348 



epithelium. The cytoplasm may be hyaline or granular with granules 

 of varying size. The rods of Heidenhain are generally seen as 

 granular threads extending from the basement membrane toward the 

 periphery. A non-granular thread-like structure, ergastoplasm, may 

 also be seen extending from the basement membrane toward the peri- 

 phery. Between the meshes of the ergastoplasm there is a faint 

 suggestion of alveolar structure. Cell inclusions are often present 

 such as fat, lecithin, and glycogen. These may dissolve out in the 

 preparations leaving empty spaces. The epithelium of the convoluted 

 tubules generally appears as a syncytium, especially when it is low, 

 but when it is high intercellular borders may be seen. The border 

 of the cell toward the lumen may assume various appearances. It 

 may be a simple membrane thin or thick. It may appear hyaline, 

 striated or brush-like with variations between these forms. Large 

 vesicles are occasionally seen within the lumen. The changes enumerated 

 below due to maceration may be considered to a great extent ex- 

 aggerations of what we may see under normal conditions. 



Technique. 

 The tissues were all taken directly from the freshly killed animal, 

 placed in the macerating fluid and from there after varying periods of 

 time tranferred directly to Zenker's fluid. They were sectioned in 

 paraffin 5 i-l thick and stained with iron-alum-haematoxylin followed 

 by acid fuchsin and picric acid. This was found in general a most 

 satisfactory stain but Delafield's haematoxylin followed by eosin was 

 better to show the Schaumstruktur. 



Vesicles. 

 A prominent feature of many nephritis sections is the presence 

 of spherical forms within the lumen of the convoluted tubules. They 

 are found sometimes in acute but most commonly in chronic nephritis. 

 The most typical ones with a strong tonoplastic membrane are found 

 in the dilated tubules of chronic interstitial nephritis. They may be 

 few in number or so numerous as to become jammed together and 

 lose their spherical aspect. Their edges coming in contact give a 

 reticuled appearance to the lumen. These vesicles can be produced 

 artificially by maceration in distilled water, but they do not appear 

 after maceration in 9% NaCl or more concentrated solutions. This 

 seems to make their production a mechanical aflair depending on the 

 laws of osmosis. Their presence is not peculiar to the kidney but 

 they may be found in almost any gland under certain pathological 



