THE USE OF STRONGER STAINING SOLUTIONS. 125 



(3) Sixty per cent, alcohol, in which they remain 

 until no more colouring matter is given off from them. 

 Bach section must be carefully spread out in the al- 

 cohol with a needle, as otherwise it rolls up, or forms 

 folds and wrinkles, which can never be wholly got 

 rid of afterwards. 



(4) The section is next examined in water. If 

 bacteria are to be seen, although only indistinctly, on 

 account of the too great coloration of the rest of the 

 section, it can be treated agaiu with acid and alcohol, 

 as described in paragraphs 2 and 3. If, on the other 

 hand, a contrast staining is desired, the section is 

 taken out of the water and placed in 



(5) Aqueous solution of vesuvin (that is to say, if 

 the first staining was effected by means of either blue 

 or violet ; if, however, this was done with fuchsine, 

 methylene blue must now be used). The sections are 

 left in for from five to ten minutes, after which they 

 are 



(6) Washed with distilled water until no more 

 colouring matter is given off; they are then examined 

 as described in paragraph 4. If the sections are to be 

 kept as permanent preparations, they must be further 

 treated as described in Chapter XII. 



This method is also especially useful for the dis- 

 covery of tubercle bacilli. 



III. (1) The sections are-«stained as in II. 1 with 

 aniline water Solution of gentian violet-. 



