262 CLINICAL BACTERIOLOGY. 



with extraordinary frequency (in fifty per cent, of diseased 

 animals), even when no tuberculous changes are appreciable 

 in the udder. 



If the frequency of tuberculosis in cows is considered 

 in some districts it occurs in from twenty to fifty per cent, 

 of all the cows the danger from the use of unboiled 

 or insufficiently boiled milk, especially the mixed milk of 

 large cities, and particularly for children, must be obvious. 

 The hydrochloric-acid content of the stomach does not 

 afford sufficient protection. The tubercle-bacilli pass the 

 barrier interposed by the stomach, and gain entrance, at 

 least in part, uninjured, into the intestine: A large pro- 

 portion of the cases of tuberculosis of the intestine and 

 the peritoneum, which is so common in childhood, may be 





Fig. 56. Tubercle-bacilli in sputum; Zeiss' homogeneous immersion &, Oc. 4; X 

 about 1000 diameters. 



attributed to the use of such infected milk. The use of 

 meat from tuberculous cows probably gives rise to the 

 development of intestinal tuberculosis only exceptionally. 

 The parts that contain nodules are not permitted to be 

 offered for sale, and the parts free from nodules contain no 

 bacilli. Only in cases of acute general miliary tuberculosis 

 could meat free from tubercles contain bacilli, carried to it 

 through the blood. 



The diagnostic demonstration of tubercle-bacilli is of 

 the highest importance for the early recognition of tuber- 

 culosis. Owing to the specific behavior of tubercle-bacilli 

 with relation to stains, the demonstration of the micro- 

 organisms can be made with the greatest certainty by means 

 of the microscope. 



