80 CARMINE STAINS. 



epithelium, and lastly, other structures. A nuclear stain. 

 Permanent. 



137. Aqueous Ammonia-Carmine (GIERKE, Zeit f. wiss. Mik., 

 1, 1884, p. 76). To powdered carmine add sufficient ammonia 

 to dissolve it completely, and leave the solution exposed to 

 the air in a capsule for several days. Filter, and keep the 

 solution in a stoppered bottle. Do not use it for staining 

 before two years at least. By that time it will contain no 

 more free ammonia, but carbonate of ammonia in its place. 

 For staining, add to distilled water as many drops of the solu- 

 tion as will give a liquid of a pale rose tint. Sections should 

 remain in the liquid for twenty-four hours. It is very impor- 

 tant to carry out the staining as directed, slowly, in dilute 

 solutions. In this way chromic objects stain well. For sec- 

 tions of encephalon the hardening ought to have been done in 

 a chromic liquid, and all treatment with alcohol ought to be 

 carefully avoided until staining is accomplished; alcohol should 

 not even be used for wetting the section knife. 



138. Aqueous Ammonia- Carmine (HoYEE, Biol. Centralb. ii, 1882, 

 p. 17). " Dissolve 1 gr. of carmine in a mixture of 1 2 c.c. of strong 

 liquor ammonise and 6 8 c. c. of water. Heat in a glass vessel on a sand 

 bath until the excess of ammonia has evaporated. (So long as free ammonia 

 is present large bubbles are formed in the fluid, and the latter shows the 

 usual dark purple colour of carminate of ammonia. When the free ammonia 

 has evaporated small bubbles appear, and the solution takes a brighter red 

 tint.) The solution is left to cool and settle, and by filtering the bright 

 red deposit (which may be used over again) is separated from the neutral 

 dark fluid, which by the addition of chloral hydrate can be kept for a long 

 time " (see also below, 141). 



139. Aqueous Ammonia- Carmine, other Formulae (RANVIEK, Tnufr 

 Technique, p. 97. HUXLEY and MAETIN, Pract. Elemen. Biol., p. 2(>S. 

 FEEY, Le Microscope, p. 167). 



)3. Neutral and Acid. 



140. Ranvier's Neutral Carmine (kindly communicated by Dr. 

 MALASSEZ, see Traite des Mothodes Techniques, fyc., of Lee et 

 Henneguy, p. 82). Make a simple s<>lut ion of carmine in wnter 

 with a slight excess of ammonia ;md expose it to the air in ;i 

 deep crystallizing dish until it is entirely dried up. It should 

 be allowed to putrefy if possible. Dissolve I lie dry deposit in 

 pure water, and filter. 



