74 VACCINE AND SERUM THERAPY 



and finally even the mouse will not succumb. The 

 exact length of time required for attenuation in each 

 instance can be determined only by experimentation. 

 Pasteur uses two vaccines, the first prepared as 

 above, the second attenuated to a less degree. The 

 second vaccine is injected ten to twelve days after the 

 first. The immunity reaches the necessary degree 

 in about ten days after the second inoculation, and 

 lasts about one year. Statistics show that this 

 method of vaccination has been thoroughly satis- 

 factory. 



2. Immunisation tcitJi Immune Serum. — The serum 

 is obtained from hyperimmunised animals. This 

 serum gives a passive immunity, and has also curative 

 effects in cases where the disease is localised, and if 

 given shortly after infection, prevents the develop- 

 ment of the disease. Such immune serum also 

 renders good service in practice, especially in cases 

 where infection threatens or where anthrax has 

 already appeared in the herd. The action of the 

 injected serum becomes effective in a few hours. 

 However, this passive immunity only lasts from one 

 to two weeks. It is therefore advisable in cases of 

 continued danger of infection to render the animals 

 actively immune. 



3. Immunisation with Immune Serum and Cultures, 

 — This method is recommended by Sobernheim for a 

 lasting, combined, passive and active immunisation. 

 Cattle and horses are injected on one side of the 

 body with 5 c.c, calves with 3 to 5 c.c, and sheep 



