CONGESTION OF THE KIDNEYS. 



363 



inflammatory processes of the kidney. That repeated colds may 

 cause chronic nephritis is not positively demonstrated. 



Patholog-ical anatomy. Formerly there were recognized two 

 quite distinct principal forms of chronic nephritis — parenchymatous 

 nephritis and interstitial nephritis^ but modern researches have 

 established the unity of the inflammatory process ; they have 

 shown that, in chronic nephritis, the so-called renal parenchyma 

 (the epithelial cells) and the interstitial tissues are inflamed at the 

 same time in very different degrees. If in human pathology we still 

 preserve the division into chronic parenchymatous nephritis and 

 interstitial nephritis or renal atrophy, it is because this distinction 

 is of utility from a clinical point of view. It is generally admitted 

 that atrophy represents the last stage of chronic parenchymatous 

 nephritis. In our animals nothing is known as to the existence of 

 a non-inflammatory renal atrophy, so that we shall continue to 

 <îonsider chronic parenchymatous nephritis and chronic interstitial 

 indurative or atrophic nephritis as two successive degrees of renal 

 phlegmasia. Although these two morbid states may ofler certain 

 anatomical and special clinical characters, yet they represent only 

 stages of development of one and the same process, sclerous ne- 

 phritis forming the ultimate state of parenchymatous nephritis. 



1. Stage of chronic parenchymatous nephritis. The 

 histological alterations vary considerably according to the degree 

 of intensity of the inflammation, the abundance, localization, or 

 difl'usion of the epithelial alterations, and the inflammatory oedema. 

 In certain cases we find the epithelium of the glomeruli tumefied 

 .and in the course of fatty degeneration or desquamated on the inside 

 of the capsules ; the epithelium of the uriniferous canaliculi is tume- 

 fied, turbid, degenerated, necrosed, desquamated, and its canals are 

 full of epithelial cylinders. In inflammatory œdema of the kidney, 

 on the contrary, we observe a cellular infiltration especially marked 

 in the neighborhood of the veins ; the uriniferous canaliculi and 

 Bowman's capsules are filled with white corpuscles of an inflam- 

 matory exudate (exudative or hyaline casts); we may also recognize 

 red corpuscles in more or less large numbers in it. In one case 

 we have found a gelatinous infiltration of the connective tissue 

 surrounding the openings of the uriniferous canaliculi. 



By macroscopic examination the kidney appears little or not at all 

 altered m many cases ; but frequently also alterations of structure 

 impress certain modifications of form or coloration upon it. We 



