4 BULLETIN 34G, U. S. DEPAKTMENT OF AGKICULTTJEE. 



the use of Pasteur anthrax vaccine to three months from the date of 

 its preparation. 



The injection of an inert product into animals would impart to 

 the stock owners and veterinarians who employ it a false sense of 

 security and would bring this method of vaccination into disrepute. 

 At times no doubt great losses have resulted from the application 

 of inert vaccines. 



Other disadvantages of the Pasteur method which must be con- 

 sidered are, first, that it requires two handlings of the animals 

 before immunity is established; second, that the losses from vac- 

 cinations are not insignificant; third, that its standardization is 

 not carried out very accurately; and, fourth, that its administration 

 in herds where the disease has already made its appearance is liable 

 to induce the disease, through the reduction of the resistance of the 

 animal during the process of vaccination, and for this last reason it 

 is best adapted for use only with herds in which the disease has not 

 yet appeared. 



These deficiencies of the method have been recognized by many 

 investigators, who have endeavored to devise other methods of 

 vaccination, and particular attention < has been directed toward the 

 preparation of a spore vaccine, because of its superior keeping 

 qualities. In Russia at the present time the method of Zenkowsky, 

 and in Hungary a spore vaccine prepared by Detre, are being suc- 

 cessfully employed; although, aside from their keeping qualities, 

 these products have all the other disadvantages of the Pasteur 

 method. Successful vaccination by spore vaccines was also demon- 

 strated by Nitta, in Japan, and by others. Other means of vaccina- 

 tion with attenuated living cultures, aggressions, dead bacteria, etc., 

 were tried, but proved of no advantage. 



Sclavo, Sobernheim, and others have established that injections 

 of increasing amounts 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. 



PRODUCTION OF SERUM. 



The animals which are selected for the preparation of serum are 

 subjected to a preliminary treatment either by sero-vaccination or by 

 Pasteur's method, then at certain regular intervals they are infected 

 with increasing doses of virulent anthrax cultures. For this purpose 

 they receive in about 10 to 14 days following the preliminary treat- 

 ment an injection of from 0.005 to 0.001 of a loopful of virulent cul- 

 ture. In sheep it is advisable to exercise greater care, especially at 



