THE SPIROCHMTACEM 633 



Mix with 25 c.c. of pure anhydrous glycerin at 60 C. 

 When dissolved add 25 c.c. of pure methyl alcohol, also at 

 60 C., allow mixture to stand over-night, then filter. 

 To stain the smears take from the above "stock" solution 

 1 c.c. and mix with 10 or 12 c.c. of 1 : 1000 potassium car- 

 bonate in distilled water. Pour this diluted stain over 

 the smears and allow to stand for from a quarter to half 

 an hour. If the smear be very thick, exposure to the stain 

 should be longer. Wash repeatedly in clean water until the 

 smear has in general a pink tinge. This clearing up may be 

 hastened in thick smears by immersion for an instant in 

 methyl alcohol, followed by repeated washings in water. 

 When dried, the preparations are examined in the way 

 common to microscopic examination of bacterial prepara- 

 tions. 



Silver Impregnation. Stern's Method. Prepare smear; 

 dry in incubator at 37 to 38 C. for several hours (do not 

 heat over flame). 



Immerse in 10 per cent, silver nitrate solution and expose 

 to diffuse day-light (not direct sun-light) for from several 

 hours to several days. When the preparation is of a deep 

 brown color and shows a metallic sheen, wash thoroughly 

 in clean water, dry and mount for examination. 



The organisms are seen as black threads or spirals in a 

 brown field. 



India Milk Method. Mix a drop of the suspected blood 

 or exudate with a drop of India milk on one end of a slide. 

 With the edge of another slide draw this quickly down the 

 length of the slide so as to make an even tolerably thin film. 

 Allow to dry. Examine by the usual method. Any organ- 

 isms present will appear as colorless objects in an almost 

 black field. The picture is that of a photographic negative. 



