METHODS OF STUDYING BACTERIA 53 



XVI. Capsule Stain of Welch 



(i) Pour glacial acetic acid on film. After a few seconds 

 replace with anilin-water gentian-violet without washing in 

 water. (2) Remove all acid by several additions of stain, 

 and allow it to act for three to four minutes. (3) Wash and 

 examine in salt solution 0.8-2.0 per cent. 



XVII. Romanowsky Stains 



A compound dye originally used for malarial parasites, but 

 now employed in some of its modifications in staining blood- 

 films, bacteria in tissues, and protozoa generally. 



The stain is difficult to prepare, and can be purchased of 

 supply houses to better advantage. 



The chief modifications are: 



Leishman's stain, consisting of a i per cent, solution methyl- 

 ene-blue, to which 0.5 per cent, sodium carbonate has been 

 added and allowed to stand for twelve hours in incubator at 

 65 C., and then ten days at room temperature, and a solu- 

 tion of eosin (i: 1000) in water. Equal parts of these solu- 

 tions are mixed and allowed to stand for six hours. After it 

 has been washed and dried, the precipitate is dissolved in 

 methyl-alcohol. 



Giemsa Stain: 



Azur II. eosin 3 parts 



Azur II 8 " 



Glycerin (pure) 250 



Methyl-alcohol 250 " M. 



Azur is a mixture of methylene-blue and eosin prepared in 

 a special way. 



Jenner's Stain. 1.2 per cent, aqueous solution of water- 

 soluble eosin; i per cent, aqueous solution methylene-blue 

 (Grubler); equal parts of each. Mix; allow to stand twenty- 

 four hours, wash the precipitate, dry it, dissolve 0.5 gm. in 

 100 c.c. methyl-alcohol. 



J. H. Wright's Stain. Made in much the same way as 

 Leishman's. The precipitate is not washed, but the satur- 



