9O PRACTICAL DAIRY BACTERIOLOGY 



detect the presence of tuberculosis, the method is too unreliable 

 to be of practical value as a means of testing milk. Nowhere, 

 as yet, has the examination of milk for the detection of the 

 presence of this organism been undertaken as a method of 

 municipal routine, and whether this will ever be done is doubt- 

 ful. Such study, however, demonstrates beyond peradventure 

 that the milk of tuberculosis animals may contain tuberculosis 

 germs. 



It is then clearly important to know at what stage of the 

 disease the milk may become thus affected, and upon this sub- 

 ject there has been a large amount of experimenting with more 

 or less contradictory results. If the disease is located in the 

 udder, the milk is practically sure to be infected with tuber- 

 culosis bacilli in greater or less numbers. Perhaps 8 per cent, 

 of the tuberculous cattle have the disease in the udder (Pear- 

 son), although some place the number lower. If the disease 

 occurs elsewhere in the body, but not in the udder, the results 

 are less certain. It has be'm shown, however, that some animals 

 that react to the tuberculin test without showing signs of the 

 disease in the udder produce milk containing tuberculosis 

 bacilli. Such reacting animals clearly have the disease, but it 

 is apparently located elsewhere in the body than in the udder; 

 their milk may produce tuberculosis when inoculated . into 

 guinea-pigs, indicating that under some conditions animals that 

 have no visible signs of udder disease may produce infected 

 milk. 1 It is not of so much importance to settle the matter 

 absolutely as it seems at first, because many animals are doubt- 

 less infected with the disease in the udder without showing it 

 by any visible signs. Moreover, an animal affected with the 

 disease may at any moment have the disease attack the udder, 



1 Rabinowitsch. Zeit. f. Hyg., xxxvii., p. 439, 190i. 

 Mohler. Bui. 44, Bu. An. Ind., 1903. 

 Obermuller. Hyg. Ruiid., p. 712, 1897. 

 Pettersson. Cent. f. Bact., xxxii., p. 274, 1903. 

 Beck. Hyg. Rund., p. 490, 1901. 



