288 TUBERCULOSIS 



(2) Immunity Phenomena in Tuberculosis. Koch's Tuber- 

 culin-R. The study of immunity phenomena in tuberculosis 

 dates from the introduction by Koch in 1897 of the substance 

 denominated by him "Tuberculin-R." 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 water 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 substances present 

 in the glycerin-bouillon extracts originaUy 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, -^ J^ mgrm. being the initial dose, tuberculin-R 

 was said to produce immunity against the original extract, 

 against tuberculin-O, and against living and virulent tubercle 

 bacilli. Further research has not confirmed this last result. 



Itoch's New Tuberculin. Another preparation has also been 

 introduced, known as " Koch's new tuberculin " (Bazillenemul- 

 sion). 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. 



Scientific enquiry into the action of these new tuberculin 

 preparations has resulted in attempts being made to recognise in 

 their effects phenomena similar to those produced by organisms 

 such as the typhoid and cholera bacteria, the investigation of 

 which has brought out the complex processes at work in the 

 reaction of an organism against invading bacteria. The phen- 

 omena manifested in such cases consist in the formation of 

 immune-bodies, precipitins, agglutinins, and opsonins. 



(1) Immune-bodies and Precipitins. Evidence for the 

 existence of these in tuberculosis has been sought by applying 



