TUBERCULIN PREPARATIONS. 57 



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 

 combatted by the natural fighting powers of the individual. 



The knowledge that this old tuberculin represents only a partial aggressin, 

 Various or toxin, and by that is meant that it does not contain all the necessary 

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

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



the missing properties of the old tuberculin. 



The most important of these preparations was made by Robert Koch. Those which 

 are of frequent use are: 



a. Old tuberculin (T. Tuberculin) preparation described on page 47. 



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 without 

 doubt 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 Maraglianos (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 

 filtration. 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 therefore 

 corresponds more or less to that of old tuberculin. 



Another set of preparations have as their basis the insoluble 



New bacterial substance which 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 Ruckstand or Residual 

 Tuberculin. 



The technique is carried out by making cultures of young tubercle bacilli which 

 are then thoroughly dried in vacuum and finely ground in mortars. The pulverized 

 bacilli are agitated in distilled water and the turbid mass is centrifugalized. The 

 sediment thus obtained composes the T. R. or the tubercle bacilli residue. 



T. R. therefore contains the aqueous insoluble components of the tubercle bacillus, 

 while the soluble ones are retained in the opalescent supernatant fluid which Koch calls 

 TO (Tuberculin Original). 



