398 Bacteria in Relation to Country Life 



necessarily contain tubercle bacilli. They may be de- 

 tected with certainty only when the animal is suffering 

 from generalized tuberculosis, or has tuberculous 

 lesions in the udder. Nevertheless, even though the milk 

 as it is secreted may be free from these germs, they may 

 find their way into it during the process of milking. 



The feces of tuberculous cattle, even when the disease 

 is not advanced, may contain millions of living tubercle 

 bacilli. The animals do not expectorate and the tubercu- 

 lar matter thrown off from their lungs passes through 

 the alimentary canal and is excreted without involving 

 thereby the destruction of the organisms. It is estimated 

 that the thirty pounds of moist feces produced daily 

 by the average cow would contain, in the case of diseased 

 animals, 37,000,000 microscopically demonstrable tuber- 

 cle bacilli. 



Considering the ease with which particles of such 

 feces find their way into the milk from the body of the 

 cow, from the air, from the bedding, and from the walls 

 and floor of the stable, it is not at all surprising that the 

 germs of bovine tuberculosis are so frequently found in 

 market milk and in market butter. Further proof as 

 to the infectiousness of the feces from the tubercular 

 herds may be found in the alarming increase of tuber- 

 culosis among hogs that are allowed access to such 

 feces, or are fed on skimmed milk. Experimentally, 

 also, the disease may be readily imparted to hogs by 

 adding quantities of feces from tubercular cows to the 

 milk or other food given to them. 



The claim has been advanced that bovine tubercle 

 bacilli cannot produce tuberculosis in human beings. 



