292 TUBERCULOSIS 



of dried and powdered acid-fast bacilli, the Timothy-grass bacillus being 

 most suitable ; growth is slow, the colonies appearing after about four 

 weeks in the primary cultures. 



Smegma Bacillus. This organism is of importance, as in form and 

 staining reaction it somewhat resembles the tubercle bacillus and may be 

 mistaken for it. ' It occurs often in large numbers in the smegma prpe- 

 putiale and in the region of the external genitals, especially where there is 

 an accumulation of fatty matter from the secretions. Morphologically it 

 is a slender, slightly curved organism, like the tubercle bacillus, but 

 usually distinctly shorter (Fig. 88). Like the tubercle bacillus, it stains 



with some difficulty and 



/ - resists decolorisation with 



*' strong mineral acids. Most 



- >*"* observers ascribe the latter 



* k fact to the fatty matter with 



,^ *^ \f which it is surrounded, and 



^ j ^^ t ' . find that if the specimen is 



treated with alcohol the or- 



f ganism is easily decolorised. 



Czaplewski, however, who 



. % * * has cultivated it on various 



/ g '\ '" ' \ ' % media, finds that in culture 



*fv V* x / it shows resistance to decolor- 



<f \ isation both with alcohol and 



^ 4 ' with acids, and considers, 



*/ ^ 01 therefore, that the reaction 



*^L ,\., 



ing fatty medium. We have 

 found that in smegma it can 

 be readily decolorised by a 



FIG. 88. Smegma bacilli. Film preparation minute's exposure to alcohol 



of smegma. after the usual treatment with 



Ziehl-Neelsen stain, x 1000. sulphuric acid, and thus can 



be readily distinguished from 



the tubercle bacillus. We, moreover, believe that minor points of differ- 

 ence in the microscopic appearances of the two organisms are quite sufficient 

 to make the experienced observer suspicious if he should meet with the 

 smegma bacillus in urine, and lead him to apply the decolorising test. 

 Difficulty will only occur when a few scattered bacilli retaining the fuchsin 

 are found. 



Its cultivation, which is attended with some difficulty, was first effected 

 by Czaplewski. On serum it grows in the form of yellowish-grey, 

 irregularly rounded colonies about 1 mm. in diameter, sometimes 

 becoming confluent to form a comparatively thick layer. He found that 

 it also grew on glycerin agar and in bouillon. It is non- pathogenic to 

 various animals which have been tested, unless very large doses are used. 

 Cowie has found that acid-fast bacilli are of common occurrence in the 

 secretions of the external genitals, mammae, etc., in certain of the lower 

 animals, and that these organisms vary in appearance. He considers that 

 the term "smegma bacillus" probably represents a number of allied 

 species. 



The question may be asked Do these results modify the 

 validity of the staining reaction of tubercle bacilli as a means of 



