266 AGRICULTURAL BACTERIOLOGY 



to one-half of one per cent, by the use of the vaccine dis- 

 tributed by the Bureau of Animal Industry of the United 

 States Department of Agriculture. 



The vaccine is made by inoculating an animal with the 

 blackleg bacillus. After death the affected muscular tissue 

 is removed and reduced to a pulp, which is then squeezed 

 through a cloth. The juice is dried quickly at 95 F. 

 The cake thus obtained may be stored for long periods, 

 since it contains the resistant spores of the organism. 



When it is desired to prepare vaccine, the dried mater- 

 ial is mixed with water and heated to from 212 F. to 219 

 F. for seven hours. This treatment weakens the spores to 

 such an extent that a fatal form of the disease is not pro- 

 duced when a suspension of the material obtained after heat- 

 ing is injected into animals. But one treatment is neces- 

 sary. The fact that only animals between the ages of six 

 and eighteen months are susceptible to blackleg, and the fur- 

 ther fact that vaccination will protect during the suscepti- 

 ble period have made the preventive treatment a great prac- 

 tical success. More than 25,000,000 doses have been dis- 

 tributed by the government to stock-raisers. 



Hemorrhagic septicemia. Sudden death with no well 

 defined symptom is likely to be ascribed to poison or light- 

 ning. The next most common cause to which sudden death 

 in cattle and sheep is ascribed is anthrax. As has been 

 pointed out, the use of specific biological products in pre- 

 vention necessitates the correct diagnosis of the first cases 

 of "death in a herd, in order that effective means of control 

 may be employed. Another disease, commonly known as 

 hemorrhagic septieemia from the fact that the causal or- 

 ganisms produce reddened congested areas in the tissues, is 

 not infrequently confounded with the above causes of death. 



The organism causing the disease is one of a large group 

 producing a number of diseases in different animals. 



