THE SUPRARENAL SYSTEM 273 



with osmium, the preparations are treated with alcohol, chloro- 

 form, or xylol, or cleared and mounted in Canada balsam or 

 bergamot oil, it will be seen that the granules have become dis- 

 solved, leaving a diffuse brown coloration in the cells. Mounted 

 in oil of cloves, however, they remain black for weeks, and in 

 glycerine for even longer. 



The cortical granules are best seen by means of the specific 

 dyes for fat, provided that, after fixing the portions of suprarenal, 

 no powerful fat solvents such as ether, chloroform, or alcohol, are 

 employed in the further treatment. The best method of preparing 

 the specimens is to fix in formalin, cut frozen, and stain with 

 sudan III or scarlet R, when the granules will take on a red 

 colour. If subsequently treated with osmium (twenty-four hours 

 in Altmann's mixture), however, the granules in these frozen sec- 

 tions unlike fat, which usually stains black immediately take on 

 a brown colour and become black only when further treated with 

 alcohol. If, however, after treatment with osmium, the frozen 

 sections are treated with bergamot oil, the brown granules will 

 immediately dissolve ; if ether or xylol are used, solution follows 

 very rapidly ; chloroform and benzine are slower in their effects, 

 but solution follows within a quarter of an hour. If, after treat- 

 ment with osmium, the granules are treated with alcohol until 

 they become black (twenty-four hours), they will still dissolve 

 rapidly and entirely in bergamot oil, though to a less extent in 

 the other fat solvents ; they will still dissolve, though very 

 slowly, in ether and xylol, but they cease to be soluble in benzine 

 and chloroform. 



For the study of the cytological structure of the suprarenal 

 cortex, the best results are obtained by fixing in formalin, formalin- 

 Mtiller, Zenker's fluid, and particularly in the different osmium 

 solutions. By these methods the cortical granules are at first 

 browned and become black only after treatment with alcohol. 



On account of the solubility of the granules in ether and 

 xylol, these reagents cannot be used to prepare sections for paraffin 

 imbedding; the granules are, however, insoluble in chloroform 

 or benzine, and these may be employed. 



Sections should not be cleared in xylol or mounted in Canada 

 balsam, as the cortical granules are to a large extent dissolved 

 by these, so that, after a few days, only a few blackened or brown, 

 osmium-stained cortical cells remain. When mounted in oil of 

 cloves, the granules last for some weeks. The most satisfactory 

 results are obtained by clearing and mounting sections which 

 have been stained with osmium in glycerine or a saturated solution 

 of potassium acetate. 



In addition to the lipoid granules of the cortex, Alt- 

 mann's fuchsinophile granules stain readily, even in embryonic 

 suprarenals (Plecnik). These are round bodies of the same size 

 as the lipoid granules; they are composed of several layers 

 18 



