49 
There is apparently no difference in the subsequent immunity 
whether the intoxicating injection be given subcutaneously, intra- 
peritoneally, or intracranially. In these cases the immunity was 
tested twenty-four hours after the second injection. 
We present preliminary evidence suggesting that antibodies are 
concerned in the mechanism of anaphylaxis. The mixture of normal 
horse serum with the blood serum of a sensitive guinea pig apparently 
increases the toxicity of the horse serum for sensitive guinea pigs. 
We have shown that guinea pigs may remain sensitive one thousand 
and ninety-six days; that is, a little over three years. 
80937— Bull. 50—09 4 
