256 TUBERCULOSIS 



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- 

 peritoneal 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 

 extent at warm summer temperature, it is doubtful whether all 

 the conditions necessary for growth are provided to any extent 

 in nature. At any rate, the great multiplying ground of tubercle 

 bacilli is the animal body, and tubercular tissues and secretions 

 containing the bacilli are the chief, if not the only, means by 

 which the disease is spread. The tubercle bacilli leave the body 

 in large numbers in the sputum of phthisical patients, and when 

 the sputum becomes dried and pulverised they are set free in 

 the air. Their powers of resistance in this condition have already 

 been stated. As examples of the extent to which this takes 

 place, it may be said that their presence in the air of rooms 

 containing phthisical patients has been repeatedly demonstrated. 

 Williams placed glass plates covered with glycerine in the 

 ventilating shaft of the Brompton Hospital, and after five days 

 found, by microscopic examination, tubercle bacilli on the surface, 

 whilst Klein found that guinea-pigs kept in the ventilating shaft 

 became tubercular. Cornet produced tuberculosis in rabbits by 



