88 



most fixers may be used, Mercuric chlorid, Zenker's fluid, Flem- 

 ming's fluid or Hermann's fluid. If, however, it is desired to pre- 

 serve the mucus granules (mucinogen?) in the cell-body, alcoholic 

 or picric acid fixers are usually required, and the tissue at no time 

 subsequently should be placed in water or aqueous solutions. Be- 

 cause of its acid character mucus stains w T ith basic stains, the first 

 two methods given below being very selective. If cell granules are 

 desired, remember the caution as to the avoidance of water. 



233. Mucicarmine. ( 103). Fix as recommended above. 

 Stain paraffin sections 1 to 24 hours; wash in water, dehydrate, 

 clear and mount in balsam. It may be used diluted with 50% or 

 67% alcohol. 



234. Muchematein. ( 93). Employ in the same manner as 

 mucicarmine. The alcoholic formula is indicated if cell granules 

 are to be preserved. 



Staining of the nuclei with hematoxylin ( 88, 89) or carmine ( 98) 

 or elastin stain ( 125) may be previously given; a picro-fuchsin 

 stain may follow it. Excess of alum (aluminium salts) or presence 

 of acid must be avoided, hence wash thoroughly with water if there 

 has been previous staining. 



235. Basic anilin stains usually give sharp, often differen- 

 tial stains (metachromasia) for mucus. Methylene blue, toluidin 

 blue, or gentian violet may be recommended. Safranin after Flem- 

 ming's fluid fixation often gives a delicate stain for mucus. 



E. Micro-chemical Tests. 



Micro-chemical tests for inorganic elements must occasionally 

 be employed, particularly in cytological work. The methods have 

 been largely elaborated by Macallum to whose papers references are 

 given. 



236. Iron. (a). Berlin Blue Reaction. Alcohol fixation and 

 the freezing microtome should be employed. Rinse sections in 

 distilled water, 2% potassium ferrocyanate, 4 to 5 hours, 1% Hcl 

 alcohol several hours, rinse in water, dehydrate, clear with clove oil; 

 balsam. A carmine stain may be given, before or afterwards. 



(b) Ammonium Sulphide Reaction. Place sections in am- 

 monium sulphide solution (freshly prepared) for 5 to 20 minutes; 

 (dark green color); rinse quickly with water, dehydrate, clear in 

 clove oil, mount in balsam. 



