3. Atrophy.—In the third stage, the kidneys are smaller, or of normal size, or even larger than normal. The capsule is adherent. The surface of the kidney is irregular and granular, its color a dusky yellow. Its consistence is hard. The cortex is thinned. The pyra mids are smaller. The fat about the pelvis is increased in amount. The tubes are dilated and filled as in the second stage, or are col lapsed and folded together. Most of the Malpighian bodies are shrivelled and fatty. If the exudation between the tubes has become organized, we find masses of connective-tissue cells and fibres.
This description of the lesions, taken as it was from nature, is as true now as when it was written. But yet _our present pathological knowledge makes us interpret these lesions somewhat differently.
In 1852 Dr. George Johnson published a work on kidney diseases which, like that of Frerichs, has had a durable effect on medical opinions. He distinguishes five forms of Bright's disease.
1. Acute Desquamative Nephritis.—The form of disease occurring after scarlet fever, exposure to cold, etc. This corresponds to Fre richs' first stage. Johnson, however, lays mcst stress upon the de squamation of the epithelium, and but little on the exudation in the tubes. Exudation between the tubes he does not mention.
2. Chronic Desquconative Nephritis.—This corresponds to the sec ond and third stages of Frerichs. Johnson describes the degenera tion of the epithelium, the denudation of the tubes of their epithe lium, their dilatation and collapse, and the presence of coagulated material within them. The Malpighian tufts are thickened or atrophied. The arteries are thickened. He regards the production of new fibrous tissue as an accidental and unessential phenomenon.
3. Waxy Degeneration of the Kidney.—Under this name Johnson describes kidneys which are of large size, their cortex thick and white, their tubes filled with waxy material. This waxy material he sup poses to be produced by a degeneration of the epithelium. The large hyaline casts found in the urine he calls waxy, and seems to consider them diagnostic of this form of kidney disease.
4. Acute Non-desquamative Disease of the Kidneys.—This is char acterized during life by scanty or suppressed urine, but containing no albumin, and no casts, or only a few waxy ones. The kidneys are of normal size; the epithelium of the tubes is somewhat altered.
5. Chronic Non-desquamative Disease.—The kidneys are usually large, very rarely atrophied. The cortex is thick and white. The convoluted tubes are more opaque than usual. The Malpighian bodies and arteries are thickened.
6. The Granular Fat Kidney.—This form may be a consequence of the non-desquamative disease, of acute desquamative inflammation, and rarely of chronic desquamative disease. The kidneys are large, the cortex white, mottled with yellowish granulations. These yellow granulations are formed of tubes containing oil-globules. The ves sels and Malpighian bodies are thickened. Sometimes the same yel low, fatty granulations are found in atrophied kidneys.
7. The Mottled Fat Kidney.—All the tubes of the cortex contain oil-globules, and there are red spots of congestion or extravasation.
To Traube (1856) belongs the merit of recognizing chronic con gestion of the kidney as a lesion with an entirely different cause from that of other forms of Bright's disease; and also of calling attention to the fact that blood-contamination cannot be the only cause of the cerebral symptoms.
In 1858 Virchow, in his " Cellular Pathology," developed the doc trine that in Bright's disease either the tubes, the stroma, or the Malpighian bodies are principally involved, and that we can, there fore, distinguish a parenchymatous nephritis, an interstitial neph ritis, and an amyloid degeneration of the kidney. This doctrine has had a lasting effort on all subsequent classifications.
Grainger Stewart distinguishes: 1. The 12fiammatory Form—This has three stages : (1) That of inflammation; (2) That of fatty transformation; (3) That of atro phy. These correspond very closely with the three stages described by Frerichs.
2. The Waxy Form.—This also has three stages : (1) That of simple degeneration of the vessels; (2) That in which a secondary alteration of the tubes is superadded; and (3) That of atrophy.
In the first stage, the kidney is of normal size, the tubes are un altered; only the Malpighian bodies and small arteries have under gone waxy degeneration.
In the second stage, the kidney is enlarged, the cortex thick and white, with Malpighian bodies and small vessels waxy; the tubes contain hyaline casts; their epithelium is swollen; their basement membrane may be waxy.