THE UEINAEY TRACT. 755 



attempt to localize the inflammatory processes (which, as*generally agreed, 

 form the basis for all the changes of renal tissue described as Bright's 

 disease) in the principal histological components of the kidney, namely, in 

 the tubular epithelium, in the blood-vessels, and in the connecting stroma, 

 cannot be carried out. I am not familiar with any form of inflammation, 

 whether of the kidney or of any other glandular organ, which can begin 

 and also run its course in only a single one of the constituent tissues. Under 

 all circumstances every one of the histological components is involved in the 

 process, not only in the mildest catarrhal inflammation, but also in the severe 

 form of suppuration. 



To me no other method of elucidating the forms of renal inflammation 

 seems possible than a comparison with analogous processes in glandular 

 organs in general, whose simplest representatives are the mucous mem- 

 branes. If we remember that in inflammation the blood-vessels are impli- 

 cated by the production of an exudate, and the other histological constituents 

 by morphological changes brought about by nutritive disturbances of the 

 living matter, we shall have to regard every inflammatory process as a disease 

 of the tissue in its entirety. Neither the blood-vessels, nor the connective 

 tissue, nor the epithelium alone can exclusively afford the substratum of 

 an inflammatory process, but always these components coincidently. What- 

 ever in the tissue is endowed with life will become active and then produc- 

 tive during a nutritive disturbance, and only in the case of the death, of the 

 so-called gangrene of the tissue is the idea admissible that the tissue is 

 destroyed and remains passive. 



In analogy to the varieties' of the inflammatory processes in mucous 

 membranes, we may also speak of a catarrhal, croupous, suppurative and 

 diphtheritic inflammation of the kidney. Each of these varieties may be cir- 

 cumscribed or diffuse ; each can gradually pass into the other without our 

 being able to draw sharp lines between them, either with the naked eye or 

 with the microscope. 



We will accordingly retain this principle of division. The term "croup- 

 ous nephritis" has been declared to be inadmissible, because the fibrinous 

 nature of the casts, and hence their identity with the croup membrane of 

 other mucous membranes has not been demonstrated. True, croup-mem- 

 brane and casts are neither morphologically, nor microscopically, nor chemi- 

 cally entirely identical. I shall however, try to explain these differences and 

 believe that I am justified in upholding the variety of croupous nephritis on 

 account of all its accompanying conditions. I shall not consider the diphthe- 

 ritic variety of inflammation, since it mainly affects the renal pelvis and 

 calices. 



(1) The Catarrhal (Desquamatiue, Interstitial) Nephritis. The phenomena 

 which are characteristic of mild catarrhal inflammation in a mucous mem- 

 brane are oadematous swelling of the connective tissue, swelling and granular 

 cloudiness of the epithelial covering, and subsequent desquamation of the 

 epithelium. The blood-vessels which, even to the naked eye, appear filled 

 and dilated, under the microscope show a more or less complete distension 

 with blood-corpuscles, without apparent alteration in the structure of their 

 wall. It never has been doubted that the oedematous swelling of the connect- 

 ive tissue and the desquamation are due to a serous exudation from the 

 blood-vessels, in spite of the fact that the exudation, as such, cannot be seen 

 under the microscope. The presence of the exudate within the tissue (paren- 



