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 \ 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. 

 i, 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. 



