practice, it was not thought safe to allow persons to inhale it in whom there was reason to believe there was any disease of the heart or lungs, or who had any tendency to an affection of the brain and nervous system. But for some years past I have been in the habit of administering it to individuals of this description, and have as yet had no cause to regret it. In such cases I have thought it prudent to have the vapour of the ether inhaled more slowly, so that it may be more diluted with atmospheric air than under ordinary circumstances; of course, the patient could not be brought as soon under its influence as when taken in the ordinary way.

The state of the system which is produced by the inhalation of ether is that of narcotism, similar precisely to what is induced by drinking immoderately wine or other alcoholic liquors. It is a state of intoxication more transient and less dangerous than that from alcohol. Its effects pass off sooner, because the vapour of the ether begins to escape from the lungs as soon as the patient ceases to inhale it; while alcohol taken into the stomach is carried into the circulation, and mixes with the blood, and in this way acts longer, if not more powerfully on the brain, though its narcotic effect is not so soon produced. It is possible that life might be destroyed by the inhalation of ether, if it be continued uninterruptedly for a great length of time and a great quantity inhaled. Fatal congestion of the brain might thus be produced, as sometimes happens when alcoholic liquor has been taken to excess. But no person of ordinary prudence would administer it in this way. Long before the occurrence of such a result, symptoms of an unequivocal character would indicate the approaching danger.

When death follows the inhalation of chloroform, on the other hand, there is no merciful premonition. The late Dr. Snow, whose experience on the subject was perhaps greater than that of any other person, thought that "sudden palsy of the heart is the cause of sudden death from chloroform." In death by asphyxia, the heart beats for some minutes after breathing has ceased; "whereas in some cases of death by chloroform, the breathing has been proved to go on up to the time the pulse stopped, and after it."

With the hope that those who may have occasion to employ any anaesthetic agent will at least make a fair trial of rectified sulphuric ether, I respectfully submit these remarks to my professional brethren.

ART. III.

Nutrition, Inflammation, and Ulceration of Articular Cartilage. By RD. BARWELL F.R.C.S., Assistant-Surgeon, Charing Cross Hospital.

Ir a careful physiologist and pathologist, who does not assume too much as granted,. and who examines each difficulty before galloping over it, will study minutely the present doctrine of the nutrition of articular cartilage, as it may be gathered from all writers on the subject, he will feel persuaded, at the end of his labour, that there is a deficiency somewhere in the chain of reasoning, and elsewhere something unnecessarily assumed. In fact, he will encounter many propositions which are not proven; some of which he cannot receive; and he will find his belief barred in several directions.

The first difficulty he will meet with is this, that almost all observers have assigned: as a source of nutriment for articular cartilage the vessels of the synovial membrane and its secretion; but if he examine a fine vertical section of any articular cartilage in any animal, he will find those cartilage-corpuscles which lie near the attached surface well developed, and containing each from two to six nucleated cells, and near this surface not only do the cells in each corpuscle, but also the corpuscles themselves, tend to arrange themselves perpendicularly to the surface; and when a corpuscle divides, as takes place by generation of cells within it, it does so in the same direction. As the object is passed under the glass towards the free surface, he will be struck by a change in this. respect; the cells no longer remain in the capsule so constantly perpendicular to one

another, and as they divide, they do so as frequently horizontally as in any other direction; at last the divisions and the groupings all tend strongly to the horizontal; the cells themselves are flattened in the same direction, till at last they become mere scales, three or four layers of which (fig. 5), lying close together, form the extreme free edge of the section; that is, the unattached surface of the articular cartilage consists of three or four layers of flattened cells, lying quite close together and overlapping each other's edges. Now, to suppose for one moment that the nutriment which supplies growth to this body should be derived from the free surface, thus consisting of flattened cells, is to think directly contrary to all that we know of nutrition by cells. And therefore, as the growth of these cells evidently takes place from the attached portions, so is it evident that there must be some means of supplying nutriment to that surface. Moreover, the presence of large loops of vessels in the cancelli, immediately next the joint, points to the same

fact.

Thus, it being clear that the nutriment of cells growing from a deep surface could not be derived from a superficial one, it becomes necessary to examine into the anatomy of the cartilage and bone, and their mode of attachment to each other. A paper, on the "Organization and Nutrition of Non-vascular Animal Tissues," by Mr. Toynbee, is published in the Philosophical Transactions' for 1841. The author describes the epiphysal cartilage, its vascularization and conversion into bone, and continues thus:

"In adult life, when the epiphysal cartilage has been ossified, the cancelli of the latter are separated from the articular cartilage by a layer of bone, to which may be given the name of articular lamella. The nature of this lamella is worthy of particular attention. It is composed of two sets of osseous layers; the one, dense and thick, is continuous with the vertical fibres of the cancelli; the other, delicate and thin, principally composed of osseous corpuscles, is situated at right angles to the latter, and fills up the interspaces of the vertical fibres. Is this articular lamella complete? I have never been able, by the aid of the microscope, to discover any orifices in it, nor have I been able to force mercury through it."

Todd and Bowman, in their 'Physiological Anatomy,' vol. i., p. 93, give Toynbee's account of this articular lamella, and refer to his paper. Even Kölliker, whose care and accuracy are so well known, has given an inexact account of this bony layer. He says:*

"The condition of the bone, immediately under the articular cartilage, deserves especial mention; it consists, indeed, at almost every joint, of a layer of imperfectly-formed bonematter, true bone-tissue being only found deeper. This layer, which is from 0.04 to 0.16 of a line in thickness, is formed of a yellow, generally fibrous substance of bony hardness, which, indeed, is really ossific, but which contains no trace of Haversian canals, and no formed lacunæ. Instead of the latter, one finds round or oval bodies lying together in heaps or rows, which in section appear very dark, and which therefore might be taken for bone corpuscles filled with granules of lime. By adding oil of turpentine this error may be avoided; and we find that, as with the real osseous lacunæ of dry bones, the dark appearance is due to air, and the formation in question consists of thick-walled granular cells, still retaining their contents (fat and granules), showing here and there traces of canaliculi and partly calcified; in other words, that they are undeveloped bone-cells."*

"This is a circumstantial account, as far as the black bodies in the articular lamella are concerned; they lie together in rows, between each member of which there is a layer, more or less thick, of the compact lamella, and thus there is no communication between each such cell (as there are no canaliculi), that is, fluid cannot pass through the dense bone material from one to the other, as Toynbee seems to have believed when he wrote that "this thin layer has already been stated to be almost entirely composed of osseous corpuscles, which, without doubt, assist to convey the fluid from the cancelli into the cartilage" (loc. cit. p. 172). Thus, according to the results to be obtained by studying the observations of the authorities on this subject, the bony cancelli are cut off entirely from any communication with the joint-cartilage by a dense ill-developed impenetrable structure.

*Mikroskopische Anatomie, Band i. p. 818.

In fact, although we have at one side of the articular lamella evident demand for nutriment, on the other evident arrangement for its supply, yet in the lamella itself there is no means of carrying the supply to the demand, not even the ordinary means which would have existed had it consisted of the usual bone-tissue with its lacunæ and canaliculi.

On making some pathological investigations on the diseases of cartilages, I could not avoid being profoundly impressed with the apparent contradiction above described, particularly as it threw some of the morbid processes under examination into even a worse confusion than itself laboured under. It thus became necessary, in my mind, that the nutrient mechanism of articular cartilage should be fully investigated, the present physiology and pathology of that substance being based upon notions, which, as they involve contradiction, must necessarily be either false or imperfect.

It first appeared desirable to make out the mode in which the cancellous structure close to the joint end of the bone was arranged, the more so as in the above mentioned 'Philosophical Transactions' the structure is figured as a set of regularly disposed dark squares, surrounded by lighter margins, like a series of picture-frames hung close together; and as room for tortuous vessels in such structure could hardly be imagined, I undertook a series of investigations to establish how their spongy texture was formed, how the vessels ran in it, and in what exact manner the lamella shuts out the cavities from the joint. For these purposes many sections were made of the joint ends of bone, and examined under a low magnifying power; it was then seen that the cancelli are not regular square cavities symmetrically arranged, but form large holes in the sections, of various shapes, and without any regularity of arrangement. The bony scales which divide these cavities are crowded with the ordinary bone cells and their branches, which, under a glass magnifying only ten diameters, look like little dots; the articular lamella has rather a lighter appearance, and even with so low a power may be seen to be of variable thickness. Fig. 1 represents a section of a part of the lower end of the human tibia. Several bones were examined belonging to different mammalia, rabbit, sheep, pig, ox, dog, horse, &c.; the only difference between them appears to be that the smaller the bone, the more compact is the tissue, more especially in little animals, as the rabbit, where the blood channels are relatively not

nearly so large and numerous as in the analogous joints of the human subject. (Fig. 1.)

diameters.

治露

A like section examined under a ten times higher power, shows that, besides the irregular large cancellous openings, there are running through the bony plates normal Haversian canals, with their Fig. 1. Cancelli and articular lamella from concentric system of laminæ and lacunæ. The arti- lower end of human tibia, magnified about 10 cular lamella is lighter in colour-i.e., more transparent than the rest of the bone; in it bone cells and canalicula are absent, but there are several black opaque spots of an oblong form, with the long axis at right angles to the lamella, and two or three of these arrange themselves at a certain distance from each other in interrupted rows having the same direction. The lamella is a little darker, a little more brown, like ordinary bone, near its attached than its free surface; it looks as though at this part it had been stained. In no instance does the lamella lie immediately over, and never shuts in, a cancellous cavity; on the contrary, ordinary bone structure always intervenes between such cavity and the lamella. In places the osseous tissue surrounding a cavity near the margin of the lamella encroaches thereon very much; in other places, where the cavity is deeper from the surface, the osseous tissue recedes, and the lamella projects into the bony structure; thus, the articular layer is very uneven in thickness, its free edge is also serrated rather finely but unevenly. (Fig. 2.)

Fig. 2. Cancelli and articular lamella from lower end of human tibia, magnified 100 diameters.

In examining an injected preparation of the articular end of a bone, it will be found. that near the joint, immediately under the lamella, is a rich plexus of vessels, which

forms a series of loops, and that in the curved portion of each loop the vessel appears dilated. This plexus is not in the long bones derived from the common nutrient arteries, but springs from some of the numerous branches which surround the joint, and they are probably the remains of those vessels which Mr. Toynbee has described as supplying the epiphysal cartilage at the time of its ossification. In each one of the cavities near the articular lamella is a vascular twig, which does not entirely fill the space, but is surrounded more or less by loose fibrous tissue and by fat. In no place does a vessel touch the articular lamella, ordinary bone structure always intervening, as has been already stated.

On applying higher powers, one sees in many sections little more than this, particularly if they be mounted in Canada balsam; but in those, whether made by grinding down the bone or by cutting thin slices with a sharp knife, that are preserved in fluid, indications were seen which tempted me to go on examining the structure of this articular lamella, until at last I convinced myself that it in reality consists of a series of very minute parallel tubes, which run in a wavy course from the bony to the cartila

ginous surface. Among these, but having no special, if any, communication with them, are the bodies mentioned by Kölliker as undeveloped bone-cells. In some sections-those, namely, which are not made quite parallel with the axis of the joint from which they are taken the tubes of the articular lamella cannot be made out, but the section is minutely dotted from those tubes having been cut across. Fig. 3 is a tolerably successful representation of this structure. It will be seen that certain portions of the articular lamella are rendered darker than others, and

Fig. 8. Cancellous structure and articular lamella from this is a condition very difficult to make out; upper end of the human humerus, showing tubular structure of the lamella, magnified 500 diameters.

yet perhaps I may pretty confidently affirm that it arises from the tubular structure having become so bent in those lines that the canals have been cut through, giving a brown, darker, and finely mottled character to that part. This structure is similar in every mammal in which I have examined the lamella, but perhaps it is plainer in the rabbit than in any other I have yet seen.

Fig. 4. Articular lamella, section parallel to surface, from lower end of human tibia, magnified 700 diameters.

Having thus succeeded in ascertaining the structure, as seen laterally, it seemed advisable to view the same part from above; for this purpose a joint end with as flat a surface as possible, was chosen; either end of the tibia in most animals answers this purpose sufficiently: the cartilage being scraped away, a small piece of the articular lamella was detached, and ground thin enough to be transparent. In this view the black spots or undeveloped bone-cells are less elongated, all the rest of the section is studded with dots, which, under a sufficient power, and where the section is very thin, appear as small round holes. This structure is the same in all animals that I have examined. (Fig. 4.)

Thus the articular lamella, supposed until now to be a compact, impenetrable layer of bone, is in reality a structure as tubular as dentine, but the tubes are much finer and less straight; they do not shine as black as the lines in dentine, probably because they are finer, and therefore do not refract light to the same degree. They are, I believe, the minutest set of tubes yet discovered in the body, certainly in any of the hard portions, and some of the tubes lately reported to exist in the softer parts are, to say the least,

doubtful. It is necessary that they should be sought for under a high power and with a very good light, which can be varied by Gillott's condenser, or by other means. Articular cartilage has been so often described, that it must be needless to do more than refer to the sketch already given of the method in which the cells lie, and again to insist upon the fact of the greater crowding of these bodies near the superficial surface, and on their ultimate drying into scales, which overlie each other on that surface-an arrangement which has caused many observers to believe in the existence of an epithelium. If the superficies of fresh cartilage be shaved off thin with a very sharp knife, the section will indeed have the appearance of a layer of epithelial cells; but if a thin slice through its substance be examined, the gradual horizontal arrangement and flattening of the cells will leave no doubt as to the true structure of its superficies. (Fig. 5.)*

Fig. 5. Cartilage from human astragalus, magnified about 700 diameters, showing the perpendicular arrangeinto an oblique, subsequently into a horizontal, position, ment of corpuscles at the lower part, gradually curving and drying into scales. CHESTNU

The

Some observers, Mr. Toynbee among them, found that in the foetus vessels run across the cartilage, even into the middle of joints. In neither a foetal hare nor calf that I had the opportunity of examining, could I discover any such arrangement, nor any trace of it in a stillborn child. Nor have I been able to discover epithelium overlying the cartilaginous surface: what Mr. Bowman took for that structure was, I believe, the superficial layer of cells as above described, which, in the yet unused joint, is finer than when it has been subject to wear and tear. absence or presence of vessels upon the foetal cartilage is of importance, because if present it would establish the fact of a structure lining a cavity being nourished by its free surface. Besides, as it is clear that, at least during intra-uterine life, there is large provision for nutrition of the cartilage from the deep surface, the presence of such vessels would show that a structure having one free, one attached surface, might be nourished from both. Moreover, it would prove that a cellular structure might be nourished from the surface towards which the cells grow. But the two first facts would be isolated, and the latter is hardly conceivable; and as others besides myself have failed to discover this arrangement, there must have been in the observation of such vessels some occult source of error.

Thus articular cartilage is not so dead and unorganized a material as is generally imagined, as is proved by the care taken to supply to it nutriment in finely divided streams the most available form possible for use. The great vascularity of the parts, which furnish this supply (a vascularity consisting of dilated and dilatable vascular loops, which are not destined for the nourishment of the bone, since this structure has its own Haversian canals,) shows that the vital actions of cartilage must be active; and although we shall probably never be able to make experiments proving their rate of growth, yet have we on record one or two cases, which show that other changes may be very rapid, so as to confound the conventional idea of the inertness of articular cartilage. Mr. Arnott has reported a case of this sort. A man was bled, and six days afterwards was attacked with phlebitis; six days after its commencement-i. e., on February 4th-pain in the left knee, with some swelling, was observed; on the 8th of the month the man died.

*This arrangement has, however, not been described as is here done, because it is so difficult to procure sections sufficiently thin, that go all through the cartilage, the outer layers of cells breaking easily from a very thin slice. It may best be managed by cutting away cartilage and articular lamella from the cancelli, scraping the osseous matter away, then laying the cartilage on a piece of cork, and beginning from the formerly attached surface, cutting slices with a well made and sharp Valentin's knife.

+ Kölliker could not make out any vessels on the surface of foetal cartilage.

Medico-Chirurgical Transactions, vol. xv.