GENUS BACTERIUM 2G3 



be considered as practicable at present. M'Fadyean, 35 von 

 Behring, 36 Pearson, 3T Calmette and Guerin, 38 T. Smith, 39 

 and others have investigated this subject. The methods 40 " 

 best known are those of Pearson and von Behring. They con- 

 sist in inoculating calves with attenuated human tubercle bac- 

 teria. Haring, Sawyer and Morgan 41 tested von Behring 's 

 method experimentally without satisfactory results. A few 

 workers believe that it may be possible to obtain a practical 

 method for vaccinating cattle against tuberculosis. The pres- 

 ent knowledge of the nature of tuberculosis does not indicate 

 the possibility of an efficient and practical vaccine for it being 

 developed along the lines that have been followed. 



OTHER PATHOGENIC ACID-FAST BACTERIA. 



Johne's disease (chronic bacterial enteritis in cattle). 

 In 1895, Johne and Frothingham x described a chronic disease 

 in cattle characterized by intestinal disturbances and pro- 

 nounced wasting of flesh and a thickening of the mucous mem- 

 brane of the intestine. Upon section, they found large num- 

 bers of acid-fast bacteria directly beneath the mucous mem- 

 brane of the affected portions of the intestine. Morphologi- 

 cally, this organism resembles the tubercle bacterium. It varies 

 in size from 1 to 2 /x in length, although individuals of 4 ^ 

 have been observed. The bacteria are not particularly intra- 

 cellular but are found lying free single and in chains in the 



33 M'Fadyean. Jour. Comp. Path, and Therap., Jan. 1901. 



30 von Behring. Beitrage zur experimentellen Therapie, 1902. 



37 Pearson. Report Sixth International Congress on Tubercu- 

 losis, Washington, D. C., Vol. IV-ii, 1908, p. 1002. 



38 Calmette and Guerin. Ann. de 1'Inst. Pasteur, Oct. 1905; May 

 1906; July, 1907. 



39 Smith. Jour. Med. Research, Vol. XVIII (1908) p. 451. 



40 For a review of methods for immunizing cattle against tu- 

 berculosis, see paper by Mohler and Schroeder, Proceedings of the 

 Am. Vet. Med. Asso., 1910, p. 158. 



41 Haring, Sawyer and Morgan. Proceedings Am. Vet. Med. 

 Asso., 1909, p. 252. 



1 Johne and Frothingham. Zeit. f. Tiermedizin, Bd. XXI (1894). 



