ANTHRAX. 455 



bacilli themselves are present in the culture liquid. It is true that 

 they have been modified and weakened by the process adopted by 

 Pasteur, but it is not impossible for such modified virus to regain 

 its original virulence after it has been scattered broadcast by the 

 inoculation of large herds. It is obviously unsafe to have such 

 vaccine injected by a layman ; instead, it should be handled only by 

 a competent veterinarian. 



There are other disadvantages in this method of vaccination, and 

 they all must be given due consideration. The unstable keeping 

 quality of the Pasteur vaccine is a very important factor to be consid- 

 ered. Experience in this line has proved that Pasteur vaccine may 

 deteriorate within a very short time after its preparation, and in re- 

 peated instances it has proved inert within three months of its 

 preparation. When exposed to warm temperature and light, it 

 deteriorates verj?^ rapidly ; and when it is considered that the products 

 of manufacturers may be stored under unfavorable conditions in 

 branch houses and on the shelves of rural drug stores, the loss of 

 potency can be readily explained. These deficiencies have been rec- 

 ognized by many investigators, and because of the superior keeping 

 qualities particular attention has been directed toward the prepara- 

 tion of a spore vaccine by Zenkowsky of Russia, Detre of Hungarj^, 

 and Nitta of Japan. For the purpose of producing a spore vaccine 

 it is desirable to use a peptone-free agar medium, and after inocula- 

 tion with an attenuated culture of the anthrax bacillus, it is allowed 

 to grow at a temperature of 37° C. for 4 to 7 days. By this time an 

 abundance of spores will have formed. The growth is then collected 

 in sterile flasks and heated to a temperature of 60° C. for one-half 

 hour to destroy the vegetative forms of the organism. If it is desired 

 to use for vaccination one million spores, it is advisable to dilute the 

 vaccine to a quantity of which 1 cubic centimeter would contain this 

 number. Of such a vaccine 1 cubic centimeter would constitute the 

 dose for cattle and horses. In all forms of vaccination against an- 

 thrax in sheep the greatest care must be exercised, as 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 

 of that given to cattle. 



Sclavo, Sobernheim, and others have established that injections 

 of increasing quantities of virulent cultures into immune animals 

 produced a serum which has great protective value against anthrax. 

 Such protective serum may be produced in the various susceptible 

 animals. 



For immunization purposes it is advisable to use the simultaneous 

 method; that is, both the spore vaccine and the anthrax serum should 

 be injected. It is desirable to divide the herd to be treated into 



