326 SPECIFIC MICRO-ORGANISMS 



of the liquid. Chickens are very susceptible to intravenous 

 inoculation with this type of bacilli but quite refractory to the 

 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 bacilH 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 (Mycobacterium) Leprae.— Hansen in 1873 and 

 Neisser in 1879 discovered this organism in the nodular lesions of 

 leprosy. Successful artificial culture has been reported by many 

 authors but the identity of the organisms in these cultures has 

 not been established with certainty. 



B. lepra is a slender rod 0.2 to 0.45^1 wide by 1.5 to (>y. long 

 as it occurs in tissues. In its staining properties it closely re- 

 sembles the tubercle baqillus. The organism occurs in enormous 

 numbers in most of the nodular lesions of leprosy andris often 

 abundant in the nasal mucus of these cases. When less numerous 

 the antiformin method of Uhlenhuth may assist in finding them. 

 For diagnosis a small piece should be excised from one of the 

 nodules or fragments may be obtained from lesions in the nose or 

 pharynx by means of a curette. From these pieces smears on 

 slides are stained at once for acid-fast bacilli. Pieces of the 

 tissue are embedded in paraffin, sectioned and stained to demon- 

 strate the bacilli. 



Leprosy has been known since the dawn of history and has 



