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Vol. XIV, No. 6 
to use this method was Shackell, 1 who in 1909 ( p . 336) pointed out the 
application of the method to the drying of a relatively unstable toxin. 
Into each of several 9-, or 15-, cm. petri dishes, 10, or 25, cc. of the 
filtered toxin were transferred. These were kept overnight in a refrig¬ 
erator at —9 0 C. (16 0 F.). The dishes containing the frozen toxin were 
then transferred to Hempel desiccators containing sulphuric acid, one 
large or three small dishes to one desiccator. The desiccators were 
evacuated with a Geryk pump to 2 to 3 mm. of mercury and then trans¬ 
ferred to the refrigerator at — 9 0 C., where they remained until the con¬ 
tents of the dishes had dried to a paste. This generally took from 24 to 
48 hours. It is probable that the drying of this toxin must be accom¬ 
plished while it is frozen; a few attempts at drying in vacuo at room 
temperature resulted in complete loss of toxicity. To some portions of 
the toxin, which was strongly alkaline, a calculated weight of acid potas¬ 
sium phosphate (KH 2 P 0 4 ) was added for the purpose of ascertaining the 
influence of neutralization of the alkali on the keeping qualities of the 
toxin paste. 
Numerous inoculation tests were made on guinea pigs, using the dried 
toxin dissolved in water. The tests indicate that there was little, if any, 
loss in toxicity. The typical blackleg condition was found in animals 
that had died 24 hours or more after intramuscular injection of a weight 
of toxin paste corresponding to one fatal dose of the original toxin. 
It was shown by Grassberger and Schattenfroh 2 that blackleg toxin 
can kill very quickly, without macroscopic lesions. In this respect it 
differs from tetanus and other toxins, which kill rather slowly, after 
producing noticeable pathological changes. 
1 Shackell, L. F. an improved method op desiccation with some applications to biological 
problems. In Amer. Jour. Physiol., v. 34, no. 3, p. 325-340. 1909. 
* Grassberger, R., and Schattenproh, A. op. at., p. 17. 
