4 DISEASES OF THE KIDNEY. 



ANATOMICAL APPEARANCES. A kidney in a state of recent by- 

 peraemia is of a more or less dark-red color. Sometimes it is enlarged, 

 owing either to dilatation of its vessels or to serous infiltration. The 

 oedema of its parenchyma and subcapsular connective tissue renders the 

 hyperaemic organ unnaturally moist and soft, and loosens its capsule. 

 When cut into, and when the vessels of the glomeruli are much dis- 

 tended by blood, the Malpighian coils dot the surface of the section, 

 as dark-red points. 



When the hyperaemia is of long standing, particularly when there 

 is habitual engorgement, as occurs in chronic disease of the heart and 

 lung, the changes which arise are of a different kind. The kidney is then 

 but little enlarged, or remains of its normal magnitude, or may even 

 be somewhat smaller than natural. It is more resistent in texture, 

 and is of a uniform red color. Upon microscopic examination, the 

 epithelium of the urinary tubules of the cortical substance is found to 

 be swollen, the contour of the cells is ill-defined, and they are filled 

 with finely-granular contents, which clear up upon the addition of 

 acetic acid. Sometimes there is a desquamation of the degenerated 

 epithelium here and there ; and the tubules collapse after the epithe- 

 lium is expelled, causing the surface of the kidney to become uneven 

 by depressions of varying depth. Traube and Beckman have called 

 particular attention to the difference between this condition and the 

 degenerative chronic inflammation of the kidney, which we shall de- 

 scribe in Chapter IV. as chronic Bright's disease. 



While the alterations above described are going on in the epithe- 

 lium of the cortical substance, the straight tubules of the medullary 

 substance are usually found filled with a material which is sometimes 

 transparent and pale, and sometimes of a more yellow color. By mod- 

 erate pressure upon the pyramids, a large quantity of an opaque creamy 

 liquid is discharged from the papillae, which contains a great deal of 

 epithelium and a few of those casts of the tubuli, in the form of homo- 

 geneous transparent tolerably firm cylinders. 



SYMPTOMS AND COURSE. The kidney has so few nerves of sensa- 

 tion, and its capsule is so distensible, that hypersemic swelling of the 

 organ is never accompanied by pain. As the amount of urine secreted 

 depends chiefly upon the degree of pressure within the vessels of the 

 glomeruli, its secretion necessarily becomes more profuse in that form 

 of renal hyperaemia which involves the arterial system of the kidney, 

 including the vessels of the Malpighian tufts. This is almost the only 

 symptom caused by fluxion to the kidney, which arises from copious 

 drinking, hypertrophy of the left heart, compression of the aorta 01 

 iliac arteries, and dilatation of the renal arteries. The urine is copi- 

 ous in quantity, dilute in quality, of low specific suavity, and of a Dale 



