42 
clotting and the clear serum subsequently pipetted off. The citrate 
of soda was afterwards removed by dialysis (Gibson’s method) and 
the plasma proved just as toxic to treated guinea pigs as other horse 
serum. We also have the following experimental data upon this 
point : 
G. P. No. 4925. Six c. c. normal horse serum (roan) containing 1 per cent citrate soda 
injected into the peritoneal cavity. Dead in 15 minutes. 
[Previous treatment: 39 days prior, inoculated subcutaneously with 0.139 c. c. toxine 
No. 5 +3+5- c. c. antitoxic horse serum (Cutter 1465).] 
G. P. No. 4918. Injected as above. Dead in 5 minutes. 
[Previous treatment: 40 days prior, inoculated subcutaneously with 0.139 c. c. toxine 
No. 5+2^0" c - c - antitoxic horse serum (Stearns 16 H).] 
G. P. (control). The above guinea pigs were controlled by injecting 6c.c. of the same 
serum containing 1 per cent citrate of soda into the peritoneal cavity of a normal pig. 
The only effects of this inoculation were symptoms of irritation which soon passed away. 
INFLUENCE OF ANTISEPTICS. ETC. 
As much of this work was done with horse serum preserved by 
means of chloroform and trikresol (0.4 per cent) we made a control 
experiment, using horse serum as fresh as possible without the addi- 
tion of any substance. The following experiment eliminates these 
factors as having any influence upon the toxicity of the serum: 
G. P. No. 125. Three c. c. normal horse serum (roan) freshly drawn, centrifugized and 
injected into the peritoneal cavity as soon as the serum separated. Dead in 45 minutes. 
[Previous treatment: 49 days prior, inoculated subcutaneously with 0.22 c. c. toxine 
No. 7+3-g-o c. c. antitoxic horse serum (Steams 1351).] 
EFFECT OF OLD HORSE SERUM UPON SUSCEPTIBLE GUINEA PIGS. 
At one time in our work it apperaed to us that the toxic properties 
of horse serum gradually diminished in toxicity with the age of the 
serum. It was, however, soon proved by the following experiments 
that very old serums may be quite as poisonous as those freshly 
drawn. 
G. P. No. 4496. Four c.c. antitoxic horse serum (Natl. V. 2) injected into the peritoneal 
cavity. The serum was at least one and a half years old when injected. Dead in 30 
minutes. 
[Previous treatment: 25 days prior, inoculated subcutaneously with 0.19 c.c. toxine 
No. 7+1 unit of horse serum (Standard B27).] 
G. P. No. 4921. Six c. c. antitoxic horse serum over 3 years old (P. D. & Co .0495 prepared 
Dec. 15, 1902) inoculated into the peritoneal cavity. Symptoms; recovered. 
[Previous treatment : 39 days prior, inoculated subcutaneously with 0.139 c. c. toxine 
No. 5+3+g- c. c. antitoxic horse serum (Cutter 1465).] 
G. P. No. 4922. Same injection. No symptoms . a 
[Previous treatment: 39 days prior, inoculated subcutaneously with 0.139 c.c. toxine 
No. 5++ ¥ c.c. antitoxic horse serum (Cutter 1465).] 
* 
G. P. No. 4899. Same injection. Dead in 6 minutes. 
[Previous treatment: 48 days prior, inoculated subcutaneously with 0.139 c. c. toxine 
No. 5+3+p c.c. antitoxic horse serunr(Alex. 192).] 
a Explanation of occasional irregularities, p. 63. 
