2 ANNALES DE L’INSTITUT PASTEUR 
Of late years one of tlie most disputée] problems in connec¬ 
tion with the experimental research of syphilis lias been that 
of the cultivation of Treponema pallidum. This particular 
phase of the investigation lias ealled forlh profound study on 
the part of numerous experimental workers, but it was not 
until the cultivation of Treponema pallidum was undertakeu 
with a purely experimental material (namely the uncompli- 
ealed syphiloma of the rabbit s testicle, after Uhlenhuth and 
Mulzer) that the vexed question as to the identity of the spiro- 
ehaeta cultivated according to various methods was finally 
decided. We recall a time when any spirochaeta cultivated 
from human syphilitic tissue (highly impure material and 
resembling Treponema pallidum in its morphological features 
was thought to be lhe organism of syphilis (Schereschewsky, 
Mühlens, W. H. Hoffmann) ; but as the resuit of subséquent 
investigations carried outwith the pure experimental syphilitic 
material, it bas been shown that certains cultures formerlv held 
to be those of the pallidum differed essentially from a virulent 
culture derived from the latter material in heing putrefactive 
and avirulent [Noguchi (1), confirmed by the subséquent 
works of Sowade, Tomascewski, Arnheim, Shmamine, Nakano, 
Baeslack and others] (2). It has now been settled beyond 
dispute that an odor-producing Treponema is not the Treponema 
pallidum , and this conclusion has been arrived at through the 
aid of experimental syphilis produced in suitable animais. In 
commemorating the jubileeof our master Professor Melchnikotï 
it may therefore not be out of place liere to record a few of 
the phenomena observed by me during the last few years in 
connection with Treponema pallidum and olher members of 
the genus Treponema. 
The phenomena in question relate to certain modifications 
vvliich w y ere seen to occur in the hiological properties of various 
treponemata after the latter had been subjected to brief or 
prolonged cultivation on artiticial media. It may liere be 
recaîled thatl hâve succeeded in obtainingin pure cultures lhe 
jl) N oguchï, Journ. Am. Med. Assoc., July, 8, 1911, p. 102; — Münch. med. 
Wochenschr., 1901, n° 29, p. 1550; — Jour. Exper. Med., 1911, t. XIV, p. 99; — 
Jour. Exper. Med., 1912, t. XV, p. 90. 
ieN icw may be found in La Presse Médicale, n° 76, septembre 1913. 
