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No. 11.— Sections of a tuberculous heart from a cow. The light parts are tuberculous. The heart 

 muscle is greatly reduced in volume and is prevented from working properly by the tuber- 

 culous material by which it is surrounded. The picture shows how badly an animal may 

 become diseased with tuberculosis before it dies. One reason why tuberculosis is so common 

 among persons and cattle is that many persons and cattle pass tuberculosis germs from their 

 bodies before any one knows or suspects that they have tuberculosis and can give the disease 

 to others. 



