ACTION OF DEAD TUBEKCLE BACILLI 287 



has been found by Babinowitch 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 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. In 

 such cases inoculation may be the only reliable test. 



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 occa- 

 sionally traces of caseation. The bacilli can be well recognised in the 

 nodules by the ordinary staining method. Similar nodules can be pro- 

 duced by intraperitoneal injection. Subcutaneous injection, on the other 

 hand, produces a local abscess, but in this case no secondary tubercles are 

 found in the internal organs. Further, in many of the animals inoculated 

 by the various methods, a condition of marasmus sets in and gradually 

 leads to a fatal result, there being great emaciation before death. These 

 experiments, which have been confirmed by other observers, show that 

 even after the bacilli are dead they preserve their staining reactions in 

 the tissues for a long time, and also that there are apparently contained 

 in the bodies of the dead bacilli certain substances which act locally, 

 producing proliferative and, to a less extent, degenerative changes, and 

 which also markedly affect the general nutrition. S. Stockman has found 

 that an animal inoculated with large numbers of dead tubercle bacilli 

 afterwards gives the tuberculin reaction. 



Practical Conclusions. — From the facts above stated with 

 regard to the conditions of growth of the tubercle bacilli, their 

 powers of resistance, and the paths by which they can enter the 

 body and produce disease (as shown by experiment), the manner 

 by which tuberculosis is naturally transmitted can be readily 

 understood. Though the experiments of Sander show that 

 tubercle bacilli ,can multiply on vegetable media to a certain 



