MYCOBACTERIUM TUBERCULOSIS. 417 



tion of a wound of the hand by sputum (injury by a 

 broken sputum glass) have the force of experimental 

 demonstration. 



Toxins, Immunity, Immunization. From old cul- 

 tures of the T. B. upon glycerin bouillon by means of 

 evaporation and precipitation with alcohol, an albumi- 

 nous body is obtained, formerly known as ''tuberculin," 

 and now as "old tuberculin." When this is injected in 

 cases of tuberculosis (Koch), it exerts a peculiar influence 

 upon the tuberculous process. Very weak doses call forth 

 a moderate increase of inflammation at the seat of the 

 tuberculous disease, with fever, while healthy persons ex- 

 hibit neither fever nor noticeable local symptoms. As 

 pointed out by Buchner and Romer, the proteins of other 

 bacteria have an exactly similar effect upon tuberculosis. 



While Koch and some of his students obtained good, or 

 at least satisfactory, curative and immunizing results with 

 the old tuberculin in man and animals, most investiga- 

 tors, after a brief enthusiasm, abandoned the preparation 

 as very rarely useful, but also as very often injurious. 

 Then Koch sought to improve his preparation, and, under 

 the name of " Tuberculin TR," recommended a new pre- 

 paration, prepared as follows : 



Virulent T. B. are. dried and then pulverized, suspended 

 in water, again pulverized, and then separated by centrifu- 

 gation into a sediment, and a supernatant fluid. The latter 

 is decanted and only the further aqueous extract is em- 

 ployed, which is obtained by pulverizing and by separa- 

 tion of the solid ingredients by centrif ugation (Deut. med. 

 Wochenschr., 1897, 209). 



H. Buchner, following the method of E. Buchner, has 

 obtained a * ' tuberculoplasmine ' ' by trituration and com- 

 pression of fresh tubercle bacilli, concerning which no 

 practical results appear to have been published. 



Koch has completely immunized a series of guinea-pigs 

 with his TR by means of carefully but actively increasing 

 doses. Complete immunity was obtained about two or 

 three weeks after the administration of large doses. Also 

 Koch has obtained a cure in previously infected guinea- 

 pigs, but the treatment must be instituted not later than 

 eight to fourteen days after infection, because of the rapid 

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