310 ; BACTERIOLOGY. 
III. Staining of Tubercle Bacilli in Tissues. 
Thin sections of tuberculous tissues may be stained 
by the same methods recommended for cover-glass 
preparations, except that it is best not to employ heat 
to any extent. 
The Ehrlich’s Method. Place the paraffin sections in 
aniline fuchsin and leave for from one to twelve hours; 
then decolorize by placing them for about half a minute 
in dilute nitric acid (10 per cent.); wash in 60 per cent. 
alcohol until no more color is given off; counter stain 
for two or three minutes in a saturated aqueous solu- 
tion of methylene-blue, wash in water; dehydrate with 
absolute alcohol; clear up in oil of cedar or xylol and 
mount in xylol balsam. 
Method of Ziehl-Neelson. Stain the section in warmed 
carbol-fuchsin solution for one hour, the temperature to 
be not over 45° to 50°C. Decolorize for a few seconds 
in 5 per cent. sulphuric acid, then in 70 per cent. alcohol, 
and from this on as in the Ehrlich method. 
