14 Farmers* Bulletin 1069. 
METHODS OF DIAGNOSIS. 
Microscopic examinations of sputum, milk, and bowel discharges 
of mi animal are sometimes made to determine the presence of tuber¬ 
cle bacilli and to diagnose tuberculosis, but after many years of 
experience the tuberculin test is now considered to be the most 
practicable and satisfactory way of discovering the disease in the 
living animal. The inoculation of guinea pigs with emulsions made 
from milk or discharges from the living animals is sometimes resorted 
to as a means of diagnosis, but that method of examination is tech¬ 
nical and requires special scientific training and equipment. Be¬ 
sides, cases of tuberculosis may be overlooked when laboratory 
methods are used, because tuberculous animals do not always dis¬ 
charge the tubercle bacilli. 
Piq. 8 .—Liver and spleen showing extensive lesions ol tuberculosis. 
