Part V. 
THE INFLUENCE OF TIME. 
TIME NECESSARY TO RENDER A GUINEA PIG SUSCEPTIBLE. 
We know from our preliminary work that some time is necessary 
after the first injection of horse serum before a guinea pig is rendered 
susceptible to the toxic action of a second injection. The following 
series demonstrates that this time is about ten days: 
G. P. No. 4464. Six c. c. antitoxic horse serum (Natl. VIII. 17) injected into the peritoneal 
cavity. No symptoms. 
[Previous treatment: 5 days prior, inoculated subcutaneously with 0.19 c. c. toxine No. 
7+1 unit horse serum (Standard B27).] 
G. P. No. 4485. Six c. c. same serum and injection as g. p. 4484. 
[Previous treatment: 6 days prior, as g. p. 4484.] 
G. P. No. 4486. Six c. c. same serum and injection as g. p. 4484. 
[Previous treatment : 7 days prior, as g. p. 4484.] 
G. P. No. 4533. Six c. c. same serum and injection as g. p. 4484. 
[Previous treatment: 8 days prior, as g. p. 4484.] 
G. P. No. 4530. Six c. c. same serum and injection as g. p. 4484. 
[Previous treatment: 10 days prior, as g. p. 4484.] 
No symptoms. 
No symptoms. 
No symptoms. 
Symptoms; recovered. 
G. P. No. 4532. Six c. c. same serum and injection as g. p. 4484. Symptoms; recovered. 
[Previous treatment: 11 days prior, as g. p. 4484.] 
G. P. No. 4488. Six c. c. same serum and injection as g. p. 4484. Dead in 10 minutes. 
[Previous treatment: 12 days prior, as g. p. 4484.] 
G. P. No. 4525. Six c. c. same serum and injection as g. p. 4484. Dead in 45 minutes.- 
[Previous treatment: 12 days prior, as g. p. 4484.] 
G. P. No. 4487. Six c. c. same serum and injection as g. p. 4484. Dead in 60 minutes. 
[Previous treatment : 13 days prior, as g. p. 4484. [ 
G. P. No. 4531. Six c. c. same serum and injection as g. p. 4484. Dead in 45 minutes. 
[Previous treatment: 13 days prior, as g. p. 4484.] 
G. P. No. 4476. Six c. c. same serum and injection as g. p. 4484. Dead in 10 minutes. 
[Previous treatment: 14 days prior, inoculated subcutaneously with 0.22 c. c. toxine 
No Hiio c - c - antitoxic serum (Natl. IX. 18).] 
G. P. No. 4490. Six c. c. same serum and injection as g. p. 4484. Dead in 46 minutes. 
[Previous treatment: 14 days prior, as g. p. 4484.] 
G. P. No. 4529. Six c. c. same serum and injection as g. p. 4484. Dead in 47 minutes. 
[Previous treatment: 15 days prior, as g. p. 4484.] 
THE GUINEA PIG REMAINS SUSCEPTIBLE A VERY LONG TIME. 
That the guinea pig remains susceptible to the toxic action of horse 
serum a very long time is indicated in the following experiments in 
which 160 days elapsed between the first treatment and the second 
(45) 
