466 THE SOLIDS. 



the advanced stages pass into some of the states hereafter to be described. 

 The capillary vessels surrounding the tubes are not visible, and in their 

 place there is fibrous tissue, which in this form of lesion always appears 

 somewhat exaggerated. The Malpighian bodies are also frequently seen 

 in process of obliteration, and surrounded by dense capsules of fibrous 

 tissue. The epithelium is frequently altered in character, but its changes 

 follow no fixed rule. 



" The absence or scantiness of exudation, taken in connection with the 

 extent of degeneration appreciable by the naked eye, are amply sufficient 

 characters to distinguish this lesion from the extreme stages of the fatty 

 disease." 



Lesions of the Tubes and Epithelium. 



Some of these lesions have been already described under the head of 

 exudation ; but there are others which are not less important than those 

 formerly alluded to, and which are very frequently found in connection 

 with them. 



Imperfect Development of the Epithelium Cells and Nuclei. The epi- 

 thelium cells and nuclei vary in size and characters within certain limits 

 even in healthy kidneys ; the nuclei less so than the cells themselves ; but 

 in all kidneys, whether healthy or diseased, the nuclei which are most 

 closely adherent to the basement membrane are less perfectly circular, 

 and of considerably smaller size, than those lining the tubes and sur- 

 rounded by complete cellrwalls. 



Those acquainted with the normal anatomy of the kidney will be able 

 to determine the limits of variations in the epithelium and nuclei com- 

 patible with a state of health. 



In very many pathological conditions of the organ, the nuclei occur in 

 various places almost wholly devoid of cell-walls. They may be more 

 abundant or more scanty than usual ; and often appear in great profusion, 

 huddled together in confused masses, and mixed with shreds of membrane 

 and amorphous molecular matter, not soluble in acetic acid. This ap- 

 pearance of debris, which no doubt results from disintegration of the 

 cell-walls, most frequently occurs in kidneys which are abnormally soft 

 and large, and from the cut surface of which an unusually large quantity 

 of turbid whitish juice may be scraped. Such softened and altered kid- 

 neys occur frequently in fever and other diseases. 



A more unequivocal pathological change (often occurring along with 

 the above) is the small size and altered form of the nuclei throughout 

 the organs, these not being more than half the usual size and always des- 

 titute of cell- walls. Sometimes they float scattered and solitary in the field 

 of the microscope ; at other times they appear aggregated together either 

 by twos or threes, or in much greater numbers, the connecting medium 

 being a transparent and filmy substance, the nascent or undeveloped 

 cell-membrane which has separated from the basement membrane, along 



