312 BACTERIOLOGY. 
The bacillus of Lustgarten stains with equal diffi- 
culty as the tubercle bacillus, but is much less resistant 
to the action of certain decolorizing agents, such as 
mineral acids, particularly sulphuric acid. It is, asa 
rule, more resistant to the decolorizing action of alcohol 
than the smegma bacillus. : 
Biological and Pathogenic Properties. Numerous at- 
tempts have been made to cultivate the bacillus of 
Lustgarten on artificial media, but without success. 
The inoculation of animals with syphilitic tissues and 
secretions has also given only negative results, though 
in man, as is well known, such inoculation has often 
taken place, the tertiary products only being non- 
infectious; but as the bacillus has never been obtained 
in pure culture, we have no positive information as to 
its biological characters or pathogenesis. 
Lustgarten’s bacillus has been found in various syph- 
ilitic tissues and lesions, in beginning sclerosis, in the 
papules, in condylomata and gummata, and not only 
in the vicinity of the genitals, but also in the mouth, 
throat, heart, and brain. No satisfactory experimental 
evidence has been given of its causative relation to 
syphilis, but the failure to find other micro-organisms, 
and the occurrence of these characteristic bacilli in vari- 
ous parts of the body, would seem to point to their etio- 
logical importance; while, on the other hand, the long 
immunity in syphilis, so different from that in any 
known bacterial disease, casts doubt not only on the 
status of this bacillus, but also upon the bacterial 
nature of the micro-organism. The fact that the ba- 
cilli have been found occasionally in tertiary lesions— 
which, however, are known to possess no infectious 
property—may possibly be explained by the some- 
