CHRONIC BRIGHT'S DISEASE. 19 



little part in the inflammatory process which is going on in the in- 

 tervening tissues, while in others it is the prevailing seat of the dis- 

 order. We believe that it depends upon the degree of the inflam- 

 mation whether the secretory or merely the interstitial part of the 

 organ shall be invaded. We shall see by and by that chemical ob- 

 servation also teaches that cases of a very tedious insidious course 

 betoken an interstitial disease, while, on the other hand, chronic 

 cases of a more active and less protracted form indicate the exist- 

 ence of the parenchymatous disease. In the acute diffuse nephritis 

 above described, the implication of the renal parenchyma proper is 

 most apparent both from a clinical and anatomical point of view. 

 If we trace back the difference between the parenchymatous and 

 interstitial forms to a gradual variation in grade of the inflamma- 

 tion, the existence of many intervening forms will be easy of com- 

 prehension. 



In the chronic parenchymatous form, the kidney, in consequence 

 of .swelling of the epithelium and of deposits of exudation in the 

 tubules, becomes very soft and swollen, sometimes to double its nor- 

 mal size. The vessels of the cortical substance are bloodless (in 

 the cadaver at least), the capsule is opaque and easily detachable, 

 and beneath it the renal surface looks pale or yellowish, except 

 where one or two venous trunks remain filled with blood. Upon 

 section it is seen that the enlargement is all due to swelling of the 

 cortical substance, which is sometimes an inch thick ; and that the 

 pyramids take no part in the pallid coloring of the cortical sub- 

 stance, but often form a marked contrast with it by their deep-red 

 hue. Here and there a Malpighian body still remains like a red 

 point on the pale field. The chief seat of the morbid process is in 

 the convoluted tubules of the cortical substance, while the straight 

 tubules of the pyramid rarely, and in but small degree, exhibit the 

 exudation which causes the swelling and softening of the cortical 

 substance. The cylindriform deposits, which occlude and render 

 varicose many tubules, consist partly of swollen fatty epithelium, 

 partly of lymphatic elements (pus) and blood-corpuscles, but espe- 

 cially of hyaline or granular cylindrical masses. 



Many observers assume that, after a certain duration, the en- 

 larged kidney gradually shrinks and atrophies, and suppose the 

 atrophy to arise from the perishing of the glomeruli, by pressure of 

 the intracapsular exudation, and the collapse of their tubules which 

 have lost their epithelial lining. Even admitting the occurrence of 

 such obliteration of some of the tubules, it may be questioned 

 whether atrophy of the kidney can really be brought about through 

 such a process alone, and without the concomitant thickening of 



