35 
G. P. Xo. 4993. Two c. c. of the above mixture injected into the peritoneal cavity. Dead 
in 40 minutes. 
[Previous treatment: 28 days prior, inoculated subcutaneously with 0.22 c. c. toxine 
Xo. 7 + 33 -j c. c. antitoxic horse serum (Alex. A206).] 
G. P. Xo. 4988. Same injection. Dead in 30 minutes. 
[Previous treatment: 28 days prior, inoculated subcutaneously with 0.22 c. c. toxine • 
Xo. 7+tto c - c - antitoxic horse.serum (Alex. A202).] 
G. P. Xo. 4992. Same injection. Dead in 35 minutes. 
[Previous treatment: 28 days prior, inoculated subcutaneuoslv with 0.22 c. c. toxine 
Xo. 7+yjyo c - c - antitoxic horse serum (Alex. A208).] 
The above experiment was repeated as follows: 
G. P. Xo. 248. Four subcutaneous injections of 1.5 c. c. each on successive days were made, 
using roan corpuscles washed three times. The blood serum of this guinea pig developed a 
high degree of hemolytic power against horse corpuscles. The serum was mixed with 
equal quantities of normal horse serum and the mixture injected into the following guinea 
pigs: 
G. P. Xo. 4913. Four c. c. of the above mixture injected into the peritoneal cavity. Dead 
in 10 minutes. 
[Previous treatment: 41 days prior, inoculated subcutaneously with 0.139 c. c. of toxine 
Xo. 5 + 3 ^ c. c. antitoxic horse serum (Stearns 12D).] 
G. P. Xo. 4914. Two c. c. same serum injected into the peritoneal cavity. Dead in 20 
minutes. 
[Previous treatment: Same as G. P. Xo. 4913.] 
THE RELATION OF PRECIPITIN TO THE TOXIC ACTION. 
The precipitins are so specific and so closely related to the cyto- 
toxins that it natually occurred to us to determine what relation there 
may exist between the toxic power of the blood serum of the horse and 
of the guinea pig, and the power of these two serums to precipitate 
each other. 
If we inject horse serum several times into a guinea pig we would 
expect to find that the blood serum of a guinea pig so treated would 
have a power of precipitating horse serum. This we found to be the 
case; but we could not find that the injection of a single small dose of 
horse serum into the guinea pig developed this power in the guinea 
pig's blood serum. We might, however, conjecture that the union of 
the two serums under the conditions named causes a precipitation 
which is not visible, or causes a chemical union between two highlv 
organized albuminous substances having toxic properties. In order to 
test this subject more thoroughly we first made some experiments to 
determine the precipitating action of normal and antitoxic horse 
serum upon normal guinea-pig serum, as follows: 
One c. c. of horse serum in dilution of 1:21 was placed in a small 
test tube. The 0.1 c. c. of normal guinea-pig serum was added to 
each tube. These were thoroughly shaken, placed in the incubator, 
and the results read after twenty-four hours. 
