44 MANUAL OF BACTERIOLOGY. 



or violet color, as the case may be, has disappeared, which 

 requires one to several minutes. 



(d) Wash thoroughly in alcohol. 



(e) Wash in water. 



(/) Use hematoxylin as a contrast-stain for fuchsin prepara- 

 tions, and carmine for gentian-violet preparations. In the 

 latter case it is better to stain with carmine before staining 

 the bacilli. The carmine is not affected by the subsequent 

 treatment. 



(g) Wash in water. 



(h) Alcohol. 



(i) Xylol. 



(j) Balsam. 



Tubercle bacilli may also be stained in sections by Gram's 

 method; but they require to be stained in the gentian-violet 

 aniline oil for a longer time than do other bacteria which are 

 stained by this method. The same statement also applies to 

 the leprosy bacilli when stained by Gram's method. 



Nuclear stains, which may be used as contrast-stains for 

 section : 



DELAFIELD'S HEMATOXYLIN. 



Hematoxylin crystals 4 grams. 



Alcohol 25 c.c. 



Ammonia alum 50 grams. 



Water 400 c.c. 



Glycerin 100 c.c. 



Methyl-alcohol 100 c.c. 



Dissolve the hematoxylin in the alcohol, and the ammonia 

 alum in the water. Mix the two solutions. Let the mixture 

 stand four or five days uncovered; it should have become a 

 deep purple. Filter and add the glycerin and the methyl- 

 alcohol. After it has become dark enough, filter again. Keep 

 it a month or longer before using; the solution improves with 



