504 LEPROSY AND ACID-FAST BACTERIA 
reported in Russia,' Berlin,- Australia,'* and the United States.'' It is 
found in areas free from human cases, as human leprosy is found in 
locations where the disease is not found in rodents. Whether the 
human and rat leprosy bacilli are identical or not is not finally decided ; 
IVIezincescu^ and Schmitt*^ ha\e shown by the method of complement- 
fixation that the sera of human and rat lepers mutually exhibit complete 
reactions. 
ACID-FAST BACILLI OTHER THAN BACILLUS TUBERCULOSIS 
AND BACILLUS LEPR^.^ 
Following the discovery of the tubercle and leprosy bacilli, which 
exhibit the striking phenomenon of "acid-fastness," a number of 
bacteria presenting the same general staining reactions have been 
described. They are somewhat widely distributed in Nature, being 
occasionally isolated from water, grass or manure, and they are also 
found in association with man and the higher domestic animals, 
frequently occurring as parasites upon the skin, less commonly in 
the nasal secretion or sputum. 
Morphologically the acid-fast bacteria of the non-pathogenic type 
are somewhat shorter and relatively thicker than the tubercle bacillus 
(human type), and in culture they not infrequently grow in filaments 
and exhibit branching. Upon artificial media, furthermore, develop- 
ment is relatively rapid; growth usually appears within forty-eight 
hours, even at 25° to 27° C. The usual type of growth is an irregular, 
wrinkled la.^er, waxy in appearance and of variable color from gray 
to yellow, orange or even brown. ^ The injection of considerable 
amounts of the bacteria into guinea-pigs may lead to the formation 
of granulation tissue nodules, for the organisms are very insoluble in 
the body juices; superficially these nodules may resemble tubercles, 
but they differ in two important particulars— they do not develop 
progressively but are limited to the site of inoculation, and they tend 
to soften gradually and eventually to suppurate and heal spontaneously 
with scar-tissue formation. 
The best-known members of the group are: B. phlei, including the 
various bacilli isolated from grasses and manure; the smegma bacillus, 
which grows on the genitalia and the cerumen; anfl the nasal secretion 
type found occasionally on the skin, in the nasal secretion, the sputum, 
tonsillar exudates and rarely in gangrene of the lungs. It is very 
1 Stefansky: Loc. cit. 
2 Rabinovitsch: Centralbl. f. Bakteriol., orig., 190.3, 33, 577. 
3 Med. Jour. Australasia, 1907, p. 26.3. 
4 Wherry: Jour. Am. Med. Assn., 1908, 50, 1903. McCoy: Public Health Reports, 
July 10, 1908. 
5 Compt. rend. Soc. de biol., 1908, 64, 514; 1909, 66, 56. 
« University of California Pub. in Pathol., 1911, 2, 29. 
^ Weber and Taube: Die Kaltblutertuberkulose, Arb. a. d. kais. Gesundamte., 
" Tuber kulose," 1905. 
" Tuberculin is not produced by these cultures in artificial media. 
