TREPONEMATA 521 



100 c.c. of normal saline solution. One c.c. of this lecithin emulsion 

 is added to each of a number of test tubes of 5 mm. diameter. To half 

 of the tubes add 1 c.c. of the suspected syphilitic serum; to the remain- 

 ing tubes add to some a known syphilitic serum, to others normal 

 serum, and incubate the entire number about four hours at 37 C. 

 The tubes are then removed from the incubator, cooled to room 

 temperature, and those containing syphilitic serum will show a pre- 

 cipitate, which appears to develop first at the surface. It is best 

 observed against a dark background. This method has been modified 

 by Forges by the substitution of a solution of sodium glycocholate 

 for the lecithin. A freshly prepared, 1 per cent, solution of sodium 

 glycocholate is made in distilled water. The test is carried out pre- 

 cisely as in the above method, except that the suspected serum, the 

 known serum, and the normal serum are heated to 55 C. for thirty 

 minutes before being added to the solution. One c.c. each of heated 

 serum and sodium glycocholate are mixed together and kept at room 

 temperature for twenty-four hours. A precipitate forms at the sur- 

 face of the tubes containing the syphilitic serum, but does not form 

 in the tubes containing normal serum. 



Treponema Refringens. Synonym. Spirocheta refringens. 



Schaudinn and Hoffmann 1 observed Treponema refringens both in 

 syphilitic lesions in association with Treponema pallidum, and in 

 non-syphilitic lesions as well, particularly in superficial lesions of the 

 genitalia. This association of Treponema refringens with Treponema 

 pallidum in syphilitic lesions and its common occurrence in non- 

 specific genital lesions emphasize the necessity of its recognition and 

 differentiation from Treponema pallidum. 



Morphology. Observed under the dark-field microscope, Treponema 

 refringens is noticeably thicker than Treponema pallidum, measuring, 

 according to Noguchi, 2 0.5 to 0.75 micron in diameter and 6 to 24 

 microns in length. The ends are somewhat sharply attenuated and 

 they are continued as moderately stiff, delicate spiral flagella. Not 

 infrequently the middle third of the organism is slightly wavy in 

 outline, the end thirds being more closely coiled. Usually the spiro- 

 chetes are more uniformly curved. Occasionally two or three organisms 

 may be joined end to end. As a rule there are from three to eight 

 complete spirals in each organism. 



The organisms are actively motile, and observed with the dark- 



1 Arb. a. d. kais. Gesamte, 1905, xxii, Heft 2. 



2 Jour. Exp. Med., 1912, xv, 467. 



