246 TUBERCULOSIS. 



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 were occa- 

 sionally present, but no caseation, and which were charac- 

 terised by more growth of fibrous tissue than in ordinary 

 tubercle. The subject has been very fully investigated 

 with confirmatory results by Straus and Gamaleia, who find 

 that, if the number of bacilli introduced into the circula- 

 tion is large, there result 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 experi- 

 ments the bacilli were killed by exposure to a temperature 

 of 115 C. for ten minutes before being injected. Similar 

 nodules can be produced 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 experi- 

 ments, 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. The 

 long period during which the tubercle bacillus, as com- 

 pared with other organisms, retains even when dead its 

 morphological and staining characters, is a very striking 

 feature. Stockman has recently found that an animal in- 

 oculated with large numbers of dead tubercle bacilli after- 

 wards gives the tuberculin reaction. 



