IMMUNIZATION AGAINST HYDROPHOBIA 77 



reaction than the old tuberculin. Like the old, it is used in the 

 treatment of lung, bone, laryngeal, and skin tuberculosis. It 

 certainly causes a local reaction about tubercular foci, and no doubt 

 aids in the formation of an active immunity to the disease. 



The dose of tuberculin for testing purposes varies from -^ of a 

 milligram to 5 mgs. and in case the first dose does not produce a 

 reaction, it should be repeated. For therapeutic purposes one 

 begins with an injection of .000000 1 grm. or smaller and increases 

 slowly according to the patient's condition. Tuberculin should 

 only be administered by experts. 



Mallein. 



Mallein is a preparation made from the toxin of the glanders 

 bacilli, and is prepared precisely as the old tuberculin. By increas- 

 ing the virulence of the glanders bacilli, by passage through a series 

 of guinea pigs, a highly virulent bacillus is obtained. It is then 

 grown in glycerinized bouillon for a month at 37 C. The resulting 

 fluid is sterilized by heat and filtered through a Pasteur filter. The 

 filtrate is evaporated to half its quantity, and to this a small amount 

 of carbolic acid is added in order to preserve it. Of the mallein thus 

 prepared i c.c. should kill a rabbit in one to two weeks. 



In a horse with glanders, the injection of mallein is followed by a 

 large painful swelling at the injection site. With this there is a rise 

 of temperature, which is the diagnostic reaction that indicates infec- 

 tion with glanders. In this respect the reaction is like tuberculin. 

 In healthy horses no rise of temperature follows the injection, and 

 the resulting swelling more quickly subsides. Mallein has been 

 used as a prophylactic agent against glanders with some success. 



Immunization Against Hydrophobia. 



While the actual causal agent of hydrophobia has thus far eluded 

 bacteriologists, certain well marked histologic lesions have been 

 discovered in the ganglia of the central nervous system, and in the 



