349 



conditions. They are however noost noticeable and abundant in the 

 kidney because it is exposed to dilute fluid i. e. the urine when it is 

 poor in solutes and acts as a hypotonic medium to the tissues. The 

 vesicles are found not only within the tubules and capsular space but 



Fig. 1. Fig. 2. 



Fig. 1. Tubule from cortex macerated ^/^ hr. in distilled water. The lumen is 

 filled with vesicles. X 430. 



Fig. 2. Tubule from cortex macerated 1 hr. in distilled water. Vesicles are seen 

 in the process of formation. X 430. 



also within the epithelial cells and in the interstitial clefts. They 

 may be protruding from the cells or arising from the capillary tuft of 

 the glomerulus or even from a basement membrane where the epi- 

 thelium has been removed. This proves that they are not, as has 

 been suggested, essentially a secretion of the epitheUum. 



Schaumstruktur. 

 In pathological kidney cells we often find the appearance which 

 BüTSCHLi describes as Schaumstruktur. This merges into reticular 

 formation and on a smaller scale repeats 

 the change, described above, of the vesicles 

 into a reticulum in the lumen. These ap- 

 pearances of Schaumstruktur can also be 

 produced by maceration several hours in 

 distilled water. 



Fig. 3. Schaumstruktur from cortex macerated in 

 distilled water 3 hrs. X 780. 



Imbrication. 

 Epithehum with the cell axis on the bias has been described as 

 a normal condition in some kidneys. Be that as it may, some kidneys 



