382 The Diseases of Animals 
method of infection), or by being taken in with the 
food or by being inhaled and taken into the lungs. In 
the transmission of the disease from one animal to 
another, the germs are probably conveyed by one of the 
last two methods. Suckling calves may get the germs 
in the milk from a tuberculous cow, or they may take 
them upon dry food or in drinking water, where they 
Fig. 56. Section of tuberculous lung. 
were scattered by diseased animals. It is probable that 
the discharge from the nose, which contains the germs, 
heing dried, is stirred up in the form of dust, and 
when inhaled by healthy animals produces the disease. 
In a few cases it is possible that the disease may be con- 
genital. Such cases are rare, and oceur only when the 
cow’s generative organs or her whole system are 
diseased. 
