ACID-PROOF BACTERIA. 357 



present in the smegma. It is known, therefore, as the 

 smegma bacterium (bacterium smegmatis). In this 

 secretion it is found in clumps located upon or within 

 epithelial cells. It stains by the method used in staining 

 bacterium tuberculosis. It has no pathogenic power. 

 It is said to have been artificially cultivated upon coag- 

 ulated hydrocele fluid and in milk. 



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 

 numbers. Inasmuch as they are occasionally encoun- 

 tered under circumstances that might lead one to look for 

 true tubercle bacilli, and since they possess certain pecu- 

 liarities through which it has been the custom to identify 

 bacillus tuberculosis i. e., retention of the stain when 

 acted upon by acids or alcohol, and a more or less deli- 

 cate, beaded form the possibility of their being con- 

 founded with that organism is obvious. In consequence 

 they have received a great deal of attention during the 

 past few years. 



Space does not permit of a description of the twenty 



