78 



Dairy Bacteriology. 



temperature three or four degrees; in healthy animals 

 only a slight rise occurs. A positive reaction should be 

 at least from 2.2-2.5 F. above average normal, and 

 should be maintained with some fluctuations for several 

 hours. Animals in the later stages of the disease some- 

 times do not respond, but when the test is properly ap- 

 plied, it is on the whole a most satisfactory aid in diag- 

 nosis. 



77. Relation of disease organism to milk-supply. 

 While tuberculosis is widely distributed among cattle, it 



FIG. 14. Side view of tuberculous udder, showing extent of swelling in single 

 quarter. 



must not be supposed that the milk of all reacting ani- 

 mals is infected with the specific organism. In a small 

 percentage of cases, the udder and related tissues are af- 

 fected, in which case the milk generally possesses in- 



