Besides the anomalies already alluded to, we have to advert to the following morbid contents of the urinary cana-liculi.

a. The formation of calculous urinary concretions, which appear in the shape of delicate granular crystals, dispersed through the substance of the kidney, and which consist of lithic acid.

b. Entozoa; these are, besides the animalcules inhabiting the acephalo-cyst, the cysticercus and the very rare strongylus gigas.

8. Special Disease Of The Investments Of The Kidneys

1. Hypertrophy Of The Adipose Layer

The adipose tissue which surrounds the kidneys may increase in quantity coincidently with a universal increase of the fat of the body, or it may become hypertrophied by itself; in the latter case it may increase to such an extent as to force its way into the hilus of the organ, impede its nutrition, and cause a fatty infiltration of the kidney, accompanied by anaemia and pallor. It appears that rare cases of this description have been occasionally taken for Bright's disease, and this has given rise to the latter being thought analogous to fatty liver. When it has advanced to the highest stage, the kidney presents the appearance of a mere piece of fat surrounded by a mass of adipose tissue, and without the slightest traces of renal organization; the urinary passages at the same time are atrophied and obliterated.

Independently of universal adipose deposit, we find a larger or smaller excess of fat enveloping the kidneys of old people, accompanied by atrophy of the organ; it also accumulates when the kidney is affected by moderate but lasting inflammatory irritation, especially that caused by calculi, and in secondary atrophy, and obliteration of the kidney.

2. Perinephritis

This comprehends inflammation of the tunica albu-ginea and of the fascia adiposa of the kidney. It results from wounds, concussion, and urinous infiltration, and accompanies both the inflammation of the kidneys and that of the pelves and calices.

Inflammation of the tunica albuginea is characterized, as we have already had occasion to state, by development of the vessels of the cortical substance, by congestion and softening, succulence and condensation of its tissue, and by the facility with which it may be detached. It is always combined with inflammation of the cortical substance of the kidney. It is only when the latter terminates in suppuration that the disease in question has a similar issue; but it frequently leaves a fibroid thickening of various degrees, combined with induration, atrophy, and obliteration of the kidney, resulting from inflammation of the organ.

Inflammation of the fascia adiposa, which is particularly apt to supervene upon the tedious inflammation of the kidneys and their pelves, induced by calculous irritation, has the general characters of inflammation of fatty tissues; it induces condensation and rusty discoloration; atrophy and conversion of the fat into a white or slate-colored cellulo-fibrous tissue, which forms adhesions with the thickened albuginea and the peritoneum; in some cases suppuration and abscess may ensue.