218 



rabbits, etc.,) with the milk would require twenty to thirty 

 days for the disease to develop, and the small quantity of milk 

 used for the inoculation might not contain tubercle bacilli. 

 The nasal discharge and the saliva of cattle do not contain 

 tubercle bacilli unless there be erupting tubercles in 

 the lungs or somewhere along the air passages; further- 

 more, the tuberculous material, coughed up from the lungs, 

 may be swallowed when it reaches the pharynx (throat). In 

 all cases where the lungs and air passages are not tuberculous 

 the nasal discharge and saliva contain no tubercle bacilli. 

 Hence, microscopical examinations, or inoculations with 

 these materials will be of value only in a limited number of 

 cases. 



Feeding the milk of a tuberculous cow to a pig or calf 

 may develop tuberculosis in the latter in three to six 



months. 



Tuberculin Test. 



The Tuberculin Test comes the nearest being a perfect 

 diagnostic agent for determining the presence or absence of 

 tuberculosis among cattle. Tuberculin is a material that 

 was discovered by Dr. Koch ; it is a condensed filtrate that 

 is made from sterilized bouillon cultures of tubercle bacilli. 

 In 1890, Koch gave tuberculin to the medical world as a 

 prospective remedy for tuberculosis. For two or three 

 years it was extensively used as a curative agent, but it 

 gradually grew into disuse because it did not meet with the 

 success that was anticipated. During this extensive use of 

 tuberculin in the human family, phj^sicians observed that 

 it uniformly produced a fever or an elevation of the temper- 

 ature in a certain number of hours after its administration 

 to tuberculous persons. This fact led veterinarians to try 

 it as a diagnostic agent in detecting tuberculosis in cattle. 



If a sufficient quantity of tuberculin be injected beneath 

 the skin of a tuberculous animal, its temperature will rise 

 one and one-half to four or more degrees Fah. above 

 the normal in eight to eighteen hours after the injec- 

 tion. This rise of temperature is known as the "reaction" 

 in the tuberculin test. Before injecting an animal its nor- 



