Aug. 5,1918 Immunization Methods against Symptomatic Anthrax 261 
The following table gives the results of a test conducted with two 
different specimens of blackleg culture filtrate. The specimen labeled 
“1” was demonstrated to be nontoxic for guinea pigs, while 1.5 cc. of 
the sample labeled “ 2 ” would prove fatal to guinea pigs. 
Table) VII. —Results of subcutaneous 'vaccination of calves with blackleg culture filtrates 
No. 1 and 2 followed after 14 days with intramuscular inoculation of blackleg virus 
Calf No. 
Blackleg 
culture 
Filtrate No. 
Amount 
culture 
filtrate. 
Amount 
of 
virus.** 
Result. 
I. 
I. 
Cc. 
5 
5 
5 
5 
None. 
None. 
None. 
Cc. ■ 
IO 
10 
10 
IO 
IO 
10 
10 
Dead of blackleg within 48 hours. 
Do. 
Very slight swelling. Remained 
alive. 
Do. 
Dead of blackleg within 48 hours. 
Do. 
Marked extensive swelling. Animal 
recovered. 
2. 
I. 
7. . 
2. 
4. 
2.. 
ti mi . 
Control.... 
.do. 
6. 
7. 
.do. 
The virus employed was an emulsion of affected muscle tissue. 
The following test on guinea pigs tends to demonstrate an intimate 
relation between the toxicity and potency of blackleg culture filtrates. 
Table VIII .—Results of vaccination of guinea pigs with various culture filtrates followed 
after 14 days with inoculation of blackleg virus 
Culture 
filtrate No. 
Approximate 
M. L,. D. for 
350-gm 
guinea pigs. 
Amount 
vaccinated 
in each, of 
3 guinea 
pigs. 
Dose of 
^ virus 
injected 
after 14 
days. 
Result. 
1 . 
Cc. 
Nontoxic. 
Cc. 
I 
Cc. 
o- 5 
* 5 
*5 
• 5 
. c 
All 3 guinea pigs died of blackleg. 
1 of the 3 guinea pigs died of blackleg. 
Do. 
X . 
1. c 
I 
Y. 
J 
2 ; 5 
Nontoxic. 
1 
I 
All 3 guinea pigs died of blackleg. 
Do. 
7 
Nontoxic. 
I 
c. 
A 
I 
D 
Do. 
0 
T 
• 5 
RELATION OP THE NATURAL AGGRESSIN TO THE TOXIC CULTURE 
FILTRATE 
The question has often arisen as to the relation between blackleg 
natural aggressin and the toxic culture filtrate—that is, whether or not 
the immunizing principles in both products are identical. While the 
work conducted in this respect by the writer has not as yet been sufficient 
to draw absolutely definite conclusions, there is one factor which 
points to a distinct difference in the active principles of the two products. 
Of the specimens of blackleg natural aggressin tested in this laboratory 
comparatively large doses of the material produced no symptoms of 
toxemia in the guinea pigs inoculated. The same specimens, however, 
