188 JOHN SUNDWALL 



5) isaniin blue — a very faint blue stain limited chiefly to the 

 interstitial tissue. Certain cells in the alveolus also appeared 

 more deeply stained than did others. 



6) trypan red — a diffuse light red stain. 



7) sulforhodamin — a diffuse faint light red stain. 



8) pyronin — intercellular canals and lumena of ducts stained. 



Granules in fixed and stained preparations. Zenker's. At- 

 tention has already been called to the fact that the granules of 

 the intercalary duct when fixed in Zenker's solution stain deeply 

 in muchaematein and mucucarmin while the other granule 

 stains do not affect them. The tubules, on the other hand, show 

 no deeply stained granules but appear under low power only 

 diffusely and faintly stained. Careful examination of these 

 tubules with the oil emersion, however, shows various intensities 

 of staining reactions on the part of the cells — which may be 

 generally classed as follows: a) Large rounded bulging cells as 

 seen in the fresh sections. Here a faintly stained cytoplasmic 

 network is seen throughout the cell. The meshes of this net- 

 work are round and appear to hold large unstained granules. 

 The nucleus is angular or flattened and lies against the base of 

 the cell. In fresh tissues the granules of these cells are dis- 

 tinctly seen and the intergranular network is not seen, while in 

 Zenker's muchaematein preparations the granules are not 

 stained but the intergranular network is distinctly seen, b) 

 Cells more cylindrical in form frequently showing indented 

 sides as if they had been pushed in by the round bulging cells 

 (also seen in fresh preparations). They possess very faintly 

 stained granules. The nuclei as a rule are round or oval, c) So 

 called transitional cells. In the use of the term transitional 

 cells reference is made to those cells that mark as a rule the 

 junction of the intercalary duct and tubule. They possess 

 granules similar in structure and staining reaction to those of 

 the intercalary duct and are always preserved in Zenker's solu- 

 tion (figs. 11 and 12). 



Bensley's solutions. For the fixation of granules in the tubules, 

 it was necessary to use other solutions than Zenker's. The 

 granules in tubules are best preserved by Bensley's sublimate 



