Toxic Products 



721 



by marked hyperemia of the perituberculous tissue, with tran- 

 sudation of serum, softening of the tuberculous mass, and absorp- 

 tion] 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 



Fig. 286. — Massive culture of the tubercle bacillus upon the surface of glycerin- 

 bouillon, used in the manufacture of tuberculin. 



areas, could occasion a widespread metastatic invasion of the disease. 

 Old tuberculous 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 recep- 

 tion, 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 tuber- 

 46 



