The tubercles which are found in the kidney in cases of general miliary tuberculosis have usually no clinical interest, since the kidney is not, even in children, one of the points where tubercular localization is most intense, and renal tubercles are consequently but little advanced when death takes place from the extension of the disease in other organs. They present no symptoms which are perceptible among the much graver ones attending the progress of the disease elsewhere. In the disease known as tubercle of the kidney, caseous nephritis, or nephro-phthisis, masses of caseous material are deposited in the renal parenchyma which may soften, break down, and communicate with each other and with the calices and pelvis. In some cases it is probable that the disease originates in or immediately underneath the mucous membrane of the urinary passages. This process of breaking down continues much in the same way as that of a phthisical lung, until the kidney becomes little more than a hardened, irregular, knobby shell enclosing a ragged, ulcerated cavity with thickened, pus-secreting walls and filled with pus, more or less blood, and débris of kidney-structure and tubercle. In such portions of renal substance as may remain it is not unusual to find miliary tubercle. If obstruction of the ureter exists, a pyo-nephrosis may exist in addition. Rupture into the peritoneal cavity or into the intestine has occurred. It is probable that in this affection are included two processes, differing in pathology and etiology and to some extent in clinical history. It is probable that true tubercle may originate in the kidney as a result of either tubercle or cheesy inflammation elsewhere, as in the lungs, bodies of the vertebræ, or scrofulous glands. In this case there are no marked symptoms until the process of softening and breaking down has reached the mucous membrane of the pelvis. Besides this, renal phthisis sometimes succeeds, as a more local invasion, to tubercle or cheesy inflammation of the urinary passages, and in this case the symptoms appear simply as aggravations of those already present and depending upon ureteritis and pyelitis. Renal phthisis is seldom if ever an independent disease. It is often associated, besides the affections already named as standing in etiological relationship with it, with cheesy inflammation of the testicle, vesiculæ seminales, and much less frequently of the ovaries and Fallopian tubes. {65} The DIAGNOSIS of tubercle in the kidney before it has reached the pelvis is probably impossible. Pain in the back or slight albuminuria, as has been already stated, is of no diagnostic value except as pointing to some renal irritation, as to the cause of which it tells nothing. In the presence of tubercle elsewhere it might be regarded as suspicious.