Aug. s, 1918 Immunization Methods against Symptomatic Anthrax 259 
Table} IV.— Results of subcutaneous inoculation of guinea pigs a with the toxic culture 
filtrate, followed after 14 days with blackleg virus 
Guinea- 
pig No. 
Amount of 
culture 
filtrate. 
Amount of 
virus. & 
Result. 
I 
Cc. 
0.25 
Cc. 
0. S 
Dead of blackleg in 36 hours. 
2 
* 2 5 
• 5 
Dead of blackleg in 48 hours. 
3 
• So 
• 5 
Remained alive. 
4 
• 50 
• 5 
Do. 
5 
•75 
• S 
Dead of blackleg in 48 hours. 
6 
• 75 
. s 
Remained alive. 
7 
1 
Died from the effects of the blackleg toxin before the 
8 
1 
. 5 
inoculation of the virus. 
Remained alive. 
9 
Control. 
•5 
Dead of blackleg in 24 hours. 
10 
Control. 
•5 
Dead of blackleg in 30 hours. 
a Guinea pigs weighing from 320 to 380 gm. were used. The minimal lethal dose (M. L. D.) of the black¬ 
leg toxin for guinea pigs of this weight was between 1 and 1.^ cc. when administered intramuscularly. 
b The virus employed was prepared from affected muscle tissue in the manner described under Table I. 
Table; V.— Results of subcutaneous inoculation of guinea pigs ® with toxic culture filtrate, 
followed after 14 days with specially prepared blackleg virus 
Guinea- 
pig No. 
Amount of 
culture 
filtrate. 
Amount of 
virus. 
Result. 
I 
Cc. 
O.25 
Cc 
O.25 
Dead of blackleg in 24 hours. 
2 
•25 
• 2 5 
Dead of blackleg in 48 hours. 
3 
•2$ 
.25 
Do. 
4 
•25 
• 2 5 
Dead of blackleg in 72 hours. 
5 
.25 
• 2 5 
Remained alive. 
6 
. 25 
• 2 5 
Do. 
7 
• 5 
• 25 
Dead of blackleg in 48 hours. 
8 
•5 
• 2 5 
Remained alive. 
9 
•5 
. 25 
Do. 
10 
•5 
• 2 5 
Do. 
IZ 
•5 
• 2 5 
Do. 
12 
• 5 
• 2 5 
Do. 
x 3 
Control. 
• 2 5 
Dead of blackleg in 24 hours. 
14 
Control. 
* 2 5 
Do. 
IS 
Control. 
• 2 5 
Dead of blackleg in 48 hours. 
a Guinea pigs weighing 320 to 380 gm. were employed. The minimal lethal dose of the blackleg culture 
filtrate for guinea pigs of this weight was 1 to 1.5 cc. when administered intramuscularly. 
In tests of various blackleg immunizing agents on guinea pigs, difficulty 
has been experienced by most investigators with the type of virus em¬ 
ployed for the infection of the animal subsequent to vaccination. Most 
workers have employed for the purpose emulsions of affected muscle 
tissue. The procedure usually followed is to weigh out a definite amount 
of ground affected muscle tissue, emulsify with a definite amount of 
physiological salt solution, filter through a thin film of cotton, and use a 
certain quantity of the filtered solution as a test dose. It is obvious 
that a test virus prepared in this manner would not be very satisfactory, 
especially when used on small animals such as guinea pigs. The number 
of blackleg organisms such material would contain would undoubtedly 
