19H^ Action of Various Diuretics 49 



ium and killed by shooting, so as to eliminate the effect of the 

 anesthetic, the kidney shows in the gross a severe congestion of 

 the outer cortex and of the medulla. Between the cortico- 

 medullary boundary zone and the superficial portion of the cor- 

 tex there is a mid zone which appears distinctly pale as con- 

 trasted with other portions of the kidney. 



In young animals which have been subjected to a similar ex- 

 perimental technique, this pale zone of the cortex is either ab- 

 sent, or is much less pronounced, while in general the cut sur- 

 face of the kidney appears uniformly and severely congested. 



The histological study of tissue from the kidneys of these two 

 groups of animals which have not received an anesthetic shows a 

 vascular reaction which is manifested by an engorgement of the 

 glomerular vessels, but without any intro-glomerular or inter- 

 tubular exudate. The epithelium of the tubules shows a shrink- 

 age which gives to the lumen of the tubules an unusual promi- 

 nence (figure 1 and 2). Thus far the grosser pathological 

 changes in the two groups of animals are similar. The changes, 

 however, differ very strikingly in this respect. The adult ani- 

 mals show a high degree of fatty degeneration in the tubules of 

 the medullary rays and in the distal convoluted tubules, while 

 tissue from the kidneys of the young animals show this fatty 

 change to a much less extent, though when it develops the same 

 tubules are involved. This is one of the striking differences in 

 the pathological response of these two groups of animals. 



When adult animals and young animals are anesthetized by 

 the same quantity of Grehant's anesthetic per kilogram, the 

 gross and microscopic pathology of the kidneys shows the fol- 

 lowing differences. 



In the adult animals the cut surface of the kidney does not 

 show such a severe congestion and the mid-cortical zone of pale- 

 ness has perceptibly increased in distinctness and extent. The 

 microscopic study shows that the fatty changes which have 

 been induced by the uranium have been very greatly increased 

 by the anesthetic and that the pale zone of the cortex is, in part, 

 due to these changes. As a result of the effect of the enesthetic 

 the epithelium of the tubules of the labyrinth, especially the 



