284 BACTERIOLOGY. 



the flesh of tuberculous cattle. Here the same condi- 

 tions hold good as in the infection by milk, only the 

 danger is considerably less, from the fact that meat is 

 usually cooked, and also because the muscular tissues 

 are seldom attacked. In view of the great mortality 

 from tubercular diseases among mankind, the legisla- 

 tive control and inspection of cattle and milk would 

 seem to be an absolute necessity. As a practical and 

 simple method of preventing infection, especially 

 among children, the sterilization (by heat) of the milk 

 used as food must commend itself to all. It is only right 

 to state, however, that the actual proof that human tuber- 

 culosis has come from milk or food infected with bovine 

 tuberculosis is very small, and that it is perfectly pos- 

 sible that the bovine bacilli may not be as virulent for 

 man as for animals, still we know that human tubercu- 

 losis produces bovine tuberculosis in young and suscep- 

 tible animals, and the reverse is in all probability true. 

 The relation of bovine to human tubercle bacilli will 

 be discussed later in this chapter. 



Auto-infection by Swallowing Sputum. The secondary 

 forms of tuberculosis which often succeed a primary 

 infection of the lungs may be explained as an auto- 

 infection from the swallowing of sputum containing 

 bacilli, these passing through the gastric juice unaf- 

 fected. It is a wonder, indeed, that intestinal tuber- 

 culosis is not more common than it is in consumption; 

 but this is probably due to the fact that in adults the 

 intestines are comparatively insusceptible. Tubercu- 

 losis may also begin as a local infection in the lungs or 

 intestines, and theiice extend to other parts of the body, 

 until, passing into the circulation, a general miliary 

 tuberculosis results. 



