256 BOTANICAL MICROTECHNIQUE. 



5. Staining Tubercle-Bacilli. 



473. The Bacilli of tuberculosis and of leprosy are char- 

 acterized by a peculiar behavior with staining media which 

 makes possible the staining of them alone in a mixture of 

 Bacteria, and therefore their certain distinction from other 

 species of Bacteria. Of the numerous methods recom- 

 mended for staining tubercle Bacilli, only the following,, 

 due to Czaplewski (I), need be here referred to ; and I have 

 obtained excellent results with it. 



Cover-glass preparations are treated, after fixing, first for 

 a minute with carbol-fuchsin ( 468) heated to boiling. They 

 are then washed with the so-called Ebner's fluid * until 

 hardly a trace of color can be seen, are then repeatedly 

 rinsed with pure alcohol, and stained again with a mixture 

 of three parts water and one part concentrated alcoholic 

 solution of methylene blue. This is then rinsed off with 

 water, and the preparation is dried and mounted, in the 

 usual way, in balsam. 



If a mixture of tubercle Bacilli and other Bacteria, for 

 example, which can easily be prepared by mixing pure cul- 

 tures, be treated in this way, it will be found that, with the 

 exception of the very rare \Q-prz-Bacilli, only the tubercle- 

 Bacilli are colored red, while all other Bacteria are blue. 



474. The staining of tubercle Bacilli in sections can be 

 accomplished by essentially the same methods. If one has 

 paraffine sections attached to the slide with albumen ( 52), 

 they may be heated in carbol-fuchsin, whose action for a 

 few minutes is sufficient. But if the sections will not endure 

 heating, the fuchsin solution must be allowed to act for a 

 longer time (about 24 hours). It is also better to wash the 

 methylene blue from sections with alcohol, and to transfer 

 them to balsam through xylol. 



In preparations treated in this way, only any tubercle 

 Bacilli that may be present are stained red ; all other Bac- 

 teria, and the nuclei of the tissue, are blue. 



* This consists of 20 parts water, 100 parts alcohol, .5 part hydrochloric 

 acid, and .5 part sodium chloride. 



