THE UEINAEY TRACT. 759 



Up to the present time this condition was overlooked by all investigators. 

 The changes consist in the following : In the epithelia, which are often still 

 recognizable by the presence of the irregular caliber of the former tubule, the 

 nuclei or nucleoli, or also single granules, have been converted into shining, 

 irregularly shaped, nearly homogeneous lumps, some of which present dis- 

 tinct partition lines. In some tubules these lumps are present in small num- 

 bers, in others they are numerous, and finally the entire epithelium appears 

 converted into such lumps, which are separated from one another by narrow 

 rims of a cement-substance, but are in uninterrupted continuity with each 

 other by means of fine threads. This process is a recurrence of the juvenile 

 condition of living matter. As the same process invades also the connective 

 tissue, the entire structure, ( especially in the region of the narrow tubules, 

 appears converted into an indifferent or medullary tissue. From this the pro- 

 duction of connective tissue proceeds, that leads to cirrhosis and granulation 



FIG. 342. CATARRHAL NEPHRITIS. HIGH DEGREE. TRANSFORMA- 

 TION OF THE EPITHELIA INTO INDIFFERENT CORPUSCLES. 



C', convoluted tubule, lined with epithelium in the stage of "cloudy swelling"; L, 

 remnants of uriniferous tubules, whose epithelia are broken up into homogeneous, shining 

 lumps ; J, interstitial tissue, entirely converted into pale granular, or shining indifferent 

 elements. Magnified 500 diameters. 



of the kidney. It is this process formerly incorrectly regarded as entirely 

 interstitial which results in contraction of the kidney-tissue and in the pro- 

 duction of a more or less uniform granulation of the surface. (See Fig. 343.) 

 If we are to describe concisely the nature of catarrhal inflammation of the 

 kidney we should say that in the first stage it is characterized by serous transu- 

 dation into the connective tissue and cloudy swelling of the epithelia ; in the second 

 stage, by inflammatory infiltration of the connective tissue, desquamation and 

 reproduction of the epithelium ; in the third stage by a metamorphosis of the con- 

 nective tissue and of the epithelium into an indifferent or medullary tissue. The 

 inflammation maybe <>f a varying degree of severity; its course maybe acute 



