ARTIFICIEL CULTIVATION OF SPIROCHAETES 
3 
following varieties the of Treponema group : Tr. pallidum , 
Tr. per tenue, Tr. macro dentium, Tr. micro dentium, Tr. muco- 
sum , Tr. calligyrum and Tr. refringens. These were main- 
tained in pure cultures by successive transplantations and kept 
under observation for two to four years [since 1910-1912j (1). 
The salient points of interest are briefly as follows : 
From a morphological standpoint no striking modifications 
has been observed in lhese cultures. They still retain their 
original types even after a period of from two to four years. 
The staining reactions are also unatfected, altliougli tbe palli- 
dum , when grown in a fluid medium, takes up the red compo- 
nent of the Giemsa soinewhat more readily than the specimens 
in the tissue or solid culture media. On the other hand ithas 
been noticed that certain detînile alterations occur in their 
biological properlies. In the case of the pallidum the viru¬ 
lence disappeared within about four months after its purifica¬ 
tion. In that of the per tenue it was found that the strain 1 
studied lost its virulence as soon as it was freshly isolated in 
pure culture. The power possessed by the microdentium to 
produce an intense disagreeable odor remained undiminished 
for nearly one year, but this gradually and almost imperceptibly 
diminished in intensity and now after two years the odor is 
scarcely noticeable. In the case of the mucosum it was 
found that its mucin-producing property gradually weakened 
and linally disappeared within about five months after its isola¬ 
tion. Although the odor-producing property of this species 
has suffered a more graduai diminution in the course of a pro- 
longed life in culture, nevertheless it is distinctly less marked 
than was the case two years ago. The other species here men- 
tioned possess no remarkable features, and they apparently 
remain unmodified in their characteristics, none of them being 
odor-producing. 
The graduai or often sudden disappearance of the virulence 
of highly parasitic organisms, such as the pallidum and per - 
tenue , under artificial cultural conditions is not much to be 
wondered at, especially when we know from the experiments 
(1) For the literature see the bibliography in the article appearing in 
n° 76 of La Presse Médicale , sept. 1913. 
