Section of a tuberculous lung from a cow. The picture 

 shows numerous nearly round tuberculous nodules, one large 

 tuberculous cavity, and several air tubes that extend from tuber- 

 culous nodules that are softening and breaking down. When 

 tuberculous nodules in the lungs break down the material of 

 which they are composed, and which contains millions of tuber- 

 culosis germs is coughed up. Some of the germs are sprayed 

 from the mouth and others are swallowed and dischalrged with 

 the dunsr. 



