IMMUNITY IN TUBERCULOSIS 391 



particularly in cattle. Thus McFadyean found that 

 heifers which had previously been subjected to repeated 

 doses of tuberculin (old) in some cases resisted infection 

 with virulent bacilli. Behring also employed human 

 tubercle bacilli for the vaccination of cattle with satis- 

 factory results. His tulase likewise confers immunity 

 when given either by the mouth or by the stomach. 



Theobald Smith also concludes that vaccination of 

 calves with the human type of bacillus is harmless, and 

 that the procedure leads to a relatively high resistance to 

 fatal doses of the bovine bacillus. 



Calmette x states that bovine bacilli cultivated for 

 several generations upon a glycerin-bile medium develop 

 a race which is non-tuberculigenous and is tolerated by 

 bovines, that it acts as a vaccine, and by intra-venous 

 inoculation protects the animals from both experimental 

 and natural infection. 



Clinical Examination 



I. The " complement-fixation " test was first used in tuberculosis 

 by Wassermann and Briick. The method has been further elabo- 

 rated by Emery. 2 He makes use of a standard emulsion of 

 tubercle bacilli in salt solution, containing about 4 per cent, by 

 volume of solid bacillary substance. This is sterilised by inter- 

 mittent sterilisation and keeps for four to six weeks. Bacilli 

 from various sources vary somewhat, and the emulsion should be 

 standardised so that, under the conditions of the test, the comple- 

 ment of normal serum should be just completely absorbed in about 

 twenty minutes. One part of the serum to be tested is mixed with 

 4 parts of the bacillary emulsion in a small tube (e.g. a Durham's 

 tube) in the water-bath, the time of mixing being accurately noted. 

 After two and a half minutes' incubation, 4 volumes of the mixture 

 are removed and mixed with 1 volume of sensitised corpuscles (i.e. a 



1 Ann. de VInst. Pasteur, xxxiv, 1920, p. 554. 



2 Lancet, 1911, vol. i, p. 485. 



