46 MANUAL OF BACTERIOLOGY. 



(e) Wash in water. 



(f) Stain with methylene-blue solution (see page 41) 

 thirty seconds. 



(g) Wash in water. 



(h) Examine in water directly, or after drying and 

 mounting in Canada balsam. Tubercle bacilli take a brilliant 

 red color; other bacteria and the nuclei of cells are stained 

 blue. 



Gabbett's Method. This method is very popular and 

 widely used on account of its convenience. It is not as 

 reliable as the one just given. 



Gabbett's solution : 



Methylene-blue I to 2 grams. 



25 per cent, watery solution of sulphuric acid. looc.c. 



(a) The cover-glass preparation is to be made, dried, and 

 fixed by passing through the flame three times. 



(b) The carbol-fuchsin stain is applied from two to five 

 minutes to the cover-glass, held in forceps or in a watch- 

 crystal ; it need not be warmed. 



(c) Wash in water. 



(d) Gabbett's solution is applied for one minute. 



(e) Wash in water. The preparation should have a blue 

 color. It may be examined in water directly or after dry- 

 ing and mounting in Canada balsam. 



Gabbett's method has the advantage of decolorizing the 

 preparation and staining the background with methylene- 

 blue at the same time. Tubercle bacilli are colored a 

 brilliant red; most other bacteria and the nuclei of cells are 

 colored blue. The acid-proof bacilli mentioned on page 44 

 would keep the red stain also, in most cases, and would prob- 

 ably be confused with tubercle bacilli. 



Of the numerous methods of staining tubercle bacilli only 

 a few others can be mentioned. Aniline-water fuchsin, 

 aniline-water gentian-violet, or carbol-fuchsin may be used. 



