Anatomy

I reveal to men the origin of their second — first or perhaps second — cause of existence.'

'Would that it might please our Creator that I were able to reveal the nature of man and his customseven as I describe his figure.

[Precepts for the study of the foot]

You will make these two feet with the same contours turned in the same direction, and do not pay any regard to the fact that they remain the one right and the other left, because by making them so they will be easier to understand.

First you will make all these bones separated the one from the other, arranged in such a way that each part of each bone may be seen, or may be turned towards the side of that bone from which it is separated, and to which it should be reunited when you join up all the bones of these feet together in their first state.

And this demonstration is made in order to be better able to recognise the true shape of each bone in itself; and you will do the same with each demonstration of each limb in whatever direction it may be turned. Fogli Air.

[Method for the study of the arm and the forearm]

You will first have these bones sawn lengthwise and then across, so that one can see where the bones are thick or thin; then represent them whole and disjoined, as here above, but from four aspects in order that one can understand their true shape; then proceed to clothe them by degrees with their nerves, veins and muscles.

[Method for the study of the parts of the human body]

The true knowledge of the shape of any body will be arrived at by seeing it from different aspects. Consequently in order to convey a notion of the true shape of any limb of man who ranks among the

animals as first of the beasts I will observe the aforesaid rule, making four demonstrations for the four sides of each limb, and for the bones I will make five, cutting them in half and showing the hollow of each of them, one being full of marrow the other spongy or empty or solid.

[Of the bones of the arm ]

The arm, which has the two bones that interpose between the hand and the elbow, will be somewhat shorter when the palm of the hand is turned towards the ground than when it is turned towards the sky, it the man is standing on his feet with his arm extended. And this occurs because these two bones, in turning the palm of the hand towards the ground, come to intersect in such a way that that which proceeds from the right side of the elbow goes towards the left side of the palm of the hand, and that which proceeds from the left side of the elbow ends on the right side of the palm of this hand.

The arm is composed of thirty pieces of bone, because there are three in the arm itself and twenty seven in the hand. Fogli a i v.

[Of the attachment of the muscles]

The above-mentioned muscles are not firm except at the extremities of their receptacles and at the extremities of their tendons; and this the Master has done in order that the muscles may be free and ready to be able to grow thicker or shorter or finer or longer according to the necessity of the thing which they move. Fogli a 2 r.

Commence your anatomy with the head and finish it with the soles of the feet.

[Voice production — mechanism of]

Rule to see how the sound of the voice is produced in the front of the trachea. This will be understood by separating this trachea together with the lung of the man, and if this lung be filled with air and then closed rapidly one will be able immediately to see in what way the pipe called the trachea produces this sound; and this can be perceived and heard well in the neck of a swan or a goose which often continues to sing after it is dead.

One cannot swallow and breathe or make a sound at the same time.

One cannot breathe by the nose and by the mouth at the same time; and this is shown if one should attempt to play a whistle or flute with the nose and another with the mouth at the same time.

WHY THE VOICE GROWS THIN IN THE OLD

The voice grows thin in the old because all the passages of the trachea become restricted as do the other intestines. Fogli a 3 r.

The pieces of the bone of which a man's foot is composed number twenty seven, taking into account the two which are beneath the base of the great toe of the foot. Fogli a 3

v.

THE NATURE OF THE VEINS

The origin of the sea is the contrary to that of the blood, for the sea receives within itself all the rivers, which are entirely caused by the aqueous vapours that have ascended up into the air; while the sea of the blood is the source of all the veins.

OF THE NUMBER OF THE VEINS

The vein is one whole, which is divided into as many main branches as there are principal places which it has to nourish, and these branches are subdivided in an infinite number.

Movements of the neck

The neck has four movements, of which the first consists of raising the second of lowering the face, the third of turning right or left, the fourth of bending the head right or left. [. . .] are mixed movements, namely raising or lowering the face with an ear near to a shoulder, and similarly raising or lowering the face after turning it towards one of the shoulders; also raising or lowering the face after turning it to one of the shoulders while keeping one eye lower or higher than the other, and this is called separated movement.

And to these movements should be assigned the cords and muscles which are the cause of these movements, and consequently, if a man should be found lacking in power to make one of these movements as a result of some wound, one can discern with certainty which cord or muscle is impeded. Fogli a 4 r.

[The true conception of figures']

One possesses a true conception of all figures when one knows their breadth, length and depth; if therefore I observe the same in the figure of the man I shall give a true conception of it in the opinion of everyone of sound intelligence.

Explain these words for they are confused.

[Arrangement of muscles of nec\ and thorax]

Make it twice as much larger with a corresponding thickness of ribs and muscles, and it will be easier to understand.

Again this figure would be confused unless you first of all made at least three demonstrations before this with similar threads; demonstrations of which the first should be merely of the bones, then follow

with the muscles which start in the breast above the ribs, and finally the muscles that start from the thorax together with the ribs and last of all that above.

Make the ribs so thin that in the final demonstration made with the threads the position of the shoulder-blade may be visible.

[Precepts for the study of the muscles]

Before you represent the muscles make, in place of these, threads which may serve to show the positions of these muscles, which should abut with their extremities in the centre of the attachment of the muscles above their bones. And this will supply a speedier conception when you wish to represent all the muscles one above the other. And if you make it in any other way your representation will be confused.

Fogli a 4 v.

[Precepts for the study of the cervical vertebrae]

These three vertebrae should be shown from three aspects as has been done with three from the backbone.

The vertebrae of the neck are seven of which the first above and the second differ from the other five.

You should make these bones of the neck from three aspects united and from three separated: and so you will afterwards make them from two other aspects, namely seen from below and from above, and in this way you will give the true conception of their shapes, which neither ancient nor modern writers have ever been able to give without an infinitely tedious and confused prolixity of writing and of time.

But by this very rapid method of representing from different aspects a complete and accurate conception will result, and as regards this benefit which I give to posterity I teach the method of reprinting it in order, and I beseech you who come after me, not to let avarice constrain you to make the prints in . . . Fogli a 8 v.

The act of procreation and the members employed therein are so repulsive, that if it were not for the beauty of the faces and the adornments of the actors and the pent-up impulse, nature would lose the

human species.

[Movement and force of animals subject to mechanical laws]

Arrange it so that the book of the elements of mechanics with examples shall precede the demonstration of the movement and force of man and of the other animals, and by means of these you will be able to prove all your propositions.

[Anatomy of hand]

Describe how many membranes intervene between the skin and the bones of the hand.

[Precepts for study of muscles of hand]

These muscles of the hand may be made first of threads and then according to their true shape.

And they are the muscles that move all the palm of the hand.

When you have represented the bones of the hand and you wish to represent above this the muscles which are joined with these bones make threads in place of muscles. I say threads and not lines in order to know what muscle passes below or above the other muscle, which thing cannot be shown with simple lines; and after doing this make another hand afterwards at the side of it where there may be the true shape of these muscles as is shown here above. Fogli a 10 r.

REPRESENTATION OF THE HAND

The first demonstration of the hand will be made of the bones alone.

The second of the ligaments and various chains of nerves that bind them together. The third will be of the muscles which spring up upon these bones. The fourth will be of the first tendons which rest upon these muscles and go to supply movement to the tips of the fingers.

The fifth will be that which shows the second set of tendons which move all the fingers and end at the last but one of the bones of the fingers. The sixth will be that which will show the nerves that impart

sensation to the fingers of the hand. The seventh will be that which will show the veins and arteries that nourish and invigorate the fingers. The eighth and last will be the hand clothed with skin, and this will be shown for an old man, a young man and a child, and for each there should be given the measurement of the length, thickness and breadth of each of its parts. Fogli a 10 v.

[Precepts for the study of the foot]

Make a demonstration of this foot with the simple bones; then leaving the membrane that clothes them make a simple demonstration of the nerves; and then over the same bones make one of tendons, and then one of veins and artery together. And finally a single one to contain artery, veins, nerves, tendons, muscles and bones.

The muscles that move the toes at their points, both below and above, all appear in the leg between the knee and the joint of the foot; and those that move the whole toe upwards and downwards appear on the upper and lower side of the foot; and as the hand works with its arm so does the foot with the leg. Fogli a ii r.

[Precepts for the study of the foot]

Make a demonstration of these feet without the membrane that clothes the bones, which membrane takes possession of these bones, interposing itself between these bones and the muscles and tendons that move them; and by this way you will be able to show under which tendons, nerves, veins or muscle are the joints of the bones.

[Representation of the limbs in action]

After the demonstration of all the parts of the limbs of man and of the other animals you will represent the proper method of action of these limbs, that is in rising alter lying down, in moving, running and jumping in various attitudes, in lifting and carrying heavy weights, in throwing things to a distance and in swimming, and in every act you will show which limbs and which muscles are the causes of the said actions, and especially in the play of the arms.

REASON WHY TWO MUSCLES ARE JOINED TOGETHER

It often occurs that two muscles are joined together although they have to serve two limbs; and this has been done so that if one muscle were incapacitated by some injury the other muscle in part supplied the place of that which was lacking. Fogli a n v.

[Precepts for the study of the bones of the foot]

You will represent these bones of the feet all equally spread out, in order that their number and shape may be distinctly understood. And this difference you will represent from four aspects in order that the true shape of these bones in all their aspects may be more accurately known.

Make the bones of the foot somewhat separated one from another in such a way that one may readily distinguish one from another, and this will be the means of imparting the knowledge of the number of the bones of the feet and of their shape.

At the end of every representation of the feet you will give the measure of the thickness and length of each of the bones and its position.

The aspects of the foot are six, namely : below, above, within, outside, behind and before; and to these is added the six demonstrations of the separated bones between them; and there are those of the bones sawn lengthwise in two ways, that is, sawn through the side and straight so as to show all the thickness of the bones. Fogli a 12 r.

[Motor muscles of hands and wings]

No movement either of the hand or the fingers is produced by the muscles above the elbow; and so it is with birds and it is for this reason that they are so powerful because all the muscles which lower the wings spring from the breast and these have in themselves a greater weight than that of all the rest of the bird. Fogli a 12 v.

[Insertion of muscles']

You will make a second representation of the bones in which you will show how the muscles are fastened upon the bones.

Fogli a 13 r.

[Precepts for the study of the bones and the muscles of man and horse]

Note where the lowest parts of the muscles of the shoulder abed are fixed, and which are those that are attached above the bone called humerus, and which are attached above the other muscles.

Make for each bone separated by itself its muscles, that is the muscles which grow upon it.

Show all the causes of the movement of the skin, flesh and muscles of a face, and whether the muscles derive their movement from the nerves that come from the brain or no.

And do this first of all with the horse which has big muscles and parts very distinct.

See whether the muscle that raises the horse's nostrils is the same as is found here in the man at which comes out of the hole in the bone /.

[Arrangements of vessels and nerves of fingers]

Have you seen the diligence of nature in having situated the nerves,arteries and veins not in the centre but in the sides of the fingers so that they are not in any way pierced or cut by the movements of the fingers ?

[Nerves of sensibility and movement of the fingers and their independence of function]

See if you understand that this sense is employed by the player of an organ, and that the mind at such time waits on the sense of hearing. Fogli a 13 v.

[Necessary to represent and to describe]

And you who think to reveal the figure of man in words, with his limbs arranged in all their different attitudes, banish the idea from you, for the more minute your description the more you will confuse the mind of the reader and the more you will lead him away from the knowledge of the thing described. It is necessary therefore for you to represent and describe.

Should the actual thing being in relief seem to you to be more recognisable than what is here drawn, which impression springs from the fact of your being able to see the object from different aspects, you must understand that in this representation of mine the same result will be obtained from the same aspects; and therefore no part of these limbs will be hidden from you.

[Precepts for study of muscles of shoulder]

Describe each muscle, what finger it serves and what limb; represent it therefore simply, without any impediment from any other muscle that is placed over them, and in this way you will afterwards be able to recognize the parts which are injured.

You will never know the shape of the shoulder without this rule.

Write how each muscle can become extended or contracted or made thinner or thicker, and which is more or less powerful.

Represent here always together the veins and nerves with the muscles, so that one may see how the muscles are embraced by these veins and nerves, and take away the sides in order that one may see better how the larger muscle is joined to the shoulder-blade. Fogli a 14 v.

[Of the muscles]

Make a demonstration with muscles lean and thin so that the space that is produced between the one and the other may make a window in order to show that which is found behind them.

As in this representation of a shoulder made here in charcoal.

The muscles are of two shapes with two different names, of which the shorter is called muscle and the longer is called lacert.

NATURE OF MUSCLES

The tendons of the muscles are of greater or less length as a man's fleshy excrescence is greater or less. And in leanness the fleshy excrescence always recedes towards the point at which it starts fromthe fleshy part. And as it puts on fat it extends towards the beginning -of its tendon.

HOW THE MUSCLES ARE ATTACHED TO THE JOINTS OF THE BONES

The end of each muscle becomes transformed into tendon, which binds the joint of the bone, to which this muscle is attached.

OF THE NUMBER OF THE TENDONS AND OF THE MUSCLES

The number of the tendons which successively one above the other cover each other and all together cover and bind the joint of the bones to which they are joined, is as great as the number of the muscles which meet in the same joint.

If the junction of the muscle b is made with the bone of the thigh and actually with the muscle a, or the muscle b and the muscle a since they are joined together, they unite and establish themselves upon this bone of the thigh. And this third manner is more useful for the benefit of the movement of this thigh, and more certain, for if the muscle a were cut or otherwise injured the muscle b would itself move the thigh, which it could not do if it were separated from the bone between b a. Fogli a 15 r.

[Action of muscles in breathing]

These muscles have a voluntary and an involuntary movement seeing that they are those which open and shut the lung. When they open they suspend their function which is to contract, for the ribs which at first were drawn up and compressed by the contracting of these muscles then remain at liberty and resume their natural distance as the breast expands. And since there is no vacuum in nature the lung which touches the ribs from within must necessarily follow their expansion; and the lung therefore opening like a pair of bellows draws in the air in order to fill the space so formed. Fogli a 15 v.

[General precepts]

Begin your anatomy with a man fully grown: then show him elderly and less muscular: then go on to strip him stage by stage right down to the bones.

And you should afterwards make the child so as to show the womb.

[Relation between size and junction of muscles]

In all the parts where man has to work with greater effort nature has made the muscles and tendons of greater thickness and breadth. Fogli a 16 r.

[Function of muscles in breathing]

TREATS OF MAN ACCORDING TO THE INSTRUMENTAL METHOD AND THE CONTRARY

With the muscles it happens almost universally that they do not move the limb where they are fixed but move that where the tendon that starts from the muscle is joined, except that which raises and moves the side in order to help respiration.

All these muscles serve to raise the ribs and as they raise the ribs they dilate the chest, and as the chest becomes dilated the lung is expanded, and the expansion of the lung is the in drawing of the air which enters by the mouth into this lung as it enlarges.

OF THE DEMONSTRATION OF HOW THE SPINE IS FIXED IN THE NECK •

In this demonstration of the neck one will make as many shapes of muscles and tendons as are the uses of the movements of the neck. And the first as is here noted is how the ribs in their strength keep the spine of the neck straight, and by means of the tendons which go up to this spine these tendons serve a double use, that is they support the spine by means of the ribs and support the ribs by means of the spine.

And this duplication of powers situated at the opposite extremities of this tendon works with this tendon in the same manner as the tendon works with the extremities of the arch.

But this convergence of muscles in the spine keeps it upright, just as the ropes of the ship support its mast; and the same ropes bound to the mast also support in part the edges of the ships to which they are Joined.

OF THE METHOD OF REPRESENTING THE CAUSES OF THE MOVEMENTS OF ANY LIMB

Make first the motor muscles of the bone called ?he humerus; then make in the humerus the motor muscles of the arm which cause it to straighten or bend; then show separately the muscles that have their origin in this humerus, which only serve to turn back the arm when it turns the hand upside down; then represent in the arm only the muscles which move the hand up and down and from side to side without moving the fingers in it; then represent the muscles which merely move the fingers, locking them together or extending them or spreading them out or bringing them together; but first represent the whole as is done in the cosmography, and then divide it into the aforesaid parts, and do the same for the thigh, the leg and the feet.

OF THE MUSCLES THAT START IN THE RIBS REPRESENTED ABOVE

I have for a long time and not without reason doubted whether the muscles which start beneath the shoulder-blades above the third, fourth and fifth right rib, and the same also on the left side, are made for the purpose of keeping straight the spinal column of the neck to which they attach themselves with their tendons, or whether in fact these muscles, as they contract, draw themselves together with the ribs towards the nape of the neck, by means of the aforesaid tendons attached to the spinal column; and reason moves me to believe that these muscles are intended to support the spinal column, so that it may not bend in having to support the heavy head of the man, as it bends down or is raised, for the help of which the muscles of the shoulders or of the pit of the throat do not serve, seeing that the man will relax these which start in the shoulders or the pit of the throat when he raises his shoulders towards his ears, and will so take away force from his muscles; and by this loosening and contracting the movement of the neck will not be impeded, nor will the resistance of the spinal column in supporting this head. And I am further confirmed in this same opinion by the powerful shape of the ribs where these muscles are situated, which is extremely adapted to resist every weight or force which would draw the tendon a b in the contrary direction, which drawing it against the rib b r fixes it in greater power in the position r. And if this tendon had to raise the rib in order to facilitate and increase the breathing, nature would have placed this cord not in the slant a b, but in the greater slant a c. And read the propositions set forth below and in the margin, which are to the purpose. Fogli a 16 v.

[Muscles of hand, leg and foot. Dated note: 1510]

When you represent the hand represent with it the arm as far as the elbow, and with this arm the sinews and muscles which come to move this arm away from the elbow. And do the same in the demonstration of the foot.

All the muscles that start at the shoulders, the shoulder-blade and the chest, serve for the movement of the arm from the shoulder to the elbow. And all the muscles that start between the shoulder and the

elbow, serve for the movement of  the arm between the elbow and the hand. And all the muscles that start between the elbow and the hand, serve for the movement of the hand. And all the muscles that start in the neck, serve for the movement of the head and shoulders.

When you represent the muscles of the thigh, represent with these the bone of the leg, so that one may know where these muscles attach themselves to these bones of the legs.

You will then make the leg with its muscles attached to the bones of the leg, and make the bones bare. And you will follow the same plan for all the sinews.

The muscles of the feet serve for the movement of its toes, and in this movement they are aided by the tendons which spring from the muscles of the leg.

Which are the muscles of the leg which serve merely for the simple movement of the foot, and which are those of this leg that serve merely for the simple movement of the toes of this foot? And remember, in clothing the bones of the leg with its muscles to represent first the muscles that move the feet, which you will join to the feet.

Represent here the foot of the bear, the monkey and other animals, in so far as they differ from the foot of man; and put also the feet of some of the birds.

The muscles of the leg from the knee to the joint of the foot are as many in number as the tendons attaching to the upper part of the toes of the feet; and it is the same below, adding to them those which move the feet upwards and downwards and to and fro, and of these those which raise the toes are five. And there are as many muscles of the feet above and below as the number of the fingers doubled. But as I have not yet finished this discourse I will leave it for the present, and this winter of the year 1510 I look to finish all this anatomy.

The tendons that lower the toes of the feet start from the muscles which have their beginning in the sole of this foot; but the tendons that raise these toes do not have their beginning in the outer part of the thigh as some have written, but they start in the upper part of the foot called the instep. And if you desire to make certain of this, clasp the thigh with your hands a little above the knee and raise the toes of the feet, and you will perceive that the flesh of your thigh will not have any movement in it in its tendons or muscles; so it is quite true.

rT1 t 1 j r j r i Fogli a 17 r.

Precepts for the study of the foot

Use the same rule for the foot that you have used for the hand; that is representing first the bones from six aspects, namely: behind, infront, below and above, on the inside and on the outside.

[Considerations upon the origin of the muscles of the foot]

Mondinus says that the muscles which raise the toes of the feet are to be found in the outer part of the thigh; and then adds that the back of the foot has no muscles because nature has wished to make it light so that it should be easy in movement, as if it had a good deal of flesh it would be heavier; and here experience shows that the muscles abed move the second pieces of the bones of the toes; and that the muscles of the leg r S t move the points of the toes. Here then it is necessary to enquire why necessity has not made them all start in the foot or all in the leg; or why those of the leg which move the points of the toes should not start in the foot instead of having to make a long journey in order to reach these points of the toes; and similarly those that move the second joints of the toes should start in the leg.

[Precepts]

Set down first the two bones of the leg from the knee to the foot, then show the first muscles that start upon the said bones, and proceeding thus you will make one above the other in as many different demonstrations as are the stages in their positions, one above the other; and you will do it thus as far as the end of one side, and you will do the same for four sides in their entirety with all the foot, because the foot moves by means of tendons which start in these muscles of the leg; but the side where is the sole is moved with muscles that start in this sole; and the membranes of the joints of the bones start from the muscles of the thigh and of the leg.

After you have made the demonstration of the bone, show next how it is clothed by those membranes which are interposed between the tendons and these bones.

Remember, in order to make certain as to the origin of each muscle, to pull out the tendon produced by this muscle in such a way as to see this muscle move and its commencement upon the ligaments of the bones.

Avicfenna]. The muscles that move the toes of the feet are sixty.

[By way of note]

You will make nothing but confusion in your demonstration of the muscles and their positions, beginnings and ends, unless first you make a demonstration of the fine muscles by means of threads; and in this way you will be able to represent them one above another as nature has placed them; and so you will be able to name them according to the member that they serve, that is, the mover of the point of the big toe, and of the middle bone, or the first bone, etc.

And after you have given these details you will show at the side the exact shape and size and position of each muscle; but remember to make the threads that denote the muscles in the same positions as the central lines of each muscle, and in this way these threads will show the shape of the leg and their distance in rapid movement and in repose.

[The extensor and flexor muscles of the foot]

The muscles which are only used to move the foot as it rises forward are m n, which start in the leg from the knee downwards; and those which bend it towards the outside of the ankle are the muscles / n; therefore n is common to both these movements.

[Atrophy of the muscles]

I have stripped of skin one who by an illness had been so much wasted that the muscles were worn away and reduced to a kind of thin pellicle, in such a way that the tendons instead of becoming converted into muscle were transformed into loose skin; and when the bones were clothed with skin their natural size was but slightly increased.

[Topography of the muscles and motor and sensory nerves of the lower limb]

You will show first the bones separated and somewhat out of position, so that it may be possible to distinguish better the shape of each piece of bone by itself. Afterwards you join them together in such a way that they do not diverge from the first demonstration, except in the part which is occupied by their contact. Having done this you will make the third demonstration of those muscles that bind the bones together. Afterwards you will make the fourth of the nerves which convey sensation. And then follows the fifth of the nerves that move or give direction to the first joints of the toes. And in the sixth you will make the muscles above the feet where are ranged the sensory nerves.

And the seventh will be that of the veins which feed these muscles of the foot. The eighth will be that of the nerves that move the points of the toes. The ninth of the veins and arteries that are interposed between the flesh and the skin. The tenth and last will be the completed foot with all its powers of feeling. You will be able to make the eleventh in the form of a transparent foot, in which one is able to see all the aforesaid things.

[Precepts for the study of the leg]

But make first the demonstration of the sensory nerves of the leg, and their ramification, from four aspects, so that one may see exactly from whence these nerves have their origin; and then make a representation of a foot young and soft with few muscles.

All the nerves of the legs in front serve the points of the toes, as is shown with the great toe.

[By way of note]

After making your demonstrations of the bones from various aspects then make the membranes which are interposed between the bones and the muscles; and in addition to this, when you have represented the first muscles, and have described and shown their method of working, make the second demonstration upon these first muscles, and the third demonstration upon the second, and so in succession.

Make here first the simple bones, then clothe them gradually stage by stage in the same way that nature clothes them.

When defining the foot it must necessarily be joined with the leg as far as the knee, because in this leg start the muscles which move the points of the toes, that is the final bones.

In the first demonstration the bones should be somewhat separated one from another, in order that their true shape may be revealed. In the second the bones should be shown sawn through, in order that it may be seen what part is hollow and what part solid. In the third demonstration these bones should be joined together. In the fourth should be the ligaments that connect one of these bones with another. In the fifth the muscles that strengthen these bones. Sixth the muscles should be shown with their tendons. Seventh the muscles of the leg with the tendons that go to the toes. Eighth the nerves of sensation.

Ninth the arteries and veins. Tenth the muscular skin. Eleventh the foot in its final beauty.

And each of the four aspects should have these eleven demonstrations. Fogli a 18 r.

[Notes]

Of the nerves which raise the shoulders and which raise the head, and those which lower it and which turn it and which bend it across:

To lower the back. To bend it. To twist it. To raise it.

You will write upon physiognomy.

I find that the veins serve no other function than to heat, as nerves and things that have to give sensation. Fogli b 1 r.

[Vital junctions of the body]

Cause of breathing.

Cause of the movement of the heart.

Cause of vomiting.

Cause of the food descending into the stomach.

Cause of the emptying of the intestines.

Cause of the movement of the superfluous matter through the

intestines.

Cause of swallowing.

Cause of coughing.

Cause of yawning.

Cause of sneezing.

Cause of the numbness of various limbs.

Cause of loss of sensation in any limb.

Cause of the tickling sensation.

Cause of sensuality and other necessities of the body.

Cause of urination.

And so of all the natural actions of the body. Fogli b i v.

The sense of touch clothes all the surface skin of man.

HOW THE FIVE SENSES ARE THE MINISTERS OF THE SOUL

The soul apparently resides in the seat of the judgment, and the judgment apparently resides in the place where all the senses meet, which is called the common sense; and it is not all of it in the whole body as many have believed, but it is all in this part; for if it were all in the whole, and all in every part, it would not have been necessary for the instruments of the senses to come together in concourse to one particular spot; rather would it have sufficed for the eye to register its function of perception on its surface, and not to transmit the images of the things seen to the sense by way of the optic nerves; because the soul — for the reason already given — would comprehend them upon the surface of the eye.

Similarly, with the sense of hearing, it would be sufficient merely for the voice to resound in the arched recesses of the rock-like bone which is within the ear, without there being another passage from this bone to the common sense, whereby the said mouth might address itself to the common judgment.

The sense of smell also is seen to be forced of necessity to have recourse to this same judgment.

The touch passes through the perforated tendons and is transmitted to this sense; these tendons proceed to spread out with infinite ramifications into the skin which encloses the body's members and the bowels.

The perforating tendons carry impulse and sensation to the subject limbs; these tendons passing between the muscles and the sinews dictate to these their movement, and these obey, and in the act of obeying they contract, for the reason that the swelling reduces their length and draws with it the nerves, which are interwoven amid the particles of the limbs, and being spread throughout the extremities of the fingers, they transmit to the sense the impression of what they touch.

The nerves with their muscles serve the tendons even as soldiers serve their leaders, and the tendons serve the common sense as the leaders their captain, and this common sense serves the soul as the captain serves his lord.

So therefore the articulation of the bones obeys the nerve, and the nerve the muscle, and the muscle the tendon, and the tendon the common sense, and the common sense is the seat of the soul, and the memory is its monitor, and its faculty of receiving impressions serves as its standard of reference.

How the sense waits on the soul, and not the soul on the sense, and how where the sense that should minister to the soul is lacking, the soul in such a life lacks conception of the function of this sense, as is seen in the case of a mute or one born blind. Fogli b 2 r.

How the nerves sometimes work of themselves, without the command of other agents or of the soul :

This appears clearly for you will see how paralytics or those who are shivering or benumbed by cold move their trembling limbs such as the head or the hands without permission of the soul; which soul with all its powers cannot prevent these limbs from trembling. The same happens in the case of epilepsy or with severed limbs such as the tails of lizards.

FUNCTION OF LIVER, BILE, AND INTESTINES

The liver is the distributor and dispenser of vital nourishment to man.

The bile is the familiar or servant of the liver which sweeps away and cleans up all the dirt and superfluities left after the food has been distributed to the members by the liver.

The intestines. As to these you will understand their windings well if you inflate them. And remember that after you have made them from four aspects thus arranged you then make them from four other aspects expanded in such a way that from their spaces and openings you can understand the whole, that is, the variations of their thicknesses. Fogli b 2 v.

[Chyle. Mesentery]

By the ramification of the vein of the chyle in the mesentery nourishment is drawn from the corruption of the food in the intestines, and in the last instance it returns by the final ramifications of the artery to these intestines where this blood being afterwards dead it is corrupted and acquires the same stench as comes from the faeces.

The mesentery is a thick sinewy and greasy membrane in the ramifications of which are twelve chief veins, and it is joined to the lower part of the diaphragm.

See whether the mesentery has arteries or no.

In this mesentery are planted the roots of all the veins, which unite at the gate of the liver and purify the blood in the liver; and it then enters the vein of the chyle, and this vein goes to the heart and makes purer the blood which penetrates in the arteries as spirituous blood. Fogli b 3 r.

OF THE FORCE OF THE MUSCLES

If any muscle whatsoever be drawn out lengthwise a slight force will break its fleshy tissue; and if the nerves of sensation be drawn out lengthwise slight power tears them from the muscles where their ramification weaves them together and spreads and consumes itself; and one sees the same process enacted with the sinewy covering of the veins and arteries which are mingled with these muscles. What is therefore the cause of so great a force of arms and legs which is seen in the actions of any animal whatsoever? One cannot say other than that it is the skin which clothes them; and that when the nerves of sensation thicken the muscles these muscles contract and draw after them the tendons in which their extremities become converted; and in this process of thickening they fill out the skin and make it drawn and hard;  and it cannot be lengthened out unless the muscles become thinner; and not becoming thinner they are a cause of resistance and of making strong the before mentioned skin, in which the swollen muscles perform the function of a wedge.

[Precepts for demonstrations] [With drawing]

Only represent in this demonstration the first upper rib, for this of itself suffices to show where the neck is divided from the bust.

Represent the proportionate length and thickness that the nerves of the arms and legs have to each other.

Of the neck

You will use extreme diligence in making this demonstration of the neck inside, outside and in profile, and the proportions of the tendons and of the nerves between them, and with the positions where they begin and end; for if you were to do otherwise you would neither be able to treat of nor demonstrate the office or use for which nature or necessity has intended them. And in addition to this you should describe the distances interposed between the nerves themselves both as regards their depth and breadth, and the differences in the heights and depths of their origins; and you will do the like with the muscles veins and arteries; and this will be extremely useful to those who have to dress wounds. Fogli b 3 v.

[Umbilical vein]

Note if the umbilical veins are four both in males and females.

By x v umbilical vein is composed the life and the body of every animal of four feet, except those that start from the egg, such as frogs, tortoises, green lizards, chameleons and the like.

I believe that these four nerves are those of the reins or arteries.

I have found that they are of the greater veins of the reins.

The navel is the gate from which our body is formed by means of the umbilical vein. Fogli b 4 r.

This demonstration is as necessary for good draughtsmen as the derivation from Latin words is to good grammarians; for anyone must needs make the muscles of figures badly in their movements and actions unless he knows which are the muscles that are the cause of their movements. Fogli b 4 v.

[Reason for position of veins in \nee\

Nature has placed the principal veins of the leg in the middle of the thickness of the knee joint, because in the process of bending this joint the veins are less compressed than if they were situated in front of or behind the knee.

[Relation of nerves with muscles]

There are as many ramifications of the nerves as there are muscles, and there cannot be either more or less, because these muscles can only be contracted or distended by reason of these nerves from which the muscles receive their sensation. And there are as many tendons that move the limbs as there are muscles. Fogli b 5 r.

[Nerves]

The nerves in some parts of a man are round, in others flat.

The nerves start lower than the veins of the kidneys.

There are as many nerves as there are muscles in the thigh. Fogli b 6 r.

The vertebrae of the back behind the kidneys number five.

[List of anatomical demonstrations]

Three men complete.

Three with bones and veins.

Three with bones and nerves.

Three with simple bones.

These are twelve demonstrations of whole figures. Fogli b 6 v.

The vein saphena with its other collaterals and adherents which serve to supply the nourishment of the thigh ought to be inclosed by the lines that form the boundaries of the whole leg. Fogli b 8 r.

At about the centre of the height, breadth and bulk of the man there is more intricacy of structure than in any other part of him; and it is even greater in the woman who in the same part has bladder, womb, ovaries, rectum, hemorrhoidal veins, nerves, muscles, cartilages and like things. Fogli b 8 v.

Draw the arm of Francesco the miniaturist which shows many veins.

[Precepts for anatomical drawings and demonstrations}

In demonstrations of this kind you should show the exact contours of the limbs by a single line; and in the centre place their bones with the true distances from their skin, that is the skin of the arm; and then you will make the veins which may be whole upon a clear ground; and thus there will be given a clear conception as to the position of the bone, vein and nerves.

[Changes of the arteries in age}

In proportion as the veins become old they lose their straightness of direction in their ramifications, and become so much the more flexible or winding and of thicker covering as old age becomes more full with years.

You will find almost universally that the passage of the veins and the passage of the nerves are on the same path, and direct themselves to the same muscles and ramify in the same manner in each of these muscles, and that each vein and nerve pass with the artery between one muscle and the other, and ramify in these with equal ramification.

[Expansibility of the vessels}

The veins are extensible and expansible; and of this there is testimony afforded in the fact that I have seen one who has chanced to wound the common vein and has immediately bound it up again with a tight bandage and in the space of a few days there has grown a blood coloured tumour as large as a goose's egg, full of blood, and it has remained so for several years; and I have also found in the case of a decrepit man that the mesaraic veins have contracted the passage of the blood and doubled in length. Fogli b 10 r.

[Changes of the arteries, hepatic veins, and abdominal organs in the old]

The artery and the vein which in the old extend between the spleen and the liver, acquire so great a thickness of skin that it contracts the passage of the blood that comes from the mesaraic veins, through which this blood passes over to the liver and the heart and the two greater veins, and as a consequence through the whole body; and apart from the thickening of the skin these veins grow in length and twist themselves after the manner of a snake, and the liver loses the humour of the blood which was carried there by this vein; and consequently this liver becomes dried up and grows like frozen bran both in colour and substance, so that when it is subjected even to the slightest friction this substance falls away in tiny flakes like sawdust and leaves the veins and arteries.

And the veins of the gall and of the navel which entered into this liver by the gate of the liver all remain deprived of the substance of this liver, after the manner of maize or Indian millet when their grains have been separated.

The colon and the other intestines in the old become much constricted, and I have found there stones in the veins which pass beneath the fork of the breast, which were as large as chestnuts, of the colour and shape of truffles or of dross or clinkers of iron, which stones were extremely hard, as are these clinkers, and had formed bags which were hanging to the said veins after the manner of goitres.

And this old man, a few hours before his death, told me that he had lived a hundred years, and that he did not feel any bodily ailment other than weakness, and thus while sitting upon a bed in the hospital of Santa Maria Nuova at Florence, without any movement or sign of anything amiss, he passed away from this life.

And I made an autopsy in order to ascertain the cause of so peaceful a death, and found that it proceeded from weakness through failure of blood and of the artery that feeds the heart and the other lower members, which I found to be very parched and shrunk and withered; and the result of this autopsy I wrote down very carefully and with great ease, for the body was devoid of either fat or moisture, and these form the chief hindrance to the knowledge of its parts.

The other autopsy was on a child of two years, and here I found everything the contrary to what it was in the case of the old man.

The old who enjoy good health die through lack of sustenance.

And this is brought about by the passage to the mesaraic veins becoming continually restricted by the thickening of the skin of these veins; and the process continues until it affects the capillary veins, which are the first to close up altogether; and from this it comes to pass that the old dread the cold more than the young, and that those who are very old have their skin the colour of wood or of dried chestnut, because this skin is almost completely deprived of sustenance.

And this network of veins acts in man as in oranges, in which the peel becomes thicker and the pulp diminishes the more they become old. And if you say that as the blood becomes thicker it ceases to flow through the veins, this is not true, for the blood in the veins does not thicken because it continually dies and is renewed, Fogli b 10 v.

[Principal vessels of the thorax]

You will make the veins which are in the heart and also the arteries which give it life and nourishment.

[Heart and vessels]

The heart is the nut which produces the tree of the veins; which veins have their roots in the dung, that is the mesaraic veins which proceed to deposit the blood they have acquired in the liver from which afterwards the upper veins of the liver are nourished.

[Precepts for anatomical drawings]

Make first the ramification of the veins by themselves, then the bones by themselves, and then join the bones and veins together.

[Heart and vessels proceeding from the heart, and comparison with the roots and ramifications of plants]

The plant never springs from the ramification for at first the plant exists before this ramification, and the heart exists before the veins.

All the veins and arteries proceed from the heart; and the reason is that the maximum thickness that is found in these veins and arteries is at the junction that they make with the heart; and the farther away they are from the heart the thinner they become and they are dividedinto more minute ramifications. And if you should say that the veins start in the protuberance of the liver because they have their ramifications in this protuberance, just as the roots of plants have in the earth, the reply to this comparison is that plants do not have their origin in their roots, but that the roots and the other ramifications have their origin in the lower part of these plants, which is between the air and the earth; and all the parts of the plant above and below are always less than this part which borders upon the earth; therefore it is evident that the whole plant has its origin from this thickness, and, in consequence, the veins have their origin in the heart where is their greatest thickness; never can any plant be found which has its origin in the points of its roots or other ramifications; and the example of this is seen in the growing of the peach which proceeds from its nut as is shown above. Fogli but.

[Precepts for the measurements of the fingers]

Give the measurements for the fingers of man, anatomized from every limb and its positions.

[Alterations in the inner coating of the blood vessels in the old]

One asks why the veins in the old acquire great length, and those which used to be straight become bent, and the skin thickens so much as to close up and stop the movement of the blood, and from this arises the death of the old without any disease.

I consider that a thing which is nearer to that which feeds it increases more; and for this reason these veins being a sheath of the blood that nourishes the body it nourishes the veins so much the more as they are nearer to the blood.

[Arteries of the abdomen. Causes of death in the old]

The veins a b become so much constricted in the old that the blood loses its power of movement through them, and so usually becomes foul, and can no longer penetrate the new blood which sweeps it away as it used to do as it comes from the gate of the stomach, whence this good blood grows corrupt away from the bowels, and so the old fail without fever when they are of great age.

And why the bowels in the old are much constricted.

[Impossibility of the removal of the spleen in the living]

It is shown here that it is impossible to remove the spleen from men as is believed by those who are ignorant of its constituent substance, because as is here shown it cannot be extracted from bodies without causing death; and this happens because of the veins with which it nourishes the stomach.

[Vessels which provide for the nutrition of the abdominal organs]

The vein which extends between the gate of the liver and the gate of the spleen has its roots with five ramifications that ramify in the five coverings of the liver, and at the middle of its trunk there starts a

branch which spreads out in nourishment from the base of the peritoneum and extends in all its parts. And a little farther away a branch raises itself up and joins itself to the left part below the stomach, and then ends somewhat farther on in two branches at the junction with the spleen, and goes ramifying through all its substance.

[Cause of death in the old]

Veins which by the thickening of their tunicles in the old restrict the passage of the blood, and by this lack of nourishment destroy their life without any fever, the old coming to fail little by little in slow

death.

And this happens through lack of exercise since the blood is not warmed. Fogli b 11 v.

OF THE REASON OF THE HEAT OF THE BLOOD

The heat is produced by the movement of the heart, and this manifests itself because in proportion as the heart moves more swiftly the heat increases more, as is shown by the pulse of those suffering from fever which is moved by the beating of the heart.

[Drawing of heart — below: — ]

Marvellous instrument, invented by the supreme Master.

[Mechanism of action of the heart]

Heart open in the receptacle of the spirits, that is in the artery; and in m it takes or rather gives the blood to the artery, and by the mouth, b, it refreshes itself with air from the lung, and by c it fills the auricles of the heart s.

n Firm muscle is drawn back, and it is the first cause of the movement of the heart, and as it draws back it thickens, and as it thickens it becomes shortened and draws back with it all the lower and upper muscles, and closes the door m, and shortens the space that intervenes between the base and the apex of the heart, and consequently comes to empty it and to draw to itself the fresh air. Fogli b 12 r.

Of the heart. This moves of itself and does not stop unless forever.

Function of the lung in relation to the circulation

Of the lung. This is moved by others, that is, by the first mover which is the heart which as it becomes constricted draws the veins after it, with which it restores the heated air to the lung, and opens it, and this lung can close either voluntarily or through oblivion, that is, forgetfulness through excess of thought; and by this means the heart draws back from it the heated air which it has given it; but this act cannot be repeated many times for if it were not for its refreshing itself with new air it would come to suffocate.

Testicles, witnesses of coition. These contain in themselves ardour that is they are augmenters of the animosity and ferocity of the animals; and experience shows us this clearly in the castrated animals, of which one sees the bull, the boar, the ram and the cock, very fierce animals, which after having been deprived of these testicles remain very cowardly; so one sees a ram drive before it a herd of wethers, and a cock put to flight a number of capons; and I have seen the same thing happen with a hen, and also with oxen.

Delia verga. This confers with the human intelligence and sometimes has intelligence of itself, and although the will of the man desires to stimulate it it remains obstinate and takes its own course, and moving sometimes of itself without license or thought by the man, whether he be sleeping or waking, it does what it desires; and often the man is asleep and it is awake, and many times the man is awake and it is asleep; many times the man wishes it to practice and it does not wish it; many times it wishes it and the man forbids it. It seems therefore that this creature has often a life and intelligence separate from the man, and it would appear that the man is in the wrong in being ashamed to give it a name or to exhibit it, seeking the rather constantly to cover and conceal what he ought to adorn and display with ceremony as a ministrant.

[Organs which junction independently of the will}

No inferior instrument in the human body is able to suspend its action voluntarily except the lung. You see the heart which carries on its function of itself, and the stomach also and the other intestines which are joined to it, and similarly the liver the gall the spleen the testicles the kidneys and the bladder. Fogli b 13 r.

In fact man does not vary from the animals except in what is accidental, and it is in this that he shows himself to be a divine thing; for where nature finishes producing its species there man begins with natural things to make with the aid of this nature an infinite number of species; and as these are not necessary to those who govern themselves rightly as do the animals it is not in their disposition to seek after them.

[Drawing of right fydney]

Cut it through the centre and represent how the channels of the urine are constricted and how they fall drop by drop.

Describe the distance of these kidneys from the flanks and the false ribs. Fogli b 13 v.

[Passage of the urine from the \idneys into the bladder by means of the ureters]

The authorities say that the uretary ducts do not enter directly to carry the urine to the bladder; but that they enter between skin and skin by ways that do not meet each other; and that the more the bladder becomes filled the more they become contracted; and this they say nature has done merely in order that when the bladder is filled it should turn the urine backwards whence it came; in such a way that in finding che ways between membrane and membrane to penetrate into the interior by narrow ways and not opposite to that of the first membrane, the more the bladder is filled, the more it presses one membrane against the other, and consequently it has no cause to spread itself out and turn back. This proof however does not hold, seeing that if the urine were to rise higher in the bladder than its entrance which is near the middle of its height it would follow that this entrance would suddenly close and no more urine would be able to pass into the bladder and the quantity would never exceed the half of the capacity of this bladder; the remainder of the bladder therefore would be superfluous, and nature does not create anything superfluous. We may say therefore, by the fifth [section] of the sixth [book] concerning waters, that the urine enters the bladder by a long and winding way, and when the bladder is full the uretary ducts remain full of urine, and the urine that is in the bladder cannot rise higher than their surface when the man is upright; but if he remains lying down it can turn back through these ducts, and even more can it do this if he should put himself upside down which is not often done; but the recumbent position is very usual, in which if a man lies on his side one of the uretary ducts remains above the other below; and that above opens its entrance and discharges the urine into the bladder, and the other duct below closes because of the weight of the urine; consequently a single duct transmits the urine to the bladder, and it is sufficient moreover that one of the emulgent veins purify the blood of the chyle of the urine which is mixed with it because these emulgent veins are opposite to one another and do not all proceed from the vein of the chyle. And if the man sets himself with his back to the sky both the two uretary ducts pour urine into the bladder, and enter through the upper part of the bladder, because these ducts are joined in the back part of the bladder, and this part remains above when the body is facing downwards, and consequently the entrances of the urine are able to stand open, and to supply so much urine to the bladder that it fills it.

When the man is upside down the entrance of the urine is closed.

Fogli b 14 r.

[Reason of the arrangement of the human intestine in relation to nutrition ]

Animals without legs have a straight bowel, and this is why it always remains lying down, for the animal not having feet cannot raise itself on them, and if it should raise itself it returns immediately to a level position; but in the case of the man this would not take place by reason of his holding himself quite straight, because the stomach would suddenly empty itself if the twisted nature of the intestines did not check the descent of the food; and if the bowel were straight each partof the food would not come in contact with the bowels as it does in the twisted bowels.

And consequently there would remain much nutritive substance in the superfluous parts of this food which would not be able to be sucked by the substance of these bowels and transported in the mesaraic veins,

[Defecation. Intestinal movements in relation to the diaphragm]

When with the transversal muscles of the body one presses out the superfluous parts from the intestines, these muscles would not perform their function well or powerfully unless the lung were filled with air; seeing that if this lung were not full of air it would not fill with itself all the diaphragm; consequently this diaphragm remains loose, and the intestines pressed by the said transversal muscles bend towards the side that gives way to them, which would be the diaphragm. But if this lung should stay full of air and you do not afford it outlet above, then the diaphragm is taut and firm and offers resistance to the rising up of the intestines when pressed by the transversal muscles; consequently of necessity the intestines rid themselves through the straight intestine of agreat part of the superfluity which is enclosed within them.

[Precepts for the study of the liver]

I wish to cut the liver which covers the stomach in that part which covers the stomach as far as the vein which enters and afterwards emerges from this liver, and to see how this vein ramifies through this liver. But first I will have represented how all this liver stands and how it clothes the stomach. Fogli b 14 v.

All the muscles of the body are enveloped in extremely thin cartilage, and then they become changed to thicker cartilage and in that their substance ends.

[Action of the transversal muscles of the abdomen upon defecation]

The transversal muscles squeeze the intestines but not the longitudinal ones, because if it were so when the man holds himself bent and relaxes these muscles he would not have force to perform the office of squeezing them; but the transversal muscles never relax as the man bends but rather become stretched.

[Muscles of the anterior wall of the abdomen and their function]

[Drawing n r b a s h m]

a b are final longitudinal muscles; the membranes in which they become transformed pass at a right angle below the longitudinal a m.

The muscles n r s h are four and have five tendons and were not made of a single piece as the others, so that each was shorter; although where there is life with thickness there is strength, and where there

is such great length of movement there it is necessary to divide the mover into several parts, and its greater extension, exceeds its lesser extension by the third part of ©ne of its arms, and by so much more as it makes greater concavity of arch in its back, as one sees done by those contortionists who bend themselves so far backwards that they cause their hands to touch their feet, and this excess of capacity is produced by the contraction of their feet with their hands, and these muscles are made in two rows, that is right and left, from the necessity of bending to right and left.

The transversal muscles c d are those which, as they are drawn, constrict and raise the intestines and push up the diaphragm and drive out the air from the lung; afterwards as these muscles become relaxed the bowels drop and draw back the diaphragm and the lung opens.

a b is all made up of cartilage which borders on the sifac and starts from the fleshy muscles c d, which muscles enter under the ribs and are latitudinal muscles starting in the bone of the spine, and it is these alone which squeeze out the superfluities from the body.

Above the membrane a b descend the longitudinal muscles n m, mentioned above, which start in the last ribs, [run up] to the side of the Adam's apple and end below in the pubis. Fogli b 15 r.

[Muscles of the trunl(\

Note how the flesh increases above the bone as one grows fat, and how it decreases as one grows thin, and what shape it assumes and . . .

The muscle a b becomes fleshy at its end beneath the arm and in the upper part and in the lateral, or lower in the flank, and behind in the bone of the back, and in front in the middle longitudinal section of the body, and behind it ends in the vertebrae of the spine.

The muscles n m o p q are situated above the ribs, and with their angles they are converted into short thick cartilage, and they unite with the ribs where they rest, and immediately there start other muscles namely a m n, and that which is shown appears after the skin has been removed.

a b c is, covered by the muscle a above, in the second demonstration.

All the muscles which start in the body are converted into membranes, which membranes continue with the opposite muscle, passing above the lower part of the belly, as are the transversal and the slanting muscles; but the longitudinal or straight muscles go fleshy from the height of the Adam's apple to the pubis; and the muscle of the breasts which starts from all the middle of the thorax and ends in the bone of the shoulder, when it has passed a short distance below the breasts is converted into membrane and clothes the whole body. Fogli b 15 v.

The first muscle of the lower part of the belly starts in its upper part in the sixth rib of the breast and ends towards the arms after the manner of a saw in the muscles which start over the ribs, and below being changed into cartilage it ends in the bone of the hip as far as the pubis.

The muscle n m is the lower transversal, which starts in the vertebrae behind the navel, passes through the soft parts of the flank, and ends in the penultimate false rib, and becomes changed into cartilage above the longitudinal muscles; it becomes fleshy and continues as far as the pubic region. Fogli b 16 r.

[Precepts for the demonstration of the muscles of the thorax]

The demonstration of the region of the ribs requires first the plain sides bare with open spaces; afterwards the muscles which are joined to their sides with which they are chained together; then the muscles that interlace above them which serve for the movements of expansion and contraction of these sides; in addition to this the other muscles crossed above the aforesaid muscles, at different angles, serving for various movements.

[Reason of the movement of the ribs]

Of the maximum raising and lowering of the shoulders which checks the movement of the sides. Because the maximum raising and lowering of the shoulders by means of the muscles of the neck which have their base in the vertebrae of the spine, impedes when these shoulders are raised, the movement of the ribs in their descent; and as these shoulders are lowered the movement of raising these sides is impeded.

For which fact nature has made provision by means of the muscles of the diaphragm which lower this diaphragm in its concave centre; and when it is raised again this proceeds from the compressed wind enclosed in the intestines, which wind is caused by the fact that the excrements as they dry give off gases; and if the raised shoulders keep the ribs high by means of the muscle b then the diaphragm by merely moving itself by means of its muscles performs the function of opening and closing the lung; and the compressed intestines together with the condensed wind which is generated in them push back the diaphragm upwards; which diaphragm presses the lung and expels the air.

Muscles of the anterior wall of the thorax and of the abdomen

The muscle a contains in itself the breast, and descends fleshy as far as the seventh rib by the side of the Adam's apple; then having been converted into membrane it proceeds to form a covering over all the lower part of the belly and ends by joining itself to the bone of the pubis; and this muscle of the breast is composed of several muscles which all start in the thorax, and converge and end in the part of the muscles of the humerus.

a d c ends in the bone of the shoulder, and starts in the middle of the thorax, and below it does not go so far as to cover b, shown above, except by its cartilage, with which it covers all the lower part of the belly, and it ends in the flank and in the bone of the pubis. Fogli b 16 v.

[Lung]

When the lung has sent out the wind and so is diminished in quantity by an amount corresponding to the amount of the wind which emerged from it, one ought then to consider from where the space of the cavity of the lessened lung attracts to itself the air which fills up its increase, because in nature there is no vacuum.

And one asks also, since after the lung has been expanded it drives out the air from its receptacle, by what way this air escapes and where it is received after it has escaped.

[Mechanism of respiration. Action of intercostal muscles]

The lung is always full of a quantity of air, even when it has driven out that air which is necessary for its exhalation; and when it is refreshed by new air it presses on the sides of the chest, dilates them a little and pushes them outwards, for as may be seen and felt by placing the hand upon the chest during its breathing, the chest expands and contracts, and even more so when one heaves a big sigh. For nature has so willed that this force should be created in the ribs of the chest and not in the membrane that ends the substance of the lung, lest by an excessive ingathering of air in order to form some unusually deep sigh this membrane may come to break and burst itself.

[Function of the diaphragm]

The diaphragm, that is the large membrane which is below the points of the lung, is not altered nor pushed in any part by the increase of the lung, for this lung increases in width and not in length, unless this diaphragm has been driven by the wind or air which gives place to the increase of the lung, for it would then be possible for the diaphragm driven by the air to give place to its increase, and for the air to push the liver and the liver the stomach to which it serves as cover, and thus would follow the pushing of all the intestines, and this continual movement would bring about the evacuation of the intestines with so much greater speed as the exercise of the man was performed with greater vigour.

[Cause of the formation of gas in the intestines]

Of the wind that is produced in the intestines we may say that it is caused by the superfluous quantity which collects in the rectum, which becomes drier as the moisture in it evaporates more; and this vapour in the form of air distends the bowels and produces pains on finding itself confined within the colon.

[Latitudinal increase of the lung in breathing. How its expansion acts

upon the functions of the stomach

The increase of the lung when it is filled with air is latitudinal and not in its length, as may be seen by inflating the lung of a pig; and the air which is interposed between the lung when not inflated and the ribs which surround it, as the lung becomes extended escapes in the part below between the lung and the diaphragm, and causes this diaphragm to swell downwards, against the stomach, whereat this stomach being pressed transmits the things contained within it to the intestines.

[Action of the expansion of the lungs upon the pericardium and function of the pericardial fluid]

Moreover this air pressed between the lung and the diaphragm rests in the case which encloses the heart, and that small quantity of fluid which is at the bottom of this case raises itself and bathes the whole heart, and so continually by thus bathing it it moistens the heated heart and prevents it from becoming parched through the extent of its

movement. Fogli b 17 r.

[Origin of the whole body from the heart]

The whole body has origin from the heart as regards its first creation; and the blood therefore and the veins and nerves do the like, although these nerves seem manifestly all to start from the spinal marrow, and to be remote from the heart, and the spinal marrow to be of the same substance as the brain from whence it is derived.

[Origin of the spinal nerves]

Tree of all the nerves, and it is shown how these all have origin from the spinal marrow and the spinal marrow from the brain.

[Precepts for the demonstration of the nerves]

Make in every demonstration of the whole quantity of the nerves the external lineaments which denote the shape of the body. Fogli b 17 v.

[Precepts for anatomical demonstrations]

Remember never to change the contour lines of any limb by any muscle that you remove in order to uncover another; and if you only remove muscles of which one of its contour lines is contour line of a

part of the limb from which you detach it, you ought then to indicate with frequent dots the contour line of that limb which was removed by the separation of any muscle; and this you will do so that the shape of that limb which you describe may not remain an unnatural thing through having its parts taken away. And in addition to this there ensues a greater knowledge of the whole, for when the part has been taken away you see in the whole the true shape of the part whence it was taken. Fogli b 18 r.

[Of the muscles]

The long muscle a b and the long muscle a c serve to raise the thigh forward.

And they also give this thigh lateral movements, namely in spreading out and contracting these thighs; and the process of the thickening and contraction of the muscle a c comes into play in the spreading out of this thigh, and of the long muscle a b in its contraction.

[Of the rotatory movement of the thigh]

The part of the rotatory movement of the thigh to right and left is caused by the aforesaid muscles; that is the muscle a c turns the thigh inward, and the long muscle a b turns it back outward, and the two together raise the thigh.

[Reason of the insertions of the muscles]

The muscles always begin and end in the bones that touch one another, and they never begin and end in the same bone, for it would not be able to move anything unless this was itself in a state of rarity or density.

Which are the muscles which begin and finish on one side upon one bone and on the other upon another muscle?

[Topography of muscles of front region of thigh]

I wish to separate the muscle or tendon a b and show that which follows below it.

[Insertion of the muscles of the thigh at the \nee]

On to the knee arrive all the muscles of the thigh which are changed first into nerve, and then, below the nerve, each is transformed into a thin cartilage with which is bound the joint of the knee with as many peels or membranous jackets as are the muscles which descend from this thigh to the knee; and these ligaments extend four fingers' space above the joint of the knee and four below. Fogli b 18 v.

[Muscles of the thigh in relation to nutrition]

Which muscles are those which as they become lean divide themselves into several muscles, and form one out of many as they become fleshy? Fogli b 19 v.

[Various anatomical themes]

Ramification of the veins from the shoulders upward, and from the spleen to the lung.

Ramification of the nerves and of the reversive nerves to the heart.

Of the shape and position of the intestines.

Where the umbilical cord is fastened.

Of the muscles of the body and of the kidneys.

[Origin and insertion of the muscles of the foot]

The muscles which raise and lower the foot start in the leg; that is those which raise the front part start in the outside part of the leg and stop at the beginning of the big toe.

[Precepts for the study of tendons]

Note which are the principal cords and those which inflict greater injury to the animal if they were cut, and which are of less importance; and you will do this for each limb.

[Precepts for the demonstration of the bones and muscles of the leg]

Observe the proportion of the bones one with another.

And for what purpose each serves.

In this demonstration made from different aspects you take count of all the muscles which move the leg, which muscles are attached to the edges of the pelvis, in which also start the muscles that move the thigh from the knee upwards.

And also of those which bend the leg when one kneels.

[Notes concerning the muscles which become uncovered and hide

themselves in their movement]

Different muscles become uncovered in the different movements of the animals, and different muscles are those which hide themselves in such diversity of movement; and concerning this it is necessary to make a long treatise for the purpose of recognizing the places that have been injured by wounds, and also for the convenience of sculptors and painters.

[Origin of the movements of the legs and feet]

All the movements of the leg start from the muscles of the thigh, which movements are the cause of the bending of the leg, of the straightening of it when bent and of its turning to right or left.

But the movements of the feet are caused by the muscles which start in the leg; of the movements of the toes some start in the leg and some in the foot.

[Insertion of the motive muscles of the leg]

And of the motive muscles of the leg part start in the hip and part in the thigh; and of all you will give the true position. Fogli b 20 r.

OF THE ORDER OF THE BOOK

This work should commence with the conception of man, and should describe the nature of the womb, and how the child inhabits it, tnd in what stage it dwells there, and the manner of its quickening and feeding, and its growth, and what interval there is between one Itage of growth and another, and what thing drives it forth from the body of the mother, and for what reason it sometimes emerges from the belly of its mother before the due time.

Then you should describe which are the limbs that grow more than the others after the child is born; and give the measurements of a child of one year.

Then describe the man fully grown, and the woman, and their measurements, and the nature of their complexions colour and physiognomy.

Afterwards describe how he is composed of veins, nerves, muscles and bones. This you should do at the end of the book.

Then represent in four histories four universal conditions of mankind namely, joy, with various modes of laughing, and represent the cause of the laughter; weeping, the various ways with their cause; strife with various movements expressive of slaughterings, flights, fear, acts of ferocity, daring, homicide and all the things which connect with cases such as these.

Then make a figure to represent labour, in the act of dragging, pushing, carrying, restraining, supporting and conditions such as these.

Then describe the attitude and movement.

Then perspective through the office of the sight or the hearing. You should make mention of music and describe the other senses.

Afterwards describe the nature of the five senses.

We shall describe this mechanical structure of man by means of diagrams of which the three first will treat of the ramification of the bones; that is one from the front which shows the positions and shapes of the bones latitudinally; the second as seen in profile and shows the depth of the whole and of the parts and their position; the third diagram will show the bones from behind. Then we shall make three other diagrams from the same points of view with the bones sawnasunder so as to show their thickness and hollowness; three other diagrams we shall make for the bones entire, and for the nerves which spring from the nape of the neck and showing into what limbs they ramify; and three others for the bones and veins and where they ramify; then three for muscles and three for the skin and the measurements, and three for the woman to show the womb and the menstrual veins which go to the breasts. Fogli b 20 v.

THEMES PHYSIOLOGICAL AND ANATOMICAL

Figure to show how catarrh is caused.

Tears.

Sneezing.

Yawning.

Trembling.

Epilepsy.

Madness.

Sleep.

Hunger.

Sensuality.

Anger when it works in the body.

Fear likewise.

Fever.

Disease.

Where poison injures.

Describe the nature of all the limbs.

Why the thunderbolt kills a man and does not wound him, and if the man blew his nose he would not die. Because it hurts the lungs.

Write what the soul is.

Of nature which of necessity makes the vital and actual instruments of suitable and necessary shapes and positions.

How necessity is the companion of nature.

Figure to show from whence comes the semen.

Whence the urine.

Whence the milk.

How nourishment proceeds to distribute itself through the veins.

Whence comes intoxication.

Whence vomiting.

Whence gravel and stone.

Whence colic.

Whence dreaming.

ANATOMY 133

Whence frenzy by reason of sickness.

Why it is that by compressing the arteries a man falls asleep.

Why it is that a prick on the neck may cause a man to drop dead.

Whence come tears.

Whence the turning of the eyes when one draws the other after it.

Of sobbing.

[Relation of breasts and shoulder-blades in different positions of trunks

OF THE REINS WHEN ARCHED

When the reins or the back is arched the breasts are always lower than the shoulder-blades of this back.

And when the chest is arched the breasts are always higher than the shoulder-blades of the back.

When the reins are straight the breasts will always be found of the height of these shoulder-blades. Fogli b 21 r.

[Connection between object and sense]

The object moves the sense.

[Contrast between the perfection of the body and the coarseness of the mind in certain men]

Methinks that coarse men of bad habits and little power of reason do not deserve so fine an instrument or so great a variety of mechanism as those endowed with ideas and with great reasoning power, but merely a sack wherein their food is received, and from whence it passes away.

For in truth one can only reckon them as a passage for food; since it does not seem to me that they have anything in common with the human race except speech and shape, and in all else they are far below

the level of the beasts.

[Attitude in ascending]

In proportion as the step by which a man rises is of greater height his head will be so much the more in front of the foot which is uppermost.

[Attitude in stopping a course]

When the man wishes to arrest his course and to consume his impetus, necessity causes him to lean back and to make short quick steps.

[Mechanism of certain movements of the human body and foundation

of human static s]

The centre of the weight of the man who raises one of his feet from the ground rests above the centre of the sole of the foot.

[Mechanism of the ascent]

The man who goes up stairs puts as much of his weight in front and at the side of the upper foot as he puts as counterpoise to the lower leg, and in consequence the work of the lower leg only extends to moving itself.

The first thing that the man does when he ascends by steps is to free the leg which he wishes to raise from the heaviness of the bust which is resting upon this leg, and in addition to this he loads the opposite leg with all the rest of the bulk of the man together with the other leg; then he raises the leg and places the foot upon the step where he wishes to raise it; having done this he gives back to the higher foot all the rest of the weight of the bust and of the leg, leans his hand upon his thigh, thrusts the head forward and makes a movement towards the point of the higher foot, raising swiftly the heel of the lower foot, and with the impetus thus acquired raises himself up, and at the same time extends the arm which he was resting upon the knee, and this extension of the arm pushes the bust and head upwards and thus straightens the curve of the back. Fogli b 21 v.

[ Veins]

OF THE OLD MAN

Veins which mark with their main lines here and there the base of the stomach and proceed to ramify through the network that covers the intestines.

b a c is the vein which extends from the spleen to the gate of the liver and passes behind the stomach, and from a divide the vein and the artery which ramify in the net that covers the intestines; that is from a there proceed two veins which pass under the bottom of the stomach, the one behind between the ribs and the stomach, and the other in front, and proceed as has been said to ramify through the peritoneum behind and through the peritoneum in front, which is double as the figure shows; and that which the veins do is found to be done by the artery.

[Change of the vessels in the old]

I have found in the decrepit how the vein which proceeds from the door of the liver crosses behind the stomach and ramifies in the spleen, as this ramification, the veins in the young being straight and full of blood, and in the old they are twisted, flattened, wrinkled and emptied of blood.

[Changes in the liver in age]

And thus the liver which in youth is usually of a deep colour and of uniform consistency, in the old is pale, without any redness of blood, and the veins stay empty amidst the substance of this liver, which substance may be likened for its thin texture to bran steeped in a small quantity of water, and so readily disintegrating on being washed, leaving the veins that ramify within it freed from all the substance of the liver. Fogli b 22 r.

[Precepts upon the topography of the intestines]

Remember to mark the height of the stomach above the navel and with the Adam's apple, and how the spleen and the heart stand with the left breast, and how stand the kidneys or reins with the hips, and me colon and bladder and other intestines, and how much more or less remote they are from the spine than from the longitudinal muscles, and describe thus all the body with the veins and nerves.

[Thinness of the colon in the old]

The colon in the old becomes as slender as the middle finger of the hand, and in the young it is equal to the maximum breadth of the arm.

[Retraction of the omentum in the old]

The net which stands between the sifac and the intestines in the case of the old uncovers all these intestines of itself and withdraws between the bottom of the stomach and the upper part of the bowels. Fogli b 22 v.

136 ANATOMY

[Spinal marrow and nerves]

These two crusts which clothe the spinal marrow are the same as clothe the brain, that is, the pia and dura mater.

Vertebrae of the neck sawn through and removed from the middle in front, and the situation of the spinal marrow revealed and how it lives and ramifies outside these vertebrae.

[Anatomical and functional relations between nerves and muscles]

The substance of the spinal marrow enters for a certain distance within the origins of the nerves, and then follows the hollow nerve as far as its last ramifications; by which perforation it conveys sensation in each muscle, which muscle is composed of as many other very minute muscles as there are threads into which this muscle can be resolved; and each of the least of these muscles is wrapped up in almost

imperceptible membranes into which the final ramifications of the before mentioned nerves become changed, for these obey in order to contract the muscle as they retire, and to cause it to expand again with each demand of the sensation which passes through the vacuity of the nerve. But to return to the spinal marrow, this is wrapped in two membranes of which only one clothes the pith-like substance of the spinal marrow, and in emerging from the hollow of vertebrae is transformed into nerve; the other clothes the nerve, together with its principal branches, and ramifies together with each branch of the nerve, and thus forms the second cover of the spinal marrow, interposing itself between the bone of the vertebrae and the first membrane of this spinal marrow.

The spinal marrow is the source of the nerves which give voluntary movement to the limbs.

The pia and the dura mater clothe all the nerves which start from the spinal marrow. Fogli b 23 r.

[Precepts for the demonstration of the nerves of the arm]

You will make a ramification of nerves with all their muscles attached.

And then you will make this ramification with the muscles attached to the nerves and to the bones which form the whole arm.

Here each nerve of the arm is joined with all the four nerves that issue from the spinal marrow.

Here will be shown all the muscles of the arm with the nerves and veins.

Make the man with arms open and showing all his nerves and their purposes according to the list; and you should use the greatest diligence with the reversive nerves in all their ramifications.

[List of demonstrations of different parts of the human body]

A demonstration of the peritoneum without the bowels.

A demonstration of bones cut through by the saw.

A demonstration of simple bones.

A demonstration of bones and nerves.

A demonstration of bones and veins.

A demonstration of nerves and muscles.

A demonstration of veins and muscles.

A demonstration of bones and intestines.

A demonstration of the mesentery.

A demonstration of limbs and muscles that interpret the spirit.

A demonstration of woman.

A demonstration of bones nerves and veins.

A demonstration of nerves alone.

A demonstration of bones alone.

A demonstration of nerves in bones that have been sawn through

A demonstration of nerves in bones that are closed in.

A demonstration of bones and of the nerves which join themselves together, which nerves are  extremely short, and those especially that join the vertebrae within. Fogli b 23 v.

[Precepts for the topographical demonstration of the upper limb and specially the hand]

ORDER OF ANATOMY

Make first the bones, that is to say the arms, and show the motive power proceeding from the shoulder to the elbow in all its lines; then from the elbow to the arm; then from the arm to the hand, and from the hand to the fingers.

And in the arm you should show the movements of the fingers as they open; and these in their  demonstration you will place alone.

In the second demonstration you will clothe these muscles with the second movements of the fingers; and you will do this stage by stage so as not to cause confusion; but first place upon the bones those muscles which join themselves with these bones without other confusion of other muscles, and with these you will place the nerves and veins which feed them, having first made the tree of the veins and nerves above the simple bones.

[Of the nature of the teeth and their position and removal from the axis of their movements]

That tooth has less power in gripping which is more remote from the centre of its movement. As if the centre of the movement of the teeth were a the axis of the jaw I say that in proportion as these teeth are more distant from this centre a they have less power in their grip; therefore d e is less powerful in its grip than the teeth b c\ and from this follows the corollary which says: — that tooth is more powerful which is nearer to the centre of its movement or the axis of its movement; that is the grip of the teeth b c is more powerful than that of the teeth d e. (Nature made them less able to penetrate into food and with heavier points which are of greater power.) Therefore the teeth b c will have their points so much the more obtuse as they are moved by greater power; and for this reason the teeth b c will be more obtuse in proportion to the teeth d e when they are nearer the axis a of the jaws a d and a e; and for this reason nature has made the molars with large crowns to enable them to grind the food and not to penetrate

it or cut it; and in front has made the teeth sharp and penetrating and not suitable for grinding this food, and has made the eye teeth between the molars and the incisors. Fogli b 24 r.

[Reaction of pupil to stimulus of light, dilation and constriction] In the nocturnal animals the pupil proceeds to vary from a large to a larger size according to the great or greater obscurity of the night.

In these nocturnal animals the pupil also varies from a small to a smaller size according to the great or greater brightness of the day. From what has been said one concludes that these nocturnal animalshave always the same power of visual faculty in all the varieties of brightness or obscurity which can occur in times of day and of night.

The visual faculty is all in the whole pupil and all in each of its parts.

It follows that the half of the pupil sees the object in its entirety as if it was whole.

In proportion as the pupil is greater in quantity it will see its object as of greater shape and clearness; and thus conversely in proportion as it is less it will see this object as so much smaller and more obscure.

It follows that if one eye be closed the power of sight is diminished by half; and this may be proved with luminous bodies such as the sun the moon and the stars, and also with a light or fire.

This diminution of brightness may be observed without closing one of the eyes; but in lieu of closing it you must interpose the hand or the finger in front of one of the pupils between the air and the eye, and you will see with the two pupils a tract of air which will have the same boundary as the air seen by the one pupil alone, and that which is seen by one pupil will be just as much darker than that which is seen by two pupils. And the reason is as the diagram shows. Fogli b 25 r.

[Precepts for the topographical demonstration of the muscles of the

bac\]

You will make the rule and the measurement of each muscle and you will give the reason of all their functions, and the manner in which they use them and who moves them.

You will make first the spine of the back; then proceed to clothe it

in stages, one above the other, of each of these muscles, and place the nerves and arteries and veins of each muscle by themselves, and in addition to this note to how many vertebrae they are joined, and which intestines are opposite to them, and what bones and other organic instruments.

The higher parts of the thin are higher in those who have well developed muscles, and similarly with fat ones; but the difference that there is between the shape of the muscles of those who are fat in comparison with those who have well developed muscles will be described here below. Fogli b 27 r.

OF THE FUNCTION OF THE INTERCOSTAL MUSCLES

The three muscles which draw up the ribs we call the drawing muscles.

To the five [four?] muscles c d e f being created for the expansion of the breast we give the name of the expanding muscles.

The intercostal are the minute muscles interposed between the ribs which serve for the dilatation and attraction of those of these ribs; and these two so diametrically opposite movements are ordained for the purpose of collecting and breathing out the air in the lung which is enclosed in the region of the ribs; and the dilatation of these ribs proceeds from the external muscles of the ribs which are arranged as in the slant m n with the help of the three muscles o p q, which as they draw the ribs with great force upward extend their capacity in the manner that one sees done with the ventricles of the heart; but the ribs having to turn downwards would not of themselves be able to descend if the man remained lying down, if it were not for the internal muscles which have an opposite slant to the external muscles, which slant extends along the line / n.

OF THE POWER OF THE INTERCOSTAL [MUSCLES]

The function of the external intercostal muscles is to raise and expand the ribs and they are of admirable power in their position; seeing that they are established with their last upper extremities upon the same spine where begin the loose ribs, and their slant descends towards the navel. Fogli b 27 v.

[Of fingers and toes]

Each protuberance formed by the joints of the toes and fingers has a hollow in the toes and fingers contiguous to it which receives within itself this roundness; and this nature has done in order not to render their width misshapen, seeing that if the said protuberances were in contact between them the feet would become of great width, and one of two effects would also be necessary, that is that either the fingers would all be of the same length, or that one would have two joints and the other one as will be demonstrated concerning the bones, in its place.

HOW THE BODY OF THE ANIMAL CONTINUALLY DIES AND IS RENEWED

The body of anything whatsoever that receives nourishment continually dies and is continually renewed. For the nourishment cannot enter except in those places where the preceding nourishment is exhausted, and if it is exhausted it no longer has life. Unless therefore you supply nourishment equivalent to that which has departed, the life fails in its vigour; and if you deprive it of this nourishment, the life is completely destroyed. But if you supply it with just so much as is destroyed day by day, then it renews its life just as much as it is consumed; like the light of this candle formed by the nourishment given to it by the fat of this candle, which light is also continually renewed by swiftest succour from beneath, in proportion as the upper part is consumed and dies, and in dying becomes changed from radiant light to murky smoke. And this death extends for so long as the smoke continues; and the period of duration of the smoke is the same as that of what feeds it, and in an instant the whole light dies and is entirely regenerated by the movement of that which nourishes it; and its life receives from it also its ebb and flow, as the flicker of its point serves to show us. The same process also comes to pass in the bodies of the animals by means of the beating of the heart, whereby there is produced a wave of blood in all the veins, and these are continually either enlarging or contracting, because the expansion occurs when they receive the excessive quantity of blood, and the contraction is due to the departure of the excess of blood they have received; and this the beating of the pulse teaches us, when we touch the aforesaid veins with the fingers in any part whatsoever of the living body.

But to return to our purpose, I say that the flesh of the animals is made anew by the blood which is continually produced by that which nourishes them, and that this flesh is destroyed and returns by the mesaraic arteries and passes into the intestines, where it putrifies in a foul and fetid death, as they show us in their deposits and steam like the smoke and fire which were given as a comparison. Fogli b 28 r.

OF THE MUSCLES WHICH MOVE THE TONGUE

No member needs so great a number of muscles as the tongue, — twenty four of these being already known apart from the others which I have discovered; and of all the members which are moved by voluntary action this exceeds all the rest in the number of its movements.

And if you shall say that this is rather the function of the eye, which receives all the infinite varieties of form and colour of the objects set before it, and of the smell with its infinite mixture of odours, and of the ear with its sounds, we may reply that the tongue also perceives an infinite number of flavours both simple and compounded; but this is not to our purpose, for our intention is to treat only of the particular movement of each member.

Consider carefully how by the movement of the tongue, with the help of the lips and teeth, the pronunciation of all the names of things is known to us; and how, by means of this instrument, the simple and compound words of a language arrive at our ears; and how these, if there were a name for all the effects of nature, would approach infinity in number, together with all the countless things which are in action and in the power of nature; and these would not be expressed in one language only, but in a great number of languages, and these also would tend to infinite variety, because they vary continually from century to century, and in one country and another, through the intermingling of the peoples, who by wars or other mischances are continually becoming mixed with each other; and these same languages are liable to pass into oblivion, and they are mortal like all the rest of created things; and if we grant that our world is everlasting we shall then say that these languages have been, and still must be, of infinite variety, through the infinite number of centuries which constitute infinite time.

Nor is this true in the case of any other sense; for these are concerned only with such things as nature is continually producing, and she does not change the ordinary kinds of things which she creates in the same way that from time to time the things which have been created by man are changed; and indeed man is nature's chiefest instrument, because nature is concerned only with the production of elementary things, but man from these elementary things produces an infinite number of compounds, although he has no power to create any natural thing except another like himself, that is his children. And of this the old alchemists will serve as my witnesses, who have never either by chance or deliberate experiment succeeded in creating the smallest thing which can be created by nature; and indeed this generation deserves unmeasured praises for the serviceableness of the things which they have invented for the use of men, and would deserve them even more if they had not been the inventors of noxious things like poisons and other similar things which destroy the life or the intellect; but they are not exempt from blame in that by much study and experiment they are seeking to create, not, indeed, the meanest of nature's products, but the most excellent, namely gold, which is begotten of the sun inasmuch as it has more resemblance to it than to anything else that is, and no created thing is more enduring than this gold. It is immune from destruction by fire, which has power over all the rest of created things, reducing them to ashes, glass or smoke. If, however, insensate avarice should drive you into such error, why do you not go to the mines where nature produces this gold, and there become her disciple? She will completely cure you of your folly by showing you that nothing which you employ in your furnace will be numbered among the things which she employs in order to produce this gold. For there is there no quick-silver, no sulphur of any kind, no fire nor other heat than that of nature giving life to our world; and she will show you the veins of the gold spreading through the stone, — the blue lapis lazuli, whose colour is unaffected by the power of the fire.

And consider carefully this ramification of the gold, and you will see that the extremities of it are continually expanding in slow movement, transmuting into gold whatever they come in contact with; and note that therein is a living organism which it is not within your power to produce. Fogli b 28 v.

OF THE MUSCLES WHICH MOVE THE LIPS OF THE MOUTH

The muscles which move the lips of the mouth are more numerous in man than in any other animal; and this order is a necessity for him on account of the many undertakings in which these lips are continually employing themselves, as in the four letters of the alphabet b f m p y in whistling, laughing, weeping and other actions like these. Also in the strange contortions used by clowns when they imitate faces.

WHAT MUSCLE IS THAT WHICH SO TIGHTENS THE MOUTH

THAT ITS LATERAL BOUNDARIES COME NEAR TOGETHER?

The muscles which tighten the mouth lessening thus its length are in the lips themselves; or rather these lips are the actual muscles which close themselves. It is true that the muscle alters the position of the lip below the other muscles which are joined to it, of which one pair are those that distend it and move it to laughter; and that which contracts it is the same muscle of which the lower lip is formed, which restrains

it by drawing in its extremities toward its centre; and the same process goes on at the same time with the upper lip; and there are other muscles which bring the lips to a point and others that flatten them, others are those which cause them to curl back, others that straighten them, others which twist them all awry, and others that bring them back to their first position; and so always there are found as many muscles as correspond to the various attitudes of these lips and as many others as serve to reverse these attitudes; and these it is my purpose here to describe and represent in full, proving these ovements by means of my mathematical principles.

OF THE MOVEMENTS OF THE MUSCLES OF THE MOUTH

WITH ITS LATERAL MUSCLES

There are many occasions when the muscles that form the lips of the mouth move the lateral muscles that are joined to them, and there are an equal number of occasions when these lateral muscles move the lips of this mouth, replacing it where it cannot return of itself, because the function of muscle is to pull and not to push except in the case of the genitals and the tongue. But if the contracting of the mouth draws back its lateral muscles equally this mouth will not of itself regain its lost length unless the said lateral muscles go back there; and if these lateral muscles extend the length of the mouth for the creation of laughter it is necessary for these lateral muscles to be drawn back by the contracting of the mouth when laughter ceases. Fogli b 29 r.

[Umbilical cord and rein]

These four nerves have not in themselves any portion of blood; but when they enter the navel they become changed into a thick vein which then extends to the gate of the liver and goes ramifying through its lower part, in which part each of its lowest ramifications ends anddoes not extend any higher.

Of the aforesaid four umbilical veins the outer pair form the sifac, the membrance adjacent to the peritoneum, and then bend downwards and end in the first ramification of the vein and the greater artery, which lies over the spine of the back.

The exterior ramification of the umbilical vein is enclosed between the first and the second membranes with which frequently the child is born.

[Origin of the umbilical vein; its relation with the artery and its course]

This umbilical vein is the origin of all the veins of the creature that is produced in the matrix, and it does not take its origin in any vein of the pregnant woman, because each of these veins is entirely separated and divided from the veins of the pregnant woman, and the veins and arteries are found together in pairs; and it is extremely rare for one to be found without the other being in company with it, and the artery is almost always found above the vein because the blood of the artery is the passage for the vital spirit, and the blood of the veins is that which nourishes the creature. And of these ramifications represented those which are raised up are ordained for the nourishment of the third thin membrane of the matrix, and the lower veins, set obliquely, are those which feed the last membrane which is contiguous to the animal that is clothed by it; and both the one and the other of these membranes often emerges, together with the creature, out of the matrix of the mother; and this occurs when the animal is not able to break it for then it emerges enveloped; and this is an easy thing, because these two extremely thin membranes as has been said above are not in any way connected with the said matrix which is also equipped with two membranes of considerable thickness, fleshy and covered with nerves.

Fogli b 29 v.

[Intercostal muscles]

CONCERNING THE NERVES THAT COMMUNICATE

SENSATION TO THE INTERCOSTAL MUSCLES

(MESOPLEURI)

The small muscles situated slantwise which descend from the upper part of the spine and terminate towards the Adam's apple derive their name from the pleura, and they are interposed between one rib and another merely in order to contract the intervening spaces; and the nerves which communicate sensation to these muscles have their origin in the spinal marrow which passes through the backbone, and the lowest point at which they start in the spinal marrow is where the spine borders upon the reins. Fogli b 30 r.

OF SPIRITS

We have just now stated that the definition of a spirit is a power united to a body, because of itself it can neither offer resistance nor take any kind of local movement; and if you say that it does in itself ofler resistance, this cannot be so within the elements, because if the spiritis a quantity without a body, this quantity is what is called a vacuum, and the vacuum does not exist in nature, and granting that one were formed, it would be instantly filled up by the falling in of that element within which such a vacuum had been created. So by the definition of weight which says that gravity is a fortuitous power created by one element being drawn or impelled towards another, it follows that any element, though without weight when in the same element, acquires weight in the element above it, which is lighter than itself; so one sees that one part of the water has neither gravity nor levity in the rest of the water, but if you draw it up into the air then it will acquire weight, and if you draw the air under the water then the water on finding itself above this air acquires weight, which weight it cannot support of itself, and consequently its descent is inevitable, and therefore it falls into the water, at the very spot which had been left a vacuum by this water. The same thing would happen to a spirit if it were among the elements, for it would continually create a vacuum in whatsoever element it chanced to find itself; and for this reason it would be necessarily in perpetual flight towards the sky until it had passed out of these elements.

WHETHER THE SPIRIT HAS A BODY AMONG THE ELEMENTS

We have proved how the spirit cannot of itself exist among the elements without a body, nor yet move of itself by voluntary movement except to rise upwards. We now proceed to say that such a spirit in taking a body of air must of necessity spread itself through this air; for if it remained united, it would be separated from it and would fall, and so create a vacuum, as is said above; and therefore it is necessary, if it is to be able to remain suspended in the air, that it should spread itself over a certain quantity of air; and if it becomes mingled with the air two difficulties ensue, namely that it rarefies that quantity of air within which it is mingled, and consequently this air, becoming rarefied, flies upwards of its own accord, and will not remain among the air that is heavier than itself; and moreover, that as this aetherial essence is spread out, the parts of it become separated, and its nature becomes modified, and it thereby loses something of its former power. To these there is also added a third difficulty, and that is that this body of air assumed by the spirit is exposed to the penetrating force of the winds, which are incessantly severing and tearing in pieces the connected portions of the air, spinning them round and whirling them amid the other air; and therefore the spirit which was spread through this air would be dismembered or rent in pieces and broken, together with the rending in pieces of the air within which it was spread.

WHETHER THE SPIRIT HAVING ASSUMED A BODY OF AIR CAN MOVE OF ITSELF OR NO

It is impossible that the spirit diffused within a quantity of air can have power to move this air; and this is shown by the former section in which it is stated that the spirit rarefies that quantity of air within which it has entered. This air consequently will rise up above the other air, and this will be a movement made by the air through its own levity, and not through the voluntary movement of the spirit; and if this air meets the wind, by the third part of this section this air will be moved by the wind and not by the spirit which is diffused within it.

WHETHER THE SPIRIT CAN SPEAK OR NO

Wishing to prove whether or no the spirit can speak, it is necessary first to define what voice is, and how it is produced, and we may define it as follows: — the voice is movement of air in friction against a compact body, or of the compact body in friction against the air, which is the same thing; and this friction of compact with tenuous substance condenses the latter, and so makes it capable of resisting; moreover, the tenuous substance, when in swift motion, and a similar substance moving slowly, condense each other at their contact, and make a noise or tremendous uproar; and the sound or murmur caused by one tenuous substance moving through another at a moderate pace [is] like a great flame which creates noises within the air; and the loudest uproar made by one tenuous substance with another is when the one swiftly moving penetrates the other which is unmoveable, as for instance the flame of fire issuing from the cloud, which strikes the air and so produces thunderbolts.

We may say therefore, that the spirit cannot produce a voice without movement of air, and there is no air within it, and it cannot expel air from itself if it has it not, and if it wishes to move that within which it is diffused it becomes necessary that the spirit should multiply itself, and this it cannot do unless it has quantity. And by the fourth part it is said that no tenuous body can move unless it has a fixed spot from whence to take its motion, and especially in the case of an element moving in its own element, which does not move of itself, except by uniform evaporation at the centre of the thing evaporated, as happens with a sponge squeezed in the hand, which is held under water, since the water flows away from it in every direction with equal movement through the openings that come between the fingers of the hand within which it is squeezed.

Of whether the spirit has articulate voice, — and whether the spirit can be heard, — and what hearing is, and seeing; — and how the wave of the voice passes through the air, — and how the images of objects pass to the eye. Fogli b 31 r. and 30 v.

[S\uU and vertebral column}

If nature had added the muscle a c in order to bend the head towards the shoulder it would have been necessary that the spinal column of the neck should bend as the bow bends by reason of its cord; consequently nature in order to avoid this inconvenience created the muscle a b which draws down the side of the skull a with a slight bending of the bone of the neck, because the muscle a b draws the side of the skull a towards b, the root of the spinal column of the neck, and as the skull is fixed on a small axis above the front of the bone of the neck it bends very readily to right and left without there being too much curve of the bone of the neck. Fogli b 32 r.

[Precepts for demonstration of vessels of the nec\ and their importance for the life]

But make this demonstration from three different aspects, namely in front, at the side and behind.

If you tighten the four veins on each side where they are in the throat he whose veins are pressed will suddenly fall on the ground asleep and as though dead, and will never wake of himself; and if for the hundredth part of an hour he is left in this condition he will never wake any more either of himself or by the help of others.

[with drawing]

a are ramifications of arteries.

b is the ramification of the veins.

c is the cephalic vein.

n are two veins which enter into the vertebrae of the neck in order to nourish them.

o is the basilical vein.

S are the apoplectic veins. Fogli b 32 v.

[Trachea. (Esophagus. Stomach]

How the rings of the trachea do not join for two reasons; the one is because of the voice, and the other is in order to allow space for the food between these and the bone of the neck.

[Wandering nerve and its function^ and varied structure of the brain]

Note in what part the left reversive nerve turns, and what function it serves.

And note the substance of the brain whether it is thinner or thicker above the starting of the nerves than in its other parts; and see in what manner the reversive nerves communicate sensation to the rings of thetrachea, and which muscles are those that give the movement to these rings in order to produce the voice deep, medium or shrill.

The reversive nerves start in a b, and b f is the reversive nerve that descends to the door-keeper of the stomach, and its companion the left nerve descends to the case that encloses the heart, and I believe this to be the nerve that enters into the heart.

[The heart a muscle nourished li\e the others by arteries and veins]

The heart in itself is not the beginning of life; but it is a vessel formed of thick muscle, vivified and nourished by the artery and vein as are the other muscles. True it is that the blood and the artery which purges itself in it are the life and nutriment of the other muscles, and it is of such density that fire can hardly injure it; and this is seen in the case of men who have been burnt, in whom after the bones have been burnt to cinders the heart within still bleeds; and nature has made this great capacity of resistance to heat so that it may be able to resist the great heat generated in the left side of the heart by means of the blood of the artery which becomes attenuated in this ventricle.

The variation of the voice starts from the dilatation and contraction of the rings of which the trachea is composed; dilatation which is produced by the muscles which join with these rings; and the contraction is produced I believe by itself because it is formed of cartilage which bends of its own accord in order to return to the shape first given to it.

Fogli b 33 v.

[Varying relation of size of artery and vein of nec\]

Note whether the artery is thicker than the vein, or the vein than the artery, and do the same with children, young people and old ones males and females and creatures of the earth air and water. Fogli b 34 r.

[Origin of all the veins of the gibbous part of the heart]

The root of all the veins is in the gibbous part of the heart, that is of the skin of the blood; and this is manifest because there it is thicker than elsewhere, and goes on ramifying an infinite number of times through every limb of the creature.

I Vdm from the liver to the spleen and their junction]

Of the two thick veins which go from the liver to the spleen, which come from the larger veins of the spine, I think that these are amasscrs of the superfluous blood, which being every day evacuated by the

mcsaruic veins is deposited in the bowels, causing the same stench when it has reached there that arises from the dead in the sepulchres, and that is the stench of the excrements.

[With figure]

Ramification made by the navel and the vein and the artery in the gate of the liver.

Represent first all the ramifications of the veins which come to the gate of the liver, all together, and then each by itself separately in three or if you prefer four demonstrations; I said three because the vein and the artery make the same journey. Fogli b 34 v.

[The olfactory and optic nerves and their relations] [With figures]

abed are the nerves that convey odours.

The nerves start from the last membrane which clothes the brain and the spinal marrow.

e n nerves are the optic nerves which are situated below the nerves called caruncular; but the optic serve the visual faculty and the caruncular the olfactory.

[Process for examination of the brain and the basilar nerves]

You will take to pieces the substance of the brain as far as the confines of the dura mater which is interposed between this basilar bone and the substance of the brain; then note all the places where this dura mater penetrates the basilar bone, with the nerves clothed by ittogether with the pia mater; and this knowledge you will acquire with certainty whenever by diligence you raise this pia mater little by little, commencing with the extremities, and noting from one part toanother the position of the before mentioned perforations, commencing first at the right or left side, representing this in its entirety; and then you will follow the opposite part, which will give you knowledge as to whether the foregoing is well situated or no, and it will also bring you to an understanding of whether the right part is similar to the left part; and if you find that it varies you will look again in the other anatomies whether this variation is universal in all men and women.

Note where the exterior parts meet the interior parts. Fogli b 35 r.

[Preparation of the hemorrhoidal veins]

Cut the subject in the middle of the spine; but first bind the chyle(vein) and artery, so that it may not pour out, and thus you will be able to see the hemorrhoidal veins in halves, that is in each division of this subject.

OF THE FOOD WHICH MAKES CORRUPTION

I say that the extremities of the mesaraic veins which attract to themselves the substance of the food enclosed in the intestines are enlarged by means of the natural heat of the man, because the heat separates and enlarges and the cold assembles and constricts; but this would not be sufficient if to this heat were not added the stench formed by the corruption of the blood returned by the arteries to these intestines, which blood acts in these intestines not otherwise than it does in bodies that have been buried; which stench enlarges the intestines and penetrates into all the interstices and swells and puffs out the bodies in the shape of casks; and if you should say that this stench arose from the heat in the bodies this would not be found to be the case with the inflated bodies which are covered with snow, and the power of the stench is much more active and multiplies much more than does that of the heat. Fogli b 36 v.

DEMONSTRATION OF THE BLADDER OF THE MAN

[Reins, ureters, bladder and urethra]

First demonstration

Of these three demonstrations of bladders, in the first are represented the ureteral pores and how they part from the reins L h, and join together at the bladder two fingers space above the starting point of the neck of this bladder, and at a short distance on the inside of this meeting point these pores discharge the urine into the bladder, from p b into n f, in the manner that is shown in part in the channel 5, whence it is then poured through the pipe of the penis a g.

It remains for me in this case to represent and describe the position of the muscles which open and close the passage of the urine to the mouth of the neck of this bladder.

Second demonstration

In the second demonstration one represents the four ramifications namely right and left of the veins that feed this bladder, and the right and left artery which gives it life, that is spirits.

And the vein is always situated above the artery.

Third demonstration In the third demonstration is contained how the vein and artery surround the beginning of the ureteral pore m n in the position n, and there is shown the interlacing of the ramification of the vein with the ramification of the artery.

[Entry of the urine into the bladder]

The urine, after departing from the kidneys, penetrates in the ureteral pores, and from these passes into the bladder, near the centre of its height, entering into this by means of small perforations made transversely between one coat and another; and this slanting perforation was not made because nature doubted whether this urine could return to the kidneys, because this is impossible by the fourth [rule] concerning channels (de' condotti) where it is stated: — 'the water which from a height descends by a thin vein and penetrates under the bottom of the sheet of water cannot be compared as to its reflex movement, unless there is as great thickness in the sheet of water as the thickness of the descending vein, nor any greater height of water in this than the depth in the sheet of water.' And if you were to say that the more the bladder fills the more it closes, to this one will reply that the fact of such perforations being pressed together by the urine which closed these walls would prevent the entrance of the rest of the urine as it descends, which cannot be by the fourth mentioned previously, which states that the thin raised-up urine is more potent than the low and wide which is in the bladder. Fogli b 37 r.

You will make this demonstration. Trachea, whence the voice passes.

CEsophagus (meri), whence passes the food.

Nerves (ipopletiche), whence pass the vital spirits.

Backbone, where the ribs begin.

Vertebrae, whence start the muscles which terminate in the nape of the neck and raise the face towards the sky.

[Precept? for the demonstration of the intestines]

Describe all the heights and breadths of the intestines, and measure them by fingers in halves and thirds of fingers of a dead man's hand, and for all put at what distance they are from the navel the breasts or the flanks of the dead.

[The relation of the lungs to the bronchial tubes]

The substance of the lung is expansible and extendible, and it is interposed between the ramifications of the trachea, so that these ramifications may not be dislodged from their positions; and this substance interposes itself between this ramification and the ribs of the chest, after the fashion of a soft feather bed.

Remember to represent the mediastinum (heart cavity) with the case of the heart, with four demonstrations, from four aspects, in the manner that is written below.

[How to describe the thoracic organs]

Make first the ramification of the lung, and then make the ramification of the heart, that is of its veins and arteries; afterwards make the third ramification of the mixture of the one ramification with the other; and these mixtures you will make from four aspects, and you willdo the like with the said ramifications which will be twelve; and then make a view of each from above and one from below, and this will make in all eighteen demonstrations.

You will first make this lung in its entirety, seen from four aspects, in its entire perfection; afterwards you will represent it so that it is seen perforated merely with the ramification of its trachea in four other

aspects.

After you have done this do the same in the demonstration of the heart, first entire, and then with the ramification of its veins and arteries.

Afterwards you will make it seen from four aspects how the veins and arteries of the heart mingle with the ramification of the trachea; then make a ramification of nerves alone from four aspects, and then weave them in four other aspects of the heart and lung joined together;

and observe the same rule with the liver and spleen, kidneys, matrix and testicles, brain, bladder and stomach. Fogli b 37 v.

[Description of the region of the mouth}

Here the lips become muscles, moving the lateral muscles with themselves.

And then the lateral muscles move the lips.

It is necessary to note first as to the bones of the face, in what part arise and whence come the nerves which first open and then close the lips of the mouth, and where the muscles are attached which are penetrated by these nerves.

[Nerves and muscles of the mouth and their functions in various movements]

The nerve n m in the lower lip and the nerve o p in the upper lip are the cause why the mouth closes  ith the help of the muscles of which these lips of the mouth are formed.

The muscles called lips of the mouth as they become compressed towards their centre draw the lateral muscles after them; and as the lateral muscles draw back in themselves, contracting, they then draw back the lips of the mouth and so this mouth expands.

The final contraction of the mouth makes it equal to half what it is when it is at its greatest extension, and it is the same with regard to the greatest breadth of the nostrils of the nose and of the interval interposed between the tear-ducts of the eyes.

OF THE NERVES WHICH TIGHTEN THE LIPS

The movements that the lips make as they tighten are two, of which one is that which presses and strains the one lip against the other, the second movement is that which compresses or shortens the length of the mouth ; but that which presses the one lip against the other does not proceed beyond the last molars of the mouth, and these when they are drawn are of such great power that, keeping the teeth somewhat open, they would draw the lips of the mouth within the teeth, as is shown in the mouth g h which is drawn by the muscles r by its sides.

[Which muscles are those that tighten the mouth across?]

The muscles that tighten the mouth across as is shown above are the lips themselves, which draw the sides of the mouth towards the centre; and this is shown us by the fourth [rule] of this which says: — the skin which forms the covering of the muscles that draw always points with its wrinkles to the spot where is the cause of the movement; and by the fifth: no muscle uses its power in pushing but always in drawing to itself the parts that are joined to it; therefore the centre of the muscles called the lips of the mouth draws to itself the extremities of this mouth with part of the cheeks, and for this reason the mouth in this function is always filled with wrinkles. Fogli b 38 v.

[How to describe the cranium]

Where the line a m intersects the line c b there will be the meeting place of all the senses; and where the line r n intersects the line h f there will be the axis of the cranium in the third of the divisions of the head.

Remember when you represent this half head from the inside to make another which shall show the outside turned in the same direction as this, so that you may better apprehend the whole. Fogli b 40 r.

[Orbital cavities (The antrum of Highmore)]

I wish to take away that part of the bone, the support of the cheek, which is found within the four lines abed, and to show through the opening revealed the breadth and depth of the two cavities which hide behind it.

In the cavity above is hidden the eye, the instrument of sight, and in that below is the humour which nourishes the roots of the teeth.

The cavity of the bone of the cheek resembles in depth and breadth the cavity which receives the eye within it, and in capacity it is very similar to it and receives veins within it by the holes m which descend from the brain passing through the passage which discharges the excess of the humours of the head in the nose.

Other perceptible holes are not found in that of the cavity above which surrounds the eye. The hole b is where the visual faculty passes to the sense, the hole n marks the spot at which tears rise from the heart to the eye, passing by the channel of the nose. Fogli b 40 v.

I Cavity of the cranium. Seat of the concourse of all the senses and its relations]

The concourse of all the senses has below it in a perpendicular line the uvula where one tastes the food at a distance of two fingers, and it raises itself above the tube of the lung and above the orifice of the heart for the space of a foot; and it has the junction of the bone of the cranium half a head above it; and it has before it in a horizontal line at a third of a head away the tear-duct of the eyes; and behind it it has the nape of the neck at two thirds of a head and on the sides the two pulses of the temples at equal distance and height. The veins which are shown within the cranium in their ramification produce an imprint of the half of their thickness in the bone of the cranium, and the other half is hidden in the membranes which clothe the brain; and where the bone has a dearth of veins within it is replenished from without by the vein a m, which after having issued forth from the cranium passes into the eye and then in the . . . Fogli b 41 r.

[Cavities of the face and their relation]

The cavity of the socket of the eye and the cavity of the bone that supports the cheek, and that of the nose and of the mouth are of equal depth, and end below the seat of the senses x in a perpendicular line.

And each of these cavities has as much depth as the third part of a man's countenance, that is from the chin to the hair.

[The different \inds of teeth and their function]

Six upper molars have three roots each and they have two roots in the outer side of the jaw and one in the inner side, and the two last of these are cut in two or four years or thereabouts.

Next come four premolars of two roots each, one on the inside and outside of the jaw, then follow the two maestre (canines) with only one root, and in front are the four teeth which do the cutting and have

one root only.

The lower jaw has also sixteen teeth as above; but its molars have only two roots; the other teeth are as those in the upper jaw; in animals 1 MS. il senso comune. the teeth of which there are two fasten on the prey, the four cut it up, the six grind it. Fogli b 41 v.

ON THE SECOND DAY OF APRIL 1489 THE BOOK ENTITLED

'OF THE HUMAN FIGURE'

[Veins of the face]

The vein m is raised up and enters under the bone of the cheek, and through the hole of the socket of the eye passes between the under side of the eyeball and the bone that supports it, and in the middle of the said passage this vein pierces the bone, and drops down half a finger's space, having pierced through the surface of the bone under the edge of the socket n mentioned above; there it commences to raise itself up, and after marking for some distance the edge of the eye passes from the tear-duct and finally within the eyelids after having raised itself for a space of two fingers, and there commences the ramification whichspreads through the head. Fogli b 42 r.

[Various themes in anatomy and physiology]

What nerve is the cause of the eye's movement and makes the movement of one eye draw the other ?

Of closing the eyelid.

Of raising the eyebrows.

Of lowering the eyebrows.

Of shutting the eyes.

Of opening the eyes.

Of raising the nostrils.

Of parting the lips with teeth clenched.

Of bringing the lips to a point.

Of laughing.

Of wondering.

Set yourself to describe the beginning of man when he is created in the womb.

And why an infant of eight months does not live.

What sneezing is.

What yawning is.

Epilepsy.

Spasm.

Paralytic.

Trembling from cold.

Perspiration.

Fatigue.

Hunger.

Sleep.

Thirst.

Sensuality.

Of the nerve which is the cause of the movement from the shoulder to the elbow.

Of the movement that is from the elbow to the hand.

From the wrist to the beginning of the fingers.

From the beginning of the fingers to the middle of them.

And from the middle to the last joint.

Of the nerve which is the cause of the movement of the thigh.

And from the knee to the foot and from the ankle to the toes.

And so to their centres.

And of the turning movement of this leg. Fogli b 42 v.

[How nature gives animals the power of motion]

ON MACHINES

Why nature cannot give the power of movement to animals without mechanical instruments, as is shown by me in this book on the works of movement which nature has created in the animals. And for his reason I have drawn up the rules of the four powers of nature without which nothing through her can give local movement to these animals. We shall therefore first describe this local movement and how it produces and is produced by each of the other three powers. Then we shall describe the natural weight, for though no weight can be said to be other than accidental, it has pleased us to style it thus in order to distinguish it from the force which in all its operations is of the nature of weight and is for this reason called accidental weight, and this is the force which is produced by the third power of nature, that is, the inherent or natural power. The fourth and last power will be called percussion, that is, the end or restraint of movement. And we shall begin by stating that every local insensible movement is produced by a sensible mover, just as in a clock the counterpoise is raised up by man who is its mover. Moreover the elements repel or attract each other, for one sees water expelling air from itself, and fire entering as heat under the bottom of a boiler and afterwards escaping in the bubbles on the surface of the boiling water. And again the flame draws to itself the air, and the heat of the sun draws up the water in the form of moist vapour which afterwards falls down in thick heavy rain.

Percussion however is the immense power of things which is generated within the elements. Quaderni i i r.

[Description of the human body in process of dissection]

THE ORDER OF THE BOOK

This plan of mine of the human body will be unfolded to you just as though you had the natural man before you. The reason is that if you wish to know thoroughly the parts of a man after he has been dissected you must either turn him or your eye so that you are examining from different aspects, from below, from above and from the sides, turning him over and studying the origin of each limb; and in such a way the natural anatomy has satisfied your desire for knowledge. But you must understand that such knowledge as this will not continue to satisfy you on account of the very great confusion which must arise from the mixture of membranes with veins, arteries, nerves, tendons, muscles, bones and the blood which of itself tinges every part with the same colour, the veins through which this blood is discharged not being perceptible by reason of their minuteness. The completeness of the membranes is broken during the process of investigation of the parts which they enclose, and the fact that their transparent substance is stained with blood prevents the proper identification of the parts which these cover on account of the similarity of the blood-stained colour, for you cannot attain to any knowledge of the one without confusing and destroying the other.

Therefore it becomes necessary to have several dissections: you will need three in order to have a complete knowledge of the veins and arteries, destroying all the rest with very great care; and three others for a knowledge of the membranes, 'panniculi', three for the tendons, muscles and ligaments, three for the bones and cartilages, three for the anatomy of the bones, for these have to be sawn through in order to show which are hollow and which not, which are full of marrow, which spongy, which thick from the outside inwards, and which thin. And some have great thinness at one part and thickness at another, and at another part they are hollow or filled with bone or full of marrow, or spongy. Thus it may be that all these conditions will sometimes be found in the same bone and there may be another bone which has none of them. Three also must be devoted to the female body, and in this there is a great mystery by reason of the womb and its foetus.

 Therefore by my plan you will become acquainted with every part and every whole by means of a demonstration of each part from three different aspects; for when you have seen any member from the front with the nerves, tendons and veins which have their origin on the opposite side, you will be shown the same member either from a side view or from behind, just as though you had the very member in your hand and went on turning it from side to side until you had a full understanding of all that you desire to know.

And so in like manner there will be placed before you three or four demonstrations of each member under different aspects, so that you will retain a true and complete knowledge of all that you wish to learn concerning the figure of man.

Therefore there shall be revealed to you here in fifteen entire figures the cosmography of the 'minor mondo' (the microcosmos or lesser world) in the same order as was used by Ptolemy before me in his Cosmography. And therefore I shall divide the members as he divided the whole, into provinces, and then I shall define the functions of the parts in every direction, placing before your eyes the perception of the whole figure and capacity of man in so far as it has local movement by means of its parts.

And would that it might please our Creator that I were able to reveal the nature of man and his customs even as I describe his figure!

And I would remind you that the dissection of the nerves will not reveal to you the position of their ramification nor into which muscles they ramify by means of bodies dissected either in flowing water or in lime water; because, although the origin of their derivation may be discerned without the use of the water as well as with it, their ramifications tend to unite in flowing water all in one bunch just as does flaxor hemp carded for spinning, so that it becomes impossible to find out again into which muscles the nerves are distributed or with which or how many ramifications they enter the said muscles.

[Dissection of the human hand]

OF THE HAND FROM WITHIN

When you begin the hand from within first separate all the bones a little from each other so that you may be able quickly to recognise the true shape of each bone from the palmar side of the hand, and also the real number and position of each, and have some sawn through down the centre of their thickness, that is lengthwise, so as to show which is empty and which full. And having done this place the bones together at their true contacts and represent the whole hand from within wide open. Then set down the complete figures of the first ligaments of the bones. The next demonstration should be of the muscles which bind together the wrist and the remainder of the hand. The fifth shall represent the tendons which move the first joints of the fingers. The sixth the tendons which move the second joints of the fingers. The seventh those which move the third joints of these fingers. The eighth shall represent the nerves which give them the sense of touch. The ninth the veins and the arteries. The tenth shall

show the whole hand complete with its skin and its measurements, and measurements should also be made of the bones. And whatever you do for this side of the hand you should do the same for the other three sides, that is from the palmar or under side, from the dorsal sideand from the sides of the extensor and the flexor muscles.

And thus in the chapter on the hand you will make forty demonstrations; and you should do the same with each member.

And in this way you will attain complete knowledge.

You should afterwards make a discourse concerning the hands of each of the animals, in order to show in what way they vary, as with the bear, in which the ligaments of the tendons of the toes are joined above the neck of the foot. Quaderni i 2 r.

Not abbreviators but forgettcrs (obbliatori) should they be called who abridge such works as these. Quaderni 1 4 r.

Make a discourse on the censure deserved by scholars who put obstacles in the way of those who practise anatomy and by the abbreviators of their researches. 1

I Nothing superfluous or lacking in nature]

Nothing is superfluous and nothing is lacking in any species of animal or product of nature unless the defect comes from the means which produce it. Quaderni 1 4 v.

IF THE WIND WHICH ESCAPES FROM THE TRACHEA CONDENSES ITSELF IN ITS TRANSIT OR NO

All the air that enters into the trachea is of equal quantity in all the degrees which are produced by its ramification; after the manner of the branches born during the seasonal growth of the plants which every year, if the various thicknesses of all the branches that have been produced are reckoned together, equal the thickness of the stem of their plant.

But the trachea contracts itself in the larynx in order to condense the air, which seems a thing of life as it comes from the lung to create the various kinds of voices, and also to press and dilate the different passages and ventricles of the brain, because if the trachea were thus dilated at its upper end as it is in the throat, the air would not be able to condense itself and perform the duties and benefits which are necessary to life and to man, that is in speaking, singing and the like.  And the wind which is suddenly expelled from the lung as it produces the deep sighs proceeds by the help of the wall of the abdomen (mirac?) which squeezes the intestines, and they raise the diaphragm that presses on the lung. Quaderni 1 5 v.

There may be a veiled significance in the use of the word 'abbreviatori' as the term was also applied to the secretaries at the Chancery of the Vatican. Leonardo in one of his letters complains of having been impeded in his anatomical researches as a result of information laid before the Pope.

IF THE HEART AT ITS DEATH CHANGES POSITION OR NO

The change of the heart at its death is similar to the change which it undergoes during the expulsion of its blood, and is somewhat less. This is shown when one sees the pigs in Tuscany, where they pierce the hearts of the pigs by means of an instrument called a borer, which is used for drawing wine out of casks. And thus turning the pig over and tying it up well they pierce its right side and its heart at the same time with the borer, thrusting it in in a straight line. And if this borer pierces the heart when it is distended the heart as it expels the blood becomes contracted and draws the wound to the top together with the point of the borer; and the more it raises the point of the borer withinthe more it lowers the handle of the borer outside; and afterwards when the heart is distended and drives this wound downwards the part of this borer which is outside makes a movement that is the opposite to that of the part within which moves together with the movement of the heart. And this it does many times, so that at the end of life that part of the borer that is outside remains in the middle of the two extremities, where were the last contrary movements of the heart when it was alive. And when the heart becomes quite cold it shrinks somewhat and contracts as much as it had extended when warm because heat causes a body to increase or diminish when it enters into it or leaves it; and this I have seen many times and have observed such measurements having allowed the instrument to remain in the heart until the animal was cut up. . . .

And from the greatest to the smallest movement of the heart of this animal is about the thickness of a finger, and at the end the heart remains with its point out of its usual position by about half the thickness of a finger; and pay attention lest you make a mistake in taking this measurement because sometimes the handle of this borer will not make any change whether the heart is living or dead; and this occurs when the heart receives its wound half way in the process of its contracting, in which position it remains when it is dead. And sometimes this handle makes the greater change and this occurs when the heart receives its wound during its period of greater or less length, and thus it will make as many varieties of distances as are the variations in the length or shortness of the heart when it is wounded. More-pVCJ this handle will make greater or less changes according as the point of the borer penetrates further or less into the heart; for if the point of the iron transfixes the heart it makes a lesser movement from the centre of its movement, that is from the place, than it would do if the iron had only wounded the heart in the front part of its anterior wall; and on this point I will not dwell further because a complete treatise on these movements has been compiled in the twentieth book on the forces of the lever. And if you should consider that when the heart had been transfixed the length of the borer could not follow the movement spoken of above through it being impeded by the anterior wall of the heart you must understand that in the extension and dilation of the heart, it draws or drives the point of this iron along with its motion; and the iron which finds itself in the anterior wall enlarges its wound both upwards and downwards, or to put it better moves it seeing that the roundness of the thick part of the iron does not enlarge since it does not cut, but carries with it the front wound of the heart, compressing the part of the heart in contact with it now from the upper part of the wound, now from the lower part, and such rarefaction and compression is easily made by this heart when it is warm because it is less dense. Quaderni 1 6 r.

[Notes on anatomy]

You should make the liver in the embryo differing from that of man, that is with the right and left parts equal.

But you should make first the anatomy of the hatched eggs.

Say how at four months the child is half the length and so is one eighth the weight that it will be at birth.

Describe which and how many are the muscles that move the larynx in the production of the voice. Quaderni 1 10 r.

{Development of embryo]

Do this demonstration also as seen from the side, in order to give information how much one part may be behind the other; and then do one from behind in order to give information as to the veins covered

by the spine and by the heart and greater veins.

Your order shall commence with the formation of the child in the womb, saying which part of it is formed first and so on in succession, placing its parts according to the times of pregnancy until the birth, and how it is nourished, learning in part from the eggs which hens make. Quaderni i 12 r.

And you who say that it is better to look at an anatomical demonstration than to see these drawings, you would be right, if it were possible to observe all the details shown in these drawings in a single figure, in which, with all your ability, you will not see nor acquire a  knowledge of more than some few veins, while, in order to obtain an exact and complete knowledge of these, I have dissected more than ten human bodies, destroying all the various members, and removing even the very smallest particles of the flesh which surrounded these veins, without causing any efTusion of blood other than the perceptible bleeding of the capillary veins. And as one single body did not suffice for so long a time, it was necessary to proceed by stages with so many bodies as would render my knowledge complete; and this I repeated twice over in order to discover the differences.

But though possessed of an interest in the subject you may perhaps be deterred by natural repugnance, or, if this does not restrain you, then perhaps by the fear of passing the night hours in the company of these corpses, quartered and flayed and horrible to behold; and if this does not deter you then perhaps you may lack the skill in drawing essential for such representation; and even if you possess this skill it may not be combined with a knowledge of perspective, while, if it is so combined, you may not be versed in the methods of geometrical demonstration or the method of estimating the forces and strength of muscles, or perhaps you may be found wanting in patience so that you will not be diligent.

Concerning which things, whether or no they have all been found in me, the hundred and twenty books which I have composed will give their verdict 'yes' or 'no'. In these I have not been hindered either by avarice or negligence but only by want of time. Farewell. Quaderni 1 13 v.

[Drawings describe natural things better than words]

[Note at side of drawing of heart showing the arrangement of the veins and arteries]

With what words O writer can you with a like perfection describe the whole arrangement of that of which the design is here?

For lack of clue knowledge you describe it so confusedly as to con vey but little perception of the true shapes of things, and deceiving yourself as to these you persuade yourself that you can completely satisfy the hearer when you speak of the representation of anything that possesses substance and is surrounded by surface.

I counsel you not to cumber yourself with words unless you are speaking to the blind. If however notwithstanding you wish to demonstrate in words to the ears rather than to the eyes of men, let your speech be of things of substance or natural things, and do not busy yourself in making enter by the ears things which have to do with the eyes, for in this you will be far surpassed by the work of the painter.

How in words can you describe this heart without filling a whole book? Yet the more detail you write concerning it the more you will confuse the mind of the hearer. And you will always then need commentators or to go back to experience; and this with you is very brief, and has to do only with a few things as compared with the extent of the subject concerning which you desire complete knowledge. Quaderni 11 1 r.

[Praise of the Creator in anatomy]

[Drawing of action of the muscles of the heart, followed by descriptive note in which occurs the sentence:]

This the Inventor made for the cause shown in the figure above, which reveals how the Creator does not make anything superfluous or defective. Quaderni 11 3 r.

[Anatomy of nec\ — Praise of the Creator]

Each of the vertebrae of the neck has ten muscles joined to it.

You should show first the spine of the neck with its tendons like the mast of a ship with its shrouds without the head; then make the head with its tendons which give it its motion upon its axis.

a b are muscles which keep the head upright, and so do those which originate in the clavicle, c b, joined to the pubes by means of the longitudinal muscles.

Show in the second demonstration which and how many are the nerves that give sensation and movement to the muscles of the neck.

n is one of the vertebra of the neck to which is joined the beginning of three muscles, that is of three pairs of muscles which are opposite each other, so that the bone where they have their origin may not

break.

O speculator concerning this machine of ours let it not distress you that you impart knowledge of it through another's death, but rejoice that our Creator has ordained the intellect to such excellence of perception. Quaderni n 5 v.

Why the heart does not beat nor the lung breathe during the time that the child is in the womb which is filled with water; for if it should draw a breath it would instantly be drowned. But the breathing and the beating of its mother's heart works in the life of the child which is joined to her by means of the umbilical cord as it works in the other members.

Therefore during every harmonic or as you may say musical tempo the heart makes three movements, as is contained below, of which tempos an hour contains one thousand and eighty. The heart therefore moves three thousand five hundred and forty times in each hour in the process of opening and shutting. And it is this frequency of movement which warms the thick muscles of the heart, and this heat warms the blood that continually beats within it. It heats it more in the left ventricle, where the walls are very thick, than in the right ventricle with the thin wall. And this heat makes the blood grow thinner and turns it to vapour and changes it into air, and would change it to elemental fire, if it were not that the lung renders help at this crisis with the coolness of its air.

But the lung cannot send air into the heart, nor is this necessary since, as has been said, air is generated in the heart, and this, as it becomes mingled with the warm thick moisture, evaporates through the extremities of the capillary veins at the surface of the skin in the form of perspiration; and moreover the air which is breathed in by the lung, enters continually dry and cold, and issues forth moist and warm. But the arteries which are joined by continual contact to the network of branches of the trachea, spreading through the lung, are what catches the coolness of the air as it enters into this lung. Quaderni 11 11 r.

[Balance of heart in man and animals]

And if you say that the left external wall (of the heart) has been mad: thick in order that it might acquire greater weight, so that it should make a counterpoise to the right ventricle, which has a great weight of blood, you have not reflected that this balancing was not necessary, seeing that all the land animals except man have the heart in a recumbent position; and the heart of man also lies thus when he is lying in his bed. But you would not be weighing the matter well in your conclusion, because the heart has two supports which descend from the collar bone, from which by the fourth of 'De Ponderibus* the heart is not able to balance itself, if there is not a single support above, and these two supports are the Arteria Aorta and the Vena cava; and furthermore if the heart is deprived of the weight of the blood as it becomes restricted and gives it in deposit to its upper ventricles, the centre of gravity of the heart would then be on the right side of the heart and thus its left side would be lightened. But this theory of balancing is not a true one as was said above because the animals which lie or which stand on four feet have the heart lying as they are themselves, and with these no balancing of the heart is sought.

And in the case of the bat which when it sleeps always places itself upside down, how does the heart balance with the right and left ventricle? Quaderni 11 17 r.

WHY THE PRINCIPAL VALVES OF THE RIGHT VENTRICLE

ARE MADE WITH SO LITTLE MEMBRANE AND

SUCH A NETWORK OF CORDAE

This thing was ordained by nature in order that as the right ventricle commences to shut, the escape of the blood from its huge capacity should not suddenly cease, because a portion of that blood had to be given to the lung, and it would not be given if the valve had stopped  the exit. But this ventricle shut itself when the lung had received its quantity of blood and so [from] the right ventricle it was able to press through the pores of the median wall into the left [MS. right] ventricle; and at the same time the right auricle became the depositary of the excess of the blood which it passes to the lung, and this suddenly gives it to the opening of this right ventricle restoring itself through the blood with which the liver supplies it.

HOW MUCH BLOOD IS THE LIVER ABLE TO GIVE IT

THROUGH THE OPENING OF THE HEART?

It restores as much of it as it consumes; that is a minimum part, because in an hour the heart opens about two thousand times. There is great weight.

The right ventricle was made heavier than the left one in order that the heart may stand in a slanting direction; and when the blood rises out of the left ventricle and lightens it this blood goes from it towards the left side with the centre of its gravity when it is in the upper ventricles.

The heart has four ventricles, that is two upper ones called auricles of the heart, and two lower than these called the right and left ventricles. Quaderni n 17 v.

[Definitions]

Definition of the instruments.

Discourse on the nerves, muscles, tendons, 'panniculi' (membranes) and ligaments.

The function of the nerves is to convey sensation; they are the team of drivers of the soul, for they have their origin from its seat and command the muscles so that they move the members at the consent of the will of this soul.

The muscles the ministers of the nerves draw to themselves the sinews which are joined to these members in a similar manner.

The tendons are mechanical instruments which have no sensation of themselves but carry out as much work as is entrusted to them.

The membranes (panniculi) are joined to the flesh being interposed between the flesh and the nerve, and most frequently they are joined to the cartilage.

The ligaments are joined to the tendons and are of the nature of membranes (panniculi) which bind together the joints of the bones and are converted into cartilage, and they are as many in number at every joint as are the tendons which move the joint and as are the tendons opposite to these which come to the same joint, and these ligaments join and mingle together, helping strengthening and connecting one with another.

The cartilage is a hard substance, like, let us say, hardened tendon or softened bone, and its position is always between the bone and the tendon because it partakes of both substances, and it is flexible and unbreakable, the flexibility acting in it like a spring.

Pellicles are certain muscular parts which are made up of flesh, tendons and nerves, the union of these forming a composition which is capable of being extended in any direction; flesh is a mixture made up of muscles, tendon, nerve, blood and artery.

Bone is a hardness, inflexible, adapted for resistance, and is without sensation and terminates in the cartilages which form its extremities; and its marrow is composed of sponge, blood, and, soft fat coated over with a very thin tissue. The sponge-like substance is a mixture of bone, fat and blood.

The membranes (panniculi) are of three kinds, that is, made up of tendons, made up of nerves, and made up of nerves and tendons; and the mixed membrane is woven of tendon, nerve, muscle, vein and

artery.

The membranes that are between the tendons and the cartilages are so formed as to unite tendon with cartilage in a large and continuous joint so that it may not break through excess of force; and when the muscle itself thickens it does not draw to itself the tendon or any member, but the muscle is drawn by the tendon towards the membrane and the cartilage, as happens with the muscles inside the ventricles of the heart when they shut their openings. But the muscles of the other members are drawn towards the bone where they are joined, and draw their tendon behind them together with the member that is joined to this tendon.

The tears come from the heart and not from the brain.

Define all the parts of which the body is composed, commencing with the skin with its outer coating which often detaches itself through the action of the sun. Quaderni 11 18 v.

[Six constituent parts of movement]

There are six things which take part in the composition of the movements; namely bone, cartilage, membrane, tendon, muscle and nerve, and these six consequently are in the heart. Quaderni 11 23 r.

[With sectional drawing 'in congressu']

I reveal to men the origin of their second — first or perhaps second —cause of existence.

Through these figures will be shown the cause of many dangers of ulcers and diseases.

Division of the spiritual from the material parts.

And how the child breathes and how it is nourished through the umbilical cord; and why one soul governs two bodies, as when one sees that the mother desires a certain food and the child bears the mark of it.

And why the child [born] at eight months does not live.

Here Avicenna contends that the soul gives birth to the soul and the body to the body and every member, but he is in error. Quaderni in 3 v.

The child does not draw breath in the body of its mother because it lies in water, and whoever breathes in water is immediately drowned.

Whether the child while within the body of its mother is able to weep or to produce any sort of voice or no.

The answer is no; because it does not breathe neither is there any kind of respiration; and where there is no respiration there is no voice.

Ask the wife of Biagino Crivelli how the capon rears and hatches the eggs of the hen when he is in the mating season.

They hatch the chickens by making use of the ovens by the fireplace.

Those eggs which are of a round form will be cockerels and the long-shaped ones pullets.

Their chickens are given into the charge of a capon which has been plucked on the under part of its body, and then stung with a nettle and placed in a hamper. When the chickens nestle underneath it it feels itself soothed by the sensation of warmth and takes pleasure in it, and after this it leads them about and fights for them, jumping up into the air to meet the kite in fierce conflict. Quaderni in 7 r.

Book 'On the Water' to Messer Marco Antonio. 1

1 Marco Antonio della Torre. Context shows that text refers to presence of water in uterus during gestation.

I With drawing of child in womb]

In the case of this child the heart does not beat and it does not breathe because it lies continually in water. And if it were to breathe it would be drowned, and breathing is not necessary to it because it receives life and is nourished from the life and food of the mother.

And this food nourishes such creature in just the same way as it does the other parts of the mother, namely the hands feet and other members. And a single soul governs these two bodies, and the desires and fears and pains are common to this creature as to all the other animated members. And from this it proceeds that a thing desired by the mother is often found engraved upon those parts of the child which the mother keeps in herself at the time of such desire; and a sudden fear kills both mother and child.

We conclude therefore that a single soul governs the bodies and nourishes the two [bodies]. Quaderni in 8 r.

[How one mind governs two bodies]

As one mind governs two bodies, in as much as the desires the fears and the pains of the mother are one with the pains that is the bodily pains and desires of the child which is in the body of the mother, in like manner the nourishment of the food serves for the child and it is  nourished from the same cause as the other members of the mother, and its vital powers are derived from the air which is the common living principle of the human race and of other living things.

[Colour of s\in due to parents — seed of mother as potent as that of father]

The black races in Ethiopia are not the product of the sun; for if black gets black with child in Scythia, the offspring is black; but if a black gets a white woman with child the offspring is grey. And this shows that the seed of the mother has power in the embryo equally with that of the father. Quaderni in 8 v.

[On sheet with drawings and notes of foetus in uterus]

See how the birds are nourished in their eggs. Quaderni in 9 v.

[Representation of lungs with bronchiae and vessels]

When you represent the lung make it perforated so that it may nor obstruct what is behind it, and let the perforation be all the ramifications of the trachea and the veins of the artery (aorta) and of the vena cava and then outside these draw a contour line round about them to  show the true shape, position and extent of this lung.

Quaderni in 10 r.

[ With drawings of action of lungs]

Represent first all the ramification which the trachea makes in the lung and then the ramification of the veins and arteries separately, and then represent everything together. But follow the method of Ptolemy in his Cosmography in the reverse order: put first the knowledge of the parts and then you will have a better understanding of the whole put together. Quaderni in 10 v.

[With drawing]

This is the lung in its case.

The question arises where the lung becomes cooler or more heated, and the same is searched for in the heart.

It has to be ascertained whether the wall of the heart interposed between its two ventricles is thinner or thicker as the heart becomes longer or shorter, or one may say as it expands or contracts.

It is our opinion that during the process of dilation it increases its capacity and the right ventricle draws blood from the liver and the left ventricle at such time draws blood from the right one.

As many times as the pulse beats so many times does the heart expand and contract. Quaderni iv 3 r.

[Of the muscles]

No one can move others if he does not move himself. Quaderni iv 5 r.

[Relation of reversive nerves to heart and brain. Seat of soul. Origin of vital powers. Action of heart. Relation of movement of heart and lung]

Follow up the reversive nerves as far as the heart, and observe whether these nerves give movement to the heart or whether the heart moves of itself. And if its movement comes from the reversive nerves

which have their origin in the brain then you will make it clear how the soul has its seat in the ventricles of the brain, and the vital powers derive their origin from the left ventricle of the heart. And if this movement of the heart originates in itself then you will say that the scat of the soul is in the heart and likewise that of the vital powers, so that you should attend well to these reversive nerves and similarly to the other nerves, because the movement of all the muscles springs from these nerves which with their ramifications pour themselves into these muscles. Many are the times when the heart draws into itself some of the air which it finds in the lung, and returns it after it is heated without this lung having gathered other air from outside.

It is proved that it must of necessity be as is here set forth, and this is that the heart which moves of itself only moves in opening and shutting itself; this opening and shutting creates motion along the line that lies between the cusp and the base or corona of the heart; and it cannot open without drawing into itself air from the lung, which it immediately blows out again into the lung, where it will afterwards be seen that this lung will be restored by a vigorous movement of sudden deep breathing from the new refreshment of cold air; and this occurs when a fixed purpose of the mind banishes into oblivion the respiration of the breath.

In closing itself the heart with its nerves and muscles draws behind it the powerful vessels which proceed from the heart to unite with the lung; and this is the principal cause of the opening of the lung, because it cannot open unless the vacuum increases, and the vacuum cannot acquire any increase unless it refills itself, and finding the air more suitable for this restoration of the vacuum it refills itself with it. This heart afterwards as it contracts comes to reopen itself, and as it reopens itself it relaxes the drawn-out nerves and vessels of the lung, from which it follows that the lung closes itself up again and at the same time restores the increase in the vacuum of the heart through the wind which it blows out of itself, and in part sends out of the mouth the superfluous air for which neither in it nor in the heart is there any capacity. Quaderni iv 7 r.

[Subcutaneous vessels in the groin and armpit]

From the inner parts of the arms and of the thighs go veins that form branches from their main stems and these run all over the body between the skin and the flesh.

And remember to note where these arteries part company from the veins and the nerves. Quaderni iv 8 r.

[Tonsils]

The two tonsils are formed on the opposite sides of the base of the tongue and are in the shape of two small cushions interposed between the bone of the maxilla and the base of the tongue so as to create a space between the two, so that on one side it may be capable of receiving the lateral roundness of the convex formation of the tongue caused by it bending, and may with its convex part wipe away the food from the angle of the maxilla round the lateral parts of the base of the tongue.

Twenty-eight muscles in the roots of the tongue.

[Of tongues]

[Leonine and bovine species]

This is the reverse of the tongue [drawing], and its surface is rough in many animals and especially in the leonine species, such as lions, panthers, leopards, lynxes, cats and the like which have the surface of their tongues very rough as though they were covered with very small  sails, somewhat flexible; and when they lick their skin these nails penetrate down to the roots of the hairs, and after the fashion of combs they carry away the minute animals which feed upon them.

And I once saw how a lamb was licked by a lion in our city of Florence, where there are always from twenty five to thirty of them and they bear young. With a few strokes of his tongue the lion stripped off the whole fleece with which the lamb was covered, and having thus made it bare he ate it; and the tongues of the bovine species are also rough. Quaderni iv 9 v.

[Pronunciation of vowels]

The membrane interposed between the passage that the air makes in part through the nose and in part through the mouth is the only one which man uses in order to pronounce the letter a, that is the membrane a n, and though the tongue and lips may do what they can, this will never prevent the air which streams out from the trachea from forming the sound a while in this concavity a n. Moreover u is formedat the same place with the help of the lips which tighten and thrust themselves out a little; and the more these lips thrust themselves out the better do they pronounce the letter u. True it is that the epiglottis m rises somewhat towards the palate.

And if it were not for it doing thus, the u would be changed into o, and this o . . .

And whether when a o u are pronounced distinctly and rapidly it is necessary that in pronouncing them continuously without any interval of time the opening of the lips should go on continually contracting, that is that in pronouncing a they should be wide apart, closer together in pronouncing o and much closer still in pronouncing u.

It is proved how all the vowels are pronounced with the back part of the movable palate which covers the epiglottis; and moreover such pronunciation comes from the position of the lips by means of which a passage is formed for the air as it streams out carrying with it the created sound of the voice, which even when the lips are closed streams out through the nostrils, but when issuing through such passage will never become a demonstrator of any of these letters.

From such an experiment one may conclude with certainty that the trachea does not create any sound of vowel but that its office only extends to the creation of the aforesaid voice and especially in a o u.

[The muscles of the tongue]

The tongue is found to have twenty-four muscles which correspond to the six muscles of which the mass of the tongue which moves in the mouth is composed.

The present task is to discover in what way these twenty-four muscles are divided or apportioned in the service of the tongue in its necessary movements, which are many and varied; and in addition to this it has to be seen in what manner the nerves descend to it from the base of the brain, and in what manner they pass into this tongue distributing themselves and breaking into ramifications. And it must further be noted how and in what manner the said twenty-four muscles convert themselves into six in the formation they make in the tongue. And furthermore you should show whence these muscles have their origin, that is in the vertebrae of the neck at the contact with the oesophagus, and some in the maxilla on the inside, and some on the trachea on the outside and laterally. And similarly how the veins nourish them and how the arteries give them the spiritus, (and how the nerves give them sensation).

Moreover you shall describe and represent in what way the procedure of varying and modulating and articulating the voice in singing is a simple function of the rings of the trachea moved by the reversive nerves, and in this case no part of the tongue is used.

And this is proved by what I have proved before, that the pipes of the organ do not become deeper or sharper through the change of the fistula (that is that place in which the voice is produced), in making it wider or narrower; but only through the change of the pipe to be wide or narrow or long or short as is seen in the expansion or compression of the winding trumpet, and also in the pipe which is of fixed width or length, the sound varies according as the wind is let into it with greater or less impetus. And this amount of variation is not found in the case of objects struck with a greater or less blow, as is perceived when bells are struck by very small or very large clappers; and the same thing occurs with pieces of artillery similar in width but differing in length, but in this case the shorter piece makes a louder and deeper noise than the longer one. And I do not go into this at greater length because it is fully treated in the book about harmonical instruments. And for this reason I will resume my discourse concerning the func-tions of the tongue where I left it.

The tongue works in the pronunciation and articulation of the syllables which are the constituent parts of all words. This tongue is also employed during the necessary revolutions of the food in the process of mastication and in the cleansing therefrom of the inside of the mouth together with the teeth. Its principal movements are seven;

namely stretching out, drawing together and drawing back, thickening, shortening, spreading out and pointing; and of these seven movements three are composite because one cannot be created without another also being created joined to it of necessity; and this is the case  with the first and the second, that is with stretching out and drawing together, for you cannot stretch out a substance which is capable of being expanded without it contracting and straightening itself on all its sides. And a similar result occurs in the third and fourth movements which are contrary to the two first, that is in the thickening and shortening. Alter these come the fifth and sixth movements which together form its third movement made up of three movements, namely spreading 1 iiit pointing and shortening.

Although human subtlety makes a variety of inventions answering by different means to the same end, it will never devise an invention more beautiful more simple or more direct than does nature, because in her inventions nothing is lacking, and nothing is superfluous; and she needs no countervailing weights when she creates limbs fitted for movement in the bodies of the animals, but puts within them the soul of the body which forms them, that is the soul of the mother which first constructs within the womb the shape of the man, and in due time awakens the soul that is to be its inhabitant. For this at first remained asleep, in the guardianship of the soul of the mother, who nourishes and gives it life through the umbilical vein, with all its spiritual members; and so it will continue for such time as the said umbilical cord is joined to it by the secundines and the cotyledons by which the child is attached to the mother. And this is the reason why any wish or intense desire or fright experienced by the mother, or any other mental suffering, is felt more powerfully by the child than by the mother, for there are many cases in which the child loses its life from it.

This discourse does not properly belong here, but is necessary in treating of the structure of animated bodies; and the rest of the definition of the soul I leave to the wisdom of the friars, those fathers of the people who by inspiration know all mysteries. I speak not against the sacred books, for they are supreme truth. Quaderni iv 10 r.

HERE FOLLOWS [CONCERNING] THE ARTICULATION OF THE HUMAN VOICE

The extension and restriction of the trachea together with its dilation and contraction are the cause of the variation of the voice of the animals from high to deep and from deep to high; and as regards the second of these actions, as the shortening of the trachea is not sufficient when the voice is raised it dilates itself somewhat towards the top part, which does not receive any degree of sound but produces a raising of the voice of this remnant of the shortened pipe. But of this we.shall make an experiment in the anatomy of the animals, by pumping air into their lungs and compressing them, and so narrowing and dilating the fistula which produces their voice. Quaderni iv 10 v.

Here is a doubt as to the pannicles which close up the blood in the antechamber of the heart that is in the base of the aorta, whether nature could have dispensed with them or no, since one may clearly

see how the three walls or hinges where such pannicular valves of the heart are established, are those which by their swelling shut this blood out from the heart when the heart reopens on the side below these valves.

And this last closing nature carries out in order that the great force which the heart employs in this left ventricle, as it reopens in order to draw into itself the blood that percolates through the narrow interstices of the wall that divides it from the left ventricle, should not for the restoring of the vacuum be obliged to draw with it the most delicate pannicles of the said valves of the heart.

The revolution of the blood in the antechamber of the heart, the base of the aorta, serves two effects, of which the first is that this revolution multiplied in many aspects causes great friction in itself, and this heats and lightens the blood and increases and vivifies the spiritus vitales which always maintain themselves in warmth and moisture. The second effect of this revolution of the blood is to close up again the opened gates of the heart with a complete system of fastening with its first reflex movement.

As many as are the times which this gate expels the blood so many are those which the heart beats, and for this reason those who are feverish become inflamed. Quaderni iv n r.

Between the cords (cordae) and threads of the muscles of the right ventricle there are interwoven a quantity of minute threads of the nature and shape of the minute muscles which form the worm in the brain and of those which weave the rete mirabile; and these wind themselves round the most minute and imperceptible nerves and weave themselves with them. And these muscles are in themselves very capable of expansion and contraction, and they are situated within the fury of the rush of the blood, which passes in and out among the minute cords of the muscles before they are converted into the membranes (pannicuii) of the valves.

Before you open the heart inflate the ventricles of the heart commencing from the artery of the aorta; and then tie them up and consider their size. Afterwards do the same with the right ventricle or the right 'orecchio'; and by so doing you will see its shape and its purpose, for it was created in order to expand and contract and so cause the blood to revolve as it passes through its cells which are full of tortuous passages divided by rounded walls without any angles, in order that the motion of the blood not finding any angular obstructions may have an easier revolution in its eddying course. And thus it comes to warm itself with so much more heat in proportion as the movement of the heart is the more rapid. So it sometimes attains to such great heat that the heart is suffocated; and I have already seen one case where it was burst as a man was fleeing before his enemies, and he poured out perspiration mingled with blood through all the pores of his skin; and this heat forms the spiritus vitales. And thus heat gives life to all things; as one sees the heat of the hen or of the turkey-hen giving life and growth to the chickens, and as the sun in returning causes all thefruits to blossom and burgeon. Quaderni iv 13 r.

[Division of surface of heart by vessels. Peeling the flesh off to find certain vessels}

The heart has its surface divided into three parts by three veins which descend from its base, of which veins two terminate the extremities of the right ventricle and have two arteries in contact below them. As regards the third vein I have not yet seen whether it has an artery with it, and consequently I am about to remove some of the flesh of the surface in order to satisfy myself. But the surface space of the heart enclosed within its arteries occupies half the surface circle of the thickness of the heart and forms the outer wall of the right ventricle.

[Heating by churning, and by the action going on in the heart]

Observe whether when butter is being made the milk as it revolves becomes heated; and by such means you will be able to prove the efficacy of the ventricles of the heart, which receive and expel the blood from their cavities and other passages, as made only in order to heat and refine the blood and make it more suitable for penetrating the wall through which it passes from the right to the left ventricle, where by means of the thickness of its wall, that is of that of the left ventricle, it conserves the heat which this blood brings to it. Quaderni iv 13 v.

[Tendons]

Describe the tendons of any limb from four aspects and how they are diffused through the muscles, and how the muscles produce the tendons and the tendons the joints etc. Quaderni iv 15 r.

[The tree of the vessels (with drawing) ]

ANATOMY OF THE VESSELS

Here shall be represented the tree of the vessels generally, as Ptolemy did with the universe in his Cosmography; then shall be represented the vessels of each member separately from different aspects.

Make the view of the ramification of the vessels from behind, from the front and from the side; otherwise you would not give true knowledge of their ramifications, shape and position.

The ventricles of the brain and the ventricles of the semen are equally distant from the ventricles of the heart. Quaderni v 2 r.

[Muscles represented by strings of fire-heated copper wire] Make this leg in full relief, and make the tendons of copper wire that has been heated in the fire; and then bend these according to their natural form; and having done this you will be able to draw them from four sides, and to place them as they are in nature and to speak about  their functions.

The immediate causes of the movements of the legs are entirely separated from the immediate cause of the movement of the thigh, and this is what makes the power.

[Of the muscles]

When you have finished the bones of the legs put the number of all the bones, and at the end of the tendons set down the number of these tendons. And you should do the same with the muscles, the sinews, the veins and arteries, saying: — the thigh has so many, and the leg so many and the feet so many and the toes so many; and then you should say: —so many are the muscles which start from the bones and end in the hones, and so many are those which start from the bones and end in another muscle; and in this way you describe every detail of each limb, and especially as regards the amifications made by certain muscles in producing different tendons.

These four legs should be on one and the same sheet of paper so that you may be the better able to understand the positions of the muscles and to recognise them from different sides. Quaderni v 4 r.

[Anatomy of the brain with details of an experiment to discover the true form of the ventricles]

After we have clearly seen that the ventricle a is at the end of the neck where pass all the nerves which communicate the sense of touch we may judge that this sense of touch passes into such ventricle, seeing that nature works in all things in the briefest time and way possible; therefore the sense would go with longer time.

[Experiment]

Make two air holes in the horns of the great ventricles and insert melted wax by means of a syringe, making a hole in the ventricle of the memoria, and through this hole fill the three ventricles of the brain; and afterwards when the wax has set take away the brain and you will see the shape of the three ventricles exactly. But first insert thin tubes in the airholes in order that the air which is in these ventricles may escape and so make room for the wax which enters into the ventricles. 1 Drawing with names of parts: — imprensiva, sensus communis, memoria.

Model of the sensus communis.

Cast in wax at the bottom of the base of the cranium through the hole m before the cranium was sawn through. Quaderni v 7 r.

[Anatomy of intestines]

Draw the intestines in their position and detach them ell by ell, first tying up the ends of the part removed and the part remaining. And after you have removed them you must draw the margins of the mes According to the editors of the Quaderni, Leonardo was the first to make casts of the cerebral ventricles, and several hundred years elapsed before the idea occurred to any other anatomist. entery from which you detach such part of the intestine; and when you have drawn the position of this intestine you will draw the ramification of its vessels; and so you will go on in succession until the end.

And you will commence on the right intestine but you will make the entry on the left side at the colon. But first of all you must remove with your chisel the pubic bone and the bones of the hips in order to observe accurately the position of the intestines. Quaderni v 24 r.

Nature has made all the muscles which connect with the movements of the toes attached to the bone of the leg and not to the thigh, for if they were attached to the bone of the thigh, they would fold up when the knee-joint was bent and become fixed under the knee-joint, and not be able without great difficulty and fatigue to serve these toes; and the same happens with the hand, by means of the bending of the elbow of the arm. Quaderni vi 17 r.

Uncover gradually all the parts on the front side of a man when you make your anatomy; and so continue to do even to the bones. Quaderni vi 21 r.

CONCERNING THE HUMAN FORM

Which part is that in man which never puts on flesh as he grows fat?

Which is that part which as a man becomes thin is never reduced with too perceptible a thinness?

Among the parts which grow fat which is that which grows most fat?

Among the parts which become emaciated which is that which becomes most emaciated?

Among men who are powerful in strength which muscles are of greater thickness and more prominent?

You have to represent in your anatomy all the stages of the limbs from the creation of man down to his death, and down to the death of the bones, and (to show) which part of these is first consumed and which part is preserved longer.

And similarly from the extreme of leanness to the extreme of fatness.

ON PAINTING

Which muscles are those which stand out as people grow old or in the young when they become lean?

Which are the places in the human limbs in which the flesh never increases on account of any degree of fatness or diminishes on account of any degree of leanness.

What has to be sought for in this question will be found in all the surface joints of the bones, as shoulder, elbow, joints of the hands and fingers, hips, knees, ankles and toes and similar things which shall be spoken of in their places.

The greatest thickness which the limbs acquire is in the part of the muscle that is farthest away from their attachments.

The flesh never increases upon the parts of the bones which are near the surface of the limbs.

In the movement of man, nature has placed all those parts in front which on being struck cause a man to feel pain; so it is felt in the shins of the legs and in the forehead and nose. And this is ordained for man's preservation, for if such power of enduring suffering were not inherent in these limbs the numerous blows received on them would be the cause of their destruction. Quaderni vi 22 r.

OF THE MOVEMENTS OF THE FINGERS OF THE HANDS

The movements of the fingers are chiefly those of extension and bending. Extension and bending are done in various ways, that is sometimes by bending all in one piece at the first joint, at another time by bending or straightening themselves half way at the second joint, and at another time by bending in their whole length and at the same time in all the three joints. If the two first joints are prevented from bending the third joint will bend more readily than before, but it can never bend of itself alone if the other joints are free, but all the three joints must bend. In addition to the above-mentioned movements there are four other diief movements, of which two are upwards and downwards, and the two others go from side to side, and each of these is produced by a single tendon. From these there follow an infinite number of other movements made always with two tendons; and if one of these tendons does not function properly the other takes its place. The tendons are made thick on the inside of the finger and thin on the outside; and on the inside they are attached to every joint but not on the outside. c.a. 99 v. a

OF THE MUSCLES

Nature has provided man with functional muscles which draw the sinews and these are able to move the limbs according to the will and desire of the common sense, after the manner of officials stationed by their lord through various provinces and cities to represent and carry out his will in these places. And the official who on more than one occasion has carried out the commission given him by the mouth of his lord will then himself at the same time do something which does not proceed from the will of the lord. So one often sees with the fingers how after having with utmost docility learnt things upon an instrument as they are commanded by the judgment they will afterwards play them without the judgment accompanying. The muscles which move the legs do not however perform their functions without the man becoming conscious of it. c.a. 119 v. a

Saw a head in two between the eyebrows in order to find out by anatomy the cause of the equal movement of the eyes, and this practically confirms that the cause is the intersection of the optic nerves, that is of the equality of movement, if the eyes observe minutely the parts of a circle, and there are nerves which cause them to make a circular movement. c.a. 305 v. b

OF ARTERIES

There are three varieties of arteries, of which one is wide at the bottom and narrow at the mouth, another wide at the mouth and narrow at the bottom, and the third is of uniform width. c.a. 369 v. e

The navel is the point of junction of the offspring ^ith the sheath which clothes it; it spreads out branches and is attached to the matrix as a button is to a buttonhole, a briar to a briar or a burr to a burr. c.a. 385 r. a

OF THE NERVES

The hand that holds the stone within it when it is struck with a hammer feels a part of the pain which the stone would feel if it were a sentient body. a 33 r.

OF THE BLOOD THAT THERE IS IN THE CROWN OF THE HEAD

It would seem to be a simple proposition that if anyone should break the crown of a man's head nothing would flow forth from this fracture except such blood as lay between its edges. In fact every heavy thing seeks low places; blood possesses weight and it appears impossible that of itself it could ever rise to a height like an aerial and light thing. And if you wished to say that by the extension that the lung makes in

the lake of blood, when this lung in the ingathering of the breath fills itself with air, and in becoming deflated drives from the lake the blood, which escapes into the veins and makes them increase and swell, and that it is this swelling which causes this blood to flow out from the above named fracture of the crown of the head, this opinion is at once confuted by the fact that the veins are quite capable and adapted to serve as a convenient receptacle for the increase of the blood without it having to flow out by the fracture of the head as though deprived of such receptacle.

WHY THIS BLOOD ESCAPES BY THE CROWN OF THE HEAD

The spiritual parts have power to move and to carry with them in their course the material parts. We see that fire by reason of its spiritual heat sends out of the chimney amid the steam and smoke matter that has body and weight, as is seen with soot which if you burn you will see reduced to ashes. So the heat that is mingled with the blood finding itself evaporate by the fracture of the head desiring to return to its element, carries in its company the blood with which this heat is infused and intermingled. The reason why the smoke rises up with such fury and carries substances with it is that as the fire attaches itself to the wood it is nourished and fed by a fine moisture, and as this moisture becomes thicker than can be consumed by the heat that is within the fire, the fire desires to return to its element, and carries the heated vapours with it, as may be seen if you distil quicksilver in a retort; you will see that when this silver of so great weight is mingled with the heat of the fire it ascends and then in smoke falls down again into the second container and retakes its former nature. a 56 v. and 57 r.

Observe how the shoulder changes with all the movements of the arm, moving up and down, inwards and outwards, backwards and forwards, and so also with turning movements or any other movements. And do the same with the neck the hands and feet and the chest above the hips. e 17 r.

PAINTING

O painter skilled in anatomy, beware lest the undue prominence of the bones sinews and muscles cause you to become a wooden painter from the desire to make your nude figures reveal all their emotions.

And if you wish to remedy this you should consider in what way the muscles of old or lean persons cover or clothe the bones, and furthermore note the principle on which these same muscles fill up the spaces of the surface which come between them, and which are the muscles that never lose their prominence in any degree of fatness whatsoever, and which those whereof the tendons become indistinguishable at the least suggestion of it. And there are many cases when several muscles grow to look one from the increase of fat, and many in which when any one becomes lean or old a single muscle divides into several; and in this treatise all their peculiarities shall be set forth each in its place, and especially with regard to the spaces that come between the joints of each limb. Further you should not fail to observe the variations of the aforesaid muscles round the joints of the limbs of any animal, due to the diversity of the movements of each limb; for on no side of these joints does the indication of these muscles become completely lost by reason either of the increase or diminution of the flesh of which these muscles are composed.

And you should do the same for a child from its birth down to the time of its decrepitude, through all the stages of its life, such as infancy, childhood, adolescence, youth etc. And in all you should describe the changes of the limbs and joints and show which grows fat and which thin. e 19 v - an d 20 r.

Describe which are the muscles and tendons that become prominent or concealed through the different movements of each limb, and which do not do either. And remember that such action is very important and very necessary for such painters and sculptors as profess to be masters. e 20 r.

Which nerves or sinews of the hand [or foot] are those that bring close together and separate from each other the fingers and toes of the hands and the feet? f 95 v.

The heart is a principal muscle in respect of force, and it is much more powerful than the other muscles.

I have written of the position of the muscles which descend from the base to the point of the heart, and the position of the muscles which spring from the point of the heart and go to the summit.

The auricles of the heart are the ante-chambers of this heart which receive the blood from the heart when it escapes from its ventricle from the beginning to the end of the pressure, for unless a part of this quantity of blood escaped the heart would not be able to shut. c 1 v.

Give the anatomy of the leg up to the hip from all its sides, in every action, so as to show everything; veins, arteries, nerves, tendons and muscles, skin and bones; then with the bones in section in order to show the thickness of the bones. k 108 [28] r.

[Sinews and muscles]

The sinew which guides the leg which is joined to the kneecap feels it more effort to raise the man up in proportion as the leg is more bent. The muscle which acts upon the angle formed by the thigh at its junction with the bust has less difficulty and has less weight to raise because it does not have the weight of the thigh; and besides this it has stronger muscles because they are those which form the buttocks. l 27 v.

Piscin da Mozania at the hospital of Brolio has many veins.

For the arms and legs. Forster 11 65 r.

The simple members are eleven, namely cartilage, bones, nerves, veins, arteries, membranes, ligaments and tendons, skin and flesh and fat.

OF THE HEAD

The parts of the vessel of the head are ten, namely five external and five internal.

The external are: — hair and skin, muscular flesh, large membrane and the skull. The internal are these: — dura mater, pia mater, brain; below return the pia mater and the dura mater which enclose the brain between them, then there is the rete mirabile, and then the bone foundation of the brain, and from thence proceed the nerves. Forster in 27 v.

[Drawing — head in median section]

a hair, n skin, c muscular flesh, m large membrane, o skull, that is bone of skull.

b dura mater, d pia mater, / brain.

r pia mater below, t dura mater, / rete mirabile, s bone foundation. Forster in 28 r.

Hippocrates says that the origin of our semen is derived from the brain, and from the lungs and testicles of our forefathers where the final decoction is made; and all the other members transmit their substance to this semen by sudation, because there are no apparent channels by which they could arrive at this semen. Forster in 75 r.

IV

Comparative Anatomy

'Second demonstration interposed between the anatomy and the life.

For this comparison you should represent the  legs of frogs, for these have a great resemblance

to the legs of the man both in the bones and in the muscles!

[Comparative Anatomy]

Represent here the foot of the bear and of the monkey and of other animals as far as they differ from the foot of man; and put also the feet of certain of the birds. Fogli a 17 r.

[Comparative Anatomy]

[Drawing of arm] Man a b m n.

[same] Monkey c d p o.

In proportion as the nerve c d takes the bone o p nearer to the hand so this hand raises a greater weight; and this is the case with the monkey which is more powerful in its arms than the man is according to his proportion. Fogli b 9 v.

[Man, Lion, Horse, Bull]

Man. The description of man, in which is contained those who are almost of the same species just as the baboon, the ape and others like these which are many.

Lion and its followers, such as panthers, lions, tigers, leopards, lynxes, Spanish cats, gannetti and ordinary cats and the like.

Horse and its followers such as the mule, the ass and the like which have teeth above and below.

Bull and its followers which are horned and without upper teeth,

such as buffalo, stag, fallow-deer, roebuck, sheep, goats, ibex, milch cows, chamois, giraffes. Fogli b 13 r.

COMPARATIVE ANATOMY

[Organs of the senses in man as compared with those of other animals] I have found in the constitution of the human body that as among all the constitutions of the animals it is of more obtuse and blunt sensibilities, so it is formed of an instrument less ingenious and of parts less capable of receiving the power of the senses. I have seen in the leonine species how the sense of smell forming part of the substance of the brain it descends in a very large receptacle to meet the sense of smell which enters among a great number of cartilaginous cells with many passages that go to meet the above-mentioned brain.

The eyes of the leonine species have a great part of their head as their receptacle, so that the optic nerves may be in immediate conjunction with the brain. With man the contrary is seen to be the case for the cavities of the eyes occupy but a small part of the head, and the optic nerves are thin and long and weak; consequently as one sees they work feebly by day and worse by night, whereas the aforesaid animals see better by night than by day; and the sign of this is seen in the fact that they hunt their prey by night and sleep by day as do also the nocturnal birds.

The light or pupil of the human eye as it expands or contracts gains or loses the half of its size; and in the nocturnal animals its increase or decrease is more than a hundred times. This may be seen in the eye of the owl a nocturnal bird by bringing a lighted torch near to it, and still more by making it look at the sun, for then you will see the pupil which once occupied the whole of the eye diminished to the size of a grain of millet, and by this diminution it becomes equal to the pupil of the eye of man and clear shining things seem the same colour to it as they appear at this time to man, and as much more as the brain of this creature is less than the man's brain : from which it comes about that as the pupil increases in the night time a hundred fold more than that of the man it sees a hundred times as much light as the man does, in such a way that this power of sight is not afterwards subdued by the darkness of night. And the pupil of man which only doubles its quantity sees only faint light and almost like the bat which does not fly in times of too great darkness. Fogli b 13 v.

[Differences between the human intestines and those of other animals] Write of the varieties of the intestines of the human species, apes and

such like; then of the dilTerences that are found in the leonine species, then the bovine and lastly in birds; and make this description in the form of a discourse. Fogli b 37 r.

Then you shall make a discourse on the hands of each animal in order to show how they vary, as in the bear in which the ligaments of the tendons of the toes of the foot are connected over the neck of the

foot. Quaderni 1 2 r.

Describe the tongue of the woodpecker and the jaw of the crocodile. Quaderni 1 13 v.

Take out a bull's liver to make an anatomy. Quaderni 11 6 v.

Look at the dead dog, its lumbar muscles and diaphragm and the movement of its ribs. Quaderni 11 7 v.

Analyse the movement of the tongue of the woodpecker. Quaderni iv 10 r.

[With drawings of onion and human head in section}

If you cut an onion down the centre you will be able to see and count all the coatings or rinds which form concentric circles round the centre of this onion.

Similarly if you cut a man's head down the centre you will cut through the hair first, then the skin and the muscular flesh and the pericranium, then the cranium and within the dura mater and the pia mater and the brain, then the pia and dura mater again and the rete mirabile and the bone which is the foundation of these.Quaderni v 6 v.

[With figures}

[Comparative anatomy. Bones and joints. Muscular contours in obesity and in emaciation}

Junction of the fleshy muscles with the bones, without any tendon or cartilage — and you should do the same for several animals and birds.

Show a man on tiptoe so that you may compare a man better with other animals.

Represent the knee of a man bent like that of the horse.

To compare the bone structure of the horse with that of the man you should show the man on tiptoe in representing the legs.

Of the relationship that exists between the arrangement of the bones and muscles of the animals and that of the bones and muscles of the man.

Show first the bones separated with the sockets where they join, and then join them together, and especially the hip-joint or the joint of the thigh.

Describe which muscles disappear in the process of growing fat, and which are uncovered as one becomes emaciated.

And note that those portions of the surface of the fat which protrude most will stand out most when one grows thin.

Where the muscles are separated from one another you should show outlines, and where they are tightly fastened together; and you should draw only with the pen. Quaderni v 22 r.

SECOND DEMONSTRATION INTERPOSED BETWEEN

THE ANATOMY AND THE LIFE 1

For this comparison you should represent the legs of frogs, for these have a great resemblance to the legs of the man, both in the bones and in the muscles; you should afterwards follow this with the hind legs of the hare, for these are very muscular and the muscles are well defined because they are not hampered by fat. Quaderni v 23 r.

[Diagrams]

PUPIL OF OWL. PUPIL OF MAN

The pupil c represents its size in the daytime, that is at the greatest brightness of the day.

a c shows how it increases in the maximum darkness of the night, and so it goes changing from a greater to a less quantity according to the greater or less obscurity of the night.

1 This passage is cited by the editors of the Quaderni d'Anatomia as a proof of Leonardo having acquired a full understanding of the difference between scientific anatomical dissection and contour anatomy.

PUPIL OF CAT

If the darkness of night is a hundred degrees more intense than that of evening, and the eye of man doubles the size of its pupil in darkness, this darkness is lessened by half in this eye because it has edoubled half its visible potency: there remain therefore fifty degrees of intensity of darkness. And if the eye of the owl has its pupil increased a hundred times in the aforesaid darkness it increases its visual capacity one hundred times, so that one hundred degrees of visual capacity are acquired, and because things which are equal do not overcome one another the bird sees in the darkness with the pupil increased a hundredfold as in the day with the pupil diminished ninety nine parts in the hundred.

And if you were to say that this animal does not see light by day and for this reason it remains shut up, to this I reply that the bird only shuts itself up in the day in order to free itself from the mobbing of birds which in a great multitude always surround it with a loud clamour, and frequently they would be put to death if they did not hide themselves in the grottos and caverns of the high rocks.

Of the nocturnal animals only the lion species changes the shape of its pupil as that enlarges or lessens : for when it is at the utmost stage of diminution it is long in shape, when half way it is oval, and when it has attained to its utmost expansion it is circular in shape.c.a. 262 r. d

[With sketches of head of horse]

The distance between the one ear (of a horse) and the other should equal the length of one of the ears.

The length of the ear should be the fourth part of the face. a 62 v.

Death in the old without fever is caused by the skin of the veins which go from the spleen to the gate of the liver becoming so thick that they close up and no longer allow a passage to the blood which feeds them.

The continual passing of the blood in these veins makes them thicken and harden so that at last they close up and prevent the passage of the blood.

The spaces or hollows in the veins of the animals and the long course of the humour that nourishes them harden and finally contract. The hollows of the veins of the earth come to be enlarged through the long continuous passage of the water. Fir.

MUSCLES OF ANIMALS

The hollows interposed between the muscles should not be of such a kind that the skin seems as though it covers two sticks placed to touch each other, as in c; and not in such a way as to seem like two sticks at a little distance from each other and with the skin hanging idly with a loose curve as in /; but it should be as in j, laid over the spongy fat that lies between the angles, as in the angle n m o, which angle springs at the end of the contact of the muscles. And because the skin cannot descend into such an angle nature has filled it with a small quantity of spongy or as I prefer to call it vesicular fat, that is containing small cells full of air, which become condensed or rarefied according to the increase or rarefaction of the substance of the muscles; in which case the hollow i has always a greater curve than the muscle. g 26 r.

Make an anatomy of different eyes and see which are the muscles that open and close the above mentioned pupils of the eyes of animals.

OF THE EYES OF ANIMALS

The eyes of all animals have pupils which have power to increase or diminish of their own accord according to the greater or less light of the sun or other luminary. In birds however the difference is greater, and especially with nocturnal birds of the owl species such as the long eared the white and the brown owls; for with these the pupil increases until it almost covers the whole eye or diminishes to the size of a grain of millet, preserving all the time its round shape. But in the lion species such as panthers, leopards, lionesses, tigers, wolves, lynxes, Spanish cats and others the pupil as it diminishes changes from the perfect circle to an elliptical figure thus [fig.] as is seen in the margin.

Man however having a more feeble vision than any other animal is less hurt by excessive light and his pupil undergoes less increase in dark places. As regards the eyes of the above-mentioned nocturnal animals, in the horned owl which is the largest nocturnal bird the power of vision is so much increased that even in the faintest glimmer of night which we call darkness it can see more distinctly than we in the radiance of noon, when these birds stay hidden in dark recesses; or if they are compelled to emerge into the sunlit air the pupil contracts so much that the power of vision diminishes at the same time as the size of the pupil. c 44 r.

[Drawings of part of skeleton of horse]

Of the muscles that attach themselves to the bone. Horse. k 102 [22] r.

[Drawing: part of skeleton of horse]

Here I make a note to show the difference there is between man and horse and in the same way with the other animals.

I commence first with the bones, and then go on to all the muscles which proceed from and end in the bones without tendons, then to those which proceed from and end in the bones with tendons and then those which have a single tendon on one side, k 109 [29-30] v.

When the eye of the bird closes with its two coverings it closes first the secondina, and this closes it from the lachrymal gland as far as the angle of the eye, and the first (covering) closes it from below upwards. And these two movements having intersected cover it first from the direction of the lachrymal gland, because they have already seen themselves safeguarded in front and below; and they only reserve the upper part because of the dangers from birds of prey which descend from above and behind, and they will first uncover the membrane in the direction of the angle, for if the enemy comes behind the bird will have the opportunity of flying forward. It also has the membrane called the secondina of such texture as to be transparent, for if it did not possess this shield it would not be able to keep its eyes open against the wind which strikes the eye in the fury of its swift flight.

And its pupil expands and contracts as it beholds less or greater light, that is, radiance. b.m. 64 v.

[Sketch — bust of man and measurements]

The trunk a b will be one foot at its narrowest part, and from a [to] b will be two feet which will form two squares.

And the horse in its narrowest part goes three times into the length which makes three squares. Quaderni vi 4 r.