62 TUBERCULIN THERAPY 



Although tuberculin cannot be considered as the aggressin or toxin of 

 the tubercle bacilli, it simulates these substances with sufficient closeness 

 to warrant its use in tuberculosis. It brings about an immunity against 

 some of the poisonous products of the tubercle bacillus, leaving the others 

 to be taken care of by the natural fighting powers of the individual. 



The knowledge that this old tuberculin represents only a partial aggres- 



Various sin, or toxin, and by that is meant that it does not contain all the neces- 



Tuberculin sary elements for the establishment of a true immunity, has led to the 



Preparations, production of a large group of preparations which are supposed to supply 



the missing properties of the old tuberculin. 



The more important of these preparations were originated by Robert Koch. 

 Those which are of frequent use are: 



a. Old tuberculin (T. Tuberculin) preparation described on page 45. 



b. Original old tuberculin (T. O. A. Tuberculin Original Alt.) 



The latter consists of the original nitrate of the tubercle bouillon culture and varies 

 from the old tuberculin in that it is not heated and reduced to i/io its volume. 

 The omission of heating is certainly not without effect, inasmuch as high heat 

 modifies in some way the soluble bacterial substances. This preparation has 

 not been used therapeutically by Koch himself. Spengler and especially Denys, who 

 have made wide use of it under the name of "Le bouillon nitre," have been its main 

 supporters. 



c. Vacuum tuberculin (V. T.) is the original tuberculin which has been reduced in 

 vacuum to i/io its volume. 



d. The aqueous tuberculin of Maragliano (Tuberculina Aquosa) is closely allied to 

 the above tuberculins. It contains all the water soluble extracts of the living tubercle 

 bacilli obtained by extraction of the living bacteria in distilled water, followed by 

 nitration. As is evident, it is prepared on the same principle as Brieger's bacterial 

 extracts and Wassermann-Citron's artificial aggressins. 



The above mentioned tuberculin preparations are all very much alike 

 in that they contain the soluble bacterial elements. Their action there- 

 fore corresponds more or less to that of old tuberculin. 



Another set of preparations have as their basis the insoluble 



New elements of the bacteria and cannot as such, in either living or 



Tuberculin dead form, be absorbed. Since, however, the absorption 



Preparations. O f bacteria is a prerequisite to their proper action, it was 



necessary to so alter the body substances of these bacteria that 



they could be taken up. Koch found that this was best accomplished by 



thoroughly pulverizing the bacilli in large mortars. And by this means the 



first preparation which he obtained was 



e. New tuberculin T. R. (Koch) (Tuberculin Rlickstand or Residual 

 Tuberculin). 



Cultures of young tubercle bacilli are thoroughly dried in vacuum and finely 

 ground in mortars. The pulverized bacilli are agitated in distilled water and the 



