312 SPECIFIC MICRO-ORGANISMS 



mammalian types. Mice and rabbits are also susceptible, while 

 guinea-pigs are relatively resistant. The avian tubercle bacillus has 

 been found in human tuberculous lesions in a very few instances. 



Bacillus Tuberculosis var. Piscium. This variety occurs 

 in natural tuberculous lesions of snakes, fish, turtles and frogs. 

 The bacillus is quite different from the preceding varieties, as 

 it grows rapidly on ordinary media at temperatures ranging from 

 12 to 36 C., and the bacilli developed on the poorer media are 

 often not at all acid-proof. When grown in bouillon with fre- 

 quent shaking the culture becomes diffusely cloudy, and the 

 organisms of such cultures are said to be motile. Most warm- 

 blooded animals are wholly refractory to inoculation, but, in 

 the guinea-pig, inoculation has sometimes been followed by the 

 production of typical tubercles with epithelioid and giant cells, 

 usually encapsulated and tending to heal. 



Bacillus (Bacterium) Leprse. Hansen in 1873 and Neisser 

 in 1879 discovered this organism in the nodular lesions of leprosy. 

 Cultures were first obtained by Clegg in 1908 by inoculating 

 leprous tissue onto agar along with living amebae and the vibrio 

 of Asiatic cholera. Pure cultures of B. leprcz were subsequently 

 obtained by heating the mixture to kill the other organisms. 

 Inoculation of cultures into mice and guinea-pigs is said to pro- 

 duce leprous nodules but the evidence has not appeared to be 

 very convincing. More recently Duval and Couret 1 after very 

 extensive investigations, in which Clegg's work was confirmed, 

 have been able to produce very typical leprosy in a monkey by 

 repeated injections of a pure culture, resulting in general dissemi- 

 nation and death one year after the last injection. The results 

 have not been confirmed and is a subsequent paper 2 Duval is 

 inclined to question the value of his previous animal experiments, 

 and even suggests that the organism employed plays only a 

 negligible part in leprosy. 



B. leprce is a slender rod 0.2 to 0.45/4 wide by 1.5 to 6ju long 



1 Journ. Exp. Med., Vol. XV, pp. 292-306. 



2 Duval and Wellman, Journ. Inf. Diseases, 1912, Vol. XI, pp. 116-139. 



