740 Tuberculosis 



Tuberculin does not exert the slightest influence upon the 

 tubercle bacillus, but acts upon the tuberculous tissue, aug- 

 menting the poisonous influence upon the cells surrounding 

 the bacilli, destroying their vitality, and removing the condi- 

 tions favorable to bacillary growth, which for a time is 

 checked. This action is accompanied by marked hyperemia 

 of the perituberculous tissue, with transudation of serum, 

 softening of the tuberculous mass, and its absorption into 

 the blood, a marked febrile reaction resulting from the 

 intoxication. 



Virchow, who well understood the action of the tuberculin, 

 soon showed that as a diagnostic and therapeutic agent in 

 man its use was attended by grave dangers. The destroyed 

 tissue was absorbed, but with it some of the bacilli, which, 

 being transported to new tissue areas, could occasion a 

 widespread metastatic invasion of the disease. Old tuber- 

 culous lesions which had been encapsulated were sometimes 

 softened and broken down, and became renewed sources of 

 infection to the individual, so that, a short time after an 

 enthusiastic reception, tuberculin was placed upon its proper 

 footing as an agent valuable for diagnosis in veterinary 

 practice, but dangerous in human medicine, except in cases 

 of lupus and other external forms of tuberculosis where the 

 destroyed tissue could be readily discharged from the surface 

 of the body. 



Many, however, continued to use it, and Petruschky* has 

 reported, with careful details, 22 cases of tuberculosis which 

 he claims have been cured by it. 



Recently there has been a return to the use of tuberculin 

 for the diagnosis of tuberculosis, it being claimed that by the 

 use of minute doses, several times repeated, the charac- 

 teristic reaction and a positive diagnosis can be obtained 

 without danger. 



von Pirquetf found that if a drop or two of Koch's (old) 

 tuberculin is placed upon the skin of a tuberculous child, 

 and a small scarification made through the drop with a 

 sterile lancet, a small papule develops at the point of inocula- 

 tion that is not unlike a vaccine papule. It is at first bright, 

 later on dark red, and remains for a week. Out of 500 tests 

 made, the results were positive in nearly every case of 

 clinical tuberculosis. The most characteristic reactions 



* "Berliner klin. Wochenschrift," 1899, Dec. 18-25. 

 t Ibid., May 20, 1907. 



