THE RELATION OF HYPERSUSCEPTIBILITY TO VARIOUS INFLUENCES. 
We have alread}^ shown that h}^persusceptibility to the action of 
horse serum in the guinea pig has no evident relation to hemol^^sis or 
precipitins. AYe offer the following experiments, planned with the 
object of correlating hypersusceptibility with other phenomena: 
RELATION TO AGGRESSINES. 
The work of Bail upon aggressine induced us to try whether a simi- 
lar action ma}^ explain h}^persusceptibility. The following experi- 
ments indicate that no relation exists between the two phenomena. 
PERITONEAL FLUID FROM NORMAL GUINEA PIG INTO SENSITIZED 
GUINEA PIG. 
Eight c. c. of normal horse (No. 15) serum was injected into the 
peritoneal cavit}" of a normal guinea pig. This produced no symptom. 
Two hours later the animal was chloroformed and about 6 c. c. of fluid 
was taken from the peritoneal cavity and injected into the following 
sensitized guinea pig: 
G. P. No. 7050, Six c. c. of above fluid into peritoneal cavity. Dead, 20 minutes. 
[Previous treatment: 57 days prior, 0.142 c. c. toxine No. 5+2^0 c. c., antitoxic 
horse serum (S. 063H), subcutaneously.] 
PERITONEAL FLUID FROM SENSITIZED GUINEA PIG INTO NORMAL 
GUINEA PIG. 
Six c. c. of normal horse (No. 15) serum was injected into the peri- 
toneal cavity of G. P. No. 7051, which had been sensitized fifty-seven 
days previously with 0.142 c. c. toxine No. 5+^io c. c. axtitoxic horse 
serum (S. 063H). The guinea pig developed typical symptoms and 
died in fifteen minutes as a result of the second injection. Fifteen 
minutes after the death of this guinea pig about 4 c. c. of the peri- 
toneal contents were withdrawn and injected into the peritoneal cavity 
of a normal guinea pig. This caused no symptoms. 
PERITONEAL FLUID FROM SENSITIZED GUINEA PIG INTO SENSITIZED 
GUINEA PIG. 
Six c. c. normal horse (No. 15) serum was injected into the perito- 
neal cavity of a sensitized guinea pig (No. 7068) which had received 
fifty-five days previously a subcutaneous injection of 0.142 c. c. toxine 
No. 5 + lio c. c. antitoxic horse serum (Natl. V, 7). As a result of the 
second injection of horse serum the guinea pig had characteristic 
symptoms and died in thirty minutes. Fifteen minutes after the 
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