bony. They are more easily split transversely than in any other direction, their broken surface presents a fibrous appearance, but when placed under the microscope forthwith lose it, and exhibit none other than a regular pellucid substance with ovate corpuscles. These are ranged in the manner of clusters; their longitudinal diameter is situated transversely, as is very distinctly perceived in the thick cartilage covering the joint surface of the knee-cap. On the corpuscles being thus arranged depends the fibrous appearance." (p. 25.)

TODD and BOWMAN (a), however, consider there is a difference between temporary and articular cartilage. In the latter "the cells are oval or roundish, often disposed in small sets of two, three, or four, irregularly disseminated through a nearly homogeneous matrix which is more abundant than in the former." This, however, is in reality all the difference which even they point out, as although they say "in the inner part of the cartilages of incrustation (a term applied to articular cartilages by some anatomists) we usually find the cells assuming more or less of a linear direction and pointing towards the surface, which arrangement is probably connected with a corresponding peculiarity of texture of the intercellular substance, but which it is more difficult to distinguish; for these specimens have a disposition to fracture in a regular manner along planes vertical to the surface, and the broken surface is striated in the same direction." Yet had they previously stated, in reference to temporary cartilage, "When ossification begins, the cells which hitherto were scattered without definite arrangement become disposed in clusters or rows, (MIESCHER'S exact expression corpuscula racemorum in modum consita,) the ends of which are directed towards the ossifying part." (p. 90.)

The fibrous structure of articular cartilage as described by WILLIAM HUNTER is explained in the following way by HENLE (b):- "I have sometimes observed," says he, "the contour of the cavities projecting from one longitudinal row of cavities (in the cartilage) to the next, and it appeared as if a part of the cavity together with the enclosed cells were separated by a cleft. It is, however, possible that these are the hollow parts of one system of long canals which twisted, or perhaps also in rare cases divided angularly, penetrate the cartilage from its lower towards its upper surface, and remain in the cleft partially in the one and partly in the other segment. By this formation is satisfactorily explained why the articular cartilage presents a fibrous fractured surface, and seemed to the old observers to consist of fibres which ran perpendicularly through its thickness. Next the free surface they are more lamellar and can be separated into delicate plates (MECKAUER). The flattened cells of this layer have the closest resemblance with the epithelial cells of the synovial membrane and often subside imperceptibly into it; but usually a layer of connecting tissue forms the boundary between them." (p. 796.)

"Most cartilages," says HENLE, " are devoid of vessels. The joint-cartilages at their adhering surface are in contact with the very vascular bones, at their free surface they are overspread with synovial membrane; in the connecting tissue of which, however, in the newly born child, and sometimes even in the adult, vessels pass from the edge, and are rendered apparent by injection. Perhaps they originally cover the entire surface and subsequently are obliterated towards the edge from which they are reflected out of the synovial membrane upon the capsular ligament. But in the adult no branches either from the bone or from the synovial membrane penetrate into the cartilage." (pp. 802, 3.)

"The cartilaginous covering of joints is not at first separate from that part of the bone cartilage which will be ossified. During the period of ossification there is a considerable layer of vessels between the cartilage and the already perfectly ossified parts, and it is easy to separate the two parts" (as already stated by HUNTER.)" Both have irregular surfaces, elevations, and depressions, by which they hold together. In 'proportion as ossification extends towards the epiphysis, the vascular layer shrinks and the adhesion becomes more intimate. In newly-born children, however, pretty wide but only slightly branching canals with blood-vessels from without, and from the surface, covered with synovial membrane, penetrate the cartilage deep enough to reach the epiphysal cartilage. When the formation of cartilage is completed, the vessels retract from it, and in the adult its nutrition seems derived only from the vessels of the adjacent bone and perichondrium, perhaps in the joint cartilages also mediately from the synovia which comes from the vessels of the synovial membrane, and the so-called Haverschian glands. The taking up of the plasma thus follows by saturation and thereto seems the special use of the cavities of cartilage. *Macerated cartilage is often distinctly

*

(a) Physiological Anatomy and Physiology of Man, chap. iv. London, 1843. 8vo.

*

(b) Allgemeine Anatomie. Lehre von den Mischungs und Formbestandtheilen des menschlichen Körpers. Leipzig, 1841. 8vo.

reddened by imbibition of the red colour of the blood, and the reddening is greater, the more the cells proportionally exceed the basement; most distinctly therefore in fœtal cartilage. If the blood in the living body carry unnatural colouring substances, as for instance the bile pigment, it penetrates the cartilage, which, therefore, in jaundice, becomes yellow, as noticed by BICHAT." (pp. 808, 9.)

TOYNBEE (a) observes, in reference to articular cartilage :-" Although they are properly considered as non-vascular tissues, they appear to be pervaded by blood-vessels at an early period of their development, or, perhaps, it would be more correct to say, that as growth proceeds, the cartilage increases, so as to occupy the space that had previously been permeated by vessels. I have been able," he continues, "to demonstrate that vessels are never found within these cartilages when fully developed; but at that period vessels form convolutions in their immediate vicinity. These vessels are separated from articular cartilage, at adult age, by a layer of bone; and in fibro-cartilage, at the same period, they uniformly terminate within the boundary of its fibrous tissue. Over a certain portion of the free surface of both these tissues blood-vessels extend, but they do not penetrate into their substance. The investigations which are about to be detailed lead, I think, to the certain conclusion, that articular cartilage in the adult state is principally nourished by fluid derived from the vessels of the cancelli of the bone to which it is attached, which exudes through the coats of those vessels, and makes its way into the substance of the cartilage through the intermediate lamella of bone. The cartilage of fibro-cartilage is nourished, in like manner, by liquor sanguinis, derived from vessels situated in the contiguous fibrous portion. The vessels ramifying in a certain extent of the free synovial surface of both these species of cartilage, contribute, doubtless, to their nutrition, but not to near the same extent as do the vessels of the opposite side. With respect to the actual process of nutrition, I shall only observe here, that the cells of these structures must be regarded as having the function which has been ascribed to those of all non-vascular tissues, viz., that of promoting the circulation of and modifying the nutrient liquor. In connexion with this process, however, it will be seen that articular cartilage presents, in its adult state, very minute canals, which may be regarded as existing for the reception of the nutrient fluid, and for its circulation through the mass of cartilage; their presence is especially required in this particular form of cartilaginous structure, from the great degree of density which it possesses. * The

portion of bone upon which articular cartilage rests is, in some instances, formed by the ossification of a distinct cartilaginous epiphysis. In non-epiphysal bones, the extremity of the shaft of the bone performs the same functions with regard to the articular cartilage situated upon it as do the epiphyses in those bones which are provided with them. There is this difference in articular cartilage, with regard to its nutrition during and after its development, that in the former state there is no positive separation of it from the cartilage which is subsequently converted into bone, and in which its nourishing vessels are contained; whilst, in the latter state, these vessels are separated from it by an osseous lamella. The free surface of articular cartilage during, as well as after, its development, is covered by synovial membrane, to which it is attached by cellular membrane." (pp. 162, 3.)

TOYNBEE concludes, from examinations he has made, "that during the most early periods, the cartilage of the epiphysal extremities of bones does not contain any bloodvessels, and that, notwithstanding their absence, the cells of this cartilage are developed, and its growth carried on; and that, at the same time, the cells of the epiphysal and the articular cartilage are formed and developed without the presence of vessels;" and "that. at the more early period of foetal development, the synovial surface of cartilage does not contain blood-vessels." (pp. 164, 5.)

According to the same observer, in the second stage of development the epiphysal cartilage "presents, except at its articular surface, numerous depressions of various depths. The deepest may be regarded as canals, some of which are single, others bifid; they terminate in blind sacs. The direction of some of these canals is towards the centre of the epiphysis, of others towards its point of attachment to the osseous shaft, and of others towards the articular cartilage. Some of these canals are of a large size, and are frequently considerably dilated at their blind extremities. They do not penetrate into the substance of the articular cartilage; they are for the reception of branches of sanguiferous vessels. When the epiphysis is minutely injected, the depressions upon its surface will be found to contain congeries of convoluted vessels, which are more drawn out the deeper the depression, until at length, in the interior of the canals and their divisions, single and nearly straight vessels are found. These epiphysal vessels have a very peculiar disposition. They consist of an artery having a course more or less (a) Already cited.

VOL. I.

straight, which terminates in a dilatation, or in convoluted branches, from which the vein arises. From the fact of the presence of these vessels, which converge towards, and form convolutions internal to the articular cartilage, it may be inferred that they supply the cells of the latter with a nutrient fluid. As the articular cartilage increases in thickness, and the ossific nucleus which is developed in the epiphysal cartilage becomes larger, these vessels gradually recede from between them, and leave a considerable mass of non-vascular cartilage between the osseous nucleus and the synovial membrane; all of this appears to be articular cartilage, which is now nourished by the vessels in the interior of the nucleus. The supply of blood-vessels in the cancelli of the osseous nucleus is remarkably abundant; they are large, and are separated from the surrounding cartilage by an extremely delicate lamina of bone, which is principally made up of osseous cells. I am induced to believe that at this stage of development, as in adult age, the fluid passes from the bone into the cartilage and nourishes it. *** The articular cartilage, at this early period of life, is thicker than in the adult state. Although devoid of canals for the reception of blood-vessels, it presents numerous minute canals, which pervade that portion of it contiguous to the osseous nucleus, and they course from the latter towards the synovial membrane, which, however, they do not reach. They are minute, and extremely numerous; they divide, sub-divide, and communicate with each other, and form dilatations. The parietes of these canals present distinct rounded cells, which in some places are arranged in rows and groups. The substance between these tubes is transparent, and contains no corpuscles. The articular cartilage above described is gradually being converted into bone during the whole of life." (p. 165-7.)

on the

The nutrient vessels of articular cartilage during its development, which are situated betwixt it and its synovial membrane, "are contained and ramify in a considerable layer of cellular tissue," by which that membrane is attached to the articular cartilage, and from which TOYNBEE detached nearly the whole. His statement, however, that "these vessels have been alluded to by Dr. WILLIAM HUNTER under the name of circulus articuli vasculosus,'" is quite incorrect, as reference to the passage already quoted will prove; in which HUNTER says, they " plunge in by a great number of small holes, and disperse themselves into branches between the cartilage and the bone;" and not entire surface of the articular cartilage," as described by TOYNBEE. "It is difficult," says this latter writer, "to state generally at what period of fatal existence these vessels, which have been spoken of in the first stage as forming convolutions around the joints, are prolonged upon its (the articular cartilage's) surface." But, after having studied with care these stages, he states, that "at between the third and fourth month of fœtal life these vessels are simply a mass of delicate convolutions, situated between the synovial membrane; at the fifth month, these convolutions are somewhat unravelled, so as to extend over the surface of the cartilage to the distance of about half a line; and at between the seventh and eighth months, they are drawn out and prolonged to the distance of a line and a half. At this stage, these vessels consist of arteries of considerable size, which radiate in a straight course from the attachment of the ligamentum teres. They give off but few branches, and, previous to terminating, divide and sub-divide, but do not much diminish in size. They terminate by turning and forming loops with the small veins. Subsequent to the eighth month these vessels begin to recede in their course; and at birth, and the periods subsequent to it, they are again found to be gathered immediately around the point of attachment of the ligamentum teres. After these vessels have receded, the position they occupied at the more early periods may be for some time detected by the white aspect of the cellular tissue between the cartilage and the synovial membrane." In the knee-joint there is a little difference: "The arteries which have run straight towards the centre of circulation, give off small branches, forming a delicate net-work communicating with the small veins, and terminate either by turning in their course, and forming broad loops with the venous radicles, or empty themselves into a single vessel from which the veins arise." (p. 168.)

The canals in adult cartilage, already mentioned, TOYNBEE describes as “irregular in their distribution; some are merely dilated cavities; frequently several of these cavities are elongated and arranged serially, running from the attached towards the free surfaces of the cartilage. At the free or synovial surface these canals do not exist; the cells of the texture at this part being elongated and flattened, and having their long diameters parallel to the free surface. These canals contain a transparent fluid, which is seen to ooze from them after a section. It is most probable that the uninjected vessels mentioned by MECKEL, BICHAT, and others, were these canals and sinuses." (pp. 169-70.) The observations just alluded to are the following:-MECKEL (a) says, (a) Handbuch der Menschlichen Anatomie, vol. i. Halæ et Berol., 1815–20.

'Cartilages do not receive vessels carrying red blood, although in cutting them distinct vessels are frequently observed in their substance." BICHAT (a) observes that in cartilage "no blood-vessels are distinguishable. The exhalant system carries only white juices; but as this system is continued to the arteries of the neighbouring parts, so that the organic sensibility is there elevated by weak irritants, and so brought into relation with the red globules of the blood, that they pass readily, whence arises the redness which cartilage assumes, as seen in inflammation, wounds, &c. It is exactly the same as occurs in inflamed conjunctiva, &c. When the irritation ceases, the sensibility resumes its natural type, and the red globules at the same time become alien to the cartilage, which recovers its whiteness. We know not the nature of the white fluids ordinarily circulating in the vascular system of cartilage. They are very susceptible of becoming the vehicle of the bile, or, at least, of its colouring substance, when diffused throughout the animal economy in jaundice.” (p. 129-30.) MÜLLER (6) states, that “in tendons, ligaments, and cartilage, there are blood-vessels, but few in number." (p. 362.) In BRODIE's opinion the cartilages are vascular. He says:-" Up to the period of growth being concluded, we must suppose the articular cartilages to be vascular, otherwise we cannot account for the changes of bulk and figure which mark their progress towards complete development. In the child, canals or sinuses may be seen ramifying through their substance, containing blood, and manifestly intended to answer the purposes, though not constructed with the distinct tunics of ordinary blood-vessels. In the adult person these canals for the distribution of blood are not perceptible. This proves that they are very minute, but not that they are altogether wanting." (p. 111.) He also supports his opinion by the analogy of "the transparent cornea of the eye, in which no vascular structure can be detected under ordinary circumstances, but the existence of vessels in it is proved by the changes which it undergoes in disease; and when it is inflamed such vessels become distinctly visible, injected with red blood. So we meet with occasional though rare instances of vessels containing red blood extending from a diseased bone into the cartilage covering it." Also by the exposure of the joint cartilages to friction without being affected by it, which "cannot be explained unless we admit the cartilages to possess a power of reparation; and this must be supposed to depend, as in other textures, on the action of blood-vessels modified by that of the absorbents." And lastly, he brings forward the occasional conversion of an articular cartilage "into a number of ligamentous fibres, each of which is connected by one extremity to the bone, whilst the other is loose towards the cavity of the joint. Here is a morbid alteration of structure, the occurrence of which seems to indicate that there must be such a vascular apparatus entering into the formation of cartilage as enables new materials to be deposited and old materials to be absorbed, and without which morbid alterations of structure do not take place in other parts of the body." (p. 111-13.)

TOYNBEE, however, asserts, that "into the substance of healthy cartilage he has never been able to trace blood-vessels, and his researches induce him to believe that they do not possess any. (p. 170.) Of the same opinion, also, is BECLARD (c), who says:—“ These cartilages have no vessels; delicate injections and microscopic examinations exhibit the capillary vessels terminating at the circumference and adhering surface without ever penetrating their substance." (p. 466.) And CRUVELHIER (d) still more decidedly affirms, that "the diarthrodial cartilages do not present any trace of organization." (p. 162.) The importance of the subject will, I trust, be sufficient apology in regard to this long anatomical digression, in which it will be observed that WILLIAM HUNTER appears to have held generally very correct views on the structure of cartilage, excepting as to its fibrous character. The reader will also be struck with the near resemblance of the opinions held by TOYNBEE and HENLE. I have, indeed, mentioned those of the latter author first, as in the course of the narrative it was convenient so to do. But the statements of both were published in the same year, and it is scarcely possible that either could have had knowledge of the views of the other.-J. F. S.]

At first, the patient feels only little and passing pain, which is increased by the motions of the joint, but ceases when it is at rest. It gradually becomes continuous, and spreads from the joint over the bones. After several weeks or months, the swelling of the joint is affected with a slight external inflammation. This swelling is neither great nor fluctuating, and has pretty much the form of the joint. After a shorter or longer time,

(a) Anatomie Générale, vol. iii. Edit. 1812. (b) Handbuch der Physiologie, vol. i. Coblentz, 1834.

(c) Anatomie Générale.

(d) Observations sur les Cartilages Diarthrodiaux; in Archives Générales de Médecine, vol. iv.

suppuration in the joint occurs: it breaks, and hectic fever destroys the patient. Although the course of this disease is nearly always insidious in its beginning, peculiar conditions may increase the symptoms, and the disease assume an acute form.

MAYO (a) speaks of "three distinct forms of ulceration" of joint-cartilages, which, although they may be occasionally combined, are oftener met with separately. (p. 49.) First. Rapid absorption of cartilage beginning on its synovial aspect; the new surface, if cartilaginous, being smooth and unaltered in structure; if of bone, healthy; the absorption of cartilage being attended with inflammation of the capsular synovial membrane. (p. 50.) This form is "of rare occurrence. The absorption of cartilage takes place rapidly. It is attended with severe pain, with inflammation of the capsular synovial ligament, and generally with suppuration in the cellular tissue adjacent to the joint. The only favourable termination of the disease, that I have witnessed, is anchylosis. Second. Chronic ulceration of cartilage beginning on its synovial aspect, producing an irregularly excavated surface with fibrous or brush-like projections of the cartilage and synovial membrane, attended with inflammation of the capsular synovial membrane, and sometimes of the same membrane where it is reflected over the cartilage, the bone and the surface of cartilage towards it being healthy. (p. 53.) Third. Absorption of cartilage beginning on the surface towards the bone, attended with inflammation of the adjacent surface of the bone, with inflammation of the synovial membrane, and sometimes with sensible vascularity of the cartilage itself." (p. 59.)

[As to the inflammation of cartilage, if such there be, WILSON (b) observes, "the active powers of life are possessed by articular cartilages in a very limited degree, so much so, that the ocular demonstration is wanting of their being capable of inflammation. This affection is in other parts marked by a state of vessels easily distinguished by the eye and by the touch; but, as vessels are not to be seen or felt in these cartilages, we have not sufficiently decisive proofs of inflammation ever taking place in them. I have never seen in articular cartilages, which were completely formed, any vessels either filled with its own blood or having its cavity distended by injection." (pp. 327, 28.) JOHN HUNTER (c) takes no notice of this point at all; but, after speaking of the union of fractured cartilage by bone, proceeds:-"Sometimes the inflammation goes on to suppuration; but they (the cartilages) seem to have insufficient power to admit of ulceration, yet they may be absorbed by the absorbents of other parts, as in white swellings, when suppurated, the cartilaginous ends are removed by the absorbents on the surface of the ends of the bone that the cartilage covers. It may be ulcerated in this manner in other joints also: in the knee we find all the different stages of absorption of cartilage; granulations will shoot from under the cartilage, and sometimes, when there is not much matter in the joint, these granulations will inosculate and form a bony union. (p. 535.)

WILSON says that "the synovial membrane which lines the capsular ligament, and is reflected from it over part of the bone to the edge of the articular cartilage, will indeed sometimes pass a little way on the surface; it there becomes inseparably connected with the cartilage, and its appearance is then lost." But he continues:-" In a diseased state of joint, I certainly have seen the surfaces of the articular cartilages covered by a membrane, but this membrane I have no reason to believe to have been originally more than a coating of coagulable lymph; it is of different degrees of thickness, and at first easily peels from the surface it covers, but it soon becomes organized and very vascular. In a preparation, belonging to the Windmill-street museum, vessels seem to pass from this new formed membrane into little inequalities on the surface of the cartilage, and it is far from improbable but that absorbent vessels may be among these, and which are employed, along with the absorbents from the bone, in removing the articular cartilage. ** *I do not mean to deny the possibility of the removal being attempted partially by vessels belonging to their own substance, so as to produce some of the appearances called ulceration of cartilages; but we are deficient in proofs of this, and, from what I have observed of the state and appearance of diseased joints, I am induced to abide by the opinion entertained by JOHN HUNTER, that the removal of articular cartilages is generally effected by the vessels of the neighbouring more vascular parts, viz., of the bones and synovial ligaments, and occasionally by the vessels of coagulated and organized lymph." (pp. 328, 29.)

(a) On Ulceration of the Cartilages of Joints; in Med.-Chir. Trans., vol. xix.

(b) Lectures on the Structure and Physiology of

the parts composing the Skeleton, and on the Diseases of the Bones and Joints, &c. Lond., 1820. 8vo. (c) Lectures; PALMER'S Edition.