110 Diseases of Poultry 



munity to the bird which will last about 18 days ^ after each 

 injection. The fact that such immunity is not permanent 

 renders it of little value in treating an infected flock. 

 Lisoff ^ reports the use of such a serum in a large number of 

 epizootics (3876 birds) and states that the disease can 

 easily be held in check. As a curative agent he says the 

 figures show a reduction in mortality from 90 to 22 per cent 

 where the serum was used. 



Such protective serum is largely used in Denmark and 

 other countries for treating geese and other birds which are 

 being shipped into the country. 



Other methods of producing immunity against this disease 

 have also been tried. These involve the injection of dead 

 cultures or of living avirulent cultures or of the sterilized 

 exudate obtained by injecting cultures into the pleural cavi- 

 ties of other animals. In the main these methods have not 

 proven very successful in a practical way. For instance the 

 majority of avirulent cultures will not produce immunity 

 against all virulent strains. This whole question is now 

 being studied by the Rhode Island Experiment Station.^ 



' Kitt, T., "Monatsh. Prakt. Tierheilk." Bd. 16, pp. 1-19, 1904. 



2 Lisoff, P. W., ["Anti-fowl-cholera Serum and Its Practical 

 Significance"]. (Russian) Vet. Nauk (St. Petersburg), Bd. 40, 

 pp. 804r-818, 1910. 



* For example see : 



Hadley, P. B., and Amison, E. E., "A Histological Study of 

 Eleven Pathogenic Organisms from Cholera-like Diseases in Domes- 

 tic Fowls." Rhode Island Agr. Expt. Stat. Bui. 146, pp. 43-102, 

 1911. 



Hadley, P. B., "The R61e of Homologous Cultures of Slight 

 Virulence in the Production of Active Immunity in Rabbits." 

 Rhode Island Expt. Stat. Bui. 150, pp. 81-161, 1912. 



— — "The Reciprocal Relations of Virulent and Avirulent Cul- 

 tures in Active Immunization." Rhode Island Expt. Stat. Bui. 

 159, pp. 383-403, 1914. 



