THE ACID-PROOF BACTERIA. 365 



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called "bacillus of syphilis," that he had discovered in 

 primary syphilitic lesions and in the secretions from 

 syphilitic ulcers. In staining reactions, but more espe- 

 cially in morphology, this organism is said to be stri- 

 kingly like bacterium tuberculosis. He found it in the 

 tissues, usually within the bodies of large, apparently 

 swollen, cells. He found it not only in the primary sores 

 about the genitalia, but in the syphilitic lesions of the 

 remote organs as well. As this organism has never 

 been cultivated artificially, and as the majority of com- 

 petent observers, working upon the most promising 

 material, have failed to detect it, the prevailing opinion 

 is to the effect that the organism is not regularly asso- 

 ciated with syphilis and has nothing to do with its 

 causation. 



It is not unlikely that bacterium smegmatis and bac- 

 terium syphilidis are identical. 



THE ACID-PROOF BACTERIA. In addition to the 

 species mentioned, quite a group of other "acid-proof" 

 bacteria, as they are called, have been described by dif- 

 ferent investigators. They are characterized by staining, 

 as does bacterium tuberculosis, by retaining the stain 

 to a greater or less extent when treated with acids and 

 alcohol, and by being in many instances strikingly like 

 bacterium tuberculosis in their morphology. The mem- 

 bers of this group seem to be distributed pretty widely 

 in nature. They have been detected in non-tuberculous 

 sputum, in gangrene of the lung, in the normal intestinal 

 contents of man and domestic animals, in the soil, in 

 fodder i. e., grass, hay, and seed in manure, and in 

 butter. They are not regularly found under any of these 

 conditions, and they are rarely present in very large 



