PATHOGENIC BACTERIA. 293 



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 tendencj' to tuberculosis 

 than to the inheritance of the tubercle bacilU themselves. 



Agglutination of the tubercle bacillus is said to occur with 

 the serum of cases of tuberculosis under certain circumstances. 

 The reaction does not seem Hkely to be of practical value. 



Tuberculin is made by concentrating a culture of tubercle 

 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 products of tubercle 

 bacilli. It was proposed by Koch as a remedy for tuberculosis, 

 but it has not met with great success, and is Httle used as a 

 therapeutic agent. It has been found, however, of great value 

 in the diagnosis of tuberculosis, especially in cattle. When 

 tubercuHn is injected into a tuberculous animal there results 

 considerable general disturbance, of which the most noticeable 

 evidence is a sudden 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 appUcation in diagnosis is practically con- 

 fined to cattle.* As a diagnostic measure in cattle it has been 

 found accurate in the great majority of cases. Concerning 

 tuberculosis in cows, see page 137. Supposing that some 

 curative principle exists in _the bodies of the tubercle bacilli 

 themselves which could not be procured from cultures de- 

 prived of their bacilh by filtration through porcelain, Koch 

 has recently proposed a new form of tubercuhn called "tuber- 

 culin R," which consists of an extract made from dried and 

 pulverized living tubercle baciUi. The value of this new 

 tubercuHn as a remedy is at least doubtful, and physicians are 

 disposed to regard it with a great deal of skepticism. 



* For details as to its use in cattle see V. A. Moore. Infectious Diseases of 

 Animals. P. 151- i9°2- 



