STAINING 753 



must be greatly overstained with the nuclear dye, since the picric acid 

 will decolorize hematein. 



Saturated aqueous solution of picric acid 100 c.c. 



1 per cent, aqueous solution of acid f uchsin .... 5 c.c. 



The acid fuchsin solution must be boiled well and filtered before 

 adding to the picric acid solution,, otherwise a precipitate will occur 

 and the mixture be spoiled. 



1. Stain with Delafield's or Bohmer's hematoxylin, fifteen to thirty 

 minutes. 



2. Wash well with water. The sections should be almost black. 



3. Stain with picro-f uchsin, three to five minutes. 



4. Einse quickly in water (water removes the fuchsin). 



5. Dehydrate in absolute alcohol, clear, and mount. 



Weigert's Elastic Tissue Stain. This method gives a specific stain 

 for elastic fibers; it may be used alone, or in combination with hema- 

 tein and picro-fuchsin. 



1 per cent, aqueous solution of basic fuchsin . . 100 c.c. 



2 per cent, aqueous solution of resorcin 100 c.c. 



Boil the mixture in a porcelain dish, and while hot, add liquor 

 ferri sesquichlorati (Pharm. Ger., Ill), 25 c.c. 



Heat and stir for five minutes; a heavy precipitate is formed. Cool 

 and filter. Dry the precipitate in a porcelain dish over a water bath 

 or sand bath. Dissolve the dried precipitate in 200 c.c. of 95 per 

 cent, alcohol, filter and replace the alcohol lost by evaporation. Add 

 4 c.c. of pure hydrochloric acid. 



Tissues should be stained twenty to sixty minutes, then thoroughly 

 washed in water, dehydrated, cleared, and mounted. 



The following method gives very beautiful results : 



1. Stain in Delafield's or Bohmer's hematoxylin, twenty to thirty 

 minutes. 



2. Wash well with water. 



3. Stain in Weigert's elastic tissue stain, twenty minutes. 



4. Wash in water. 



5. Stain in picro-fuchsin, three to five minutes. 



6. Rinse quickly in water. 



7. Dehydrate in absolute alcohol, clear, and mount. 



Orcein may also be employed as a specific stain for . elastic fibers. 

 Mallory's Connective Tissue Stain. This method is applicable 



