62 
33 days later, 6 c. c. antitoxic horse serum (Xatl. VIII. 18) into peritoneal cavity. No 
symptoms. 
21 days later, 6 c. c. into peritoneal cavity. No symptoms. 
G. P. No. 2. Six c. c. normal horse serum (roan) injected into the peritoneal cavity. No 
symptoms. 
[Previous treatment : None.] 
3 days later, 6 c. c. antitoxic horse serum (Natl. VIII. 17) into peritoneal cavity. No 
symptoms. 
19 days later, 6 c. c. into peritoneal cavity. Symptoms. 
6 days later, 6 c. c. into peritoneal cavity. No symptoms. 
43 days later, 6 c. c. antitoxic horse serum (Natl. VIII. 18) into peritoneal cavity. 
Symptoms. 
20 days later, 6 c. c. into peritoneal cavity. No symptoms. 
G. P. No. 3. Ten c. c. normal horse serum (roan) injected into the peritoneal cavity.' No 
symptoms. 
[Previous treatment : None.] 
2 days later, 6 c. c. same serum into peritoneal cavity. No symptoms. 
3 days later, 6 c. c. antitoxic horse serum (Natl. VIII. 17) into peritoneal cavity. No 
symptoms. 
9 days later, 6 c. c. into peritoneal cavity. No symptoms. 
10 days later, 6 c. c. into peritoneal cavity. No symptoms. 
PASSIVE IMMUNITY. 
EFFECT OF NORMAL GUINEA-PIG BLOOD AND ORGANS UPON THE TOXICITY 
OF HORSE SERUM. 
As a normal untreated guinea pig is entirely insusceptible to the 
toxic substances found in horse serum, it naturally occurred to us to 
try to ascertain whether the blood serum or the juices from the 
various organs of such a normal guinea pig had a restraining, neutral- 
izing, or immunizing action when mixed with horse serum and the 
mixture inoculated into susceptible guinea pigs. 
Normal G. P. A large, full-grown female guinea pig was chloroformed, then exsanguinated. 
Various organs, mentioned below, were minced and ground separately in a mortar with 
10 c. c. of antitoxic horse serum (National VIII. 17). The mixtures were allowed to 
stand at room temperature 3 hours, then strained through cheese cloth, and injected into 
the peritoneal cavity of susceptible guinea pigs, as follows: 
G. P. No. 4365. Six c. c. of a mixture containing equal parts of antitoxic horse serum and 
normal guinea-pig serum injected into the peritoneal cavity. Death in 40 minutes. 
[Previous treatment: 31 days prior, inoculated subcutaneously with 0.22 c. c. toxine 
No. 7-j-y4o- c. c. antitoxic serum (PD&Co. No. 07173).] 
G. P. No. 4463. Six c. c. of a mixture containing equal parts of antitoxic horse serum 
(Natl. VIII. 17) and normal guinea-pig liver injected into the peritoneal cavity. Symp- 
toms, recovered. 
[Previous treatment : 26 days prior, inoculated subcutaneously with 0.22 c. c. toxine 
No. 7+2^0 c - c - antitoxic serum (Natl. VIII. 17).] 
G. P. No. 4393. Seven c. c. of a mixture containing equal parts of antitoxic horse serum 
(Natl. VIII. 17) and normal guinea-pig liver injected into the peritoneal cavity. Symp- 
toms, recovered. 
[Previous treatment: 28 days prior, inoculated subcutaneously with 0.2 c. c. toxine 
No. 59+1 unit antitoxic serum (Standard B27).] 
