(Stain with a plasma stain, if contrast is desired.)
4. Dehydrate in 80 and 95 per cent alcohols.
5. Clear in carbol-xylol.
6. Mount in balsam.
Over-ripened hæmatoxylins may stain reddish or even brownish, and too diffusely. In such cases the celloidin will be deeply stained. The addition of alum-water to the stain may counteract the fault. Alum-hæmatoxylins must always be filtered before using, as precipitates are constantly formed as the result of oxidation.
2. Carmine. Carmine is the coloring matter of cochineal, the dried bodies of the female coccus cacti, and is obtained chiefly from Honduras. The coloring principle is carminic acid (C2H22O12). When combined with alum, borax, lithium, etc., carmine gives a good, permanent nuclear stain, varying from reddish violet to deep scarlet. It is used chiefly in pathology to give a contrasting nuclear stain to the various pigments, and when specific blue stains have been used for fibrin, mucin, bacteria, elastic tissue, etc., or when a blue injection-mass has been used. Alum-carmine is the most precise nuclear stain. Differentiation with acid-alcohol is necessary after staining with borax- or lithium-carmine. Lithium-carmine is on the whole the best of the three for use as a contrast-color to the various pigments.
a. Alum Carmine.
Carmine ½-1 grm., 1-5 per cent alum solution 100 cc.; boil 20 minutes; cool; filter. Add crystal of thymol as preservative.
1. Stain 15 minutes to several hours.
2. Wash thoroughly in distilled water.