TUBERCULOSIS. LEPROSY 97 



The use of tuberculin did not prove as satisfactory 

 as Koch had expected, and was discontinued almost 

 entirely, except as a means of diagnosis in obscure 

 cases in man and as a test in dairy cows, the latter 

 being practiced extensively in all countries. 



Immunity. An attack of tuberculosis followed 

 by cure does not render the patient immune, but on 

 the contrary, seems to increase his susceptibility to 

 further infections. 



LEPROSY 



Leprosy is a chronic, infectious, endemic disease 

 caused by Bacillus leprce, an organism bearing a very 

 strong resemblance to Bacillus tuberculosis. 



The leprosy bacillus was discovered by Hansen, a 

 Norwegian scientist, in 1872 ; prior to this, certain 

 peculiar cells had been observed in leprous tissue, 

 and Hansen found large numbers of leprosy bacilli 

 lying within these "lepra cells. 11 The leprosy bacillus 

 is a slender rod, usually straight, occurring in charac- 

 teristic bundles; it is without motion, does not form 

 spores, and is usually found in the "lepra cells," al- 

 though sometimes observed in the lymphatic glands 

 and in the blood. 



In the tubercular form the bacilli occur in enor- 

 mous numbers, much greater than in the anaesthetic 

 form. 



