34 BIOLOGY OF PNEUMOCOCCUS 



fuchsin. The method, he claimed, gave a clear image suitable for 

 photography. Hiss 650 in 1902 gave two procedures, the first, a gen- 

 tian violet-potassium carbonate method, the other, and a better 

 one, a preliminary treatment with gentian violet or fuchsin fol- 

 lowed by washing with 20 per cent copper sulfate solution. The 

 Welch* formula of glacial acetic acid, followed by aniline-water 

 gentian violet gives clear pictures of the capsule. These methods 

 are widely used and give satisfactory results. 



Buerger (1905) 168 described a different and also reliable proce- 

 dure, but the intricacy of the technique prevented general adoption. 

 Malone, 860 after a preliminary staining with Congo red, treated 

 the film with dilute hydrochloric acid in alcohol, counterstaining 

 with methyl violet. Malone claimed that by this technique he 

 was able to demonstrate capsules when the Hiss method failed. 

 Wherry 1515 mixed a suspension of pneumococci in diluted serum 

 with an equal amount of 0.05 normal hydrochloric acid, spread the 

 mixture in a thin film, fixed the film with heat, and stained it 

 quickly with carbol gentian violet. Leifson 797 applied to films a 

 mixture of a saturated aqueous solution of ammonia or potassium 

 alum, tannic acid in water, 95 per cent ethyl alcohol, and saturated 

 alcoholic solution of basic fuchsin. He followed this treatment with 

 methylene blue in aqueous borax solution. This method never came 

 into general use. The Huntoon* technique is suitable only for 

 cultures and not for animal exudates. India ink is the choice of 

 some bacteriologists. It is a negative stain, in that the medium on 

 the slide is colored black, while the cells and the capsule are un- 

 stained. Levy-Bruhl and Borin, 805 however, reported that this stain 

 outlined the capsules on Type III organisms when no albuminous 

 substances were present in their "T" medium, but failed with other 

 types of pneumococci grown on this special substrate. For general 

 purposes, however, the Burke or Sterling modifications of the 

 Gram stain suffice, while the Gram stain, the Gram-Weigert, or the 



* Zinsser and Bayne-Jones.is™ 



