142 .l<'ri;.\AT> oi- TiiK M nciiKi.L SociKTY [Dec. 



of an anuria is more dependent upon the extent to which the 

 epithelial element of the kidney becomes damaged than upon 

 any lack of response upon the part of the renal vessels. 



This observation lias been confirmed in the following way. 

 Six animals have been rendered nephritic by the usual 

 amount of uranium. One kidney which serves as a control 

 (fi.g. 4) has been removed under very light ether anesthesia. 

 The animals were then given Grehant's anesthetic in the 

 usual amount. When the flow of urine had been greatly re- 

 duced, or an anuria had developed, the remaining kidney was 

 removed and studied histologically in comparison with the 

 control kidney (fig. 5). 



By employing such a method it was found that associated 

 with any decided and continued reduction in the flow of urine 

 which was not increased by a rise in general blood pressure 

 or by a vasodilation of the renal vessels from caffein, the 

 epithelial element of the kidney showed the same type of de- 

 generative change which had been found in the group of ani- 

 mals that were anuric from the commencement of the experi- 

 ment (Group IT, table 2) and the same type of changes which 

 had developed in those animals of the control groups (Groups 

 I and III) that late in the experiment became anuric. 



In conclusion; the anuric and diuretic groups of animals 

 show no changes in the vascular element of the kidney which 

 will serve to differentiate them histologically. The essential 

 pathological difference between the two groups lies in the 

 difference in the degree and extent of the involvement of the 

 epithelial element of the kidney. 



The epithelial damage in the diuretic animals is slight; 

 in the anuric group it is extensive. 



DiscussiOiSr 



It has been shown in the animals which have been used 

 in the present investigation that the renal vessels remain re- 

 sponsive to stimuli which either lead to their dilatation with 

 an increase in kidney volume or to their constriction with a 

 decrease in kidnev volume. 



