Hyperaemia of the kidneys not unfrequently occurs in the active form accompanying an exaltation of the renal functions; or as passive congestion in consequence of general marasmus, and especially in consequence of paralysis of the spinal and ganglionic nerves, such as we find in the torpid condition of the sympathetic in the insane, connected with abdominal plethora and congestion, and in paraplegic cases; it also, occurs in the mechanical form as a consequence of impeded circulation in connection with hyperaemia of other organs. The effects, are swelling of the organ (congestive turgor) and increase of size, greater depth of color of the tissues, increased density and resistancy, and loose attachment of the fascia propria. In children the tubular portion is frequently the chief seat of hyperaemia. When it has reached a high degree, it is apt to give rise to spontaneous hemorrhage (renal apoplexy), which, both in children and adults, has its main seat in the pyramids. We then find in the place of the pyramids, a spot of various dimensions, which has pushed aside a proportionate amount of parenchyma, and contains besides coagulated dark blood, the broken-up remains of the tubular substance. A cure undoubtedly ensues occasionally; the effusion gradually loses its color, and assumes a rusty and a yellow tint; it is then absorbed, and the calyx becoming obliterated, a fibro-cellular cicatrix closes up the cavity. Minute hemorrhagic spots, in the shape of ecchymoses of the tissue resulting from an acute disorganization of the blood, as well as small extravasations under the tunica albuginea, are of much more frequent occurrence.

Hyperaemia accompanied by increase of size (hypertrophy), is, according to the few cases we have been able to examine, the only anomaly of the kidney, demonstrable in diabetes by the pathological anatomist.

Anaemia of the kidneys occurs not only in connection with general impoverishment of the blood, but it is found as a more or less characteristic symptom, in all those cases in which the renal parenchyma has become impermeable from being infiltrated with coagulable matter, either owing to inflammation or deficient nutrition; this is particularly the case in that disease which is commonly cited as the type of the class, Bright's disease of the kidney.