760 



THE UEINAEY TRACT. 



or subacute ; the characteristic feature always is the serous transudation, con- 

 sequently the absence of casts, a variable percentage of albumen in the urine, 

 and the presence in the urine of tubular epithelia. The inflamed renal tissue 

 at no time ceases to be a tissue, hence, no suppuration occurs. The subse- 

 quent course is characterized by destruction of the epithelia amid continuous 

 reproduction of connective tissue, and the final atrophy of the renal tissue, re- 

 sulting in the formation of the small, contracted, granular, or cirrhotic kidney. 

 (2) Croupous (Parenctiymatous) Inflammation of tlie Kidney. The charac- 

 teristic feature of croupous inflammation of mucous membranes in general is 

 the presence of a coagulated albuminous substance on the surface, the latter 

 being partially or completely denuded of its epithelium. The inflammation 

 of the connective tissue is always a severe one, betokened by intense redness, 

 swelling, and infiltration with form-elements. Examination with the micro- 

 scope teaches that the greatest part of the so-called croup-membrane consists 



FIG. 343. CATARRHAL NEPHRITIS. HIGH DEGREE. TRANSFORMA- 

 TION OF THE EPITHELIA INTO INDIFFERENT CORPUSCLES. 



C, convoluted tubule, with coarsely granular epithelia ; E, remnants of a tubule, without 

 istinct boundary toward the interstitial tissue ; the epithelia hold shining, homogeneous 

 lumps? L, the epithelia entirely broken up into shining, homogeneous lumps ; recurrence of 

 the juvenile condition ; I, insterstitial connective tissue in a similar condition. Magni- 

 fied 800 diameters. 



of a dense net-work of coagulated fibrine, in which varying numbers of bodies 

 of the aspect of nuclei are imbedded. A similar net-work is also invariably 

 found in the air-cells of the lungs in croupous pneumonia, and the absence of 

 coagulated fibrine is regarded as an important feature of catarrhal pneumonia. 



The question as to the origin of the croup-membrane has been answered 

 in different ways. Whereas some regard the entire mass as a coagulated 

 exudation from the blood ; others (Virchow, E. Wagner) believe it to be a 

 direct product of epithelia, and others again explain the presence of plastids 

 within the croup-membrane by supposing an extensive emigration of colorless 

 blood corpuscles. 



If we take into consideration that a fluid exudate before reaching the sur- 



