772 PATHOGENIC MICROORGANISMS 



Two vaccines are prepared. Vaccine I consists of the juice of 

 infected meat, dried and heated to 100 C. for six hours. Vaccine II 

 is a similar meat- juice heated to 90 C., for the same length of time. 

 By the heating, the spores contained in the vaccines are attenuated 

 to relatively different degrees. Vaccine I in quantities of 0.01 to 

 0.02 c.c. is emulsified in sterile salt solutions and injected near the 

 end of the tail of the animal to be protected. A similar quantity of 

 Vaccine II is injected in the same way fourteen days later. 



This method has been retained in principle, but largely modified 

 in detail by various workers. Kitt 37 introduced the use of the dried 

 and powdered whole meat instead of the meat juice, and made only 

 one vaccine, heated to 94 C., for six hours. This method has been 

 largely used in this country. 38 Passive immunization with the 

 serum 39 of actively immunized sheep and goats has been used in 

 combination with the methods of active immunization. 



37 Kitt, Ref . from Grassberger und Schattenfroh, loc. cit. 



38 Report of Bureau of Animal Ind., Wash., 1902. 



39 Arloing, Leclainche et Vallee, loc. cit. 



