392 BACTERIA PATHOGENIC TO MAN 



immunity in cattle it is advised to use a dried powder of the muscles 

 of animals which have succumbed to the disease, and which have been 

 subjected to a suitable temperature to ensure attenuation of the viru- 

 lence of the spores contained therein. Two vaccines are prepared, as 

 in anthrax a stronger vaccine by exposing a portion of the powder to 

 a temperature of 85 to 90 C. for six hours, and a weaker vaccine by 

 exposing it for the same time to a temperature of 100 to 104 C. In- 

 oculations are made with this attenuated virus into the end of the tail 

 first the weaker and later the stronger. These give rise to a local reac- 

 tion of moderate intensity, and the animal is subsequently immune from 

 the effects of the most virulent material and from the disease. Fourteen 

 days are allowed to elapse between the two inoculations. The results 

 obtained from this method of preventive inoculation seem to have been 

 very satisfactory. According to the statistics, including many thou- 

 sand cattle treated, the mortality, which among 22,300 non-inocu- 

 lated cattle was 2.20 per cent., has been reduced to 0.16 per cent, in 

 14,700 animals inoculated. When danger of immediate infection 

 exists, it is advisable to inject some antitoxin with the vaccine. This 

 lessens the reaction and gives immediate immunity. 



