500 LEPROSY AND ACID-FAST BACTERIA 
These differences are quantitative rather than quahtative, how- 
ever, and cannot be individually relied upon to establish an absolute 
differentiation between the two organisms. The most distinctive 
difference is the "lepra cell" with its large number of acid-fast bacilli 
in groups with their long axes arranged in parallel. 
Isolation and Culture. — Clegg^ cultivated an acid-fast organism from 
lepers by growing the organism upon agar symbiotically with amos bse, 
then killing the amoebse by an exposure to 60° C. for thirty minutes. 
The bacilli, once acclimatized to artificial media, grew readily. Duval- 
has also cultivated acid-fast bacilli directly from lepers. Animal 
experimentation and serological studies have been inconclusive thus 
far. Kedrowski'' described a pleomorphic streptothrix-like organism 
which grew in artificial media as a non-acid-fast streptothrix, but 
tended to change to a pleomorphic, diphtheroid, acid-fast bacillus. 
(Plate III.) When this diphtheroid bacillus is injected into rats or mice 
it becomes acid-fast and resembles B. leprae in detail. Bayon^ states 
that Kedrowski's organism is the true leprosy bacillus, and that 
the diphtheroid form is one stage of the typical acid-fast type seen 
in leprous nodules. The entire subject of the cultivation of B. leprae 
on artificial media must be regarded as sub judice. 
Products of Growth.— Dey eke and Reschad* isolated a streptothrix 
(Streptothrix leproides) from a leper; from cultures of this organism 
a fatty acid-glycerin ester was prepared, to which the name nasiin 
was applied. Rost*^ isolated an acid-fast organism from lepers, upon 
salt-free media. A substance, leprolin, w^as prepared from broth cul- 
tures of this organism precisely as tuberculin is prepared. Neither 
nastin nor leprolin have been successful clinically judging from avail- 
able information. 
Pathogenesis.— //^///iflr^i.— McCoy and Goodhue^ have summarized 
obser\'ations of the infectiousness of lepers in the leper settlement in 
the Hawaiian Islands as follows: of 119 men, practically all Hawaiians 
living in the same house with lepers, 5 (4.4 per cent) developed 
leprosy; of 106 women, practically all Hawaiians, living in the same 
house with lepers, 5 (4.71 per cent) developed leprosy; of 12 women, 
all Caucasians, nurses and members of religious orders, living among 
lepers, none contracted the disease; but of 23 Caucasian males, 3 
contracted leprosy. The shortest period in which the disease appeared 
after exposure was three years (2 cases) ; the longest seventeen years. 
Heiser^ has recorded a case which developed after a two-year incubation 
period. Arning*^ inoculated a condemned criminal with leprosy bacilli 
derived from a leper and the criminal de\'eloped leprosy. Several other 
> Philippine Jour. Sci., 1908, 4, 403. 
2 Jour. Exp. Med., 1910, 12, 649; 1911, 13, 365. Jour. Am. Med. Assn., 1912, 58, 1427. 
3 Ztschr. f. Hyg., 1901, 37, 52. ^ Centralbl. f. Bakteriol., ref., 1913, 56, 592. 
5 Deutsch. med. Wchnschr., 1907, 33, 89. Deycke: Lepra, 1907, 7, 174. 
« British Med. Jour., 1905, i, 294. ' Public Health Bull., 1913, No. 61. 
» Jour. Am. Med. Assn., 1914, 62, 205. 
9 Centralbl. f. Bakteriol., 1889, 6, 201. 
