MYCOBACTERIUM SMEGMATIS. 425 



Upon agar smeared with blood the growth was scanty, like 

 streptococci ; upon glycerin : agar, like dewdrops ; upon 

 the ordinary nutrient media it grows poorly or not at all. 

 The organism was not pathogenic. Czaplewski (eod. loco) 

 has observed a little better growth in a culture, and also 

 yellow, honey-like growths on potatoes. See also Griin- 

 baum (eod. loco, No. 45, p. 1254). 



Stolz (A. H. xxx, 156) has described a very closely 

 related, beautifully branching, but not especially acid- 

 proof organism, which grows very poorly in cultures. 



In practical medicine more interest attaches to the ques- 

 tion whether the smegma bacillus can be differentiated from 

 the T. B. microscopically from its staining properties, than to 

 its cultivation. This delicate question, with which we have 

 had no personal experience, has been the subject of very 

 much investigation. According to Grethe (Fort. d. Med., 

 1896, No. 9), a method of Weichselbaum is to be especially 

 recommended for differential diagnosis. The preparation 

 is stained with hot carbol-fuchsin, thus staining the T. B. 

 and smegma bacilli red ; then a saturated alcoholic solu- 

 tion of methylene-blue is allowed to act upon it (how long 

 is not stated), when gradually, even in the thickest parts 

 of the preparation, the smegma bacilli become blue, the 

 tubercle remaining red. 



According to the careful studies of Bunge and Trauten- 

 roth, there are, as was to be expected, acid-proof smegma 

 bacilli which are quite different from one another, but none 

 of them retains the stain after the following process : 

 Absolute alcohol, three hours; 5% chromic acid, fifteen 

 minutes; carbol-fuchsin, two to three minutes; dilute sul- 

 phuric acid, two to three minutes; concentrated alcoholic 

 solution of methylene-blue, at least five minutes. Hon- 

 sell (C. B. xxi, 700) recommends for the same purpose: 

 Ordinary carbol-fuchsin stain, ten minutes in acid alcohol 

 (absolute alcohol 97 parts, HC1 3 parts), wash in water, 

 washing in alcoholic methylene-blue diluted one-half. 

 Only the T. B. remain red. 



For differential diagnosis, after a preparation has been 

 stained according to the usual method for T. B. with 

 gentle action of acid, and acid-proof red rods are found, 

 then a second preparation must be stained by one of these 



