MICROSCOPIC EXAMINATION 137 



It is then rinsed in water, and examined or dried and 

 mounted. 



The differentiation between tubercle bacteria and sapro- 

 phytic acid fast organisms. The method of differentiating 

 tubercle bacteria from other members of the acid fast group 

 devised by Fontes and recommended by the Committee on 

 Standard Methods for the Bacteriological Diagnosis of Tu- 

 berculosis 3 of the laboratory section of the American Public 

 Health Association is as follows : 



(a) Stain the preparation by the ordinary carbol fuchsin 

 method, (b) Wash in tap water, (c) Stain about two min- 

 utes with carbol crystal violet (carbol gentian violet gave bet- 

 ter results), (d) Treat with lugol solution until no more 

 metallic mirrors are found. (Decolorization is more easily 

 affected if at this point the preparation is blotted thoroughly.) 

 (e) Treat with aceton-alcohol (equal parts of aceton and al- 

 cohol until the stain ceases to wash out), (f) Rinse thoroughly 

 in distilled water and counterstain with methylene blue. 



Peterson 4 found that it^ was impossible to differentiate 

 betw r een tubercle bacteria and non pathogenic acid fast organ- 

 isms that frequently appear in the feces and milk of cattle by 

 any of the known methods of decoloration. 



Staining spirochaetes. For this purpose Giemsa's stain 

 is quite generally used. The method of Giemsa 5 is really a 

 modification of the Romanowsky method. It is widely appli- 

 cable, being of great value in the staining of the spirochaetes, 

 especially Treponema pallida, Vincent's spirilla, protozoa, and 

 Negri bodies. The stain has been modified several times by its 

 originator, the following being the formula given by him in 

 1904. The substance referred to as azur II and purchasable 

 under that name, consists of pure methylenazur chloralhy- 

 drate combined with an equal quantity of methylene blue 

 chloralhydrate. The substance referred to as azur II-eosin is 

 a combination of this substance with eosin. 



3 Jour, of the Am. Public Health Asso., Vol. I (1911) p. 273. 



4 Peterson. Kept, of the N. Y. State Veterinary College, 1909-1910, 

 p. 65. 



Giemsa. Centralbl. f. Bakt, Bd. XXXVII (1904) p. 308. 



