618 INFECTION AND IMMUNITY. 



in vitro of an acid-fast organism was obtained from the 

 transplanted leprosy tissue on the above mentioned media 

 from four cases of leprosy which corresponded in every 

 essential to the leprosy bacillus, jtfot only did the 

 leprosy bacilli develop in the original cultures but they 

 continued to grow in subcultures. That the artificial 

 growth is B. leprce there can be no doubt, as the morpho- 

 logic and cultural features and the animal tests have 

 clearly proved. 



Lugai has shown that the leprosy bacillus is 

 pathogenic for Japanese dancing mice. The ba- 

 cilli not only multiply at the site of inoculation 

 but become disseminated throughout the body, 

 \ producing lesions having the typical characters of 

 leprous lesions in man. Nicolli is said to have 

 produced leprous nodules in monkeys by inocu- 

 lating them with diseased tissue, and finally Duval 

 has produced typical leprosy of the tubercular type 

 in the monkey (Macacus rhesus), by means of pure 

 cultures of leprosy bacillus. 



So far as known, the organism has no natural 

 existence outside the human body, and it is dis- 

 seminated only by the secretions of the diseased. 

 It is discharged chiefly through the secretions of 

 the nose and the upper respiratory passages, the 

 surfaces of which are so commonly the seat of lep- 

 rous ulcers, and also through ulcerating lesions of 

 the skin. Expectoration, sneezing and coughing 

 have approximately the same significance for the 

 dissemination of leprosy bacilli as of tubercle ba- 

 cilli. However, the organisms which are found in 

 the sputum and nasal secretions appear to be 

 largely degenerated, a condition which may lessen 

 Transmission, the inf ectiousness of these substances. 



The infectiousness of the leprosy bacillus is of a 

 low character. "Epidemiologic experience teaches 



