2 54 
Journal of Agricultural Research 
Vol. XIV, No. 6 
Numerous tests and experiments have been conducted with both 
agents, but from the standpoint of production of the two products the 
efforts of the writer have been concentrated principally on the prepara¬ 
tion of the toxic culture filtrate. 
GERM-FREE VACCINE OR NATURAE AGGRESSIN 
Based on Bail's 1 2 work on aggressins, Sch6bl 3 tried and was able to 
immunize calves and guinea pigs against blackleg by vaccinating them 
with sterilized edematous fluid from animals which had died of the 
disease, the sterilization of the edematous fluid being accomplished 
through treatment with toluol. 
Franklin and Haslam 3 conducted numerous experiments with an im¬ 
munizing agent based on this same principle and emphasized its value 
in the prevention of blackleg. The writer has prepared one lot of such 
a product and has tested with very satisfactory results a number of 
specimens of similar material received from various outside sources. 
The following procedure is followed in preparing the product. 
Susceptible animals are inoculated intramuscularly with an emulsion 
prepared from the affected muscle tissue of animals dead of blackleg. 
The animals usually succumb to the disease in from 36 to 48 hours. 
The skin is then removed, and the edematous fluid from the affected 
area and the affected muscle tissue is collected. The tissue is then 
finely ground and together with the edematous fluid collected is placed 
in fruit jars and is frozen, an ice-salt mixture being used. After 
several hours' freezing the jars are removed and inverted over funnels 
containing thin films of cotton, the funnels all draining into a pan which 
converges to the center, from which by means of a spout the thawed 
fluid is discharged into a bottle. Ice is kept packed around the bottle 
in order to keep the fluid at a low temperature, as the process of thawing 
requires considerable time even in warm weather. This freezing process 
is necessary to facilitate filtering. After the dripping from the jars 
ceases, the “clots” are pressed to extract more of the fluid, but the mate¬ 
rial thus obtained is kept separate from the other fluid and is filtered last, 
as it passes through considerably slower and tends to clog the apparatus. 
The product is filtered twice through Berkefeld filters (first through one 
of “V” and then through one of “N” porosity), is preserved with chloro¬ 
form (0.5 per cent), and is ready for testing. 
1 Bail, Oskar, vergleichende untersuchungen uber milzbrandfeindliche eigenschaften in 
Organismus des HUNDES tjnd kaninchens. In Centbl. Bakt. [etc.], Abt. i f Bd. 37, No. 1, p. 10-21. 1900. 
- UNTERSUCHUNGEN UBER NATURI 4 CHE UND KUNSTLICHE MILZBRANDIMMUNITAT. In Centbl. Bakt. 
[etc.], Abt. 1, Bd. 33, No. 5, p. 343“353» i9°3- 
2 SCHOBL, otto. WEITERE VERSUCHE UBER AGGRESSINIMMUNISIERUNG GBGEN RAUSCHBRAND. In 
Centbl. Bakt. [etc.], Abt. 1, Bd. 62, No. 3/4, p. 296-304. 1912. 
8 Franklin, O. M., and Haslam, T. P. the strength and composition op blackleg vaccines. In 
Jour. Infect. Diseases, v. 19, no. 3, p. 40&-415. 1916. 
