28 
Table shovnng the remits of injecting Jj c. c. of normal horse serum (roan) into the peritoneal 
cavity of guinea pigs from Iff to 56 days prior with 2 j 0 c. c. of the Mood serum of other 
animals. 
Xo. of 
guinea 
Pig- 
173 
175 
195 
213 
211 
187 
189 
190 
183 
181 
199 
198 
200 
203 
204 
205 
Rabbit. 
do. . 
Cat 
Dog.... 
do. . 
Hog.... 
do. . 
Sheep . . 
do. . 
do. . 
Chicken 
do. . 
do. . 
Han 
do. . 
do. . 
Previous treatment. 
Kind of serum. 
Days 
prior. 
Result. 
2 i 0 c. c.. 
55 
Symptoms, recovered. 
.do 
55 
Do. 
.do 
55 
Do. 
.do 
56 
Do. 
.do 
56 
Do. 
.do 
51 
Do. 
.do 
51 
Do. 
.do 
47 
Xo symptoms. 
.do 
51 
Symptoms, recovered. 
.do 
51 
Do. 
.do 
47 
Xo symptoms. 
.do 
47 
Symptoms (?), recovered. 
.do 
47 
Symptoms, recovered. 
. .do 
52 
Xo symptoms. 
.do 
52 
Symptoms,, recovered. 
.do 
52 
. Do-. 
We think it is plain from the above that this action is not strictly 
specific for horse serum; that is, guinea pigs treated with horse 
serum are rendered somewhat susceptible to the subsequent injection 
of the serum of certain other species and that guinea pigs treated with 
the serum of other animals are slightly sensitive to the toxic action of 
horse serum. However, it is also perfectly plain from this series of 
experiments that the action is quantitatively specific, for it will be 
noticed that of the many guinea pigs sensitized with the blood serum 
of animals other than the horse, none died from subsequent injections 
of large quantities (6 c. c.) of horse serum. The same may be said 
of the action of these other serums upon guinea pigs previously 
treated with horse serum. While most of these serums produced 
symptoms, none of the guinea pigs died. 
In other words, there is plainly a distinct quantitative difference, 
both in the results of the power of horse serum to render guinea pigs 
susceptible to other serums and in its toxic action upon guinea pigs 
sensitized by other serums. 
The action of horse serum upon other animals than the guinea pig 
is treated of in another chapter (p. 55). 
ARE OTHER BLOOD SERUMS EQUALLY TOXIC? 
We now know that guinea pigs previously treated with small 
injections of horse serum become very susceptible to subsequent 
injections of horse serum, but only slightly susceptible to the blood 
serum of other animals. It becomes important to determine whether 
