306 BACTERIOLOGY. 



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 the diagnosis of pathological conditions 

 occurring in these localities. 



According to Hueppe, the differential diagnosis be- 

 tween 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 decolor- 

 ized by treatment with mineral acids, particularly sul- 

 phuric 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. 



To differentiate, then, between the four organisms he 

 recommends the following order of procedure, based on 

 the above reactions : 



1. Treat the preparation, stained with carbol-fuchsin, 

 with sulphuric acid ; the syphilis bacillus becomes de- 

 colorized, the reaction being almost instantaneous. 



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

 if it is the smegma bacillus, this will rob it of its color. 



3. If it is still not decolorized, it is either the lepra 

 or tubercle bacillus. 



Grethe (Fortschritte der Med., 1896, No. 9) recom- 

 mends the following as a trustworthy means of distin- 

 guishing between the tubercle bacillus and the smegma 

 bacillus : stain in hot carbol-fuchsin solution, wash off 



