SYPHILIS 497 



regular, and narrow spiral, is actively motile, possessing 

 a single delicate flagellum at each end, and it may have 

 an undulating membrane. It stains feebly and with 

 difficulty. Another spirochaete, the S. refringens, fre- 

 quently accompanies, and must not be mistaken for, the 

 T. pallidum in ulcerating lesions ; the former is more 

 refractile and coarser, has fewer twists and forms a wider 

 spiral, and stains deeper and more readily than the latter. 

 The T. pallidum is found generally in all primary and 

 secondary lesions of syphilis, e.g. the primary sore and 

 adjacent lymphatic glands, in the papular and roseolar 

 eruptions, in condylomata and mucous patches. It has 

 also occasionally been found in the spleen and blood. In 

 congenital syphilis the T. pallidum is met with in the 

 bullous eruptions, blood, and organs, and is particularly 

 abundant in the spleen and liver (Plate XXIII. a). 



Tertiary lesions are generally considered to be non- 

 infective, and the T. pallidum is usually difficult to find 

 in them. It has, however, been detected in the peripheral 

 portions of gummata and in syphilitic aortitis, and may 

 persist in the body for years after the primary lesion. 

 Noguchi, after a careful search, has detected the spiro- 

 chaete in the brain in cases of general paralysis (in 48 

 cases out of 200 examined) and also in the posterior columns 

 in a case of tabes. 



The T. pallidum is now universally regarded as the 

 specific organism of syphilis, being present not only in 

 the human lesions but in experimental lesions of inoculated 

 apes (see below). It must be recognised that spirochaetes 

 are of frequent occurrence in various non-syphilitic ulcera- 

 ting and other lesions, e.g. in the mouth and in pyorrhoea, 

 in yaws and ulcerating granuloma (in yaws they are specific 

 forms, see p. 495), in ordinary ulcers and in carcinomatous 

 tumours. Generally the T. pallidum can be distinguished 

 microscopically from the other species, but care is necessary. 



32 



