468 THE SOLIDS. 



ful management of the light : they preserve the shape of the tubules, 

 and contain no nuclei or structures of any kind. Similar films are 

 occasionally seen in the sediment of urine. They are probably thrown off 

 from the denuded basement membrane. 



" Obliteration of the Tubes. The basement membrane, which, with the 

 few closely adherent oval nuclei above described, is now the sole remain- 

 ing structure of the tubes, soon undergoes a change. It loses the 

 cylindrical form proper to it in the fresh and natural kidney, and becomes 

 flattened by the pressure of the surrounding parts. Its cavity is thus 

 obliterated, and what was a tube assumes the appearance of a transparent 

 riband, dotted here and there with small oval nuclei, which, when seen 

 at the edges, appear to be inclosed between two layers of membrane. 

 These riband-shaped portions of membrane appear to present consider- 

 able tenacity and elasticity ; by their greater density, and by the con- 

 stant presence of the small oval nuclei so often mentioned between their 

 layers, they are in most cases readily distinguished from the delicate 

 films which have been referred to above. They are very various in 

 diameter, but are always inferior in this respect to the normal tubes ; 

 and they appear to break up spontaneously into smaller portions-, each 

 of which contains from one to six or more nuclei : these portions are of 

 various sizes ; they are usually broadest in the middle, and taper to a 

 point at both ends. The smallest of them contain only a single nucleus, 

 and present an appearance in every respect like that of young fibres of 

 areolar texture, or those fusiform cells, which have been called fibro- 

 plastic. I think it probable that the whole of the diseased basement 

 membrane ultimately splits up into fibres of this kind. While these 

 changes are proceeding, the capillary vessels, which have ceased to be 

 subservient to secretion, are usually obliterated: the consequence of 

 this double obliteration of vessels and tubes is a considerable degree of 

 atrophy in the diseased parts ; and as the atrophy takes place at first 

 chiefly in the cortical substance, great irregularities of the surface 

 generally supervene : thence arises the appearance so well described and 

 figured by Dr. Bright (Plate III. fig. 2.), in which, from the atrophy 

 of the cortical substance, the bases of the pyramids ' are drawn towards 

 the surface of the kidney.' 



" When oleo-albuminous exudation supervenes on the above derange- 

 ment of the tubes, or when desquamation supervenes on the former 

 (circumstances which I conceive to be of very common occurrence), the 

 exudation most commonly takes the form of the granulations of Bright, 

 which are deposited chiefly in the diseased tubes ; and the atrophy pro- 

 ceeding around these, they become salient, and the surface generally 

 irregular, giving rise to the tuberculated state of the surface so common 

 in all the later stages of the granulated kidney. (Bright, Plate III. 

 fig. 1 ; Rayer, Plate VII. fig. 6. Plate IX. fig. 8.) As the atrophy, 

 however, proceeds, the granulations are gradually absorbed ; and when 



