314 BACTERIOLOGY. 
mata, suggests that the bacilli found in such lesions were, 
perhaps, tubercle bacilli, and represented a mixed in- 
fection. This may have been true of some cases, no 
doubt, as the differentiation of new-growths of tertiary 
syphilis and tuberculosis is often difficult; but the differ- 
entiation of the two bacilli can usually be made by their 
different powers of resistance to the decolorizing action 
of acids. Finally, other micro-organisms have been 
described and claimed to be the specific cause of syph- 
ilis, but none of these discoveries have been confirmed. 
From this it appears that though there is no conclusive 
proof of the fact, there is some possibility, but hardly 
a probability, that Lustgarten’s bacillus is the true cause 
of syphilis. Its position at present is too doubtful to 
make its detection of any diagnostic value. 
Syphilitic Infection. Infection of those not immune 
can take place at any time when an abrasion, however 
small, is brought in contact with the blood or secretions 
from the primary or secondary lesions of syphilitics. 
The differential diagnosis of Lustgarten’s bacillus 
must be made from the tubercle bacillus, the smegma 
bacillus, and the leprosy bacillus. According to Hueppe, 
the differential diagnosis between these four organisms 
depends upon the following reactions: When stained 
by the carbol-fuchsin method commonly employed in 
staining the tubercle bacillus, the syphilis bacillus be- 
comes almost instantly decolorized by treatment with 
mineral acids, particularly sulphuric acid; whereas the 
smegma bacillus resists such treatment for a much 
longer time, and the lepra and tubercle bacillus for a 
still longer time. On the other hand, if decolorization 
is practised with alcohol instead of acids the smegma 
bacillus is the first to lose its color. The bacillus tuber- 
