158 



TUBERCULOSIS 



SO that a beginning lesion no larger than a walnut may cause 

 a pronounced rise of temperature and such a tubercle may be 

 difficult to find, especially if located in the marrow of some 

 bone. 



(2) Where there is no reaction and the disease exists. It 

 is generally admitted that advanced cases often fail to react, 

 but here the test itself is of little importance as the disease can 

 be detected by the clinition on physical examination. When, 

 however, tuberculin is carefully prepared and scientifically 

 administered, these exceptions are exceedingly rare. 



The practical value of tubercuhn, however, lies in its effi- 

 ciency in the arts of comparative and sanitary medicine. It is 

 in the practical application that difficulties are encountered. 

 The many details and precautions enumerated as absolutely 

 fiouFfs ArrER Injection 



Fig. 35. Irregular temperatures following tuberculin that are not caused by 

 tuberculosis. ( Curtice. ) 



essential to the best results are often considered too tedious and 

 time consuming, and consequently the practice has come too 

 generally into vogue of neglecting or ignoring many of the 

 precautions. In order that the te.st may be practicable, some 

 practitioners resort to a shorter method of procedure even at 

 the risk of an occasional error. 



§ 118. Prevention. Tuberculosis, like other infectious 

 diseases, can be very largely prevented. To accomplish this it 

 is necessary to keep tuberculous animals from entering the 



