84 APPLIED BACTERIOLOGY 



Ehrlich's Aniline Gentian Violet.— This powerful staining 

 solution is prepared as follows : 



Saturated alcoholic solution of gentian violet 11 c.c. 

 Saturated aqueous solution of aniline ... 100 c.c. 



The aniline solution is prepared by shaking about 5 c.c. of 

 colourless aniline with 100 c.c. of distilled water for some 

 time, when most of the aniline passes into solution. This 

 solution is now filtered through a wet filter, which will 

 prevent the undissolved aniline from passing through into 

 the filtrate. The gentian violet in this stain can be replaced 

 by fuchsine or methyl violet, using 11 c.c. of saturated 

 alcoholic solution. 



The solution prepared as above should not be kept for 

 longer than about two weeks, but should be made fresh and 

 filtered before use. 



Ziehl's Carbol-Fuchsine. — This stain is much the same as 

 the above, except that, instead of aniline, carbolic acid 

 (phenol) is used as the mordanting agent. The solution 

 is prepared by taking : 



Fuchsine ... ... ... ... 1 gramme 



Phenol ... ... ... ... 5 grammes 



Distilled water ... ... ... 100 c.c. 



The fuchsine is very finely powdered and added to the 

 water, together with the phenol ; the whole is allowed to 

 stand, with frequent agitation, until dissolved. Frequently 

 10 c.c. of alcohol are added to dissolve the fuchsine more 

 easily ; but this is not necessary, and the addition reduces 

 the staining power of the solution. The solution is filtered 

 before use. This solution has the advantage over those 

 prepared with aniline, that it will keep any length of time, 

 although its staining power is not so great. 



loffler's Methylene Blue. — This solution is prepared by 

 taking : 



