(3) Flush once with alcohol.
(4) Apply tincture of iodin for one to two minutes.
(5) Thoroughly wash off the iodin with alcohol and dry in the air.
(6) Stain about three seconds with weak anilin-gentian-violet freshly made up as follows: Anilin oil, 10; water, 100; shake; filter; and add 5 c.c. of a saturated alcoholic solution of gentian violet.
(7) Rinse off the stain with 2 per cent. solution of sodium chlorid, mount in this solution, and examine with a one-twelfth objective.
Buerger suggests a very useful variation as follows: After the alcohol wash and drying, the specimen is stained by Gram's method ([p. 39]), counter-stained with aqueous solution of fuchsin, washed, and mounted in water. The pneumococcus holds the purple stain, while all capsules take on the pink counter-stain.
Smith's Method.—This somewhat complicated, but not difficult, method is very useful as a routine stain for the sputum. It brings out well all cells and all bacteria except the tubercle bacillus.
(1) Make thin smears, dry, and fix in a flame in the usual manner.
(2) Apply anilin-gentian-violet a few seconds, gently warming until steam rises.
(3) Rinse in water.