DIFFERENTIAL DIAGNOSIS OF BACILLI. 265 



particularly in the microscopic examination of urine 

 and pathological secretions from the genito-urinary 

 tract and from the rectum, for of the three species two 

 are frequently found in these localities, viz., the so-called 

 smegma bacillus, located in the smegma and often seen 

 beneath the prepuce and upon the vulva, both normally 

 and in disease, and the bacillus of syphilis, described by 

 Lustgarten as contained in syphilitic manifestations, 

 particularly in primary sores. The third organism of 

 this group — the bacillus of leprosy — because of its rarity, 

 is not so likely to cause error in diagnosis of troubles 

 occurring in these localities. 



According to Hueppe, the differential diagnosis 

 between the four organisms depends upon the following 

 reactions : When stained by the carbol-fuchsin method 

 commonly employed in staining the tubercle bacillus the 

 syphilis bacillus becomes almost instantly decolorized 

 by treatment with mineral acids, particularly sulphuric 

 acid, whereas the smegma bacillus resists such treatment 

 for a much longer time, and the lepra and tubercle 

 bacillus for a still longer time. On the other hand, if 

 decolorization is practised with alcohol, instead of acids, 

 the smegma bacillus is the first to lose its color. The 

 bacillus tuberculosis and the bacillus of leprosy are 

 conspicuously retentive of their color even after treat- 

 ment with both acids and alcohol. 



Tp differentiate, then, between the four organisms he 

 recommends the following order of procedure, based on 

 the above reactions : 



1. Treat the stained preparation with sulphuric 

 acid; the syphilis bacillus becomes decolorized, the 

 reaction being almost instantaneous. 



2. If it is not at once decolorized, treat with alcohol ; 



