47 
Table No. 20. — Sensitized guinea jpig serum plus normal horse serum — Continued. 
EXPERIMENT NO. 4. 
G. P. No. 
G. P. 
weight. 
First injection. 
Inter- 
val, in 
i days. 
Second injection. 
Result. 
101 
0.01 c. c. normal horse 
(Frank) serum, subcu- 
taneously. 
56 
0.2 c. c. equal mixture of 
sensitive guinea-pig se- 
rum and normal horse 
serum, into brain. 
Very severe symp- 
toms. 
102 
0.01 c. c. normal horse 
(Frank) serum, subcu- 
taneously. 
56 
0.2 c. c. equal mixture of 
sensitive guinea-pig se- 
rum and normal horse 
serum, into brain. 
Dead in 4 minutes. 
103 
0.01 c. c. normal horse 
(Frank) serum, subcu- 
taneously. 
56 
0.2 c. c. equal mixture of 
sensitive guinea-pig se- 
rum and normal horse 
serum, into brain. 
Very severe symp 
toms. 
104 
0.01 c. c. normal horse 
(Frank) serum, subcu- 
taneously. 
56 
0.2 c. c. equal mixture of 
sensitive guinea-pig se- 
rum and normal horse 
serum, into brain. 
Very severe symp- 
toms. 
105 
0.01 c. c. normal horse 
(Frank) serum, subcu- 
taneously. 
56 
0.2 c. c. equal mixture of 
sensitive guinea-pig se- 
rum and normal horse 
serum, into brain. 
Very severe symp- 
toms. 
Control 
0.01 c. c. normal horse 
(Frank) serum, subcu- 
taneously. 
56 
0.1 c. c. normal horse 
(Frank) serum, into 
brain. 
Marked symptoms. 
Control 
0.01 c. c. normal horse 
(Frank) serum, subcu- 
taneously. 
56 
0.1 c. c. normal horse 
(Frank) serum, into 
brain. 
Marked symptoms. 
Control 
0.01 c. c. normal horse 
(Frank) serum, subcu- 
taneously. 
56 
0.1 c. c. normal horse 
(Frank) serum, into 
brain. 
Severe symptoms. 
Control 
0.01 c. c. normal horse 
(Frank) serum, subcu- 
taneously. 
56 
0.1 . c. c. normal horse 
(Frank) serum, into 
brain. 
Severe symptoms. 
Control 
0.01 c. c. normal horse 
(Frank) serum, subcu- 
taneously. 
56 
0.1 c. c. normal horse* 
(Frank) serum, into 
brain. 
Marked symptoms. 
TIME. 
The longest interval that has elapsed between the first and the 
second injection of serum in guinea pigs in our work previously 
reported has been seven hundred and thirty-two days. We have 
recently, however, tested the susceptibility of a guinea pig that had 
received the first injection of serum one thousand and ninety-six 
days (a little over three years) before it was tested for its suscepti- 
bility. This animal was found to be still extremely sensitive. We 
believe that sensitive guinea pigs retain their susceptibility during 
their entire life. 
