Part 3

Not only the quality, but also the quantity of the fluids contained in the organic muscles, has an influence upon their contractility. 1st. The word plethora is certainly employed too loosely in medicine; but we cannot doubt that the state which it expresses sometimes exists; now the more blood there is in the heart, the more are its contractions accelerated. 2d. I have many times made transfusion in dogs, whether with a view to that alone, or in researches relative to respiration and circulation. Now I have always observed, that by not opening a vein, to empty the blood as fast as the external jugular receives it (for I always choose this vein for the experiment) by thus producing consequently an artificial plethora, I have, I say, always observed that the motion of the heart was accelerated. I have even seen the eye of a dog become bright and as it were inflamed; in others this phenomenon has not been observed. 3d. We know that in running, in which all the muscles by contracting press out from all sides the venous blood contained in their texture, this which enters the heart in abundance, makes it palpitate powerfully. 4th. There is not doubt but that the quantity of urine and excrements as much and more than their quality, is for the bladder and the rectum, a cause of involuntary contraction. 5th. We know the serious consequences that arise from giving emetics and cathartics in too large doses. 6th. A glass of tepid water often does not produce vomiting when a pint will bring it on powerfully, &c. &c.

_Artificial Stimuli._

The artificial stimuli are in general all the bodies in nature. Such is in fact the essence of organic contractility, that a muscle because it is in contact with a body to which it is not accustomed, instantly contracts. If the muscles are not irritated by the organs that surround them and with which they are in relation, it is because habit has blunted the sensation which arises from this relation. But when these organs change their modifications, when extracted from the body of the animal, they become cold, and are afterwards applied to the organic muscles laid bare, they will make them contract.

Caloric, by its absence which constitutes cold, as by its presence from which arises heat, can equally excite the muscles and in general all the organs. At the instant we open the thorax or the pericardium of a living animal, the heart is agitated with a suddenly increased force; it is because the air acts upon it, and it passes from the temperature of the body to another which is different. All the aeriform fluids, light, all fluids, &c. are stimuli of the muscles. If we see the heart emptied of blood, the stomach and intestines deprived of the substances that ordinarily enter them, contract with more or less force when they have been taken out of the body, it is because the surrounding medium, and the substances with which it is charged, contribute to produce this effect; they are then the stimuli of these organs.

In general the artificial stimuli act in different ways; 1st, by their simple contact; 2d, by tearing or cutting mechanically the fibres; 3d, by tending to combine with them; 4th, there are some of whose mode of action we are completely ignorant; such for example is electricity.

When the stimuli act only by simple contact, the fluids are, all things being equal, more efficacious than the solids, because they stimulate by a greater number of points; as they irritate not only the surfaces of the organ, but penetrate also into the interstices of the fibres. The solids produce an effect in proportion to the extent of their excitement, to the greater or less pressure that they exert, to their density, their softness, &c. They are almost always fluid substances that nature employs for stimuli in the ordinary state.

Tearing is a mode of excitement more active than contact. The heart, the intestines often inert when they are only touched by the scalpel, contract powerfully when the point of it excites them. Cutting produces a less sensible effect than tearing. Cut transversely, the fibres oscillate and are agitated only by the sensible organic contractility, whilst by the contractility of texture they experience an evident retraction.

Chemical excitement is, in the greatest number of cases, the most advantageous; but it is necessary here to distinguish that which belongs to the horny hardening, from that which is the effect of irritability brought into action. 1st. Plunge a frog without skin and alive into a concentrated acid; instantly every thing is disorganized; the reagent acts so strongly, that we can distinguish neither horny hardening nor contractility. 2d. Weaken the acid a little and plunge into it, the inferior extremities only of a frog; in an instant they stiffen by the contraction of the extensors, which overcome the flexors; for in this experiment, this is almost a constant phenomenon; withdraw the animal; its thighs remain immoveable, life has been extinguished in them; the contraction that has come on is a horny hardening, and not a vital phenomenon. A dead frog plunged into the same liquor experiences the same phenomenon. 3d. Weaken the acid still more; the instant the animal is plunged into it its limbs contract; but relaxation succeeds the contractions; these are alternate motions; it is the irritability that begins to be put into action. Yet if the acid is not very weak, some marks of the horny hardening still remain, and the animal has a stiffness in the motions of the inferior extremities, the evident result of the first degree of this horny hardening. 4th. Finally, if the acid is very weak, it becomes a simple irritant which puts in action the sensible organic contractility, without altering the texture of the fibres; the animal after coming out of the fluid preserves the same power of motion.

These experiments which it would be easy to multiply upon animals with warm blood, but which I have never attempted upon them, evidently show what belongs to the horny hardening, and what is the effect of vital contraction. Yet there is not an exact limit between them, and there is one degree of weakness of the acid in which these two causes of motions are confounded.

There is a mode of excitement to which authors have not paid attention; it may be called negative; it is that of which I spoke just now on the subject of caloric, the privation of which is oftentimes a very active stimulant. In the different experiments that I have had occasion to make, this has frequently struck me. Apply a stimulant to a muscle, it contracts; but at the end of some time the motion ceases, though the contact continues; remove the stimulant, the motion frequently returns in an instant. In general, nothing is more common in the heart, the intestines, &c. than their contractions ceasing under the continued action of a stimulant, and returning instantly upon its absence. I confess that this phenomenon is not as invariable and constant as that of the contraction produced by the application of the stimulus which succeeds a state of non-excitement; but this happens very often. We might say that the organic sensibility is in this case like the animal, that every new state affects it, whether it be positive or negative. The passage from non-excitement to excitement is more lively; but the opposite passage is not less when it is sudden. Moreover this manner of describing the sensible organic contractility in exercise, deserves some further experiments.

_Of the Sensible Organic Contractility considered in relation to the Organs._

The sensible organic contractility, considered in the organ in which it has its seat, exhibits numerous varieties which are relative; 1st, to the diversity of texture; 2d, to age; 3d, to sex; 4th, to temperament, &c.

_First Variety. Diversity of the Muscular Texture._

The animal contractility is everywhere the same in the voluntary muscles, because their organization is uniform. All things being equal as to the number and length of the fibres, the phenomena of contraction are exactly the same everywhere; here, on the contrary, the varieties of texture inevitably produce varieties in the vital properties.

Each involuntary muscle is at first especially in relation with the fluid which ordinarily acts as its stimulus. The blood alone can regularly support the motions of the heart. Let this fluid be altered in any manner, the contractions become irregular. All foreign substances forced into the veins produce this phenomenon. The urine, which supports with harmony the motions of the bladder, would disturb those of the heart, if it circulated in its cavities. The blood, more soft in appearance than the urine, can agitate convulsively the bladder, if it happens to be in it. I took care with Desault of a patient affected for a long time with retention of urine, and whom he had cut for a very large stone. After the operation, the urine remained stagnant in the bladder as long as it was alone, but when a little blood entered this organ, it contracted involuntarily and the bloody urine was evacuated. The excrements, which could continue for a long time in the rectum without making it contract, would make the stomach heave in an instant, &c. All these phenomena are to be referred to varieties of sensibility of the mucous membranes, varieties which we shall notice again. They prove evidently that each muscle has a degree of organic contractility which is peculiar to it, and that this or that fluid of the economy can exclusively, in a natural state, put it in exercise in a regular manner.

Foreign fluids exhibit the same result; the emetic which makes the stomach contract, is injected with impunity into the bladder; purgatives do not produce vomiting, &c. This relation of foreign fluids with the sensible organic contractility takes place, whether, as in the preceding case, these fluids are applied to the mucous surfaces corresponding to the muscles, or whether they come to the muscles by the circulation, as the experiments have proved which were made in the last age upon the introduction of medicinal substances into the veins; experiments of which Haller has collected a great number of results. We have seen in these experiments, the circulation present to all the organs sometimes an emetic, and the stomach alone contracts; sometimes a purgative, and the intestines only enter into action, &c. Taken in by cutaneous absorption, medicinal substances occasion the same phenomenon. Applied by friction, purgatives, emetics, &c. do not make all the organic muscles contract, though the circulation presents them to all, but only those with which their sensibility is in relation.

In the various affections of which they are the seat, we see the organic muscles having each a peculiar mode of irritation answer to each stimulus, and remaining deaf, if we may so say, to the voice of the others.

_Second Variety. Age._

Age modifies wonderfully the sensible organic contractility. In infancy it is very evident; the muscles answer with extreme ease to the stimuli; the bladder retains the urine with difficulty; children void it in sleep involuntarily; the heart contracts with a rapidity of which the pulse is the measure; all the digestive phenomena are more prompt; hence there is less interval between the returns of hunger. It is a phenomenon analogous to that of the voluntary muscles, in which the rapidity of the motions is found, in the first age, connected with their small degree of force.

After infancy, the susceptibility of the muscles to answer to their stimuli, is constantly diminishing; thus all the great phenomena of organic life are continually becoming slower. The number of pulsations, the duration of digestion, the longer continuance of the urine, &c. are the thermometer of this slowness.

In old age the whole is weakened; the action of the organic muscles gradually diminishes. Those of the bladder and rectum are the most exposed to lose their contractile faculty; hence the retention of urine, which is a frequent companion of old age; hence also the accumulation of fecal matters above the anus, a disease almost as common as the first at this age of life, though it has received less attention from practitioners. Rich people and those accustomed to the luxury of the table are especially subject to it. I have seen much of it, as much even as of retention of urine, in the last year of the practice of Desault. The intestines and the stomach languish more slowly in their functions. It is the heart which resists the most; it is the ultimum moriens, as it has been the first in exercise; the duration of its pulsations measures exactly the duration of organic life.

_Third Variety. Temperament._

Temperament modifies in a remarkable manner organic contractility. We know that in some the pulsations are more frequent, the digestive and urinary phenomena more rapid; that in others, every thing is marked by more slowness in organic life; now these varieties have evidently their primitive source in the varieties of the contractility of the heart, the stomach, the intestines, &c. which have under this relation a great influence in the difference of the temperaments. With respect to this there are two essential observations to be made; 1st. The varieties of force of the organic muscles do not always coincide with those of the muscles of animal life. Thus we see an individual with feebly developed exterior forms, with an evident weakness of the muscles of the extremities, whilst the activity of digestion, of the urinary evacuations, &c. announces the greatest energy in the sensible organic contractility. I would remark with regard to this, that the heart is more frequently in relation of force with the external muscles than the stomach, the intestines and the bladder. A full pulse, well developed, is usually found with an athletic constitution; whilst often this constitution is united in the same subject to a feeble gastric system, and especially the force of this gastric system is frequently connected with external weakness. This fact, which the different temperaments demonstrate to us in man, is evident in the series of animals. Those who, like the carnivorous ones, have a very powerful animal muscular system, have the parietes of the gastric cavities like membranes. These parietes are strong in the herbivorous classes; they become very conspicuous in the gallinaceous. In general, mastication over which the animal contractility always presides, is in animals in an inverse ratio of the force of trituration of the stomach, over which the sensible organic contractility presides.

2d. The varieties of this property, relative to temperaments, exhibit another phenomenon almost always foreign to the animal muscular system. In fact in this the varieties are always general; we are able by exercise to strengthen this or that muscular region; but the differences of forces which are natural, always influence the whole system. The arms and the legs, the thorax and the abdomen are uniformly contractile in the different divisions of the muscles that belong to them. On the contrary, it is rare to see this uniformity in the involuntary muscles. One almost always predominates over the others; sometimes it is the heart, sometimes the stomach and sometimes the bladder. The gastric viscera even are frequently not all at the same level as to force. The stomach is feeble when the intestines preserve their ordinary action; and reciprocally the intestines too contractile expel immediately fecal matters and thus produce a diarrhœa, though the stomach may perform its functions well. This essential difference in the two muscular systems arises from the circumstance that the contractility of one depends upon a common centre, the brain; whilst that of the other on the contrary has its principle insulated in each organ in which it exists.

_Fourth Variety. Sex._

Women in general resemble children in the phenomena of sensible organic contractility. The weakness of the motions coincides with their greater rapidity in this sex, all whose internal muscles, like the external, are more delicate and less strongly developed than in man. It might be said that the contractile power of the womb has been formed at the expense of the forces of all the other organs. In experiments, females give results much less decided and always less durable than males. The motions of the heart, the stomach, the intestines, &c. cease sooner; these motions are less; it requires stronger stimuli to produce them, &c.

_Fifth Variety. Season and Climate._

In winter and in cold climates, in which the cutaneous organ contracted, and having as it were the horny hardness from the impression of the surrounding air, has but a feeble action, all the internal functions more active, require more energy in the forces that preside over them; all the digestive, urinary and circulatory phenomena are more evident. I do not know that there has yet been made any comparative experiments upon irritability in the different seasons; but I am persuaded that they would give different results.

_Sensible Organic Contractility considered in relation to the Action of Stimuli upon the Organs._

We have just described separately the stimulant and the organ stimulated; each being separate there is no effect upon the sensible organic contractility; from their union alone results the exercise of this property. What happens in this union? We know not. To wish to know it, would be to wish to know how one body attracts another, how an acid combines with an alkali, &c. In attraction, affinity and irritability, we can only trace the phenomena to the action of bodies upon each other. This action is the utmost limit of our researches.

But that which ought not to escape us here is, that in this last property, the action is never immediate. There is always between the stimulus and the organ something intermediate which receives the irritation; this intermediate organ is a delicate membrane and continuous with that of the arteries for the heart; it is a mucous surface for the gastric viscera and the bladder. This intermediate organ is more susceptible of receiving excitement than the muscle itself. I have uniformly observed that by irritating the internal surface of the heart, its contractions are greater, than by laying its texture bare externally by removing its serous covering and afterwards stimulating it. The same is true with regard to the organic muscles of the abdomen.

Is there between the intermediate organ excited and the organ which contracts, any nervous communications that transmit the impression? I think not, the cellular texture is sufficient. In fact the serous surfaces and the organic muscles have only this texture as a means of union. The life of the first is in no way connected with that of the others, since they often leave them as we shall see, and yet they can transmit excitement to them. The pericardium and the peritoneum, irritated in their portion corresponding with the organ that we wish to move, produce a contraction in it. This fact is known to all those who have made the least experiment; it is almost always in this way that we stimulate the heart, the stomach, the intestines, the bladder, &c. By carrying the stimulus over the serous surface but very lightly, and so as not to communicate the motion to the fleshy fibres, we obtain a result. Yet simple contact is not sufficient to transmit the irritation; for example, by leaving the external layer of the pericardium applied to the heart and afterwards irritating it, the organ remains immoveable. If we separate the peritoneum from above the bladder, so as to break all the cellular adhesions, and afterwards reapply and stimulate it, the same immobility is observed.

When the intermediate organ that receives the excitement is diseased, the contractility is uniformly altered. The same stimulus produces slow or rapid contractions, according as the affection raises or diminishes the sensibility of this intermediate organ. A slight inflammation of the exterior of the bladder produces a kind of incontinence of urine; that of the intestines occasions diarrhœa, &c. &c. On the contrary, old catarrhs of the bladder, the affections in which weakness of the mucous surface of this organ predominates, are the frequent causes of retention.

I would observe that the existence of this intermediate organ is a remarkable difference between the sensible organic contractility and the insensible, for this organ does not exist in this last, in which the same system receives the impression and reacts upon the body that has produced it; for example, in the glandular, serous, cutaneous systems, &c. the fluid which enters them for secretion or exhalation produces in them the sensation, which is instantly followed by the reaction. In the sensible contractility on the contrary, one system feels and another is moved. This kind of mobility is less removed from that of animal life, in which the organs of the senses and those of the motion being wholly different, are very distant from each other.

_Sensible Organic Contractility considered in relation to its duration after Death._

This duration is longer than that of the animal contractility. When the spinal marrow is irritated, the external muscles remain immoveable, whilst the internal ones are still in activity. There have been so many examples related of this duration, Haller has multiplied experiments so much upon this point, that there is no occasion for me to give proofs here of a fact of which no one can any longer doubt. To this duration are owing the evacuations of fecal matter and urine which often take place an instant after death; the vomitings that are observed in some subjects, if not in as evident a manner as during life, at least sufficient to raise the aliments into the mouth of the dead body, which is often completely filled with them, as I have frequently seen.

It is necessary, in relation to this duration, as in relation to that of the animal contractility, to distinguish two species of death; 1st, those that take place suddenly; 2d, those which are the consequence of long disease.

In every sudden death, produced either by a violent lesion of the brain, as in apoplexy, concussion, compression, effusion, &c. or by an affection of the heart, as in syncope, a wound, or a ruptured aneurism; or by a cessation of the action of the lungs, as in asphyxia from deleterious gases, a vacuum, submersion, &c. the duration of contractility is very evident; general death comes on first, then the organs die partially; each vital force is afterwards successively extinguished.

In every kind of death slowly produced, in all those especially which are preceded by a disease of weakness, it is the partial death of each organ that first takes place; each vital force is weakened and extinguished, gradually, before the cessation of them as a whole, which constitutes general death, comes on; when this death takes place, none of the lives peculiar to each organ remains, whilst most of these lives continue for a longer or shorter time after sudden death.