172 BA CTERIOL G Y. 



quantity of alcohol poured over the surface and washed 

 oif instantly. The water on the cover-slip is now ab- 

 sorbed from the edge of the cover-slip with clean filter- 

 paper. The carbol-fuchsin stain is now applied and 

 heated just enough to generate a thin vapor. The stain 

 should not act for more than from one-half to one minute. 

 The cover-slip is now dried, then xylol is poured over 

 the surface, the excess being removed with filter-paper. 

 The cover-slip is now mounted in xylol balsam. 



STERN'S METHOD FOR THE STAINING OF SPIRO- 

 CHA^ETE PALLIDA. The spiral organism discovered 

 in the lesions of syphilis by Schaudinn and Hoffman, 

 and generally regarded as the cause of syphilis, is most 

 easily demonstrated by the following simple method : 



Prepare cover-slips from the serous exudate of the 

 syphilitic lesion. Allow them to dry, first at ordinary 

 room temperature, then for an hour at 37 C. Do not 

 heat over the flame. Immerse them in a 10 per cent, 

 silver nitrate solution in a clear glass dish and expose to 

 diffuse day light (not direct sun light) for several hours 

 until the films take on a brownish color and a metallic 

 lustre. Then wash in water and mount for examin- 

 ation. The spirochsete will be seen as almost black 

 spirals lying in a more or less granular field. 



