This tissue may be met with in any of the tissues of the body, but is less seen upon the serous membranes of the cranial and peritoneal cavities, whereas in the joint cavities it is common. It is provoked, as just stated, by the presence of tubercle, and has the power of penetration into and substitution for almost all the other tissues of the body. Thus in a primary tuberculous focus within the bone a granuloma will form and extend its limits, while the surrounding bony tissue melts away before it; and it is by the growth of this tissue in a particular direction that tuberculous products from within the bone cavity are finally carried to the surface. When this material has escaped from bone, or from tissues without the bone, toward the surface its presence is marked by induration, by livid discoloration of a limited area of skin, with elevation of the surface, which finally breaks down and shows discolored, bleeding, and pouting granulations, which in the absence of restraint now proliferate more rapidly, and often to the point where they loose their former blood supply, and consequently necrose upon the surface. This is the _fungous granulation tissue_, especially of the German writers, and may be met with upon the surface, or is frequently seen in opening into joint cavities and other tissues infected by tubercle. The appearances of this fungous tissue are modified somewhat by environment and pressure: in joints flat and radiating masses of it will be found, extending along the synovial surfaces and into the articular crevices. This fungous tissue may grow in any direction, but apparently advances in the direction of least resistance. It leads to complete perforations of the flat bones, like those of the skull, while tuberculous masses from the dura may cause multiple perforations, the granulation tissue finally escaping through the overlying skin. In tuberculosis of synovial sheaths and bursæ it extends along and may completely fill and even distend them. It will separate tissues which were united together, and it may lead to disintegration and disorganization of the firmest textures in the body. So long as it is not exposed to the air nor to pyogenic infection, it will preserve its characteristics for a considerable length of time. Immediately upon exposure it is likely to break down, and infection will travel speedily along it into the deeper cavity whence it has sprung. A mass of this tissue contained within the normal tissues, condensed more or less by pressure, uninfected, and not freely supplied with blood, is entitled to the name of _tuberculous gumma_, whose tendency, however, is too often to break down and suppurate. Such gummas may be found in any part of the body, and differ only in unessential respects from the diffuse and more or less infiltrated masses of granulation tissue which occupy serous cavities or which extend in various directions.