458 THE SOLIDS. 



net-work in which the tubes are packed, and which now appears more 

 abundant in consequence of the wasting of the tubes. 



" It has already been stated that the Malpighian bodies are unaffected 

 in the progress of this disease ; and this is true, in so far as they re- 

 main, for the most part, free from any deposit or accumulation in their 

 interior : but they must necessarily be affected by the changes occurring 

 in other parts of the organ. Thus the destruction of many of the Mal- 

 pighian bodies is a necessary consequence of the simultaneous wasting of 

 the vessels and tubes which occurs in the advanced stages of chronic 

 nephritis : and, during the progress of the disease, the vessels of the 

 Malpighian tuft will be in a state of more or less active congestion, in 

 proportion to the rapidity of secretion and of cell development in the 

 tubes ; and one consequence of this congestion of the Malpighian bodies 

 will be the escape of serum into the tubes, and the mixture of albuminous 

 matter with the urine. The quantity of albumen in the urine will be 

 great in proportion as the disease approaches in activity to that form 

 which I have called ' acute desquamative nephritis.' When the disease 

 is chronic and inactive, there may be no albumen in the urine, or, it 

 may be present in quantities so small as not to be detected by the 

 ordinary chemical tests. In such cases, as, indeed, for the accurate 

 discrimination of all forms of renal disease, the microscope will be 

 found an invaluable aid. It must be remembered that the essential 

 change in this disease is a destruction of the epithelial cells in the 

 manner already described ; the best evidence of this change being in 

 progress is, the presence in the urine of moulds of the urinary tubes, 

 composed of more or less disintegrated epithelium ; and such evidence 

 I have repeatedly obtained, when no albumen could be detected by the 

 ordinary heat and nitric acid tests. 



" A sufficient explanation has already been given of the small quantity 

 of the saline constituents excreted by the kidneys in cases of chronic 

 nephritis. It is manifest, that, if the epithelial cells are the agents by 

 which the solid constituents of the urine are separated from the blood, 

 a deficient excretion of these materials will be a necessary consequence 

 of the greater or less destruction of the epithelial cells. 



" Before concluding this communication on the inflammatory diseases 

 of the kidney, it appears desirable to allude very briefly to the subject 

 of my last paper, viz. ' Fatty Degeneration of the Kidney ; ' my object 

 being to show how essentially distinct are the two forms of disease ; 

 and, at the same time, to explain the manner in which they are some- 

 times combined. 



" For some months past, I have been aware that fatty degeneration of 

 the kidney occurs in two distinct forms. 



" In the simple fatty degeneration of the kidney, all the tubes be- 

 come almost uniformly distended with oil. In a slight degree and in the 

 earlier stages, it is often found, after death, in cases where there is no 

 reason to suspect that it has been productive of any mischief during life : 



