With malignant endocarditis, with surgical pyæmia, and with the curious cases called idiopathic pyæmia, small emboli seem to find their way into the smallest branches of the renal artery. They do not produce infarctions, but small abscesses. In these cases the kidneys are increased in size and dotted with little white points surrounded by a red zone. These little white points are formed by an infiltration of pus-cells between the tubes, and in the larger foci by a breaking down of the kidney-tissue. Colonies of micrococci are sometimes, but not always, found in the Malpighian tufts, the veins, and the abscesses. {100} SYMPTOMS.--These embolic abscesses can hardly be said to have any clinical history. Whatever symptoms may belong to them are lost in those of the general disease from which the patient is suffering. 3. Idiopathic Abscesses.--Occasionally cases of abscesses of one of the kidneys are met with. They last a long time, and when the patient dies both the kidney tissue and the pelvis are involved to such an extent as to render the anatomical diagnosis difficult. The greater part of the kidney-tissue is destroyed and replaced by sacs full of pus; the pelvis is dilated and its walls thickened. The surrounding connective tissue is thickened; perforations and sinuses may extend into the surrounding connective tissue, into the large intestine, and through the diaphragm into the lung. SYMPTOMS.--At first these cases are apt to be very obscure. An irregular febrile movement accompanied with rigors comes and goes, lasting for shorter or longer periods. The patients lose appetite, vomit occasionally, and become emaciated and anæmic. With this there may be pain over the region of one of the kidneys. After a time a tumor may make its appearance in the position of one kidney--a tumor which can be felt through the anterior abdominal wall. If the abscess communicates with the pelvis of the kidney and the ureter remains pervious, pus and fragments of kidney-tissue are discharged with the urine. The pus is usually discharged at intervals, and at such times the size of the tumor diminishes. In other cases the pus burrows in other directions--into the retro-peritoneal connective tissue, the peritoneal cavity, the colon, or through the diaphragm into the lung. These cases are apt to run a protracted course and terminate fatally. TREATMENT.--The only plan of treatment likely to cure the patient is a surgical one--either to extirpate the diseased kidney, or to cut down on the abscess and treat it on the antiseptic plan like any deep abscess.