TREPONEMATA 581 
or less uniform, faint cloudinjij of the medium. The associated con- 
taminatino; organisms are for the most part confined chiefly to the 
hue of inoculation. At the end of the period of incubation the tube 
is broken at an appropriate level with sterile precautions and some 
of the turbid medium removed into fresh tubes of the same kind, 
and the process repeated until pure cultures of the organisms are 
obtained. If gas-producing bacteria are present the results are unsuc- 
cessful as a rule. 
Products of Growth.— The products of growth are unknown. Tre- 
ponema pallidum does not produce a characteristic and disagreeable 
odor which distinguishes it from cultures of other spirochetes in 
artificial media. ^ 
Pathogenesis. — .l»i/?/fl/. — In 1903 Metchnikoff and Roux- trans- 
mitted syphilis to a chimpanzee, and later infected other monkeys 
with material from jirimary or secondary lesions in man. These 
Fig. 80. — Treponema pallidum, congenital syphilitic liver. 
results have been amply confirmed by other investigators. The 
incubation period averages about three to four weeks. It may be as 
brief as two weeks or as prolonged as seven weeks. The lesion, his- 
tologically indistinguishable from a chancre, appears soon after the 
end of the incubation period at the site of inoculation; the regional 
glands become enlarged and indurated. Secondary lesions appear in 
about 50 per cent of successful inoculations, usually four to five 
weeks after a chancre appears. Skin lesions are somewhat indefinite, 
But the mucous patches are readily recognized. Xo tertiary lesions 
have been demonstrated in experimental inoculations into animals 
with the virus of syphilis up to the present time. Noguchi'' has suc- 
cessfully inoculated two monkeys (Macacus rhesus and Seropithecus 
1 Noguchi: Jour. Exp. Med., 1912, 15, 99. 
2 Ann. Inst. Pasteur, 1903, 17, 809; 1904, 18, 1, 657; 1905, 19, 673; 1906, 20, 785; 
Deutsch. med. Wchnschr., 1903, 29, 943. 
3 Jour. Exp. Med., 1912, 15, 96. 
