Jan. 8, 1917 
Immunity Studies on Anthrax Serum 
5i 
tion of the horses was begun in September, 1914, and continued with 
increasing doses of virus until June, 1915 (4, p. 9). Consequently at 
the time the analyses were made the serums were past the stage where 
the characteristic serum changes were to be expected. The immuniza¬ 
tion of the mules was begun in August, 1915, and mule 149 died on 
December 23, 1915. It is apparent from figure 1 that the changes in 
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the serum of mule 149 were similar to those in mule 148 shortly after 
the immunization was begun. The decline in the condition of mule 149 
is believed to be the cause of the downward slope of the curve, or vice 
versa. The curve for mule 148 is typical in so far as it shows the drop 
in protein content in the beginning of the immunization, or the “ nega¬ 
tive phase,” followed by a very pronounced rise in protein content. 
The total coagulable protein and the total globulin rose and fell together. 
