320 VETERINARY BACTERIOLOGY 



New Tuberculin or Bacillus Emulsion of Koch. The cultures 

 are prepared, dried, and ground as for the manufacture of T. R. 

 They are then suspended in glycerinated physiologic salt solution. 

 Some preservative, as phenol, is added. 



This by no means completes the list of preparations of the 

 tubercle bacillus. Most of them are of laboratory significance 

 only, the ones of any considerable practical importance being the 

 old tuberculin and the purified product. 



The use of tuberculin as a prophylactic or cure has not proved 

 successful with the lower animals, nor has it in man when used 

 in large doses. Within recent years it has come into common use 

 in the treatment of human tuberculosis, minute injections being 

 given and care taken that no febrile reaction shall follow. Deter- 

 minations of the opsonic index from time to time have been used 

 with success in the determination of the proper spacing of the in- 

 jections. This method is intended to stimulate opsonin produc- 

 tion and thus aid the body in ridding itself of the bacilli. 



The use of attenuated cultures, and particularly of cultures of 

 the B. tuberculosis from the human, has been advocated by von 

 Behring and others as a practicable vaccination method against 

 tuberculosis in cattle. This method seemed to promise good 

 results at first, but has failed when tried on an extensive scale. 



Antisera have been prepared by repeated injections of various 

 animals with tuberculin T. R. and other products of the tubercle 

 bacillus. None of them has proved successful in conferring passive 

 immunity on other individuals. 



In summary it may be stated that up to the present time no 

 practicable method of immunization against tuberculosis in cattle 

 has been developed, although in man the use of carefully regulated 

 injections of tuberculin is promising. 



Bacteriologic Diagnosis. Tuberculosis may be diagnosed bac- 

 teriologically by staining methods, animal inoculation, agglutin- 

 ation, and the tuberculin reaction. 



Diagnosis by Staining Methods. Tubercle bacilli may be 

 readily recognized by their acid-fast character when examined 

 microscopically. The presence of the characteristic acid-fast 

 bacteria in the tissues or sputum is generally sufficient to establish 

 diagnosis. This is not the case, however, with feces, milk, or 



