RURAL VETERINARY SECRETS 



121 



Lungs showing lesions of generalized tuberculosi 

 Photo by Author. 



-ame heife)-. 



THE VALUE AND RELL4BILITY OF THE TUBERCULIN TEST 



As a result of this method an accurate diagnosis may be estab- 

 lished in over 97 per cent of the cases tested. The relatively few 

 failures in diag"nosis are included among two classes of cattle. The 

 first class contains those that are tuberculous, but which do not 

 react, either because of the slight effect of an ordinary sized dose 

 of tuberculin, or an advanced case of the disease with so much natu- 

 ral tuberculin already in the system ; or on account of a previous 

 test with tuberculin which produces a tolerance to this material 

 lasting for about six weeks. The second class includes those that 



