REFERKNCES 225 



proven to be most successful. It consists in the slaughter of 

 the advanced cases and the isolation of the reacting animals, 

 which are kept for breeding purposes. The calves are .sepa- 

 rated from their dams immediately after birth and fed upon 

 the milk of healthy cows or the sterilized milk of the reacting 

 ones. This method has enabled many owners of infected 

 animals to replenish their herds in from four to six years. In 

 countries where it has been generally applied the percentage 

 of tuberculous cattle has been wonderfully reduced. 



The vaccination of cattle against tuberculosis has been 

 proposed as a prophylactic measure. The method has been 

 extensively tried by Pearson in America and von Behring in 

 Germany. Its effectiveness can not be predicted at this time. 

 The results of von Behring's experiments are promising but 

 as yet the vaccinated animals (calves) have not attained to old 

 age so that the length of the resistance that seems to be 

 established by the vaccination is not determined. Several 

 reports on the result of natural exposure to tuberculous cows, 

 after a period of two years, show the vaccinated animals to 

 be nearly as badly infected as the checks. The resul ts reported 

 by Pearson indicate that the attainment of a bacterial immunity 

 against tuberculosis in cattle is not likely to be an easy task. 

 The experiments in this direction are most interesting and 

 many investigators are hopeful for good results. At present 

 it is in the experimental stage. 



REFERENCES. 



1 \DAMi On the significance of bovine tuberculosis and its 

 eradication and prevention in Canada. Cauadian Jour, of Medicine 

 and Surgery, Dec. 1899. 



2 Curtice. The detection of tuberculosis in cattle. Annual 

 Report, Bureau of Animal Industry, U. S. Dept. Agric, 1895-96. 



3. Dorset. Experiments concerning tuberculosis. Bulletin 5-'. 

 Bureau of Animal Industry, 1904. 



4 Eber Suggestions for a uniform system of interpreting the 

 tuberculin reaction in cattle. The Jour. ComPr. Path, and Ihera., 

 Vol. XVIII (1905), P- 224. 



