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 mad(e 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- 



