260 TUBERCULOSIS 



toxic effect, and that trituration of the bacilli increases the 

 poisonous content of a culture, it is inferred that we have to deal 

 with endotoxins, but beyond this statement we cannot go. 

 Hitherto no success has attended attempts to gain a closer 

 knowledge of the nature of such substances. It has been stated 

 that albumoses of a special kind are present in tuberculin, but 

 nothing definite has emerged from the investigation of these 

 bodies. 



Active Immunisation against the Tubercle Bacillus. 

 Koch's Tuber culin-R. Our knowledge here centres round the 

 substance introduced by Koch in 1897 under the name of 

 " Tuberculin-R," or the new tuberculin. Koch's new researches 

 consisted (1) of an attempt to immunise animals against the 

 tubercle bacillus by employing its intracellular toxins ; (2) of 

 trying to utilise such an immunisation to aid the tissues of an 

 animal already attacked with tubercle the better to combat the 

 effects of the bacilli. The method of obtaining the intracellular 

 toxins was as follows. Bacilli from young virulent cultures were 

 dried in vacuo, and disintegrated in an agate mill, treated with 

 distilled water and centrifugalised. The clear fluid was decanted,, 

 and is called by Koch " Tuberculin-O." The remaining deposit 

 was again dried, ground, treated with w^ater and centrifugalised, 

 the clear fluid being again decanted, and this process was 

 repeated with successive residues till no residue remained. 

 These fluids put together constitute the " Tuberculin-R." 



From the fact that tuberculin-O gave no cloudiness when 

 glycerin was added, Koch concluded that it contained the sub- 

 stances present in the glycerin-bouillon extracts originally used 

 by him, and he held this was borne out by the readiness with 

 which a tuberculin reaction could be caused by it. Similarly, as 

 tuberculin-R gave a cloudiness with glycerin and did not readily 

 originate a reaction, he considered that it contained different 

 products of the bacillus. When injected into animals in 

 repeated and increasing doses, T Jy- mgrm. being the initial dose, 

 tuberculin-R is said to produce immunity against the original 

 extract, against tuberculin-O, and against living and virulent 

 tubercle bacilli. Another preparation has also been introduced 

 known as " Koch's new tuberculin " (Baiillenemulsion). This is 

 an emulsion of ground tubercle bacilli in water containing 50 per 

 cent of glycerin ; it thus really contains both tuberculin-O and 

 tuberculin-R. Both, especially tuberculin-R, have been used for 

 the treatment of tuberculosis in man, especially for early localised 

 lesions. In the case of both substances commencing with from 

 to yj^ mgrm, gradually increasing doses were given every 



