Cheesy degeneration and liquefaction take place in more or less degree, and though their occurrence is often not evidenced by any aggravation of the symptoms, sinus formation with persisting discharge occurs. When these sinuses occur, they generally become infected with other pus producing organisms, and aggravate the condition considerably. In the course of months or years, many such openings may occur through which masses of soft tissue or bone, either carious or necrosed (_sequestra_), may be discharged. +Diagnosis.+ This may be easy, difficult, or impossible, depending on the duration, the joint involved, and the character of the disease in any individual case. At times it is impossible to differentiate from syphilis, which, however, is quite uncommon, but with which tuberculosis has many symptoms in common. The history of the individual, and a blood examination will generally suffice. If the disease is advanced to the stage of abscess and sinus formation, there can be no doubt as the nature of the trouble. Very often the disease in the articular ends of the bones advances slowly, giving very little pain and no appreciable swelling or atrophy. There may be only an unwillingness to use the part very much, and the disease may very well be overlooked. In such insidious cases a diagnosis can be reached by aspiration and subsequent examination of the serous fluid for tubercle bacilli. An X-ray will show the rarifaction of the bony structures and the thickened periosteum. The course of tubercular joint disease is entirely dependent upon its extent at the time it is recognized, and the treatment pursued. It is of paramount importance that attention be given any persisting pain or discomfort in or near a joint, and that rest and every diagnostic aid be employed before pronouncing a case hysteria, neuralgia or “growing pains.” In a few cases the process can be arrested and little or no diminution of function remains. This, however, is the exception; there is usually destruction of the intra-articular cartilages, and of the synovial membrane, and the formation of bands of great density, which impair the motion of the part even to rigidity (_fibrous ankylosis_). The restriction of motion may be absolute if ossification of the granulation tissue lying between the epiphyses unites their eroded ends (_bony ankylosis_). At times, though recovery seems to have been secured, a sinus may persist because of some slight area of remaining caries, or because the tract itself is tubercular. In other instances a recurrence may follow after months or years of quiescence. This may be due to the setting free of encapsulated organisms, or because of a new infection at a point of least resistance.