This condition of the bones is considered by Mr. Lloye as constituting the first stage of scrofulous disease, and. he justly remarks that it is quite uncertain how long they may con tinue in this state without further miscbief taking place. The next step is the erosion or absorption of the cartilages, if the affection is situated in the head of a bone, (see JOINT1) or otherwise near an articulation, and probably about the same period the external soft parts sympathise, and lymph is extensively deposited around the deep fibrous tissues in the neigh bourhood. This lymph is afterwards to be come the seat of abscesses, which always communicate with the diseased bone, and very generally with the cavity of the adjacent joint. The limb or part is now swollen : the tume faction is round and well defined, tolerably firm in consistence, and elastic to the touch ; the colour of the skin is of a more than ordi nary paleness, and its surface is marked by the meandering lines of numerous small blue veins. The growth of the tumour seems to be limited, for having reached a given size it becomes stationary and never increases, al though the disease may appear at times even more fully developed. Subsequently the pain is very variable; that attending on sCrofulous diseases being generally described as dull and heavy rather than acute, but this idea inust be received with some linntation, for occasionally the very reverse is the truth. We have seen some patients the victims of most intense irri tation and suffering throughout every stage of carious ulceration ; and even when it is other wise, they are always liable to severe exacer bations on any injudicious attempt at motion, any improper diet or other irregularity. In all cases there seems to be a considerable ag gravation of' symptoms, both local and consti tutional, about the period when suppuration is established, and whilst the matter is progress ing towards the surface.
It may be a long time before the tumour gives indications of being about to burstexter nally, partly perhaps from the imperfect organi zation of the lymph by which the matter is secreted, and partly because it seldom takes the shortest route to the surface, but proceeds by devious and intricate windings. At length the tumour, at one limited and almost circum scribed spot, becomes soft, then assumes a dark red or purple colour, finally a small slough forms on the surface and it bursts, giving exit in general to a greater quantity of matter than the size of the abscess would have led us to anticipate. The abscess does not collapse, and although the discharge may continue in pro fusion for months, the size of the tumefaction is never proportionally diminished. After it has burst, a small papilla of very red granu lation (a most unfailing symptom of the exis tence of a diseased bone underneath) is pushed out through the aperture. From the centre of this a small drop of matter can generally be pressed, and through it the discharge flows ; never for obvious reasons profusely at a time, but still so constantly as to soil the dressings and the bed-clothes extensively in a single night. When a probe is passed down to the bottom of this ulcer, which it is not easy al ways to accomplish, the bone is felt completely denuded, soft and rotten, and the instrument sinks into it with very little resistance. Most
frequently the earthy material of the bone is removed by the absorbents ; sometimes a sinall portion of it thus detached is washed off by the discharge, and is occasionally found block ing up the little orifice, occasioning a good deal of irritation and pain, and almost always an access of fever. Sometimes the remains of the bone come away in a larger mass, quite dead, light, and porous, and, when dried, per fectly friable.
Previous to the formation of the matter, however, the pathological state of the bone has undergone a remarkable change. Hitherto we have seen that an increase of vascularity oc curred at an early period, and preceded the deposition of the soft and cheesy substance; but in proportion as this deposit is increased in quantity, the vascularity decreases, and with it the vitality of the bone. " If a scrofulous bone be injected at an early period," says Mr. Lloyd, " or before the whole of its cancellous structure is altered, the injection very freely enters its vessels ; but if it be injected at a more advanced period, there evidently appear to be fewer vessels, though it is very probable that a. fine injection may be forced into vessels which bad previously ceased to carry blood." In the correctness of this observation Sir B. Brodie coincides, as well as in the opinion 4( that this diminution of the number of ves sels, and, consequently, of the supply of blood, is probably the proximate cause of those exfo liations which sometimes occur, where the disease has existed for a considerable length of time, especially in the smaller bones." Although carious ulceration, or, as it would be more correctly termed, absorption of bone, is so frequently attended by the formation of matter and abscess, yet such is by no means a necessary consequence—at least, we have ex amples of the removal of large portions of bones without any such unfortunate accompa niment. These principally appear under two distinct forms : one, where such absorption is the result of inflammatory action within the bone itself, the most familiar illustration of which is to be found in the caries of the spine attending on some cases of angular curvature : the other, where the absorption has been occa sioned by the pressure of an aneurism, art abscess, or other tumour in the immediate neighbourhood.
Mr. Pott, and others who have described this caries of the spine, mention that, at first, the bodies of the vertebr2e seem to spread so as absolutely to become larger than in a state of health ; that the ligaments are loose and detached, and the intervertebral cartilages sepa rated from. the bone. The first part of this description is certainly not correct, for in all the subjects we have had opportunities of ex amining, nothing like an enlargement or swelling of the bone appeared. It must be recollected that dissections of this disease at an early period are rarely met with—never unless the patient had been accidentally seized by some mortal affection soon after the spine had been attacked. It may, therefore, be supposed that these early descriptions were taken from ana logy with what other bones suffer in scrofulous disease, and it is well known that, until a com paratively recent period, it was a universally received opinion that the heads of bones be came actually enlarged under similar circum stances.