PART 8.— THE EFFECT OF REPEATED INJECTIONS. 
THE IMMUNIZING ACTION OF REPEATED INJECTIONS. 
We found it desirable to obtain further data upon the effects of 
repeated injections of horse serum into guinea pigs in order to answer 
the question whether guinea pigs may be definitely immunized by 
repeated injections. 
It will be seen by the following table that 10 injections of 2 c. c. of 
serum subcutaneously was not sufficient to render guinea pigs entirely 
immune. These four guinea pigs all showed mild symptoms when 
tested intraperitoneally fifteen or seventeen days after the last injec- 
tion. 
Reference to Tables No. 34, 35, 36, pages 36, 37, 38, shows the same 
results. 
Table No. 44. — The immunizing action of repeated injections. 
G. P. 
No. 
First injection. 
Inter- 
val in 
days. 
Second injection. 
Result. 
1371 
10 injections, each 2 c. c., normal 
15 
6 c. c. normal horse (roan) se- 
Mild symptoms. 
horse (roan) serum, subcutane- 
rum intraperitoneallJ^ 
ously, coveringaperiod of 17 days. 
1309 
. . .do 
17 
do 
Mild symptoms. 
1372 
do 
17 
do 
Mild symptoms. 
1374 
do 
17 
... do 
Mild symptoms. 
THE SENSITIZING ACTION OF REPEATED INJECTIONS OF 
SMALL AMOUNTS. 
The following table shows that the repeated injections of small 
amounts are apparently as potent in sensitizing guinea pigs as one 
small injection. 
Table No. 45. — Sensitizing action of repeated injections of small amounts. 
G. P. 
No. 
First injection. 
Inter- 
val in 
days. 
Second injection. 
Result. 
1364 
5 injections, each 0.001 c.c., nor- 
mal horse (roan) serum, sub- 
cutaneously, covering a pe- 
riod of 8 days. 
rt23 
6 c. c. normal horse (roan) se- 
rum intraperitoneally. 
Dead in 40 minutes. 
1305 
do 
23 
6 c. c. normal horse (roan) se- 
rum subcutaneously. 
Dead in 70 minutes. 
1366 
do . . , 
23 
do 
Dead in 75 minutes. 
1367 
do 
23 
0.05 c. c. normal horse (roan) se- 
rum into brain. 
Severe symptoms. 
1368 
23 
0.2 c. c. normal horse (roan) se- 
rum into brain. 
Dead in 5 minutes. 
1363 
do 
23 
0.05 c. c. normal horse (roan) se- 
rum into brain. 
Severe symptoms. 
oFrom last injection. 
(51) 
