470 THE SOLIDS. 



he describes, and acquire the power of increase and endogenous de- 

 velopment. 



" Whether the bodies described by me above are the same with the 

 vesicles of Mr. Simon, I have some difficulty in determining : but they 

 are the only objects I have seen which correspond at all closely with his 

 description ; unless, indeed, it wer possible to suppose, as Dr. Johnson 

 appears to hint, that he may have mistaken the normal disposition of 

 the tubuli for a cystic structure. 



" However this may be, I am satisfied that the vesicles above described 

 are exceptional productions, and by no means invariably connected, 

 as Mr. Simon describes his vesicles to be, with the progress of the 

 desquamative degeneration. They are seen in comparatively few cases : 

 on referring to four, of which I have drawings or memoranda, I find two 

 to have been congested and waxy kidneys, with slight exudation, one to 

 have been a soft and desquamating kidney, also with slight exudation, 

 and one a granular kidney with numerous cysts, from the size of a pea 

 to that of a hazel-nut. On the other hand, I have examined organs 

 in every stage of desquamative disease without finding these bodies, the 

 production of which cannot therefore be an essential step in the degener- 

 ation and atrophy of kidneys so affected. 



" The origin and progress of these vesicles is very obscure. It is not 

 improbable that, as Mr. Simon asserts, they are transformed into the 

 larger cysts visible to the naked eye : though I confess that I have not 

 been able to trace the intermediate steps of their progress in a satisfac- 

 tory manner. On the other hand, their origin from extravasated 

 epithelial cells seems exceedingly improbable ; indeed, I have already 

 stated, that I do not think the epithelium ever becomes extravasated. 

 Moreover, the vesicles in question have all the appearance of being 

 formed within the tubes, although they afterwards become separated 

 from them. 



" From the occasional appearances of alternate distention and constric- 

 tion presented by the tubes when undergoing obliteration, I am induced 

 to believe that cysts may be formed by the occlusion and isolation of por- 

 tions of tube which have not yet lost their power of secretion. Whether 

 the vesicles in question are formed in this way, can only be determined 

 by close and repeated observation : and I have not been able to obtain 

 demonstrative evidence on this point. 



" The larger cysts in the kidney present very strong evidence of being 

 formed in connection with the secreting membrane. In one instance I 

 found their inner surface to be lined at some points with tessellated 

 epithelium, in the form of pentagonal or hexagonal flattened cells, with 

 circular nuclei ; in another case there were oval nuclei without any dis- 

 tinct cells, and a large number of free oil-globules of considerable size. 

 The existence of oil in these cysts has also been observed by Dr. Johnson. 

 Other products of secretion are also occasionally found. On one occa- 

 sion I found several cysts in a kidney, otherwise healthy in appearance. 



