TUBERCLE BACILLUS 1 99 



would cause the reaction. This shows that the grass bacilli and 

 the organism infecting the cow are not identical. We are able, in 

 this roundabout way, to differentiate the various acid-fasts (Moel- 

 ler.) By using carbol fuchsin as a stain, and a twenty-five percent 

 solution of H 2 SO 4 as a decolorizer, and after allowing the latter to 

 act for sixteen hours, it has been found that all of the "acid-fasts," 

 except the tubercle bacilli, are decolorized, but this is not always 

 reliable. The tubercle bacillus resists this acid solution seventy- 

 two hours. By using a concentrated aqueous solution of methylene 

 blue as a stain for ten minutes, at room temperature, the tubercle 

 bacillus is not colored, while the smegma, timothy-hay, and lepra 

 bacilli are well stained. The surest way to differentiate the tubercle 

 bacillus from other acid-fast organisms is by animal inoculations. 



For the discovery of tubercle bacilli in materials apt to contain 

 other acid-fasts several methods are now employed. The material 

 to be examined may be stained in the ordinary manner and then 

 decolorized by Pappenheim solution or a saturated solution of 

 methylene blue in absolute alcohol. Preparations should be dried 

 thoroughly before using such solutions. For " enriching" in 

 organisms, the bulk of material, e.g., sputum, is suspended in 

 15 percent antiformin (the proprietary name for a mixture of 

 Javelle water and caustic soda), allowed to stand in the incubator 

 for a while and the supension centrifuged. In the sediment many 

 more bacilli will be found than in the same bulk of the raw specimen. 

 This antiformin seems to dissolve mucus, tissue and all bacteria 

 except tubercle bacilli. The method can be used to procure 

 cultures. 



Even with this method organisms escape detection in certainly 

 tuberculous lesions. This is said to be due to non-acid fast, but 

 gram staining granules. They are said to be found by a modified 

 Gram-Weigert staining, according to Much. Such specimens 

 should always be injected into guinea pigs for corroboration. 



Immunity. It is possible to immunize cattle against virulent 

 bovine tubercle bacilli by inoculating them previously with a cul- 



