578 THE PON EM AT A, SPIRONEMATA, LEPTOSPIRATA 
Spironema.— Organisms with pointed ends, diameter from 0.35 to 
0.50 micron, cylindrical, or slightly flattened in cross section. The 
spirals are about 5 in number, large, wavy and inconstant. iVn axial 
filament is probably present. A delicate, flexible doubly contoured 
membrane is also found. No flagella have been demonstrated, but a 
terminal, finely-pointed filament is probably demonstrable in members 
of this group. The important members include the organisms of 
relapsing fever, as well as those forms more commonly referred to as 
Treponema refringens and Treponema phagedenis (balanitidis). 
Treponema. —The organisms are cylindrical with pointed ends. They 
measure from 0.25 to 0.3 micron in diameter and from (> to 14 microns 
in length. The spirals are regular and fairly rigid. A membrane is 
probably not present. Flagella are absent, but a finely-pointed term- 
inal filament may be demonstrated. The two most important members 
are the organisms of syphilis (Tr. pallidum) and of Yaws (Tr. per- 
tenue, or pallidulum). 
Leptospira.— The organisms exhibit pointed ends, and measure from 
0.25 to 0.30 micron in diameter, and from 7 to 14 microns in length. 
There is no axial filament, or membrane, and no terminal, finely-pointed 
spiral filament. Flagella are absent. A highly motile end portion, 
however, is present. A characteristic feature of free swimming Lepto- 
spirata is a semicircular bending of one or both ends. The organisms 
found in yellow fever and infectious jaundice belong to this group. 
(Leptospira icteroides and Leptospira icteroha^morrhagicffi.) 
TREPONEMATA. 
Treponema Pallidum. — Synonym.— Spirocha^ta pallida. 
Historical.— The organism which is now universally conceded to 
be the effective agent in syphilis was first described by Schaudinn 
and Hofi"mann.^ It was named Spirocha^te pallida by these observers, 
but it presents certain peculiarities of structure which are of sufficient 
magnitude to separate it from the group of the spirochetes. It has 
been placed in a newly established group, the Treponemata, by 
Schaudinn. It is probable that the correct name is Spironema pallidum 
{ride .supra). 
Morphology.— Treponema pallidum is a long, very thin, delicate, 
closely coiled, flexuous spiral organism w^hich measures from 0.25 to 
0.4 micron in diameter, and, on the average 7 to 8 microns in length. 
The length, however, may vary from 3 microns in very young organ- 
isms to 15 microns. The spirals, which are very regular in outline, 
are ordinarily from to 12 in number per organism; they may be as few 
as 3 to 5 in the shorter forms or as niunerous as 20 in the longer forms. 
Xoguchi- has described three morphologically recognizable types of 
' Alb. a. d. kais. Gesamte, 1905, 22, 527; Deutsch. med. Wchnschr., 1905, 31, 1665, 
1710. 
2 .Jour. Exp. Med., 1912, 15, 201. 
