420 IMMUNOLOGY 



laboratory procedure of value in the diagnosis of syphilis is one 

 whose purpose is the demonstration of Treponema pallidum in the 

 primary lesion. Since the index of refraction of the organism is 

 such that it cannot be detected readily in a drop of exudate by 

 direct microscopic examination nor stained by ordinary bacterial 

 stains or even Wright's stain, it is obvious that other methods 

 must be employed. Treponema pallidum can be identified definitely 

 in a drop of exudate by means of the dark-field as suggested by 

 Landsteiner, by staining with Fontana's silver nitrate stain, 

 Giemsa's stain, or by mixing with a drop of India ink and making 

 a smear in which the spirochetes stand out in contrast to the ink. 

 Olsen and Weller (1932) state that it can be stained by ordinary 

 bacterial stains if a phosphomolybdic acid mordant is used. It is 

 not at all impossible for the inexperienced observer to identify 

 erroneously other spirochetes as Treponema pallidum. The student 

 can better appreciate this observation from a perusal of Noguchi's 

 (1928) excellent monograph on Spirochetes. His photomicro- 

 graphs are worthy of study. 



Blood Tests of Little Value During Primary Stage. — Sero- 

 logical tests of the patient's ])l()od are of little or no value during 

 the ]n'imary stage of the disease. Levaditi, La Roche and Yama- 

 nouchi (1908) according to Chesney (1927) obtained positive 

 Wassermann reactions in a few individuals after the eighth day 

 from the beginning of the primary stage, but it is generally ad- 

 mitted that negative reactions are quite common during this 

 stage of the disease. This is because the complement fixation and 

 flocculation tests are designed to detect a heterophile-like antibody 

 called syphilitic reagin that appears in the blood stream in less than 

 half of the infected individuals during the latter part of the 

 primary stage of the disease. It is rarely present during the first 

 week or ten days after the appearance of the primary lesion. 



According to Denison and McDonald (1933) syphilitic reagin 

 was detected in 40 per cent of 110 patients during the primary 

 stage of syphilis. The Kolmer complement fixation test was positive 

 in 36.3 per cent, while the Kahn was positive in 41.8 per cent. The 

 average results obtained by the use of four dii¥erent antigens 

 yielded the figure of 40 per cent given above. The authors do not 



