B ACTERIACE^E : THE TUBERCLE BACILLUS 313 



as it occurs in tissues, much shorter in cultures. In its staining 

 properties it closely resembles the tubercle bacillus, but is less 

 constantly acid-proof in cultures. The organism occurs in 

 enormous numbers in most of the nodular lesions of leprosy and 

 if often abundant in the nasal mucus of these cases. When less 

 numerous the antiformin method of Uhlenbuth may assist in 

 finding them. Duval and his co-workers have obtained pure 

 cultures by the method of Clegg and also by planting uncontami- 

 nated leprous tissue on serum agar to which trypsin has been 

 added. Eventually the bacilli adapt themselves to growth on 

 ordinary media such as plain agar. In the first cultures the growth 

 may be slow and relatively meager, but later abundant growth 

 may be obtained in 2 to 3 days. The color is orange. Injection 

 of these cultures into mice, guinea-pigs and monkeys is ordinarily 

 followed by transient lesions which have been considered by some 

 to resemble those of leprosy. The one instance of the monkey 

 reported by Duval and Couret, mentioned above, seems to be 

 more convincing, but further work is necessary before the status 

 of these cultures can be definitely established. 



Leprosy has been known since the dawn of history and has 

 been considered to be transmissible for a long time. It is widely 

 distributed over the earth, especially in Norway, Russia, Iceland 

 and in Turkey. In the United States there are leper colonies in 

 Louisiana, Minnesota and in Hawaii. Lepers are occasionally seen 

 in the clinics of all the larger cities. 



Leprosy is universally considered to be due to the leprosy 

 bacillus, but as to mode of transmission, whether direct from 

 man to man, or from the external world, or how, little or nothing 

 is really known. It seems certain that the disease is always con- 

 tracted in some way from a previous case, but it is certainly not 

 very readily transmitted. Segregation without absolute isolation 

 is the common method of handling lepers. The disease is not 

 ordinarily inherited. 



Bacillus Smegmatis. This organism occurs in the smegma 

 on the genitals of man and other mammals and also in moist folds 



