STAINING AND MOUNTING. 203 
4. Stain in carbol-thionin for ten minutes or quarter 
of an hour. 
5. Wash in running water for ten minutes or longer. 
This removes the stain from the tissues before decolor- 
ising the bacteria, and a fairly differentiated specimen 
may be obtained if the processes of staining and wash- 
ing are carried out for suitable lengths of time. 
Unna’s polychrome methylene blue may be used in a 
similar manner, and gives even better results. The 
staining should be continued for about ten minutes and 
decolorisation effected by very short immersion in dilute 
acetic acid (about 4 per cent.) followed by a good wash- 
ing in pure water. 
6. Remove as much water from the section as you 
can without actually drying it by the cautious use of 
clean blotting paper. Then apply anilin oil until the 
section becomes perfectly translucent. Anilin oil mixes 
with water on the one hand and xylol on the other and 
can be used for dehydration just as alcohol was; the 
process is slower and several lots of the oil must be used. 
7. Wash off all the anilin oil by successive applications 
of xylol. The permanence of the preparation will depend 
on the thoroughness with which this step is carried out. 
8. Balsam and cover-glass. 
(4). Staining sections to demonstrate the tubercle 
bacillus. Applicable to the leprosy bacillus also. 
1, 2, and 3. Xylol, alcohol, and water, as before. 
4. Carbol-fuchsin heated until the steam rises for five 
minutes or longer, care being taken that the section 
does not dry up. Or the slide may be immersed in the 
stain and kept in a warm place for twenty-four hours. 
5. Dilute sulphuric acid until only a faint pink tinge 
appears after washing. This will generally require an 
immersion of ten minutes or more. 
