ON TREMULATION

CHAPTER IV.

I. It was said that the membranes, over which tremulation flows and which carry the motion into the cranium and over the whole osseous system, are of the same quality as a musical chord. To originate a sound there must be a tightly stretched string no less than a well built body of porous wood; the fittest sounding boards can effect no sound if the strings are slack. Thus also with the membranes in our body: such as is their tension or expansion, such will be the communication of the tremulation the osseous system, and such will be the increase of the sensation; but as soon as they become slack, they can communicate no tremulation for the production of sensation, even though the bony system is perfect and in all the strength of maturity.

It is now our intention to show how the membranes become expanded and attuned to receive the tremulatory motion by means of the influx of blood and lymph into their respective vessels. When these fluids press in with force and swiftness, they cause all the ducts and minutest vessels to swell up, and as the membranes consist of nothing but such vessels, it follows that the whole membranous system then becomes expanded and distended. On the other hand, when there is present any force which expels the blood or the lymph from their vessels, it follows that the membranes are let loose and become like a slack string which only can vibrate very slowly and scarcely is able to conduct the tremulation to the bridge of the instrument. The degree of fullness of life is, therefore, according to the decree of the tension of the meninges: the more these are expanded, the swifter is the course of tremulation, and the greater is the degree of what is called esprit and presence of mind; but in the degree that the membranes as it were collapse and perhaps conceal some serum or lymph beneath their folds, in the same degree is the tremulatory motion prevented, and in the same degree do we suffer from absence of mind and of understanding, the body no longer responding to what is quick and prompt.

As now the tension of the meninges is the most necessary condition for any proper kind of tremulation, let us next consider the circulation of the two principal fluids in our bodily system. It is hardly necessary to say anything here as to the circulation of the blood as much as Anatomy is very rich in knowledge on this subject. The general opinion is, however, that the blood flows from its center, or the heart, through the arteries, which gradually ramify into finer and finer arteries, until they finally terminate in little branches and delicate vessels, to the number of many thousands; all these are distributed not only over all the cuticles, but over all the membranes which are visible in the meninges and in the choroid plexus, until they present a reticulated expanse, figuring in the membranes like the finest ramifications anal leaves of a tree. After the blood then has followed the arteries into these least ramifications, it flows into the venules, and thence, by the same pressure, into the larger branches, and so, finally, through the greater veins back again to the heart to repeat the same circulation as before.

While such is the circulation of the blood through the arteries and veins, there are other little ducts, called the lymphatic vessels, which run as it were out of the wall of an artery and across to a vein, like little aqueducts pouring their fluid into the blood which is to return to the heart: these aqueducts are lymphatic nervous vessels, each surrounded by most minute nerves and membranes. Now, though the microscope has discovered something of this order, still we do not suppose that any one is as yet able to claim a knowledge of the fountains of these rivers. (SWEDENBORG'S GREAT NEURO-TRANSMITTERS HYPOTHESIS) But if we are willing to follow the guidance of sound reason, acting on the suggestion of what has been observed thus far, we cannot but conclude that just as the heart is the propelling organ of the blood, so are the cerebrum and the medulla the fountain of circulation of other fluids in the body. It is known that the cerebrum and the medulla have a reciprocal and undulatory motion, just as the heart; this motion must necessarily cause a fluid to be pressed in and out continually, propelling it to the extremities, and thence back to its original fountain. Now, out of the two medullas there flows in the nerves a fluid called the nervous serum,--as will not be denied by any person of common sense, for it is known that the nerves are humid; the same may be observed in the wood of the hardest tree, in which the sap flows up and down through the pores to all the parts of the tree. These nerves are again ramified into finer and finer branches, until they are finally expanded into membranes which clothe all parts of the body; these membranes, in their turner provide a new sheathing for the nerves, and thus accompany them back to the medullas. The fluid, which has poured itself through the fibrils of the nerves to the extreme tunics, has thus an area or space in which it may either unburden itself or else flow back again to the matres and meninges as to its own source, just as the blood returns to the heart.

It has been shown by Vieussens that these membranes extend thousands of threads or Iymphatico-nervous tubules on one hand into the bones and on the other hand into the arachnoid. and the pia mater. Through these the lymphatico-nervous vessels cause to be distilled into the medullas a fluid which that author would almost acknowledge as an animal spirit; this fluid has thus flowed out of the medulla through the nerves into e the membranes, and then back again to the medulla, making a circulation similar to that of the blood. this, at least, seems credible to us, and it is also possible that the lymphatic vessels run only from the walls of the arteries into the walls of the veins, that is, from nervous tunics into other nervous tunics.

As now the blood has its own sources of distillation, that is, the lungs, the glands, and the chyles, which form the blood before it comes into circulation in the arteries and veins, so also does the nervous fluid possess its own glandtlles, ventricles, anal vessels whence it is distilled in the brain. But let us consider these in their order. It is known that the dura and pia mater are covered on tile surface by little sanguineous and lymphatico-nervous vessels; these, again, send little tubes into the cerebrum, pouring into it the fluid which the cerebrum afterwards is to distill and pour into the medulla. The pia mater is therefore, at first, almost united with the cerebrum; the upper part of the latter, which is ash colored, is called the cortical or cineritious part, and consists of little glandules which distill the fluid; below this is the medullary part which is whitish and consists of little stri and tubules, through which a fluid may be seen flowing out of the cortical part. The cerebrum is, moreover, divided into two hemispheres, between which lies a hard medulla, called the corpus callosum; all along the latter, towards the ventricles, there is a soft substance which has been called the septum lucidum. In each hemisphere there is a ventricle or cavity surrounded within by the pia mater; between the two ventricles there is another called the fornix, and Still another, smaller one, has been found between the cerebrum and the medulla oblongata. This medulla arises from four roots and possesses two cornua from the cortical part of the cerebrum, as also from the cerebellum; these cornua are called pedunculi or processes. On the top of the medulla oblongata there is the annular protuberances surrounded with its pia tunica, and in connection with it there are two other globules, one on each side, from which arise the optic nerves, whence they are called the thalami of the optic nerves. The cortical part is inmostly in these thalami, but the medullary part is on the surface. Just below lies the infundibulum, also surrounded with the pia mater, and ending in the pituitary gland. Next follows a number of other little glands and protuberances, such as the corpora striata, the lineal glared, the ages, the sates, testes. corpora pyramidalia and olivaria, the pons Varolii, etc., concerning the nature and position of which one may consult the anatomists. Below all these the medulla runs through the great foramen of the occiput, and enters the vertebrae, where it becomes known as the medulla spinalis.

Returning now to the nervous fluid, we will understand that it is ever flowing anew from the meninges through the little lymphatico-nervous vessels, which by means of tubules carry their burden into the most minute glands of the cerebrum; from here it flows into the rnedulla and through the nerves into all the membranes and all the finest and most remote expanses of the body. It thus also flows into the muscles, where the nerves at each point send forth most minute filaments like a fine net or web; these are supposed to close in the veins and to reciprocate themselves through the heart to the finest ramifications of the arteries, anel so, in the same manner, to the brain. It is also to be observed that the inmost kernel of the medulla spinalis is a cortical or glandular substance, the other or external part being medullary, consisting of continual strife which receive the fluid from the membranes and carry it back to the brain, to be distilled over again for new use in the nerves.

It would seem that there is a difference between the lymph which drips forth from the dura mater and that which comes from the pia mater, and that both of these kinds are different from the nervous serum itself. This difference, which is not yet clearly understood may perhaps be illustrated by the difference in the humors of the eye: the humor which flows between the lamely of the tunic of the eye is supposed to be the same with the fluid which is distilled by the dura mater; this humor is aqueous and not especially sensitive, but mixed with urinous matter or with a subtle salt which as yet is but little known to chemistry; the crystalline humor, which also is the hardest, and which has its own globe or adytum in the eye, seems to be distilled by the pia mater, for the tunics on both sides of this globe are an extension from the pia mater; nevertheless, as numerous little arteries run into it, and as it has a still finer tunic on the outside, we are unable to make any certain Conclusion on this point; the third humor, which is called the vitreous, and which lies almost on the retilla, seems to flow immediately from the optic nerve and its thalamus, and it appears that the nervous serum has considerable affinity with this humor, not only because it possesses an even viscosity, being neither too fluid nor too tenacious or viscid, but because in the most minute networks it makes an expanse by its mucus which flows in through the optic nerve. All this, however, has only been said by way of suggestion.

However this nay be, it shows at least that there must be a tension in the membranes if any proper kind of tremulation is to be communicated over the whole of their expanse, so as to effect a sensation in one thing or another. This tension can arise only from the infilling of the vessels, whether it be the blood-vessels or those through which any lymph or juice is circulating. In the blood-vessels there is a certain degree of heat, while the other vessels possess a Certain degree of coolness, anel both regulate anal moderate the natural heat of the living body and produce the proper expansion of all things. Any obstruction in either of the fluids causes an obstruction either in the nerves or in the other vessels in the membranes, and prevents that tension which alone enables the tremulation to present a living sensation.

2. As now the finer degrees of tremulation require an expansion or tension in the membranes, and as the swiftness of the motions and the consequent intensity of the sensation are according to the degree of this tension, it follows that slack or flaccid membranes cannot possibly serve for any subtle activity. In a new-born infant, for instance, everything is still soft and unripe, and there is,therefore, little or no activity; with an adult , on the other hand, everything has reached its proper expansion, and all tremulations consequently flow promptly and forcibly to their effects. as well in respect to comprehension as in respect to expression; with the very aged, finally, an things must move slowly, and approach more and more to a state of dullness. because with them all the membranes have become slack and wrinkled and receptive only of the coarser undulations, so that they can have hardly any contremiscences in their whole being.

If now, from any accidental cause, the tension has been removed from the membranes, either by the blood being expelled from the finest arteries or by the nervous fluid being stopped up in the little foramina, the effect will at once be externally observable: the senses can no longer perform their functions, and the thought and the memory no longer remain distinct, but the man becomes like a mere form, almost void of life, the vital fire being gradually quenched and approaching a state of quiescence or death. This may be illustrated by the conditions of the body during various states of passion and affection.

A sudden fear causes the blood to rush back to the heart in an instant: it fills up the greater veins, withdraws from the finer arteries, and completely exhausts the most minute vessels; the muscles are deprived of blood; pallor covers all the extremities, the membranes also become exsanguious, they lose their tension, lie down slack, and become altogether unfit for the reception of a tremulation. Hence each one of the senses is deprived of the greater part of its sensitive power; the eye loses its acumen, and the same happens to the ear and the other organs; the thought and the imagination become indistinct, and the life is in danger, nay, is sometimes extinguished before the blood has been able to force its way back to lift up the collapsed vessels. Sometimes there follows a tremor, a quivering, a stroke or convulsion throughout the body, for the greater part of the life is lost as soon as the tremulation no longer can flow over a stiff expanse.

Amazement produces similar effects, in so far that everything in the body then displays a tendency to come to a standstill; even the involuntary motion seems to have stopped; the blood has hardly any impulse toward a new circulation; a general state of forgetfulness anti stupidity results, with a limpness and placidity in all the membranes, until finally a more full tremulation is able to pass over them.

Swooning is also of a similar nature: through a sudden alteration the nervous fluid or the blood rushes out of the membranes or else becomes obstructed in one place or another so as to be prevented from flowing forth to its expanses, networks, and membranous plexuses; the latter, therefore, collapse at once and become unable to receive any further tremulations, and the subject remains as it were half dead, until the blood can again flow into the membranes and expand them as before, when the life finally regains its termination and the tremulation its life.

In paralysis or other convulsions it is known that something has closed the road to the membranes or nerves through which the fluid must pass, and consequently has obstructed the motion which ought to glide over these as the proper bridges for communication in the body. Such strokes and obstructions show conclusively that there is a real circulation of the lymph, for if the fluid is obstructed in the nerves, then their membranes no longer receive any of that Iymph which must flow out to the extremities of the nerves, but they lose their tension, and the tremulation comes to a stop at the very beginning of its course without producing any sensation in the entire half of the body.

In the case of those who have died of apoplexy, or have lost the real acumen of their senses through a wild or extraordinary tremulation in the bones and the cranium, it has been observed, when the skulls of such persons have been opened, that the dura mater has been bloodless and slack, sometimes twisted into folds and wrinkles, and sometimes with the Iymph exhausted between the dura and the pia mater; the cortical and medullary parts have then been found soft and watery, the glands and the pituitary body distended, the ventricles filled with viscosity, the medulla spinalis quite rheumy and as it were inundated by stagnant water; many such cases will be found described by those who have investigated and made notes of such things. All this gazes to show that tremulation is a fac-totum as to everything living in our body, for as soon as the little membranes are no longer in a state of tensional but folded and slack, we lose all that is initiative, that is, we lose our senses, our thought, and everything else that makes us truly living. On the other hands it is wonderful to observe how everything gains a new life, each sense a new presence, and each different sensation a new alertness, as soon as a new circulation takes place, by which the fluids may again flow forth to their extremities to expand each minute vessel and hence the whole expanse or membrane which is woven together of such vessels.

In a state/psycho-somatic condition of courage, for instance, the blood flows forth into all its arterial vessels until it reaches the veins; it is then impelled into the very cuticles, and spreads a blood-red or crimson color over all the tunics; the two matres, also have now become full of fluid and thus expanded, so that the tremulation is able freely to play over them in swift motions; all the senses possess their proper life, and everything has its proper termination, comprehension, and presence.

If by any other passion, such as that of Amor and Venus , the blood has been driven into the extremes of the rnembralles, it will again be observed that all the little membranes have become expanded for tremulation to put vigorous life into all the sensations. A Condition of anger causes too hasty a circulation of the blood, fills up the little vessels too abundantly, and distends the canaliculi too greatly. The same is the case in a state of heat/over-heating, as in a sickness or fever: the smallest vessels swell up into bladders, as it were, driving the internal fire into the very cuticles.

Thus also in drunkenness, when a person has too freely imbibed such fluids as make the blood volatile: the blood then presses forward so as to expand and swell the sanguineous vessels too strongly; each sense then reaches the highest degree of its life; the tremulation becomes uncontrollable, making wild and disorderly movements in place of the ordinary and even ones. If the quality of the membranes be then examined, it will be noticed that they are gradually losing their evenness or smoothness, the sanguineous ducts make tumors here and there, and cover the membranes with waves, as it were, whence the tremulation receives a different quality, and the arteries undulate from the excited blood within. A tremulation may then, indeed, pass over the cuticle and its nervous system, but, since the arteries are thus distended, a softness will be in the road here and there, preventing the proper play of the tremulation, and obstructing the lymphatic ducts through which the tremulation should be Communicated in the first instance; the motion is thus turned into a different kind of tremor, which does not correspond with the usual one; it communicates a dull and stupid tremulation in place of the proper one, and causes what is known as madness.

3.* What great changes do not instantly result from any accidental in jury to the dura mater! Convulsions, swooning, and general collapse follow quickly, and apoplexy often leads to death; in a word, it is the shortest road to the stoppage of our whole moving life. If the medulla spinalis or the cerebellum is pierced by the smallest point of a needle, we know that death follows immediately, sometimes by a lymph being emptied out of its vessels between the membranes or the skin, whence the matres at once become wrinkled and laid into softer folds, to the hindrance of the tremulation which should pass over them. All this shows that our proper life resides especially in the membranes, and accommodates itself to their state of tension or slackness; the tremulation, therefore, accommodates itself similarly, carrying the life into whatever degree that is permitted by the tension of the membranes.

While studying the nature of the membranes and their expansion, it seems difficult to form any other theory than the one here indicated. Now if our life and nature were to consist of something else but those subtle motions which are called tremulations, what then is to be thought of those cases in which men have lost a part of the cortical substance of the brain, and yet have remained in possession of their senses? Cases have been known in which parts of the cranium have been removed by trepanning, when it has been found that the cortical substance has been evacuated by handfuls; other cases are recorded, in which both the medullary and the cortical parts have turned into a purely watery liquid, in which all the formerly distinct parts have been swallowed up, so that no proper glands, protuberances, or ventricles remain, but the whole has become like a slough of water; and yet, not with-standing all this, the senses have remained in their natural condition. We are therefore forced to conclude that life resides in the ultimates and thus in the meninges, and that it will remain there, let the internal parts be as they may, provided they are still able to furnish some kind of an even and proper fluid for the nerves, whereby the membranes may be kept in some state of tension.

Our theory may be seen illustrated still further in those cases where the whole brain has been ossified or petrified. There are on record at least two such cases, one of which may be seen in Professor Dr. Bromell's *beautiful collection. In such cases, it would seem, the fluid must be distilled immediately from the matres, dripping by little pores or canaliculi through the inner, petrified part, as in the case of other bones. It cannot, therefore, be denied but that the surrounding membranes really effect that which is usually ascribed to the inner part, that is, a motion, which is communicated to the whole system of nerves and bones, and consequently to the whole body, for the effectuation of all our sensations.

If a subject of the vegetable kingdom may be compared with an animated thing, it will be seen that nature has a similar character in both kingdoms, that is, that the living and growing force depends upon the coats and the bark through which it is flowing. Take, for instance, a tree, the trunk of which lies broken on the ground: as long as the bark still joins the two parts of the trunk, the leaves and the fruit will still continue to live on the tree; but if merely a strip of the bark be peeled off round about the trunk, all the verdure and growth will vanish and the whole tree will die. From this comparison, therefore, it is evident that it is the pleasure of nature to place what is chief and most noble in what is nest ultimate, and that all life must depend on this ultimate.

Now it may, indeed, be objected, that the dura mater is often injured in cases of trepanning or through other causes, when yet the senses are improved and retrain their proper order; still, when this happens, it will be found that the injury has been received in places which are not especially connected with the general tremulation, for if the membrane over some particular nerve be injured, the collapse does not extend itself further than to the extremity of that nerve. Similarly, if an incision be made in the meninx opposite a suture, the proper tremulation is not thereby altogether lost, although it is made somewhat slower; but if injury be done to such a part of the dura mater as may be supposed to be the very bridge or focus of the tremulations, either on the cerebellum or on the medulla spinalis, then there will at once result a shivering or twitching over the whole expanse, or the vessels will be emptied of the lymph, so that the tremulation can no longer pass over its usual bridge except as over a slack string.

4. As has been said, the tremulation requires a tension for its swift and proper communication to the cranium and the other bones, in order to be felt in the organs of sense. This may be illustrated by the quality of a musical chord, which, if slack, will merely undulate slowly without producing any sound, but, if drawn tight, will gradually give a sound which becomes clearer and sharper in the degree that the chord is drawn toward the bridge. It is the same with a drum: if the membranes are slack, the tremulations hardly reach the hundredth part of their proper distance, but if drawn tight, the swiftness of the tremulation and consequently the strength of the sound are increased so as to reach great distances.

Looking further into the cause of this, we will find it illustrated by the pendulum: the longer the pendulum the longer time does it require for each vibration, but the shorter it is, the swifter the vibration within the same measure of time. Instead of a pendulum take a rope, or line, which naturally hangs in a curve;

if now the line a o b is swung to and fro, the times required by the vibrations of the point o will be equal to the times required by a pendulum of the length of o k. If the line is drawn tighter, the cross-line k o will at once become shorter, like a shorter pendulum, resulting in a swifter vibration at o, and the tighter the line is drawn, or the more nearly into a straight line, the swifter are the vibrations. The idea of the geometricians is, therefore, that the times are as the radii and the length as the squares, which is called a duplicate ratio.* If, then, a musical chord or string always hangs more or less in a curve, it is but natural that the more it is drawn tight, the more does it approach a straight line, that is, the shorter the pendulum k o, the swifter the vibration.

It is the same with a membrane: the more it is expanded or stretched, the more are all the parts of it expanded or drawn tight into straight lines or a straight surface, and the more swiftly can the tremulation pass over this surface; thus also with a string, to which a ball is suspended and swinging, if we take hold further down the string, the vibration will at once hurry on faster; a musical chord, when gradually drawn tight, will at first give a coarse sound, then a finer and finer as it is drawn tighter and tighter. A tremulation in the body possesses exactly the same property, requiring more or less of tension if it is to express properly any sound or sensation.

5. There exist with men many different kinds of genius or temperament, which arise simply from a difference in the nature of the expansion of their membranes. Those are said to be of a sanguine temperament, with whom the blood is thin and volatile, so that it flows like an ether into the least vessels and inflates them in an instant; these persons above all others possess membranes that are filled with blood and are stiff f or the reception of tremulatory motions; all things with them are movable in the first instant and ready for effectuation in the same moment; they are more inventive, more communicative than any other persons, and more inclined to anything that requires blood in the membranes.

Those are said to be of a melancholy temperament, with whom there is a thicker kind of blood which flows with greater difficulty into the most minute of the vessels and hence does not effect its circulation in as volatile a manner; their membranes are expanded only by the greater vessels, and the matres are somewhat slack and less even or smooth than with the former, so that everything with them is effected more slowly. Phlegmatic persons, also, have a slow life, because a lymph or serum seems to predominate in the membranes, the blood having less space or lodging, whence there is less heat in the body. [Certain words in the sentence next following are obliterated in the manuscript, making four lines unintelligible.]

. . . Now, as a mass of ramifications of the nerves weave themselves about the arteries and the veins, not on]y in the body itself, but also in the brain, composing what is called the nervous tunic, it follows that as soon as any passion has originated, the blood is more or less under the control of the nerves; by the contraction of the nerves the blood is closed off from its finer vessels, while by the expansion of the nerves the blood is permitted to flow freely or is propelled forward with increased pressure, so as to expand the membranes. From this cause comes that immutable law which is exhibited in the membranes. For if the blood is obstructed in the membranes, there results at once a different attuning of the whole nature of man.

*Dr. Magnus Bromell, professor of medicine at Upsala, afterwards President of the College of Medicine ill Stockholm, and Physician to the Royal family. t I73I. Tr.

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*We understand this to mean that the length of the pendulum is as the square of the time of vibration

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