170 APPLIED IMMUNOLOGY 



grammes of the original dried whole tubercle bacilli 

 or two milligrammes of the active solid substance. 



New Tuberculin (" B, E.''), — Appreciating the 

 fact that the injection of dead bacilli, as compared 

 with " T. R.," caused an increase in the agglutination 

 of the blood, Koch advocated a second new tuberculin, 

 a bacillary emulsion {Bacillen Emulsion or B, E,), 

 This is prepared by pulverizing finely a virulent cul- 

 ture of B, tuberculosis, and suspending one part of the 

 powder in one hundred parts each of distilled water 

 and glycerin. It is standardized so that one cubic 

 centimetre contains ^ve milligrammes of dried sub- 

 stance in suspension. 



It will be borne in mind that the " new tuber- 

 culins " are suspensions, not solutions, hence they must 

 be thoroughly shaken before use. IMoreover, therapeu- 

 tically, reactions are not so noticeable as after the use 

 of " old tuberculin " and the resultant immunity is 

 greater and more durable, both of which have added 

 to their popularity. 



Denys' Tuberculin {'' B, F"),—ln 1905 Denys 

 recommended the filtrate from bouillon cultures of 

 tubercle bacilli. This tuberculin is commonly known 

 as Bouillon Filtrate or " B. F." It is essentially the 

 same as Koch's old tuberculin, differing only in that 

 no heat is used in its preparation. It contains all the 

 normal soluble products of the B, tuberculosis. 



