Part 30

I. Texture peculiar to the Cartilaginous System.

The peculiar cartilaginous texture exhibits an interlacing of fibres so compact, that it appears at first view homogeneous, formed into a mass of gelatine, without order and without any particular direction. Yet with a little attention we distinguish longitudinal fibres, which are crossed by transverse and oblique ones.

These fibres are more apparent in the cartilages of the moveable osseous extremities than in the others. They have infinitely less suppleness than the fibres of the fibro-cartilaginous substances; thus these bend without breaking, whilst the first break when they are bent considerably; the place of the rupture is smooth, with but few inequalities.

The cartilaginous texture is remarkable for many characters which distinguish it from the others. Next to the osseous texture, no one so long resists putrefaction and maceration. In the midst of a dead body wholly putrid, we find this texture almost untouched, preserving its appearance, its structure, and even oftentimes its natural whiteness. The same thing is frequently seen in gangrenous limbs in the living body. I have kept cartilaginous substances a very long time in water, which have not become altered, except a little in their colour. It would require more than a year perhaps, to reduce them to that soft, mucous, liquid pulp, to which maceration reduces most of the organs.

The cartilaginous texture contracts under the very powerful action of caloric, like all the other textures; yet this phenomenon is not apparent in the thyroid cartilage on account of its thickness, nor in the cartilages that encrust the bones, on account of their adhesion to these bones. But if we cut one in fine layers, and the others in slices, and plunge them into boiling water, they crisp up immediately and with force.

Exposed to drying, the cartilaginous texture becomes yellow, acquires a semi-transparency analogous to that of the tendons and dried ligaments; it becomes hard, contracts, diminishes in size, and loses its elasticity as it becomes hard.

Ebullition also gives it at first a yellow colour, then it cracks it upon the articular extremities, breaks it in different places, and raises it by layers which it softens, and which finally it melts almost completely to a small residue, which does not appear to be gelatinous. The softening of the cartilaginous texture renders it much more fit to be dissolved by the digestive juices than it naturally is. Swallowed raw, the cartilages would remain a long time in the stomach, whilst they are very easily digested when cooked; this is one of the very great advantages of the boiling of meat. In different experiments made upon digestion, I have found portions of cartilages still untouched in the stomach of dogs, whilst the flesh was already reduced to a pulp.

In certain cases, the cartilaginous texture is singularly altered. In the diseases of the articulation of the hip, it assumes an aspect wholly different; it is a soft substance, like lard, with very distinct vessels, sometimes with very evident fibres, having a size double, quadruple what is natural, and filling the cotyloid cavity. I have observed that then they do not become yellow, do not melt by ebullition and consequently are not gelatinous. In the same diseases, I have found the cartilaginous texture, upon the femur and the ilium, not only ossified, but changed into a substance exactly like ivory; I have preserved these two pieces.

When the cartilages become osseous, there is developed in their middle a texture analogous to that of the texture of the cells of the bones, in which the interlaced fibres leave between them very distinct spaces, and in which is deposited a kind of medullary fluid. This observation is especially applicable to those of the cavities, of the larynx, of the thorax, &c.

II. Parts common to the Organization of the Cartilaginous System.

There is cellular texture in the cartilages, though the want of interstices between their fibres, renders it very difficult to distinguish it in a natural state; in fact the development of fleshy granulations in wounds in which they are concerned, ebullition which, after having removed the gelatine, leaves a membranous and cellular residue, prove abundantly the existence of this texture, which we see besides in a very evident manner in some morbid states, in which the gelatine less copiously deposited in the cartilages, ceases to give them their usual hardness and leaves there a soft texture, often like sponge.

We do not discover any blood vessels in the cartilages. The exhalant system circulates only white fluids in them; but as this system is continuous with the arteries of the neighbouring parts, when the organic sensibility is raised in it by morbid irritations, and it thus becomes in relation with the red globules of the blood, these globules easily pass into it, and hence the redness the cartilages then have, as we see in their inflammation, in wounds of them, &c. It is this same phenomenon that we observe upon an inflamed conjunctiva, &c. When the irritating cause has ceased, the sensibility resumes its natural type, the red globules then become heterogeneous to the cartilage, which again becomes white.

We are ignorant of the nature of the white fluids which usually circulate in the vascular system of the cartilages. These fluids very easily become the vehicle of the bile, or at least of its colouring matter, which is spread through the animal economy in jaundice. We observe almost uniformly, that in this disease the cartilages are of a yellow colour, like all the other parts; the colour is more evident on their surface than in their texture, though it exists there. By opening a moveable articulation, the bilious appearance is commonly found as great there as upon the skin. Besides, all the parts, which like them, receive but few or no red globules in the ordinary state, are also found very evidently coloured. The tendons, the conjunctiva, the internal membrane of the arteries, &c. are examples of this. I have remarked in two subjects whose thyroid cartilages were ossified in the middle, that the yellow colour was much brighter in the osseous than in the cartilaginous portion. I do not know that nerves have ever been traced in the cartilages.

ARTICLE THIRD.

PROPERTIES OF THE CARTILAGINOUS SYSTEM.

I. Physical Properties.

Elasticity is a property generally extended to all organic and inorganic bodies. Among the first, it appears, that vegetables are endowed with it in the greater number of their organs; that animals, almost all of whose parts are soft, have some which return to their original state after having been stretched or compressed. Among these, the cartilages hold one of the first ranks in man. Their elasticity is very great, especially in the adult age, when their consistence is between the softness, which characterizes them in childhood, and the hardness, which is their attendant in old age. These two last properties are in fact not favourable to the elastic power.

If we plunge a scalpel into a cartilage, the edges of the divided place re-act upon it and expel it. Pressed against a resisting body, the cartilaginous extremity of a long bone becomes flat and resumes its form when the compression ceases. The edges of the thyroid cartilage, when it is cut longitudinally in the operation of bronchotomy, immediately approximate each other. The division of the cricoid ring exhibits the same phenomenon. The cartilages of the last ribs, when forced in towards the abdomen, come out of themselves, &c. &c. All these phenomena are the evident result of an elastic power. Thus nature has placed the cartilages wherever, to produce her phenomena, there is a necessity of uniting a physical to the vital forces, as in the larynx, in the nasal septum, in order to produce a sort of vibration in the passage of the air, at the extremity of the ribs, in order to be the seat of a species of twisting necessary to the mechanical part of respiration, at the articular extremities, in order to diminish the force of blows, &c.

It appears that the vital activity renders this property greater, which however remains very apparent after death. I presume that this is owing to the great quantity of gelatine they contain. 1st. We know that this substance possesses it in a very high degree, as is proved by the tremulous motion of jelly after it has become cold, by the examination of various animal glues, &c. 2d. If by ebullition we remove this substance from the cartilages, the nutritive parenchyma remains flaccid and soft. 3d. As the gelatine diminishes in our organs, the elasticity in them is less, as we see by examining the decrease of this property from the cartilages in which it predominates, to the fibro-cartilaginous organs in which it is in a smaller proportion, and to the fibrous bodies in which it is still less. It must be confessed however that many very gelatinous bodies, exhibit but very slight traces of elasticity; the skin is an example of this, and so are the tendons. Can the same substance, as it is differently operated upon by the organic laws, become the seat of properties wholly dissimilar?

II. Properties of Texture.

The cartilages are perhaps of all the organs, those in which the extensibility and contractility of texture are the least developed. We see them rarely distended and elongated; they break first. Diseases do not exhibit in the larynx those dilations so common in the other cavities, even the osseous ones. When divided, the edges, far from separating as in the skin, in a muscle, &c. approximate each other, as we have seen, by the effect of elasticity; we might say that this last property was accumulated in the cartilages at the expense of those of texture.

III. Vital Properties.

The vital properties are also very obscure in them. There is no animal sensibility in the natural state; it is only when inflammation or some other cause raises their organic sensibility, a sensibility which their functions necessarily suppose, it is only then, I say, that the brain perceives painfully the different irritations of which these organs are the seat. This becomes manifest, especially when foreign bodies are formed in the articulations, which suffer from their presence or are insensible to them, according as they irritate or not by their position, the cartilaginous extremities. There is neither animal nor sensible organic contractility in the cartilages; the insensible organic or tone alone exists in them, and this not in a great degree.

The sympathies are obscure, almost wanting in the cartilaginous system. I do not know that in the acute affections of the different organs, we observe sympathetic phenomena of sensibility or contractility in them. They remain tranquil in the midst of the general derangement which affects the other systems in this sort of diseases. In chronic affections even, they experience but little alteration; examine, for example, comparatively, the body of a man that has died a violent death, which has left his organs untouched, and that of one who has died from phthisis, dropsy, cancer, &c. you will perceive between almost all their organs a striking difference; the aspect of the muscles, of the mucous and serous surfaces, of the vessels, the nerves, &c. is entirely changed by the slow alteration they have undergone in the second; in the midst of these alterations the cartilages are unchanged, their appearance is almost the same as in a natural state.

Character of the Vital Properties.

From what has been said, it is evident that the cartilaginous life can have but little activity, that all the morbid phenomena must be characterized in these organs by a peculiar slowness, and that inflammation, for example, must always have in the cartilages, as in the bones, a chronic progress; this is rendered very clear by the following experiment. Lay bare a cartilage, divide it, and afterwards bring it in contact with a portion of a muscle, the skin, &c. also divided at their surface; the reunion does not take place, or at least not until a very long time. Why? because the life of the muscle or the skin being much more active than that of the cartilages, the inflammation of the first organs will be much more rapid than that of the second, and consequently the first inflammatory period of one will correspond to the last of the others. Now the reunion is so much the easier as the inflammatory periods correspond the more exactly in the two divided parts that are in contact. Hence why two parts of the same organ unite much more easily than two surfaces belonging to different organs. Hence why the greater the analogy in the lives of the two organs, the greater the facility with which they unite; why the difficulties increase as the differences of life become greater. Two osseous surfaces in contact require thirty or forty days to unite; the two edges of a cutaneous wound unite in two or three days. If you attempt to render continuous two organs thus unlike in their mode of cicatrization, by putting them in contact, you will succeed but slowly. Cover with skin the osseous extremity of an amputated stump; this will be in a state of suppuration, before the bone has hardly begun to soften; thus good practitioners have abandoned these pretended unions by the first intention, so much boasted of, after amputation by the flap operation. These unions would no doubt take place, if the life of the organs which enter into the composition of the flap was the same. But with the diversity of these muscular, osseous, tendinous, cellular, nervous organs, &c. it requires a long time for all their lives to be placed as it were in equilibrium, and for these organs to agglutinate at their divided extremities. I have already observed that the division of inflammations into acute and chronic gives physicians an inexact idea; for the duration of the inflammatory phenomena in the organs is wholly relative to their degree of life. An inflammation of the cellular texture and of the skin is acute, when it lasts but a few days; it is chronic when it continues forty or fifty days; in a cartilage, this last period may be that of an acute inflammation, whilst a duration of many months is necessary to make it chronic, as the diseases of the joints exhibit frequent examples.

The natural functions, as well as the morbid affections, have this slowness of the vital phenomena of the cartilages. The constant composition and decomposition, which their nutrition supposes, is not rapid. It requires a long time for nutritive substances to combine with them. I am persuaded that in animals which die suddenly from the effects of a carbuncle and whose muscles, glands, membranes, &c. almost instantly penetrated with the deleterious principles by the nutritive motion of composition, present an aliment so injurious, I am persuaded, I say, that these injurious principles not yet having penetrated the cartilages, these might be digested without danger. It is to the slowness of the motion of decomposition that must be attributed the slowness of the resolution of cartilaginous swellings; for tumours are resolved by the same laws that decompose our organs, as they are formed by the same laws that preside over their composition.

The cartilages and the analogous organs, are to the other parts of the economy, as it respects their vitality, what the zoophytes and other animals with a capillary circulation only, are to the animals better organized, to those with a general circulation and those that have a heart with a double ventricle. As much as life considered in general in the series of beings that it animates, presents a difference in its activity, so much it differs in the same respect, examined in particular in the organs of each of these beings.