EXPERIMENTS IN VACCINATION AGAINST ANTHRAX. 11 
strated their virulence for the mice and guinea pigs, but not for 
rabbits. 
For the purpose of producing a spore vaccine it is desirable to use 
a peptone-free agar media and after inoculation with the attenuated 
culture to grow the organism at a temperature of 37.5° C. for 4 to 7 
days, by which time an abundance of spores will have formed. The 
growth is then washed from the slants and collected in a sterile 
flask and heated at a temperature of 60° C. for one-half hour, to 
destroy the vegetative forms of the organism. A measured quantity 
of this suspension can then be plated out in the usual manner and the 
spore content of 1 c. c. of the suspension established. A dilution can 
then be made to the desired amount for inoculation purposes. Thus, 
if it is desired to use for vaccination 1,000,000 spores, it is best to 
dilute the vaccine to a quantity of which 1 c. c. would contain this 
number. Of such vaccine 1 c. c. would constitute the dose for cattle 
and horses, with correspondingly smaller doses for calves and sheep. 
In all forms of vaccination against anthrax in sheep the greatest 
care must be exercised, since these animals are very susceptible to the 
disease, and at times vaccines which have no ill effects on cattle will 
prove fatal to sheep ; therefore the dose of the spore vaccine for sheep 
should not be more than one- fourth the amount given cattle. 
In the preparation of spore vaccines it is essential to submit every 
lot to a test for pathogenicity by inoculating approximately 250,000 
spores — that is, 0.25 c. c. of the standard suspension — into guinea 
pigs and rabbits before employing the same for vaccination purposes. 
The guinea pigs should die in from 2 to 5 days, whereas the rabbits 
should remain alive. 
In consideration of the keeping qualities of the spore vaccine, large 
lots can be prepared without fear of deterioration. In the bottling 
and storing of the same, however, proper care should be taken to 
prevent contamination. 
TECHNIC OF ADMINISTRATION. 
For immunization purposes by the simultaneous method the serum 
should be injected first. It is desirable to divide the herd into groups 
of 10 or 12 and inject first each animal of the group with the serum, 
following this with the injection of the spore vaccine. The serum 
should be injected on one side, either on the neck or back of the 
shoulder, and the spore vaccine on the other side, the injections being 
made subcutaneously. 
In herds where the disease has already madje its appearance it is 
necessary to take the temperatures of all the animals and to subject 
to the simultaneous vaccination only those that show no rise in tern- 
