THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



Vol. X, No. 3.] January, 1917. [7ol'xx%Tl 



A' Study of the Relative Efficiency of the Various Differ- 

 ential Staining Methods Used in Identifying the Tu- 

 bercle Bacillus.* 



BY NOBLE P. SHERWOOD. 



From the Department of Bacteriology of the University of Kansas, Lawrence, Kan.) 



THERE has' been much discussion as to the classification of 

 the tubercle, leprosy, smegma, grass, and butter bacilli. 

 IMigula classifies them with the Bactereacese, while Abbot and 

 othei-s have placed them among the trichobacteria. They differ 

 from the rest of the bacteria in that they contain fats, waxes and 

 alcohols, which render them quite difficult to stain with the ordi- 

 nary basic anilin dyes, such as methylene blue, basic fuchsin, or 

 gentian violet. By covering a dried and fixed preparation of 

 these bacteria on a slide with basic fuchsin or gentian violet, and 

 steaming it from three to five minutes over a free flame, the stain 

 is taken up and retained by these organisms with much greater 

 tenacity than practically any other members of the bacterial king- 

 dom. In fact, when fuchsin is steamed into them they resist de- 

 colorization by three to five per cent aqueous solution of any of 

 the mineral acids for thirty minutes to an hour or even longer, 

 whereas other bacteria are decolorized by this treatment. For 

 this reason the tubercle, leprosy, smegma, grass, and butter bacilli 

 are called the acid-fast group of bacteria. Jordan^ says that this 

 property is due largely to the presence of mykol, one of the higher 

 alcohols. Spores of such organisms as Bacillus suhtilus and Ba- 

 cillus anthracis are also acid-fast, although the respective organ- 

 isms are not. 



This property of resistance to decolorization with mineral acids, 

 when once the organisms have the stain steamed into them, has 



* Read before Kansas Academy of Science January, 1916. 



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