some Sulphurs, some acids and much Phlegms with which there are some Salts. It mingles with the Aliments in the Mouth, and facilitates the Chewing by Moistening of them. It renders them more fluid, and by consequent fit to pass through the Conduits which must carry them elsewhere. It may be said also that by its acids and salts, it opens their small parts and makes the beginning of a dissolution. The Sulphurs enwrap its acids by a marvellous precaution of the Author of the Animal Oeconomy, to the end they may not corrode the parts which must be watered with Spittle.  
The necessity of the mixture of Spittle with the Aliments appears in that all concurs to make it. The Aliments press the Palate, and so oblige the Spittle which its Glandules contain, to run into the Mouth, by the little Excretory Vessels, which pierce its Membrane. The Crotaphite Muscle and the Masseters, by straitning and dilating themselves press the Parotides, and through their Vessels make two little streams of Spittle to run which enter on the right and left Side into the Mouth. The Digastrick by its contraction and dilatation agitates the Maxillar Glandules, and presses the Spittle out of them, which runs through their Excretory Vessels like two little streams, which discharge themselves into the Mouth. And whereas in the time of chewing all these parts play together after the manner we have said, it must needs be granted that this mixture of the Spittle with the Aliments is most necessary.  
In fine, we must examine the Tongue, which is a piece of Flesh almost of a Conical Figure. It's Basis is fastened unto the bottom of the Mouth by a little Bone which they call Os Hyoides. And from its Basis even to the middle it is fastened by its under part to the Muscles, which fill the Cavity of the Under-Jaw, so that its point is free, and does not cleave to any part.  
Under the free part of the Tongue there is a small Line made of small Tendinous Fibres, which reach from one end, even to the place where the Tongue ceaseth to cleave to the parts which fill the Cavity of the Under Jaw. This small Line is called the Bridle.  
The Hyoides Bone is placed in the bottom of the Mouth at the Basis of the Tongue. It has the Figure of a very open Fork, whose Arms cleave to an heap of Cartilages, which they call the Larynx. It is composed of many little Bones, which are joined by Cartilaginous knots. Sometimes there are but three of them, and at other times they reckon thirteen, to wit, six on each side. As for the Bone in the midst to which the Tongue is fastened, it is big in compare with the rest, which are very slender, It is likewise somewhat broad, bunching towards the Tongue and hollow towards the Larynx. On its raised side it has two small appendages which are ordinarily Cartilaginous. They call them the Horns of the Bone Hyoides.  
There are five pairs of Muscles which do make it move with the Tongue. The first is the Genthoidien which has its rise from within the Chin, and reaches to the Basis of the Bone Hyoides. These Muscles serve to raise it by the shortening of their Fibres. The second is the Sternohoïdien. It comes from the top of the Sternum, ascends alongst the Arteria Trachaea, and is fastened to the Basis of the Os Hyoides. This pair of Muscles draws it downwards. The third is the Milohyoïdien. It arises from within the Under Jaw towards the Hammers, and is inserted into the Basis of the Os Hyoides, which draws it up taking it by the sides. The fourth pair is the Coracohyïdien. It comes from the Coracoide Apophysis of the Omoplate. These have two Bellies, and are inserted into the Horns of the of Hyoides, which they draw downwards, taking it by the sides. The fifth is the Stilo Ceratohyoïdien. It ariseth from the Apophysis Stiloïdes, and is inserted into the Horns of the Os Hyoides: These Muscles restore it to its ordinary Situation, when it has been moved by others. They are pierced to give passage to the Digastrique.  
As for the Tongue, it is covered with an outer Membrane, which may be taken for the Cuticula. We find under it a substance which seems Viscuous. It is moderately thick, white on the side that touches the outer Membrane, and black on the other. They call it the Reticular Body. This Reticular Body is pierced like to a Sieve, and there ariseth from each of its Holes small Conical Bodies of a pretty hard Substance. They appear in an extraordinary manner on the Tongue of Cats. They are very long and crooked towards the point of the Tongue, like so many little Horns. We remark them also on the Tongues of Oxen and of other Animals of the same bigness. When those small Conical Bodies are plucked off, they leave considerable Holes in the Reticular Body, and their covers remain in the outer Surface of the Tongue.  
Under the Reticular Body, there is a Coat woven of Tendinous Fibres, and Filaments of Nerves of the fifth, and ninth pair, upon which appears a prodigious quantity of small Nervous Papillae. Each of these Papillae is covered with one of those Conical Bodies of which we have spoken. They pierce the Reticular Body, and terminate upon the Surface of the Tongue.  
Upon the Tongues of men there are none of those Conical Bodies which are chief remarked on the Tongues of fourfooted Animals. But the Papillae pass even to the outer Coat of the Tongue, which they elevate in little heights, and thereby render its Surface very unequal.  
They reckon three kinds of Papillae both on the Tongues of men and on those of Oxen, etc. The first are made like to the Horns of Snails, they have on the top a small round head. They are not numerous, some are placed on the sides of the point of the Tongue; there are none of them above, and many of them are found on the side of its Basis. The second are divided into small Fibres, which lose themselves in the rise of the outer Coat of the Tongue, and they are placed on its upper part. The Third are Conical and we find then, placed confusedly amongst the rest. They rise all from the Papillar Bodies, they pierce the Reticular Body, and go to the outer Membrane of the Tongue, which they elevate in heights in men, and there they rencontre the roots of the Conical Bodies in Oxen and other Animals which have them.  
In fine, the Tongue has five orders of Fibres by which it makes all its motions, besides those which are performed by the Muscles of the Os Hyoides. The first is of those which are extended in a strait, line from its Basis to its point, passing through the middle of its Body: by their Contraction they serve to draw its point towards the Base. The second is of these which passing from its Base even to its point, do furnish its two sides. By their Contraction, they move the Tongue to the right and left. The third is of those which passing from one side to the other, are interlaced with the first and cut them at right Angles. When they are shortened they make the Tongue round. This appears much more towards the point of the Tongue than elsewhere. The fourth is of those which coming from its Basis do embrace a part of the Tongue; they are interlaced with the Fibres of the first and third Order, cutting them obliquely. The effect which the shortening of them produceth, is that they draw the Tongue backward, without shortening it considerably. And the fifth is a few Fibres which derive their Origin from the Chin, and are inserted into the under part of the Tongue; they ascend even pretty far into its Body. When they are shortened, they draw the Tongue without the Mouth.  
Towards the Base of the Tongue, we remark many small Glandules, situated amongst its Fibres. They have Excretory Vessels, which yield Spittle into the Mouth, and whose Orifices do appear in many places of its Surface. Besides these, there are likewise some others observed situated on the sides of the Tongue, they call them Sublinguales. They have many Excretory Vessels, whose Orifices do appear on the Gums towards the Hammers. There runs from them, as from the rest a clear Transparent, and somewhat viscuous Liquor.  
The Fibres of the Tongue do show us that its use is to agitate the Meat in the Mouth, and to make it pass by its different motions, sometimes under the Grinders to be divided and broken. And as by all these motions it strikes the Palate, agitates the Maxillar Glandules, and that its proper Glandules are pressed from time to time, it obliges all its Glandules to yield a considerable quantity of Spittle into the Mouth. So that it is a great Instrument of Chewing.  
And in fine, when it is drawn back and raised at the same time by the Muscles of the Os Hyoides, it presses the Meat into a Conduit, called the Oesophagus, which comes to the Cavity of the Mouth, and by this means serves to the swallowing of it.   

The Ninth Discourse. Of the Oesophagus.  
WHen we trace the Aliments, we find that they go from the Mouth into a Conduit which is extended alongst the Neck and Breast, pierces the Diaphtagma and is inserted into the Stomach. They call it the Oesophagus.  
It is very true that the Aliments pass over a Cartilege, which covers the Orifice of a Pipe that enters into the Breast. This Cartilege is ordinarily lifted up, and the Aliments put it down, when they are thrust by the Tongue into the Oesophagus They call it the Epiglottis. But because the Aliments pass over it, without stopping there, and it has no use as to them, we shall not stop at it here, but shall reserve to speak of it in another place.  
After the Epiglottis the Orifice of the Oesophagus appears which they call the Pharinx. It is ordinarily shut, and does not open but to give passage to what is thrust forward that way by the Tongue, or to let out what is voided by the Stomach into the Mouth.  
It opens and shuts as is needful, by the help of seven Muscles. The first is called Oesophagian. It is strongly fastened to the two sides of the Scutiform Cartilege, and covers the Oesophagus by its Circuit. It's use is to shut the entry of the Oesophagus.  
The others are double. The first are called Sphaenopharingians. They derive their origine from within the sharp Apophyses of the Os Sphaenoides; and are obliquely inserted in the sides of the Pharinx, which they open by drawing it upwards.  
The second are the Stilopharingians. They arise from the extremity of the Apophyses Stiloides of the Bones of the Temples, and are inserted into the sides of the Pharinx, which they dilate by drawing its sides to the right and left Hand.  
The third are the Cephalopharingians. They derive their Origine from the Articulation of the Head with the first Vertebra, and spread their Fibres into the substance of the Pharinx, which they shut by the shortening of their Fibres.  
Moreover, the Oesophagus extends its self in a strait line from the Pharinx to the Stomach. It is composed of three Coats, which may be called, the inner, the middle, and the outer Coat, The inner is made up of nothing but Tendinous Fibres diversely interlaced. The middle is made up of Carneous Fibres, of which they reckon two Orders, both in Men and in other Animals. In Men the Fibres of the first Order reach alongst from the Pharinx to the Stomach, for which cause they are named Longitudinal Fibres; and those of the second Order are like to so many little Circles which do encircle the Oesophagus, above which the Longitudinals are placed. They are called Circular. In Animals, which eat with the Head downward, they have another Position. The two Orders of Fibres go spirally round about the Oesophagus. And for as much as the one go from the right to the left, whilst the others pass from the left to the right, they do in many places pass one above another. There is somewhat singular in this passing, to wit. That the Fibres which pass in one place above others, do go under them at the next rencontre, at the second they ascend above: And in fine, they pass again under them. The outer Coat is composed of Tendinous Fibres, more subtle and slender than those of the Inner. The inner and outer Coat serve for Tendons to the middle. So that we may consider the Oesophagus as a Muscle, whose inner Coat is the Head, the middle the Belly, and the outer Coat the Tail. So that in Men the Oesophagus is shortened by the swelling of the Longitudinal Fibres. And it is straitened by the shortening of the Circular. They call that shortening and this contraction of the Oesophagus its Peristaltique Motion.  
In Beasts, the shortening and contraction of the Oesophagus is much greater than in Men, for that the Musculous Fibres descend spirally and do cross one another, For when they swell, and by consequent are shortened, whilst they thereby shorten the Oesophagus, they make its Cavity less, because by their Action they wreath it.  
This  motion is made to the end that what has once past the Pharinx may not stop in the Cavity of the Oesophagus. So that we may well affirm, that the Oesophagus is framed after this manner, to thrust the Meat forward by its  motion, even into the Stomach.  
In Beasts the  motion of the Oesophagus straitens its Cavity much more than in Men, for that they Eat ordinarily with their Head downward. There is therefore more force needful to make the Meat ascend through the Oesophagus, that it may go into the Stomach.  
In fine, this  motion is called Vermicular, because the Oesophagus moves as Worms do, by straitning and shortening its self in one place, and swelling in another, which is continued from one of its ends even to the other by Undulation. The cause of this may be, that the Filaments of the Nerves do enter obliquely into the Tendinous Fibres of the Coats. For as soon as the Animal Spirits were entered into one Fiber, they would be shut up by blowing up the end of the Nervous Filament from whence they come. And so shutting the door upon others, they would hinder more from flowing in, till the Fibres were restored to their former Estate by the force of their spring. And in as much as the Longitudinal Fibres are all of a piece, and the circular ones communicate all together by the small Tendinous Fibres, the animal Spirits passing farther into the Longitudinals, and running into the neighbour circular ones, they would produce there the same effect which they had done in the former. So that continuing to run thus from the one end of the Oesophagus to the other, they would produce a Vermicular or Undulating motion, by which one place becomes more straitened and shortened, then is restored into its former estate, whilst this straitning and shortening descends farther, and so of the rest.   

The tenth Discourse. Of the Stomach, and of Chylification.  
THe Oesophagus is inserted into a kind of bag made almost like a Bagpipe; and this they call the Stomach. It is short and open at both ends. The place where the Oesophagus joins it, is on the left side, they call it the upper Orifice of the Stomach; and the other place where it is open, which is on the right, is called the Pylorus.  
The inner Coat of the Oesophagus lies within close about the upper orifice for the space of three inches.  
We find that the Stomach is made up of three Coats, the outer and inner are woven of Tendinous Fibres, and the middle is made of Carneous Fibres. All between the inner Tunicle and the middle is replenished with small Vesicular Glandules. Their Excretory Vessels pierce the inner Tunicle & form in its Cavity a small down, for which they call it the Velvet Tunicle.  
When we examine the Composition of the middle Coat we find ordinarily three orders of Fibres in Beasts, and two in Men. The first is nothing but the continuation of the Longitudinal Fibres of the Oesophagus, which extend themselves from the upper Orifice of the Stomach even to the Pylorus. And the other is nothing but the Continuation of the Circular Fibres of the Oesophagus, which are cut by the Longitudinals at right Angles. Thus it is that they are in men In Dogs, Cats etc. Besides these two orders of Longitudinal and Circular Fibres, there are two handfuls of Fibres extremely close, which extend themselves to the right and left above the Stomach, from its upper Orifice even to the Pilorus. They are nothing but the Spiral Fibres of the Oesophagus which are separated into two handfuls at the upper Orifice, and parting the one from the other, they pass alongst above the Stomach and are reunited at the Pylorus.  
All these different orders of Fibres are made to produce a  motion in the Stomach. It is by the means of this motion that the Aliments which enter into the Stomach by its upper Orifice, are sent out by the Pylorus.  
Morover the Stomach receives Arteries from the Caeliack, sends Veins to the Splenick and to the Vena Porta, the Parvagum does furnish it two branches of Nerves considerable enough, and many Nervous Filaments come from the Mesenterical Plexus: and in fine it gives rise to some Lymphatic Vessels which go into the Reservatory of the Chyle.  
There would be nothing more to be said of the Stomach, if we did not observe that the Aliments contract a considerable change during the stay they make there. In effect it is observed that they become Liquid and of a whitish colour. This Liquor is called the Chyle, and the action that produced it is named Chylification.  
To begin to examine the nature of Chylification. I observe that it produceth fluidity in the Aliments which were solid. We have learned in the Physics that Fluidity consists in the division and various motion of the Particles of fluid Bodies. So that by Chylification the parts of the Aliments must be separated from one another and diversely moved.  
This separation of the parts of the Aliments cannot be done but by bruising or by Fermentation. We know nothing in the Stomach that can so perfectly break and grind the Aliments as is needful to change them into Chyle. We must conclude then, that this Separation of the parts of the Aliments is made by Fermentation.  
We have remarked in our Discourse of the Elements of the living Body, that Fermentation is not made, but by the mixture of two Bodies of a different nature, and that it is done for the most part by the mixture of Acids and Alcalies. Nevertheless, since Alcalies are needful to dissolve Sulphurs, Phlegmes to dissolve Salts, and Acids to dissolve Alcalies, we cannot affirm that the Ferment which by its mixture makes the dissolution of the Aliments in the Stomach, is only an Acid, an Alcali, or a Phlemge; seeing by Chylification, both Salts, Sulphurs and Alcalies' are dissolved.  
But the Ferment must be composed of Principles capable of making a Fermentation, which dissolves Sulphurs, Alcalies' and Salts. And since we have established that Alcalies dissolve Sulphurs, Acids' Alcalies. and Phlegmes Salts, we must of necessity conclude that the Ferment of Chylification, is a composure of Acid, Alcali and Phlegm.  
If the Ferment of the Stomach be such, as soon as the Elements shall begin to mingle with it, its Acids will act upon their Alcalies, and by the Fermentation which they shall excite with them, will begin to dissolve the whole Mass of the Aliments. The Alcalies of the Ferment coming afterwards to pass amongst the Sulphureous parts of the Aliment, will keep them separated from one another.  
And in fine, the Phlegmes after having dissolved the Salts, will find place amongst all the parts of the Aliments, whose union will be broken by the Action of the Acids, and Alcalies.  
Some difficulty may be raised upon what we have said, that the Ferment of the Stomach was composed of Acid and Alcali; for that these two Principles cannot subsist together without a Fermentation, which would change them immediately into Salt. But if we consider, that certain Acids may have their Angles very pointed, and the sides of thess Angles very slender, and that the Pores of an Alcali may be large enough to let the Aetherial matter pass through, though an Angle of these Acids be thrust in there, we will easily comprehend after what manner an Acid may be mingled with an alcaly without exciting Fermentation, and without uniting closely with it. For in this case there will be Intervals large enough between the Concavity of the Pores of the Alcalies, and the sides of the points of the Acids which are placed there, to give passage to the matter which flows through their Pores. And since it is the obstacle which this Aetherial matter meets with in its passage, which makes it separate the parts of Bodies, it is clear that it needs not here produce any Fermentation.  
When therefore the Aliments descend into the Stomach by their weight, the press the small Glandules, which are placed between its inner and middle Coats. Since they are nothing but little Vesicles, so soon as they are pressed they empty themselves, and Distil into the Cavity of the Stomach, a sufficient dew of Ferment, which mingles with what is found there, Ferments it, dissolves it, and makes it Liquid.  
That which is Liquified gets above and obeying the Peristaltique motion of the Stomach goes out by the Pylorus. So long as this Fermentation lasts there goes away always somewhat of this sort, and when it is finished the Animal must eat or he is exposed to hunger, which proceeds from this that the Ferment being altogether pure in the Stomach it frets the inward Tunicle.  
The Ferment of the Aliments does never entirely dissolve the parts, there are always some of them which escape it. This is the Cause that the Chyle is not to be met with at the going out of the Stomach, and that it is mingled with many gross and useless parts. It is for this reason that nature has made the Chyle to pass through a long Pipe of Intestins, in which it is mingled in divers places with different Liquors, which serve to separate what is good from what might be hurtful to the conservation of the living Body.   

The Eleventh Discourse. Of the Intestines.  
THe Chyle in going out of the Stomach passes into a Conduit joined to the Pylorus, which is called the Guts, or Intestines. This Conduit makes many Circumvolutions: And in fine, after having made many wind, terminates in the Fundament.  
They divide them into six parts, to which they give different Names. The first, which they call the Duodenum, gins at the Pylorus, and ends at a place where a yellowish and oleous Liquor is discharged into the Cavity of the Intestines. It is ordinarily replenished with the Chyle such as it comes from the Stomach.  
The second, which is usually found almost empty, is called Intestinum Jejunum. It gins at the end of the Duodenum, and ends at the places where we begin to find Excrements. They give it the length of ten or twelve Palms. The third is called the Ilium. It gins at the end of the Jejunum, and ends at th' small end of a Gut, which is fastened unto the Cavity of the rest, like the bottom of a Sack. Hitherto the Intestines are very delicate and their Cavity small enough: And it is for this they are called the small Intestines. The fourth is called the Caecum, which is the small end of a Gut fastened to the rest, of which we have made mention. The fifth is called the Colum. It gins at the Caecum, and makes a great Circuit about the other Guts: We find at its entry a Membranous folding, whis is so framed, that it permits the Excrements to pass easily from the Ilium to the Colum, but does not suffer them to pass without difficulty from the Colum to the Ilium. The Cavity of the Colum is all divided into little Cells, and it ends at the place where the rest of the Guts goes strait to the Fundament. This makes the sixth Intestine, which is called Rectum The Caecum, the Colum, and the Rectum, are called the Great Intestines, because their Coats are stronger and grosser than those of the small Intestines.  
All the Intestines are made up of three Tunicles, as, the Oesophagus of the Stomach. The inner is a Texture of Tendinous Fibres diversely interlaced; the middle has two Orders of Carneous Fibres, of which the one are Circular, and the other Longitudinal: And the outer is a Texture of Tendinous Fibres. These Tunicles serve to make the  motion of the Intestines, after the same manner that it is done in the Oesophagus and the Stomach. This Vermicular motion serves to make that which is in the Intestines to pass even to the Fundament, that it may be thrown out of the Body as useless.  
Besides the three Tunicles of which we have spoken, we remark in the substance of the small Intestines, a heap of little Glandules, which send their Excretory Vessels into the Cavity of the Intestines, and Distil there a clear and transparent Liquor. We shall tell its use when we speak of the changes which the Chyle receives in passing into the Intestines.  
Moreover the Chyle is not very Liquid when it comes out of the Stomach. It resembles somewhat the Paste which is made by the Boiling of Meal with Water. It is even like to it of a grayish colour, and has much ot Viscosity. But it does not continue long in that state. It has no sooner passed the Duodenum, but a yellow and extremely bitter Liquor, which they call the Bile, comes to mingle with it.   

The twelfth Discourse. Of the Bile and of the Liver.  
WHen we inquire by Chemistry what are the Elements of the Bile, we find that it is composed of much of fixed alcaly, a little Volatile, a little of Sulphur, yet less of Earth, and much of Phlegm.  
From whence we may conclude, that the Bile mingling its self with the Chyle, receives in its Alcalies both fixed and Volatile, a part of the Acids, which hold its Sulphurs united together, and thereby keep up the Viscosity which it has in the Duodenum. So that the Sulphurs of the Chyle are after this more at liberty, and more separated one from another. Wherefore they receive amongst their parts, the Phlegm of the Bile, which dilate the whole Mass and give it a greater fluidity.  
The Bile is discharged into the Cavity of the Guts, at the end of the Duodenum by a small Hole, round about which is observed a small Spongious edge. If you put a Probe into this small Hole, it passes into a Membranous Conduit, which reacheth to the Liver. This Conduit is always full of Bile. It is therefore called Canalis Cholidochus.  
The Insertion of this Vessel into the Intestines is singular enough. At first it creeps above the hinder part of the Duodenum, and then pierces its outer Coat. Afterwards it pierces its middle Tunicle after having descended for some space between that and the outer Coat. And in fine, after having made some way between the middle. Tunicle and the inner, it pierces the inner at the place where we have observed the little Hole through which the Bile flows into the Intestines.  
The Obliquity of this Insertion serves to make the Bile run into the Intestines. And the spongious edge which environs the little Hole hinders the Bile from returning from the Intestines into the Ductus Cholidochus. For the spongious edge is a small Sphincter which keeps the little Hole shut, when the Bile does not keep it open by flowing into the Guts. And the  motion of the Intestines passing towards the little Hole, serves successively that part of the Ductus Cholidochus which creeps amongst the Membranes of the Duodenum; and thereby obliges all the Bile that is in this part of the Ductus Cholidochus to run into the Cavity of the Guts.  
After having considered all this exactly I follow the Ductus Cholidochus towards the liver, and I perceive that it is forked there, and that one of its branches goes to a Bladder situated besides the concave part of the Liver, whilst the other goes to the Liver. They call the branch which goes to the Bladder Ductus Cysticus, and that which goes to the Liver Ductus Hepaticus, and the Trunk which arises from the joining of both these which is inserted into the end of the Duodenum, Ductus Communis.  
The Hepatick. Conduit enters into the Liver accompanied with two Arteries, two Nerves and the Vena Porta All these Vessels are shut up in a Membranous sheath, which they call, Glisson's Capsula. As soon as they enter into the Liver, they are divided into many branches, and these branches into others, and thus they continue to divide till they be spread through all the substance of the Liver.  
It is here to be remarked that all these Vessels continue still to be shut up in Glisson's Capsula. It accompanies them through all, and follows all their ramifications. So that wherever there is a branch of an Artery, there is there also a branch of the Vena Porta, and one of the Ductus Cholidochus, and the whole is shut up in a branch of the Capsula. As for the Nerves they follow also the ramification of the other Vessels for some space, and in fine they form a small net, which enfolds the Arteries  
From this by the way we may conclude that the Vena Porta does not beat in the Liver, as some Authors have imagined; but that the beating of the Capsula proceeds from the beating of the Arteries which are shut up in it.  
All these Vessels enter into small Lobes, the Assemblage whereof makes up the Liver. Each Lobe is shut up in a very delicate Membrane which divides it from all the rest. Nevertheless it ceases not to adhere to them by small Tendinous Fibres. The Membrane which enfolds each Lobe degenerates into a part of the Capsula, enfolding all the Vessels which enter into the Lobe. So that Glisson's Capsula is nothing but the continuation and reunion of all the Membranes which encompass the small Lobes of the Liver.  
All these Lobes are made up of little Vascular Glandules, which touch one another. Each Glandule receives a branch of an Artery and of the Vena Porta, and there goes from it a branch of the Ductus Cholidochus, which is nothing but a continuation of the Vessel of the Glandule. They are fastened to these small Vessels as Raisins to the Trunk of the Grape. There goes also from each Glandule a branch of the Hepatick Vein, which being united make up a considerable Trunk, which goes from the Liver at its convex part, and enters into the ascending Vena Cava.  
The Vena Porta and the Arteries bring the Blood to the Glandules of the small Lobes, the branches of the Hepatick Vein carry it away again into the Vena Cava, and the Ductus Cholidochus transports into the end of the Duodenum the Bile, which the Glandules of the small Lobes have separated from the Blood.  
This is what we have discovered in following the Ramifications of the Hepatick Conduit. Let us now trace the Ductus Cysticus. I remark first that it is straitened by a small Fibrous Ring at its Insertion into the Vesicle of the Bile. So that this Fibrous Ring performs the office of a small Sphincter, which shuts the entry of the Vesicle, and hinders the Bile which usually fills it, from getting out, unless it be forced. Afterwards I consider the Vesicula Fellis. It has the figure of a small Pear, and it receives Arteries from the Caeliack, which are called the Cystick Arteries. It is made up of two Tunicles, between which there are a prodigious number of small Vesicular Glandules, which receive branches from the Cystick Arteries. The Excretory Vessels of these little Glandules do pierce its inner Coat, and make within its Cavity a small Down, from whence there flows a very clear and Transparent Bile in form of a Dew. This Bile differs from that which flows from the Hepatick Conduit, in this, that the former is of a deeper colour and abounds more in a fixed alcaly, whereas this is more fluid, and has more of a Volatile alcaly than the other.  
All the Bile which is found in the Vesicula Fellis, does not come only from the Vesicular Glandules situated between its Tunicles; but a great part of it comes from the Lobes of the Liver which are about the Vesicle. They discharge themselves into its Cavity by two or three Ductus Cholidoci, which are inserted into that part of it that adheres to the Liver. Amongst the rest there is one considerable enough which pierces the Tunicles of the Vesicula Fellis near the Fibrous Ring. The mouth of this Vessel is encompassed with a small Spongious border, which serves it for a Sphincter.  
There goes a great number of Lymphatic Vessels, both from the concave part of the Liver, and from the Vesicle, which enter into the Reservatory that is placed above the Vertebrae of the Loins.  
In fine, the Liver has three Ligaments which keep it in its situation. The first keeps it strongly fastened to the Diaphragme, and it pierces into the substance of the Liver, even to Glisson's Capsula. The second is of a good length, it is fastened to the Liver near the Bladder of the Gall, and it goes to the Navel. The third is slack, but strong and large. It derives its Origine from the Membrane which encompasses the whole Liver, and which is a production of the Peritonaeum, and it goes from thence to the Xiphoid Cartilege.  
It's upper part is Convex, and it's under Concave, is divided into three or four great Lobes, and by its under part it embraces a part of the Stomach So that when the Stomach is full of Meat, the Bladder of the Gall being then pressed, the Bile goes out by the Cystick Channel, and runs in abundance into the Duodenum, to dissolve the Chyle according as it comes from the Stomach.  
From all this therefore, we may conclude that the use of the Liver is to separate the Bile from the Blood, to perfect the Chyle in the Intestines, by dissolving its Sulphurs by its Alcalies, and by diluting it with its Phlegm.   

The Thirteenth Discourse. Of the Changes which the Chyle receives in the Intestines.  
BEsides the Bile which is discharged into the Duodenum; there is also another Liquor Clear and Transparent as Water, which advances thither, and which they call the Pancreatic Juice. This Pancreatic Juice is somewhat of the same nature with the Lympha, that is, that it is composed of Sulphurs, Phlegms and Volatile Alcalies.  
As soon as it falls into the Intestins, it mingles with the Chyle. If it rencounters any Acids in the Chyle, which keep its Sulphurs united, its Volatile alcaly charges its self with them, which frees the Sulphurs from the other Principles. The Sulphurs which are in the Pancreatic Juice, thrust themselves amongst the parts of the Chyle. They moderate the Fermentation of the Alcalies with the Acids, and hinder it from being done with too much Violence, which would occasion much disorder. And the Phlegm make way to the Alcalies and Sulphurs, and they mingle more exactly with all the parts of the Chyle.  
From all this it follows clearly enough that the Pancreatic Juice perfects the Chyle and renders it more Liquid. In men the Pancreatic Juice and the Bile do enter into the Intestine at the same Hole. And in the most part of other Animals the Pancreatic Conduit is inserted into the Jejunum two Inches below the Insertion of the Ductus Cholidochus. We remark in this Insertion of the Pancreatic Conduit almost the same circumstances which have been observed in the Insertion of the Ductus Cholidochus. About the little Hole from whence the Pancreatic Juice flows into the Cavity of the Intestines, there is a little Fibrous edge, which serves it for a Sphincter, and hinders any thing from passing from the Intestines into the Pancreatic Conduit.  
This Conduit is made of many others, which spread, through a Glandulous Body, which they call the Pancreas. The Glandules which compose it, are Vascular of a reasonable bigness. There goes from each a small Conduit which is Inosculated into the Pancreatic Conduit, and sheds into its Cavity the Liquor which the Glandule has separated from the Blood.  
The whole Pancreas is covered with one Tunicle. It receives Arteries from the Caeliack, it sends Veins to the Splenick, and some Ramifications of the Intercostal come thither, and spread through all its Body.  
It is so needful for the conservation of of the Animal, that the Chyle should be freed of its Acids, that the Author of nature has placed many heaps of Vesicular Glandules between the Tunicles of the small Intestines. They distil into these places a Liquor like unto the pancreatic Juice. By its mixture with the Chyle is finisheth what the Bile and the pancreatic Juice had so well begun.  
These small heaps of Glandules are of different bignesses. There are of them which contain more than two hundred Glandules, and there are of them again which have not thirty. Sometimes there are four of them, sometimes five, and sometimes six. Sometimes there are two of them in the Jejunum, sometimes three, and sometimes but one: we find always two or three such heaps in the Ilium.  
All the parts of the Chyle are not fit to Pass into the small Vessels which are called the Lacteal Veins. Some of them too gross, and these are they which are called the gross Excrements. The Chyle abounds in parts fit to pass into the Lacteal Veins, after that it has been prepared by the Bile and the pancreatic Juice. It is for this that its mass doth diminish so much in the Jejune Intestines for that its more subtle parts get out and pass into the Lacteal Veins. So it is observed that there are more Lacteal Veins of the Jejunum, than of all the other Intestines. At the end of the Jejunum some Excrements are found mingled with many Chylous parts. The Glandulous juice mingles with them and dissolves the Sulphurs from the Chylous parts which are there. What has thus been prepared passes likewise into the Lacteal Veins. These Excrements do afterwards pass into the Ilium, where in divers places they receive again of the Glandulous Juice, which doth produce the same effect as formerly. In fine, after they are entirely freed of their Chylous parts, they pass into the greater Intestines. They are then composed of parts which the Ferment of the Stomach could not dissolve, and of salts which are form by the union of Alcalies, of the Bile, of the pancreatic Juice, and of the Glandulous Juice with the Acids, which were engaged amongst the parts of the Chyle.   

The fourteenth Discourse. Of the Mesentery, the Lacteal Veins, Pecquets' Reservatory, and the Thoracick Conduit.  
THe Intestines adhere to the Circumference of a Membranous Ruff, which they call the Mesentery. The middle of it is so strongly fastened to the Vertebraes of the Loins, that it cannot be separated from them, unless you tear a part of it, or cut it. It is composed of two Membranes, of which the upper is a continuation of the Peritonaeum, and the inferior a Texture of Tendinous Fibres which come from the Vertebraes of the Loins.  
The Mesenterick Artery spreads many branches amongst the Membranes of the Mesentery, one part of which goes to the Intestines, and the other is spread amongst the Fibres of the Membranes which compose it. The Veins which come from the Intestines are likewise spread between the Membranes of the Mesentery, and many small Veins which come from amongst their Fibres, go thither. They are called the Mesaraick Veins. They go to the Vena Porta. Many Nerves which arise from the Vertebraes of the Loins, and from the Intercostal, are so interwoven one with another upon the Mesentery, that they form a Plexus which is called the Mesenterick Plexus. Many Nervous Fibres go from it, which are spread amongst the Fibres of the Membranes of the Mesentery, and a part of which passes even to the Intestines.  
The middle between the Membranes of the Mesentery is replenished with Far. It appears chiefly about the Mesaraick Veins. In the midst of it we find a large Glandule, and sometimes two, three or four. In Oxen and some other Animals there are many more, and they are placed towards the small Intestines. The knowledge of the structure of these Glandules does admirably serve to explain their uses. They are a heap of angular Vesicles. There is a communication between their Cavites. This is found by blowing into them after you have thrust out all that fills them. The Air passes from one Vesicle to another, and makes them appear such as we have described them.  
In fine, we discover between the Membranes of the Mesentery certain small Vessels, which come from the Intestines and pass into the Glandules of which we have spoken.  
These Vessels are ordinarily full of Lympha, and sometimes we find them full of Liquor like to Milk. which is the reason why they call them the Lacteal Veins.  
This Milk is nothing but the pure Chyle, which has passed from the Cavity of the small Intestines into that of the Lacteal Veins. There are four Experiments which confirm us in this Opinion. The first is, that the Milk which runs into the Lacteal Veins comes from the Intestines, this truth appears to the Eye, when the Lacteal Veins are pressed with the Fingers. They empty themselves of the Milk, and we see it come afterwards from the side of the Intestines to fill the Vein which has been emptied. The second is, that Milk is not to be found in the Lacteal Veins but some Hours after the Animal has eaten. The third is, that we find the Jejunum almost always empty, because of the great number of Lacteal Veins which go from it.  
Moreover the Lacteal Veins have many Valves placed very near one another. They are so disposed that they permit the Chyle to run easily into the Lacteal Veins in going from the Intestines to the Glandules of the Mesentery, but they hinder its return. They go from the Intestines in great number, and they are Inosculated many of them together accordding as they advance. By this means they make up some greater Vessels which empty the Chyle that they carry, into the Vesicles of the Glandules of the Mesentery.  
The Chyle goes into the Vesicles of these Glandules, to receive there Animal Spirits, which come thither in abundance by many Nerves which proceed from the Mesenterick Plexus. These Spirits render the Chyle more subtle and fluid by their Volatile alcaly, and if there be any acidity in it, they correct it, by receiving it into their Alcalies and changing it into Salt.  
After that the Chyle has passed through the Vesicles of the Mesaraick Glandules, it discharges its self into two or three Conduits which arise from under them. They end afterwards in a Membranous bag situated above the Vertebras of the Loins, they call it the Reservatory of the Chyle. The Reservatory is the same thing with the Cistern of the Lympha, of which we have spoken before. In this place the Chyle is mingled with much Lympha, with which the Reservatory is always full. It dilates it, and renders it more Liquid, that it may run the more easily.  
In fine, there goes from the Reservatory of the Chyle, a Conduit, which is called the Thoracick Conduit, for that it goes alongst the Vertebraes of the Thorax. Sometimes this Conduit is forked, and its branches unite again, sometimes it is altogether simple.  
The Thoracick Conduit is inserted into the Subclavian Vein, above its Insertion there is a Valve, which like a small Vault covers it. So that the Blood which runs through the Subclavian Vein, runs by without hindering the entry of the Chyle.  
When we blow in the Thoracick Conduit, we perceive many Valves in its Cavity. They are placed at very small distances from one another, and are so disposed that they permit the Chyle easily to run towards the Subclavian Vein, but they hinder it from descending into Pecquets' Reservatory.  
From whence we may conclude that the Chyle runs from its Reservatory by the Thoracick Conduit into the left Subclavian Vein. There it mingles with the Blood. Whose course it follows and goes into the Vena Cava, which carries it into the right Auricle of the Heart. The Auricle discharges it into the right Ventricle. And whereas the Chyle makes then a part of the Blood, it follows its course, and circulats with it through all the Body.   

The fifteenth Discourse. Of the Heart.  
WHen the Chyle is once entered into the Subclavian Vein, it mingles its self with the Blood, and follows its course. We must therefore follow the Blood, if we could know what becomes of the Chyle.  
The circulation of the Blood shows us that it runs from the Subclavian Vein into the Vena Cava, and from the Vena Cava it passes into a bag adhering to the right side of the Heart. This little bag they call the right Auricle of the Heart. When this Auricle is full of Blood it contracts its self, and in contracting its self sheds it into a Cavity which we find in the Body of the Heart on its right side. This Cavity is called the right Ventricle of the Heart. As soon as the Ventricle is full of Blood, it contracts its self, and empties its self by this contraction.  
It is here to be remarked, that at the opening of the right Auricle into the right Ventricle of the Heart, there are certain small Skins, which they call Valves. They are three in number, almost of a triangular Figure, whose sides are notched. Their Base adheres to the opening of the Auricle, and their point is placed within the Ventricle. Their point is upheld only by small Tendinous Fibres, strong and of a good Length, which without being stretched are strongly fastened to small carneous pillars, placed upon the concave surface of the Ventricle This disposition shows to the Eye that these Valves are so many small doors, which the Blood opens of its self, when it runs from the Auricle into the Ventricle, and which it shuts after it is entered there. Indeed as soon as the Ventricle is full of Blood it contracts its self, and the Blood is pressed equally on all sides by this contraction. For this cause it gets under these Valves, lifts up their point towards the opening of the Auricle, which is thereby so exactly shut, that no drop of Blood can pass that way. So the Blood shuts up to its self this passage, and cannot get out the way by which it has entered. Nevertheless it does not stay in the right Ventricle of the Heart, it goes out by another door, to which the beginning of an Artery is strongly fastened. This Artery is divided into many branches, which distribute themselves into the Lobes of the Lungs. At its passing from the right Ventricle it has in its Cavity three Valves made like Crescents, and ranked each at the side of the other. Their Convexity adheres to the Artery and turns towards the Ventricle, and their Concavity is disengaged and turned towards the Artery. This situation shows us that they do not oppose the motion of the Blood when it comes from the Ventricle to the Artery, but by rising up they stop its course if it press from the Artery into the Ventricle.  
After that the Blood has passed from the right Ventricle into the Lungs by the Pulmonary Artery, it returns from them by a Vein, which is called the Pulmonary Vein. This Pulmonary Vein discharges its self into a little bag, fastened to the left side of the Heart, which is called the left Auricle. As soon as this Auricle is full, it contracts its self, thrusts by its Contraction the Blood into a Cavity in the substance of the Heart, placed on its left side which is called the left Ventricle As soon as this Cavity is full of Blood it contracts its self, and by this contraction throws out all the Blood which it contains.  
That we may learn where the Blood goes when it passes from the left Ventricle of the Heart, we are to take notice that at the opening of the left Auricle there are Valves situated, after the same manner as at the opening of the right Ventricle. Their use also is the same. They permit indeed the Blood to run from the Auricle into the Ventricle, but they hinder it from coming out of the Ventricle into the Auricle when the Heart contracts its self. The Blood therefore takes another way. Indeed it gets out of the left Ventricle by another passage, which makes the beginning of the great Artery, which they call the Aorta. We find in the Cavity of this Artery next to the Heart, three Valves made Crescent ways, disposed after the same manner as those of the Pulmonary Artery. They permit the Blood to get out of the left Ventricle and to run into the Aorta, but they hinder the Blood from flowing back from the Aorta into the left Ventricle.  
There is yet an important remark to be made upon the motion of the Auricles and Ventricles of the Heart. It is, that the two Auricles do contract and dilate themselves at the same time, and the two Ventricles in like manner. With this Circumstance, that at the time the Auricles contract themselves, the Ventricles are dilated, and when the Ventricles contract themselves, the Auricles are dilated in course. Which makes us conjecture, that the Heart is a Muscle, whose Auricles may well be reputed the Antagonist Muscles.  
Before we inquire if this conjecture be a truth, it will not be impertinent to observe, that since the Auricles contract themselves at the same time, they do also at the same time shed the Blood into the Ventricles of the Heart. By the same reason the Ventricles of the Heart do at one time press the Blood into the Pulmonary Artery, and into the Aorta.  
When we consider the Heart narrowly, we perceive that it is composed of Carneous Fibres, which have all of them communication with a Membrane made of Tendinous Fibres. This Membrane is placed at the Base of the Heart, and keeps the Auricles fixed to it. Which makes us judge that the Heart is a Muscle.  
In the Heart we observe three orders of Fibres, the first is, of those which go in a strait line from the Basis of the Heart just to its point; and they lie in a small number over the right Ventricle. The second is of those which go from the Base, and after they have extended themselves to the middle of the Heart, ascend again and return to the Base from whence they came. The third is of those which go from the Base and come to the point, describing about the Heart a spiral Line. There they re-enter within the Heart, and re-ascend spirally towards the Base. Some of them end in the Ventricles, where they make a Texture of their Tendinous Fibres, which covers them on all sides. Some of those also which come into the Ventricles make those little Eminencies which are called Pillars. From the point of these Pillars go many Tendinous Strings, which are joined to the Teeth of the Valves that are placed in the opening of the Auricles.  
All these Orders of Fibres do serve by the shortening of themselves to contract the Ventricles of the Heart. The strait Fibres shorten it, the circular ones straiten it, and the spiral wring it. The Heart cannot be thus shortened, straitened and wreathed, but the Ventricles must needs be contracted. From whence we must conclude, that the Heart is a Muscle, whose action consists in straightening the Cavities which are amongst its Fibres.  
As for the Auricles, they are also composed of Carneous Fibres, of which some of them are interwoven with others. They are extended for the most part to the length, and those of them which are interwoven seem to cross them to become Circular. The shortening of the first does diminish the length of the Auricles, and the shortening of the other diminisheth their breadth. Which shows us that the Auricles are nothing but Cavernous Muscles, whose action consists in the contraction of their Cavity.  
There is a communication between the Fibres of the Heart and those of the Auricles, by the interposal of the Tendinous Fibres, which are gathered altogether pure at the Base of the Heart. We may look upon them as a Tendon common to the Heart and the Auricles. The animal Spirits therefore which the Nerves distil into this Tendon, do easily pass from the Fibres of the Heart into the Fibres of the Auricles, and from the Fibres of the Auricles into those of the Heart.  
If we would yet form to ourselves an Idea of the Heart as clear and distinct as may be, we may consider it as a Muscle with three Bellies. Each Auricle makes one, and the Body of the Heart makes the third, and the Membrane which is at the Base of the Heart where the Fibres of the Heart and of the Auricles do meet, would be the common Tendon.  
The Heart receives Arteries from the Aorta, it sends Veins to the Cava; it receives Nerves from the plexus Cardiacus and the Par Vagum.  
In fine, the Heart is shut up in a Membranous Bag which is called the Pericardium. The Pericardium is strong and it is form of a Texture of the Tendinous Fibres of the Heart, of some Veins, some Arteries and some Nerves. It contains always a little Serosity, which the small Glandules that are placed amongst the Fat of the Base of the Heart do distil into it.  
From what has been said, we may conclude, that when the Auricles are full of Blood, the Ventricles of the Heart are empty. And for that the Auricles, how soon they are full of Blood, do contract themselves; the Blood which they press into the Ventricles of the Heart, being aided by the spring of their Fibres, does dilate them, and constrains the animal Spirits to get out of them, and to run into the Auricles to accomplish their contraction. But as soon as the Auricles are contracted, the Blood which advances on all sides, joynned with the force of the spring of their Fibres, restores them to their former state. And the Spirits passing in that moment from the Auricles to the Heart, shut it up, and cause its contraction. It is for this Reason that the Auricles empty themselves when the Ventricles of the Heart are filled, and that the Auricles fill themselves when the Ventricles are emptied.  
The heart by its Contraction throws the Blood from its Ventricles into the Arteries. But for that the Artery become still narrower, the Blood cannot be thrown out impetuously without swelling them When they are thus blown up, they restore themselves to their former state by the spring of their Fibres, and by this mean make a part of the Blood which they have received run into the Veins of the Heart. And since the Heart throws out the Blood into the Arteries by several strokes, the Arteries must needs be blown up and fall again by several turns. It is this motion of the Arteries which they call the Pulse, concerning which it is to be remarked that the dilatation of the Arteries accompanies the contraction of the Heart, and the contraction of the Arteries accompanies its dilatation.  
Those who are satisfied with what they conceive clearly, will be contented to ascribe to the Heart the office of pressing the Blood into the Arteries, and of being the principal Instrument of its Circulation. They may leave to those who believe that the Heart is the Organ of sanguification, the satisfaction they have to be pleased with a conjecture ill founded, as shall be made appear afterwards.   

The Sixteenth Discourse. Of the Lungs.  
WE have said in the preceding Chapter, that when the Blood goes from the right Ventricle of the Heart it passes into the Pulmonary Artery. This Artery is divided into many great branches which enter into the Body of the Lungs, and these branches are again divided into others, and these into others, till at last the smallest of them are lost into the substance of the Lungs.  
The Pulmonary Artery is not spread alone in the Lungs. It is every where accompanied with the Pulmonary Vein, a branch of a Nerve which comes from the Par Vagum, a small Artery which goes from the Aorta, and which they call the Bronchial Artery, with a small Vein which is passing into the Vena Cava, and which they call the Bronchial Vein; and a certain Cartilaginous Conduit, which they name the Bronchiae.  
The Bronchiae are nothing but the Ramifications of a great Cartilaginous Pipe, which extends its self from the bottom of the Mouth, even to the Lungs. It lieth above the Oesophagus, and is placed in the fore part of the Neck. They call it the Arteria Trachaea.  
There is at the top of the Arteria Trachaea a horny part, which they name the Larinx. It is made up of five Cartilages. That which takes up its forepart, makes that Eminence which in men they call Adam's Bit. Its Figure is almost like unto that of that Buckler which amongst the Latins is called Scutum For this reason they name it the Scutiform Cartilege. The second is called the Annular. It is made like the Ring which the Turks make use of for drawing the Bow. It is straight before and large behind. It embraces the whole Larinx, and is fastened into the Scutiform. The third and fourth are called the Aritenoides. They are the productions of the Annular, placed on its hinder part, and separated from one another by a small slit. They make that part of the Larinx which they call the Glottis. The fifth is a Cartilege fastened above the upper part of the Scutiform Cartilege. They call it the Epiglottis. It's Figure is Triangular, and its substance softer than that of the others. It's Base adheres to the Scutiform Cartilege, and the rest of its Body is disengaged from any other part. It is usually lifted up. This is that Cartilege which the Aliments put down in passing from the Mouth, into the Oesophagus. When it is down it shuts the entry of the Trachaeal Artery, and thereby hinders the Aliments from going into it.  
The Larinx is reckoned to have thirteen Muscles. There are four of them, which are common to it with other parts, and nine which do properly appertain to it. The first pair of the common ones are named the Sternothyoidians. They arise from the top of the Sternum, lie above the Trachaeal Artery, and are fastened to the inferior part of the Scutiform Cartilege. When their Fibres are contracted they draw the Scutiform downwards. The second pair is made of the Hyothyroidians. They arise from the Base of the os Hyoides and are fastened to the Base of the Scutiform. They serve by the contraction of their Fibres to lift up the Larinx.  
The first pair of Muscles proper to the Larinx is made of the anteriour Cricothyroidians. They derive their origin from the forepart of the annular Cartilege, and they end at the lower part of the same Cartilege. By their action they dilate it. The second is made of the Posteriour Cricothyroidians. They arise from the top of the annular at its hinder part and come to the sides of the Scutiform at its upper part. When they act they straiten the Scutiform. The third is made of the Cricoavithenoidians. They derive their origine from the inner, and side part of the annular, and are inserted into the under part and the sides of the Arithenoides. By their Contraction they dilate the Glottis. The fourth is made of the Thyroarithenoidians, They come from within, and from the middle of the Scutiform, and are terminated in the sides of the Arithenoides, By their action they shut the Larinx. The ninth Muscle is called the Arithenoidian. It ariseth from the place where the annular is joined with the Arithenoides which it straitens when it acts.  
The Larinx covers the top of the Tracheal Artery, whose frame is singular enough. First we find it covered with a very delicate Membrane whose Fibres are diversely interwoven Then under this Membrane there are Cartilaginous rings. These rings are entirely Cartilaginous except on their Backside, where they are Membranous. It is by this place they touch the Oesophagus. They are not Cartilaginous that they may yield to the Oesophagus, when any great and hard morsel passes alongst its Cavity.  
These Cartilaginous Rings are not all of the same grossness. That which upholds the Larinx is greater and larger than that which follows, and this is larger than the next, and so forward. So that the more they approach the Lungs their breadth diminisheth. They are all united together by carneous Ligaments, and it is remarked that they are all equally distant the one from the other.  
When they enter into the Body of the Lungs they are named the Bronchiae. There they cease to be Membranous on their backpart and become entirely Cartilaginous. And whereas in the Tracheal Artery its Rings are equally distant from one another, in the Bronchiae, they are joined in such a manner as that a part of the Inferior Ring enters into the Cavity of its Superior.  
The Cartilaginous Rings of the Tracheal Artery, and of the Bronchiae, do cover a Tunicle composed of three principal Parts. How soon you raise up one of the Cartilaginous Rings you find a Musculous Tunicle. It's Fibres are disposed as the Fibres of the middle Tunicle of the Intestines. The Longitudinals appear first and afterwards we see the Circulars. They are placed precisely under the Longitudinals. This Carneous Tunicle covers another Tunicle which is nothing but an assemblage of small Glandules, even as the Carneous Tunicle of the Stomach does immediately cover the Glandulous. And in fine, under this Glandulous Tunicle there is another, which is nothing but a Texture of Tendinous Fibres which come from the Carneous Tunicle; There are some Filaments of Nerves, and some small Arteries and Veins.  
In the Lungs the Tracheal Artery is divided into many branches. These branches are again divided into many branches, and these again into many others, and so onward till the last end into an infinite number of small Vesicles. These Vesicles do compose the substance of the Lungs.  
The Vesicles which are gathered about one and of the Bronchiae are all encompassed with one Membrane. This Membrane is nothing but the continuation of the outer Tunicle which covers the Tracheal Artery and the Bronchiae. It is these parcels of the Lungs thus distinguish from one another by the small Membranes which enfold them, that they call the Lobuls of the Lungs.  
These Lobuls are all fastened to large Trunks of the Bronchiae as grapes to the stalk of the Cluster. It is from these Trunks of the Bronchiae that the small branch proceeds whose Capillary branches end in their Vesicles. The Lobules are likewise joined together, by small Tendinous Filaments, which keep their Tunicles contiguous. Therefore to discern them well they must be separated with the point of a Pen knife.  
The Bronchiae are every where accompanied with Arteries and Viens. So we need only trace the Bronchiae to discern the course of these Vessels. By this mean we find that their Extremities are spread into the Coats of the Vesicles, which compose the substance of the Lungs.  
And for that the Bronchiae are also accompanied with a Nerve which follows all their Ramifications, and is lost into the Vesicles of the Lungs; and in that the inner Tunicle of the Bronchiae is composed of Tendinous Fibres, in all appearance the Vesicles of the Lungs are made of nothing but a Texture of Tendinous Fibres, Filaments of Nerves, some Arteries and some Veins.  
When we blow into the Trachaeal Artery the whole mass of the Lungs swells and all the Vesicles are filled with Air. From whence I conclude that there is a communication between the Bronchiae and the Vesicles. And since we see that the Tracheal Artery communicates with the outward Air by the Mouth and the Nostrils, we may with reason conclude that all this apparatus of the Tracheal Artery and the Bronchiae has been made for conveying of the External Air into the Vesicles of the Lungs.  
But because we find that the Longitudinal and Circular Fibres of the Tracheal Artery and the Bronchiae, cannot by their action but shorten the Bronchiae and render their Cavity more narrow, we are obliged to think that the External Air is thrust out of the Vesicles of the Lungs. But since they are not made but for receiving of it, it appears that it reenters as soon as it has gone out, and that it gets out as soon as it has reentered, and that it continues thus to go in and get out, so long as the Animal is in Life. And it is this Ingress of the Air and its Egress from the Lungs, which they call Respiration.  
After we have thus examined the Structure of the Lungs, we have found indeed the force which thrusts out the Air, when it is entered into the Vesicles, but we do not perceive what may be the force which makes it re-enter there. This makes us think that that force which doth press the Air into the Lungs, is not to be sought for, in the Lungs themselves, but in some other part.  
In searching what this force may be, I consider that the Lungs are shut up in a large. Cavity which they call the Breast, and that the Breast is so closely shut up on all sides, that the Air cannot get into it but by the Tracheal Artery. By this I perceive that if the Breast dilate itself it will press the outward Air into the Lungs to fill the place, which the sides of the Breast do abandon, in the time that it enlarges its self. After the same manner that the external Air is thrust into the Cavity of a pair of bellows, according as you raise their Board's.  
Indeed we find that the Air enters into the Lungs according as the Breast is enlarged, and that it gets out as it is straitened. But because it may be enlarged for that the Air enters into the Lungs, and it may be diminished for that it gets out, we must examine the structure of the Breast, that thereby we may find how to determine.   

The seventeenth Discourse. Of the Breast.  
THe first thing I meet with in examining the Cavity of the Breast, is a very slender Membrane which covers it on all sides, and which the Anatomists call the Pleura. This Membrane is doubled on the middle of the Breast. It extends its self thus from the top of the Breast to the lower part of it, it divides it into two parts, of which the one is on the Right, the other on the Left side. They call this separation the Mediastinum or Midriff.  
Without the Pleura are the Ribs. They are inserted on one side into the Vertebraes. They are bended in form of a Parabola, and are united by a Cartilaginous knot, to a Bone which covers the forepart of the Breast, and which they call the Sternum. The Ribs touch one another towards the Vertebraes. They are separated according as they advance toward the Sternum. The space which they leave between them is all filled with Muscles, which keeps them united to one another. The first which appear are eleven in number. They derive their Origine from the top and the bottom of each inferior Rib, and ascending obliquely from behind to the Fore part, they draw the Superior Rib to the Inferior. They are called the Inner Intercostal Muscles.  
Beyond the inner Intercostals, there are eleven Muscles, which they call the outer Intercostals. They arise all from the Inferior and outer part of each Superior Rib, and are obliquely inserted in the forepart unto the Superior and outer part of each inferior Rib. Their Fibres cross those of the inner Intercostals, in form of a Burgundy Cross.  
These Muscles cannot serve by the contraction of their Fibres, but to approach the Ribs towards one another. But for as much as the Ribs are so situated that they cannot approach one another▪ but the Cavity of the Breast must be enlarged, we conclude that the use of the Intercosta Muscles is to enlarge the Breast, by drawing the Ribs upward.  
The External Intercostals are covered with many other Muscles. We observe amongst the rest one of them which comes from the Os Sacrum and the Thorny Apophyses of the Loins, and is inserted into the upper Ribs near their Roots. It gives to each one of them a double Tendon. They call it the Sacro-Lumbar, when it acts it removes the Ribs from one another by drawing them downward.  
There is after this another, which derives its Origine from the middle of the Sternum. It is fastened to the Cartilages of the true under Ribs, and to the second and third of the bastard ones. They give it the Name of the Triangular Muscle.  
After this appears a great Muscle large enough, which arises from the inner Base of the Homoplate, and is joined to the five true inferior Ribs, and to the two bastard inferior Ribs by five Tendons which resemble the Teeth of a Saw. It is for this that they Name it the Great Teethed Muscle. And when it acts, it draws all the Ribs towards the Homo plate to which it sends the Tendons.  
Then when we go back towards the top of the Breast, we find a Muscle which derives its Origine from within the Clavicle near the Acromion, and is fastened to the first Rib near the Sternum. It's use is to draw the first Rib upwards towards the Clavicle. They call it the Subclaviar.  
We find also another Muscle which comes from the Thorn of the three Inferior Vertebraes of the Neck, and the first of the Back. It is terminated by digitation into the three or four upper Ribs They call it the upper small Teethed Muscle. It draws the Ribs into which it is inserted upwards towards the Neck.  
In fine, there is yet one which ariseth from the three Inferior Vertebraes of the Back and the first of the Loins It is inserted into the three or four Inferior Ribs by digitation. It draws outwards the Ribs into which it is inserted. They call it the Inferior small Teethed Muscle.  
The Ribs are so disposed that they cannot be moved upwards without enlarging the capacity of the Breast. And since the four last Muscles of which we have spoken do draw the Ribs upwards, we may truly affirm that their use is to enlarge the Breast, and the use of the others to diminish it.  
The Breast is shut up below by a musculous wall, which they call the Diaphragm. This wall is not always bended. This may appear, in that when the Animal is dead, it is Convex towards the Breast, and concave on the other side. So by its Convexity it takes up a part of the capacity of the Breast.  
It's figure is almost round. We remark in it two essential parts, the Carneous and the Tendinous. The Tendinous occupies the middle. It is Transparent and woven of Tendinous Fibres and Nervous Filaments. The Carneous part encompasseth the Tendinous. It extends its self to the Sternum, to the Ribs, and to some Vertebrae of the Back, as well as to some of those of the Loins. It is strongly fastened to all these parts Its Fibres go in a strait line from the Tendinous part, even to the places of their Insertion.  
From whence we may easily conclude that when the Diaphragm acts the Carneous Fibres by their Contraction draw the Tendinous part towards the sides. So they make the Diaphragm lose its Convexity. And since that thereby it leaves the place which it occupied in the Breast, this Cavity is considerably enlarged. Which makes us judge that the Diaphragm serves by its action to enlarge the Cavity of the Breast.  
The Diaphragm is brought down also by the action of the Muscles which make the Ribs move upwards. The reason is that the Ribs cannot move after this manner without drawing the Diaphragm by its Extremities, which must of necessity make it lose its Convexity.  
We find therefore by the search that we have made into the whole Breast, that it is composed of certain parts which do enlarge the Cavity of it, and of other parts which do diminish it. This makes us know so evidently the way how the Respiration is made, that we cannot almost doubt but that it is performed after the manner that we are going to explain.   

The eighteenth Discourse. Of the Respiration.  
WE distinguish two times in Respiration. The time of the entry of the Air into the Breast, they Name it Inspiration, and the time of its going out, which they call Expiration. The Inspiration is made, when the Subclaviar, the Great, the two small Teethed, and the Intercostal Muscles do together draw the Ribs upwards The Diaphragm is extended also at the same time by the rising of the Ribs which draw it by its Extremities, and by the Spirits which do then run into its Fibres. So the Cavity of the Breast is enlarged and the external Air pressed by the Walls of the Cavity of the Breast. It cannot move then but on the side where it meets with the least resistance. It finds none at the entry of the Tracheal Artery, and it rencounters every where else. There it enters, it gets into the Bronchiae, from hence it passes into the Vesicles of the Lungs It blows them up as much as is needful for them to occupy as much space as the Walls of the Breast do abandon. Even as the motion which is given to the two Board's of a pair of Bellows when they are raised from one another, does thrust as much Air into the Bellows as is needful to occupy the space which the Board's of the Bellows have left.  
By this means the Muscles which serve to draw down the Ribs have their Fibres extremely stretched to the length. The Fibres of the Musculous Tunicle of the Tracheal Artery and of the Bronchiae, are also greatly stretched. Both the one and the other by their spring do rebound. The Nerves send some Spirits into their Cavity. They are shortened. By this Contraction the Ribs are forced downward. The Cavity of the Breast is diminished, and the Cartilages of the Bronchiae do re-enter into one another. So the Air which the Vesicles of the Lungs did contain is so pressed that it goes out. It passeth from the Vesicles into the Bronchiae, from the Bronchiae into the Tracheal Artery, and from thence out of the Body. And it is this going out of the Air from the Lungs, which is called Expiration.  
Since Respiration is no other thing but Inspiration immediately followed by Expiration, and this Expiration followed as quickly by a new Inspiration, and so forward; we may very well affirm that Respiration is made by means of the Muscles of the Breast, of the Diaphragm, of the musculous Tunicle, of the Tracheal Artery and of the Bronchiae. These Organs act successively. And the action of the one hinders the action of the other. From whence we conclude that we may in reason consider them as Antagonist Muscles.  
All the Blood which passeth through the right Ventricle of the Heart, goeth from thence into the Lungs, and the Lungs receive the External Air into their Vesicles. So we have ground to think that this Air produceth some change in the Blood which passeth through the Lungs.  
We remark indeed a great difference between the Blood which enters into the Lungs, and the Blood which goes out of them. That which enters by the Pulmonary Artery is of a Red passably deep, whereas that which returns from the Lungs by the Pulmonary Vein is of a bright and fluid Red.  
Behold a very considerable change which befalls the Blood in passing through the Lungs. This change cannot be made but by the Air which blows up their Vesicles, and by this means presseth the small Arteries, and the small Veins which are spread there. This pressure doth mingle more exactly the Principles of Blood and does oblige it to run more quickly into the branches of the Pulmonary Vein, to go from thence into the left Ventricle of the Heart.  
But because this exact mixture of the Principles of the Blood and this passage from the Arteries into the Veins, is not capable of producing the change that we have remarked; it must needs be that some Principle of Air extremely subtle, mingles with it. This Principle may pass through the Pores of the Arteries, and insinuate its self among the parts of the Blood.  
That which makes the thing yet more probable is, that the Blood which is exposed to the Air acquires a surface extremely Red and of a colour like to that of the Blood which comes from the Lungs by the Pulmonary Vein. By which we see that the Air produces in the Blood a bright and florid Red by being mingled with it.  
Since therefore the Air does produce this effect, we cannot in reason doubt, that the change of colour which befalls the Blood in passing through the Lungs, comes from the Air which swells its Vesicles.  
All the difference which is between the Blood of the Veins and that of the Arteries, is the same with that of the Blood which enters into the Lungs, and of that which comes from them. So we may truly affirm that this difference is made in the Lungs and not in the Ventricles of the Heart, where the Blood does not receive any alteration. For if you take Blood out of the Vena Cava, and afterwards out of the Pulmonary Artery, you shall find no difference between these two Bloods. Nevertheless that which is taken out of the Pulmonary Artery has passed through the right Ventricle of the Heart. After this if you take of the Blood of the Pulmonary Vein and afterwards of the Aorta, you shall see that these two Bloods are alike in all things, though the one has been taken at its entry into the left Ventricle of the Heart, and the other at its going out.  
It remains as yet to examine what are the principles of Air which produce the change that the Blood contracts in passing through the Lungs. When we consider the Air narrowly We find amongst many principles which compose it a Nitrous Spirit spread through all its Mass. There are in Physic and Chymie a prodigious number of Experiments, which render the thing certain. And because the Spirit of Nitre does produce in the Blood the same change with the Air, we have ground to think that the change which the Air makes in the Blood as it passes through the Lungs, proceeds from the Nitrous Spirit of the Air its mingling with it.  
The Spirit of Nitre is composed of Acids and Alcalies. The Alcalies do rarify the Sulphurs of the Blood, and the Acids ferment with its Volatile Alcalies. The Blood becomes thereby more subtle, more agitated and more ratified.  
From all this we may conclude that the Respiration serves to make the Blood pass from the Pulmonary Artery into the Pulmonary Vein, and to keep up the fermentation of it by means of the Nitrous Spirit which mingles its self with it. And since this Spirit heightens the Red colour of the Blood, it may be also said that the Respiration serves to maintain it, and that by its means the Lympha and Chyle which do mingle with it, take by degrees its Colour and Nature.   

The ninteenth Discourse. Of the Spleen.  
WHen we follow the Blood, which goes out of the left Ventricle of the Heart, we find that the first Entrail, of those which we have not yet examined, to which it goes, is the Spleen. It is of a red Colour, of a considerable bigness, placed in the lower Belly, on the left side, and a little lower than the Liver.  
In the Spleen there is an Artery and a Nerve, which do enter into it in Company, and a Vein which goes out at the same place. These Arteries end in little Membranous Cells, whose Figure does nearly resemble the Leaf of the Fearn. The Vein derives its Origine from the same Cells. This appears when we blow into the Artery, or the Vein, for the Breath passeth into the Cells.  
These Cells are all filled with small Glandules heaped upon one another, like the Raisins of a Cluster of Grapes. These Glandules receive small Branches of Arteries from the Trunk of the Splenical Artery, and Nervous Filaments from the Nerve which enters with the Artery into the Spleen. From each heap of these Glandules there goes a root of a Vein, which being united together, do compose the Splenick Vein.  
On the Surface of the Spleen we perceive many Lymphatic Vessels, which do empty their Lympha into Pecquet's Resesvatory.  
By all that we have said, it appears, that nothing enters into the Spleen, but the Animal Spirits which come by the Nerves, and the Blood which comes thither by the Arteries. There goes nothing out also but the Lympha which runs by the Lymphatic Vessels into the Reservatory of the Chyle, and the Blood which goes by the Splenical Vein. The Lympha is nothing but the Remains of the Nutritive Juice of the Spleen, and it appears not to have any other quality in this place, than what it has every where else. As for the Blood, it has the same colour and consistence which we observe in other Veins  
These Observations do extremely perplex us as to the use of the Spleen. For if the Arteries do bring unto it Blood, it may be said, that this is but to nourish it, and if the Nerves do bring thither Animal Spirits, this is but to give unto the Nutritive Juice, the fluidity that is needful So that we find nothing yet but what simply serves to the Nourishment of this part.  
Yet we cannot say that it is entirely useless. For what appearance is there that an useless part should always be found in the Animal Body, ever of the same frame and in the same situation Nature, it is like, would not have been so exact in this matter, if it served for nothing So that it is probable it has in the Animal Occonomy some use which we do not know.  
But for that on such occasions we must be satisfied with conjectures till we find better, we may suppose that a ferment distils from the Vesicles of the Glandules and that it mingles with the Blood which passeth through the Spleen. That the nature of this ferment is such that it disentangleth from the other parts of the Blood, the parts which are proper to compose the Bile.  
The reason which makes us of this opinion, is that all the Blood which goes from the Spleen passes into the Vena Porta and from thence goes to the Liver, where we know it rids itself of those parts which are fittest to compose the Bile. But this sentiment, though the most probable, has many difficulties.  
All know that an Animal can live many years after the taking out of the Spleen, but this says nothing as to its use or Inutility; since the cutting out of the Pancreas, whose uses are known and which is acknowledged to be most necessary for the maintaining of the Animal Oeconomy, does not hinder a Dog from living many years.   

The Twentieth Discourse. Of the Reins, and the ureters.  
THere are in the lower Belly two Bodies made like to French beans placed upon the loins, on the two sides of the descending Aorta, and the ascending Vena Cava. These Bodies receive Arteries from the Aorta, they call them Emulgent Arteries, and they send Veins to the Vena Cava. They call these Veins the Emulgent Veins. And these Bodies are called the Reins.  
We find them first wrapped up in a Tunicle which covers the whole Cavity of the lower Belly. Next to this there is another Tunicle which does immediately cover them. And in fine, when we have taken off these two Tunicles we discover the surface of the Reins, upon which we have the pleasure to observe an agreeable ramification of Sanguineous Vessels.  
These Sanguineous Vessels do enter into the Reins upon there Concave side which looks towards the Aorta and the Vena Cava. Many small Nerves go from the Plexus Renalis and bear them faithful Company. They are all shut up in a small Membranous Cover, and the Nerves are lost in its substance. Afterwards these Vessels are spread through the outer substance of the Reins and enter into small Glandules, of which this whole outer substance is composed.  
These Glandules are fastened to the Vessels as the Grapes to the Trunk of the Cluster. By this means they make small Lobes wrapped up into a particular Tunicle. This Tunicle enters partly into the Capsula, and partly into the Cavity of the Reins, which they call the Bassin. All these small Lobes do adhere to the one or the other of these by small Tendinous Filaments.  
From each Glandule there goes an Excretory Vessel They descend in a strait line to the Bassin, being couched one beside another. When they come near to pierce the Tunicle which makes its inward Cover, many of them join together and make up a great Pipe. This Pipe has an opening by which it communicate with the Bassine, about which opening we remark a little Rising, which they call a Papilla.  
The Cavity of the Bassin is Covered with a very thick Tunicle. It is form of the Expansion of the small Pipes which pierce it. It is afterwards so much contracted towards the Concave side of the Reins, that it takes the form of a Vessel of the bigness of a Goose feather. It descends in the form of an S. and goes into a Bag, placed in the lower part of the Abdomen, under the Pecton. They call this Bag the Bladder of the Urine.  
These Vessels they call the Ureters. They are wrapped up in the Peritonaeum, and in a proper Tunicle, which communicates with that which does immediately cover the Reins. Their Substance is Membranous and very Thick. Their Fibres are so variously interwoven that they keep no order.  
The use of the Reins is to separate a Saltish Serosity from the Blood, which passeth from the Glandules into the Bassins', and from thence runs by the Ureters into the Bladder. This Liquor they call Urine.   

The twentieth and first Discourse. Of the Bladder, and of the Urine.  
THe Bladder is a Bag into which all the Urine goes, which the Reins do separate from the Blood. Its Figure is like to that of a Pear. It is so Situated, that its wider part, which they call the Bladder, is always turned upwards, and its more narrow part, which they call the neck of the Bladder, is ever turned downwards.  
It is held in this Situation by two considerable Ligaments. The first goes from its bottom to the Navel: It hinders it from falling downwards. The second is very short. In Men it keeps it fixed upon the Rectum, in Women upon the Matrix, so that the Bladder cannot turn either to the left or right Hand. The first is inserted in its fore part, and the second in its hinder part.  
The Bladder is made up of three Tunicles. The first is nothing but a production of the Peritonaeum, which enwraps it outwardly. It is composed of Tendinous Fibres variously interwoven. The middle Tunicle is made of Carneous Fibres. Of these they reckon three Orders. The first is of some great Fibres couched on the forepart of the Bladder, which come in a strait line from its bottom even to its neck. The second is of Fibres which do enwrap the Bladder Circularly. They may be called Circular Fibres. And the third couched under the Circular, is of Fibres which cross the former obliquely, going from the left to the right Hand, from the bottom of the Bladder even to its neck. We shall call them Transverse Fibres. In fine, the inner Tunicle is composed of Tendinous Fibres, of such a Textures as has not been yet discovered. When the Bladder is not blown up, it is all wrinkled, and within it is always covered with a Mucilage. At the neck of the Bladder there is a Muscle made of strong and Circular Fibres. It is a Sphincter which keeps it always shut.  
From all this we may conclude that the Bladder is a Concave Muscle, whose outer and inner Tunicles are Tendons, and the middle Tunicle, the Belly.  
The Insertion of the Ureters into the Bladder, shows evidently enough that its use is to be the Reservatory of the Urine, and that all we have remarked in its frame. tends to no other end but to keep the Urine in its Cavity, and to thrust it forth when it is therewith filled.  
I say that the Bladder is the Reservatory of the Urine, for that the Ureters are inserted into its Cavity after such a manner, as that the Urine can easily enter there, but cannot return again into the Ureters. They creep for some space between the outer and middle Tunicles, afterwards they pierce the middle Tunicle, and creep a little farther between it and the inner, which they pierce towards the neck of the Bladder. So the Urine can pass without much difficulty from the Ureters into the Bladder. But as the Bladder swells by the abundance of Urine it straittens the ends of the Ureters which creep amongst its Tunicles, so that the Urine in the Bladder cannot enter there.  
The Sphincter of the Bladder is the cause that the Urine makes some stay in its Cavity. And least in staying there its salts should prick the inner Tunicle, nature has conveyed thither the Mucilage which anoints it on all sides.  
The Longitudinal Fibres shorten the Body of the Bladder when the Animal Spirits do contract them. The Circular and the Transverse do by their action straitten it. So when the Fibres are filled with Spirits the Bladder is Lessened in all respects. And if then there be Urine in its Cavity, it makes its passage maugre the resistance of the Sphincter, and gets out of the Body by a small Pipe which they call the Vrethra.  
This Pipe is nothing but the Continuation of the Inner Tunicle of the Bladder. In Women its opening is in the Pudendum, and in Men it extends its self into the Body of the Wand, and terminates in the end of the Balanus.  
By all that has been said we see that the Reins, the Ureters, the Bladder and the Vrethra, have been made to separate the Urine from the Blood, and to convey it out of the Body, not only as useless, but even as hurtful to the maintaining of the Animal Oeconomie.  
To understand these truths aright, it is to be observed that the Urine is almost composed of nothing but Phlegms and Volatile Salts; having but very little of Sulphur, Earth, and fixed Salt.  
The Nitrous Spirit which mingles with the Blood in the Lungs is composed of Acids and Alcalies. Its Acids coming to join with the Alcalies of the Blood do make a Salt. And for that the most part of the Alcaline parts of the Blood are Volatile, the Salt which is made of them is also Volatile. These Volatile Salts might diminish the natural Fermentation of the Blood and stop its Course. To prevent this mischief, the Author of Nature has placed the Reins into the Bodies of Animals, which do separate these Saline parts from the Mass of the Blood. And for that also a too great abundance of Phlegm, would make the Blood too slow and hinder the Spirits from acting, the Reins do not only separate the Salts, but also the Phlegms, which are the two Principles whose too great abundance would be capable of chocking the ordinary Fermentation of the Humours, upon which the life of Animals depends.  
Moreover it is remarked that when the Urine abounds in Alcalies, that is to say, when its Salts are not strongly charged with Acids, it is thick and troubled. And when it has a deal of Acids, that is, when its Salts are well furnished with them, it is more clear and Transparent. And when there is much Salt in a little Phlegm, the Urine is of a reddish Colour. And when there is much Phlegm and little Salt, it is clear, and is very near unto the ordinary Colour of Water.  
There is remarked in the Urine a little Cloud, which is form of some parts of the Mucilage, which we have said is in the Bladder. The Salts of the Urine detatch them by little and little, and carry them along with them. This Cloud appears when the Urine gins to cool, because the coolness doth condense it, and by this mean renders it more visible.   
FINIS.