VALIDITY OF THE STAINING REACTION. 257 



ment with sulphuric acid, or by using the acid-alcohol decoloriser, and thus 

 can be readily distinguished from the tubercle bacillus. We, moreover, believe 

 that minor points of difference in the microscopic appearances of the two 

 organisms are quite sufficient to make the experienced observer suspicious if 

 he should meet with the smegma bacillus in urine, and lead him to apply the 

 decolorising test. Difficulty will only occur when a few scattered bacilli 

 retaining the fuchsin occur. 



There doubtless occur in smegma distinct acid-resisting bacterial species. 

 One of these, cultivated by Laser, Czaplewski, and Neufeld, morphologically 

 resembles the diphtheria bacillus, and loses its acid-resisting property in arti- 

 ficial cultures. The bacillus cultivated from smegma by A. Moeller by the aid 

 of human serum is probably identical with the genuine smegma bacillus first 

 described by Tavel, Alvarez, and Matterstock, and resists decolorisation by 

 acids even after prolonged artificial cultivation. This latter bacillus closely 

 resembles the tubercle bacillus in morphology, but it grows at lower tempera- 

 tures in ordinary media and is non-pathogenic. 



Cowie has recently found that acid-fast bacilli are of common occurrence 

 in the secretions of the external genitals, mammae, etc., in certain of the lower 

 animals, and that these organisms vary in appearance. He considers that the 

 term " smegma bacillus " probably represents a number of allied species. 



Validity of the staining reaction. The question may be 

 asked Do these results modify the validity of the staining 

 reaction of tubercle bacilli as a means of diagnosis ? The source 

 of any acid-fast bacilli in question is manifestly of importance, 

 and it may be stated that when these have been obtained from 

 some source outside the body, or where contamination from with- 

 out has been possible, their recognition as tubercle bacilli cannot 

 be established by microscopic examination alone. In the case of 

 material coming from the interior of the body, however, sputum, 

 etc., the condition must be looked on as different, and although an 

 acid-fast bacillus (not tubercle) has been found by Rabinowitsch 

 in a case of pulmonary gangrene we have no sufficient data for 

 saying that acid-fast bacilli other than the tubercle bacillus flourish 

 within the tissues of the human body except in such rare in- 

 stances as to be practically negligible. (To this statement the 

 case of the leprosy bacillus is of course an exception.) Accord- 

 ingly, up till now, the microscopic examination of sputum, etc., 

 cannot be said to have its validity shaken, and we have the 

 results of enormous clinical experience that such examination 

 is practically of unvarying value. Nevertheless the facts es- 

 tablished with regard to other acid-fast bacilli must be kept 

 carefully in view, and great care must be exercised when only 



