ACTION OF DEAD TUBERCLE BACILLI 281 



rence 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. 



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 without has been possible, their recognition 

 as tubercle bacilli cannot be established by microscopic examina- 

 tion 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 Rabinowitch 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 hwnian 

 body, except in such rare instances as to be practically negligible. 

 (To this statement the case of the leprosy bacillus is of course 

 an exception.) Accordingly, up till now, the microscopic ex- 

 amination of sputum, etc., cannot be said to have its validity 

 shaken, and we have the results of enormous clinical experience 

 that such examination is of practically unvarying value. Never- 

 theless the facts established with regard to other acid-fast bacilli 

 must be kept carefully in view, and great care must be exercised 

 when only one or two bacilli are found, especially if they deviate 

 in their morphological characters from the tubercle bacillus. 



Action of dead Tubercle Bacilli. The remarkable fact has 

 been established by independent investigators, that tubercle 

 bacilli in the dead condition, when introduced into the tissues 

 in sufficient numbers, can produce tubercle-like nodules. Prudden 

 and Hodenpyl, by intravenous injection in rabbits of cultures 

 sterilised by heat, produced in the lungs small nodules in which 

 giant-cells, but no caseation, were occasionally present, and 

 which were characterised by more growth of fibrous tissue than 

 in ordinary tubercle. The subject was very fully investigated 

 with confirmatory results by Straus and Gamaleia, who found 

 that, if the number of bacilli introduced into the circulation were 

 large, there resulted very numerous tubercle nodules with well- 

 formed giant-cells, and occasionally traces of caseation. The 

 bacilli can be well recognised in the nodules by the ordinary 

 staining method. In these experiments the bacilli were killed 

 by exposure to a temperature of 115 C. for ten minutes before 

 being injected. Similar nodules can be produced by intra- 



