352 ANTHRAX 



containing one part per thousand of acetic acid ; the fluid is cooled and 

 filtered through paper or asbestos so as to obtain a clear filtrate ; a little 

 of this is then run on to the top of the serum, and a white ring should 

 form immediately at the junction of the fluids. The reaction sometimes 

 occurs with normal sera, but in this case does not appear for a quarter of 

 an hour. It is absolutely necessary that the serum to be used should be 

 previously tested with material derived from an undoubted anthrax case, 

 as only a certain small proportion of immune sera will give the reaction. 

 The reaction seems to depend on an effect produced between the serum 

 and substances derived from the bacilli, as it is most marked with tissues 

 containing numerous organisms. It can be obtained with material 

 which has been kept for six months, and numerous controls made with 

 tissues of animals dying from other diseases are stated to have given 

 negative results. 



