294 MANUAL OF BACTERIOLOGY. 



a case of tuberculosis may expectorate many millions of 

 tubercle bacilli in the course of twenty-four hours. Cough- 

 ing and similar efforts may serve to disseminate the bacilli 

 (see page 163). 



Concerning the occurrence of tubercle bacilli in cow's 

 milk and butter, see pages 148 and 149. 



Cases have been recorded in which the disease was trans- 

 mitted from the mother to the child in the uterus ; how fre- 

 quently this happens is uncertain. It is usual to attribute 

 greater importance to an inherited tendency to tuberculosis 

 than to the inheritance of the tubercle bacilli themselves. 



Agglutination of the tubercle bacillus is said to occur with 

 the serum of cases of tuberculosis under certain circum- 

 stances. The reaction does not seem likely to be of practical 

 value. 



Tuberculin is made by concentrating a culture of tuber- 

 cle bacilli grown in glycerin-bouillon to one-tenth of its 

 original volume, over a water-bath, and filtering through an 

 unglazed porcelain filter. It therefore represents the pro- 

 ducts of tubercle bacilli. It was proposed by Koch as a 

 remedy for tuberculosis, but it has not met with great suc- 

 cess, and is little used as a therapeutic agent. It has been 

 found, however, of great value in the diagnosis of tubercu- 

 losis, especially in cattle. When tuberculin is injected into 

 a tuberculous animal there results considerable general dis- 

 turbance, of which the most noticeable evidence is a sud- 

 den rise in temperature, while hyperemia is excited around 

 the tuberculous area. In a healthy subject the injection 

 produces no reaction. There is danger attending its use, 

 so that its application in diagnosis is practically confined to 

 cattle. 1 As a diagnostic measure in cattle it has been found 

 accurate in the great majority of cases. Concerning tuber- 



1 For details as to its use in cattle see V. A. Mi tore, "Infectious 



Diseases <>f Animals," i<)O_\ p. 151. 



