SPIROCHETE PALLIDA 517 



These organisms generally stain deeply with Giemsa's stain and 

 are of a bluish tint ; the sp. pallida is coloured a faint pink. In 

 lesions of the mouth and probably in some others, e.g., foetid 

 ulcerations, etc., there occur, however, spirochetes which are 

 indistinguishable morphologically from the sp. pallida, e.g., the 

 sp. microdentia and sp. mucosa, found in carious teeth and 

 pyorrhoea alveolaris. Both of these organisms have been culti- 

 vated by Noguchi ; they have been proved to be devoid of 

 pathogenic properties, and the cultures, - moreover, have a foul 

 odour. The sp. pertenuis of yaws (p. 524) has also the same 



; 





Fig. 158. — Film preparation from juice of hard chancre showing 

 spirochete pallida. Giemsa's stain. X2000. (From a preparation 

 by Dr. Haswell Wilson.) 



microscopical appearances. In the microscopical?' diagnosis of 

 the organism of syphilis, just as in the case of the tubercle 

 bacillus (p. 286), an all-important point is, accordingly, the 

 source of the organism ; and we may say that if we except the 

 case of yaws, which does not occur in this country, an organism 

 with the characters described above can be identified with 

 certainty as the sp. pallida provided that it is obtained from the 

 substance of the tissue lesion. The spirochsete pallida by the 

 Giemsa stain is coloured somewhat faintly, and of reddish 

 tint, whilst the regular spiral twistings are preserved; the sp. 

 refringens shows flatter, wave-like bends (Fig. 160), and, like 

 other organisms, is stained of a bluish tint. 



