570 MICROBIOLOGY OF SPECIAL Il^XJSTEIES 



serum possesses potency the test pigs should remain in a normal con- 

 dition throughout the test, except for the presence of thermal reactions 

 and slight clinical symptoms, while the two control pigs should show 

 severe S3anpt6ms in five or six days and should die in less than 

 fifteen days. 



■ The practical method of treatment in the field consists in the simul- 

 taneous injection of the h)rperimmune serum and virus (double treat- 

 ment), into healthy hogs for the purpose of immunization. The 

 amount of hyperimmune serum which should be injected varies from 

 30 c.c. to 90 c.c, depending upon the weight of the hog to be treated. 

 Thus, a hog weighing 34 kg. to 45 kg. (75 to 100 pounds) usually re- 

 ceives 40 c.c. of serum, together with i c.c. of virus. The usual dose 

 of virus for hogs above 34 kg. (75 pounds) weight is 2 c.c. For pigs 

 weighing less than 23 kg. (50 pounds) }4 c.c. of virus should be 

 injected. 



Anthrax Vaccink. — While several methods have been used in vac- 

 cinating against anthrax, probably the most important, at present, 

 is that devised by Pasteur. This method consists in the use of cultures 

 which have been attenuated by growth on artificial culture media at 

 temperatures above the optimum. The inoculation of such attenuated 

 cultures into healthy animals results in active immunization. 



The stock culture of Bad. anthracis is usually obtained from the 

 blood of a typical case of anthrax. The culture is transferred to agar 

 or broth and incubated. Two vaccines are prepared, the first being 

 less active than the second. Vaccine No. i, is made by placing in 

 suspension in sterile, physiological salt solution or other liquid, the 

 anthrax organisms which have been grown at a temperature of 42° for 

 a peiriod of fifteen to twenty days. Vaccine No. 2 consists of a 

 similarly treated culture of Bact. anthracis which hks grown at a tem- 

 perature of 42° for ten to fifteen days. Tests of both vaccines for 

 activity and safety are made by animal inoculations. Vaccine No. i 

 should kill white mice but should not cause fatal results in guinea-pigs 

 or rabbits. Vaccine No. 2 should prove fatal for both white mice and 

 guinea-pigs, but not for rabbits. 



Healthy animals are first injected subcutaneously with about i c.c. 

 of vaccine No. i. Several days or a few weeks after the application of 

 vaccine No. i, the second vaccine is injected. A severe reaction and 

 sometimes death follows the use of the vaccine. Accidents of this kind 



