244 J. W. GROVES ON SECTIONS OF ANIMAL TISSUES. 



Picro-carmine, which was first employed by Ranvier, has been 

 used and prepared in several ways, but perhaps the best is Schafer's, 

 viz. : — 



1. Add to a saturated solution of Picric Acid in water a strong 

 solution of Carmine in Ammonia to saturation. 



2. Evaporate the mixture to one-fifth its bulk over a water bath, 

 allow to cool, filter from deposit and evaporate to dryness, when 

 picro-carmine is left as a crystalline powder of red-ochre colour. 



Sections should be stained in a 1 per cent., aqueous solution, 

 requiring ten minutes for a good result ; they should then be washed 

 with distilled water, and mounted in glycerine. If it be desired to 

 preserve them in balsam, after staining, transfer direct to alcohol 

 methylated, then to absolute alcohol, after which they may be 

 cleared in oil of cloves or benzole, and then mounted. 



Carmine and indigo carmine adopted by Merbel, gives a blue and 

 a red stain, and is said to be extremely selective. 



To prepare the Red Fluid, For the Blue Fluid 



Mix each in a mortar, and allow to stand, then pour off the 

 supernatant fluid. 



1. If the sections have been hardened in chromic acid, picric 

 acid, or a bichromate, they should be washed in water till no tinge 

 appears. 



2. Place them in alcohol, then 



3. For fifteen or twenty minutes, in the two fluids mixed in equal 

 parts, after which 



4. Wash them in a saturated aqueous solution of oxalic acid, 

 where they should remain a rather shorter time than in the staining 

 fluids. 



5. When sufficiently bleached, wash them in water, to get rid of 

 oxalic acid, then 



6. They may be passed through spirit and oil of cloves, and be 

 mounted as usual in balsam. 



For Staining Blue and Red by means of Anilin Dyes 

 the best method is that Mr. Gilburt recommends for staining plant 

 sections. Dissolve : — 



Magenta crystals ... ... gr \ in | ^ , 



Alcohol ... ... ... Ji ) 



