Staining 311 



immersed, smeared side up, in a small dish of Ehrlich's 

 anilin-water gentian violet solution : 



Anilin 4 



Saturated alcoholic solution of gentian violet 11 



Water 100 



and kept in an incubator or paraffin oven for about twenty- 

 four hours at about the temperature of the body. Slides 

 upon which smears have been made can be placed in Coplin 

 jars containing the stain and stood away in the same manner. 

 When removed from the stain, they are washed momentarily 

 in water, and then alternately in 25-33 P er cent, nitric acid 

 and 60 per cent, alcohol, until the blue color of the gentian 

 violet is entirely lost. It must be remembered that the 

 action of the strong acid is powerful, and that too long a 

 time must not be allowed for its application. A total 

 immersion of thirty seconds is enough in most cases. After 

 final thorough washing in 60 per cent, alcohol, the specimen 

 is counterstained in a dilute aqueous solution of Bismarck 

 brown or vesuvin, the excess of stain washed off in water, 

 and the specimen dried and mounted in balsam. The 

 tubercle bacilli are colored a fine dark blue, while the pus- 

 corpuscles, epithelial cells, and other bacteria, having been 

 decolorized by the acid, will appear brown. 



This method, requiring twenty-four hours for its com- 

 pletion, has fallen into disuse, as it is desirable to know in 

 the briefest possible time whether bacilli are present in the 

 sputum or not. 



ZiehVs Method. Among clinicians, Ziehl's method of 

 staining with carbol-fuchsin has met with just favor. It is 

 as follows: After having been spread, dried, and fixed, 

 the cover-glass is held in the bite of an appropriate forceps 

 (cover-glass forceps), or the slide spread at one end is held 

 by the other end as a handle, and the stain (fuchsin, i ; 

 alcohol, 10; 5 per cent, phenol in water, 100) dropped upon 

 it from a pipet. As soon as the entire smear is covered 

 with stain, it is held over the flame of a spirit lamp or 

 Bunsen burner until the stain begins to volatilize a little. 

 When vapor is observed, the heating is sufficient, and the 

 temperature can be maintained by intermittent heating. 



If evaporation take place, a ring of incrusted stain at the 

 edge prevents the prompt action of the acid. To prevent 



