YEASTS AND MOULDS 341 



is taken on a slide, teased out in a drop of acetic acid 

 (which renders the epithelial cells almost invisible), and 

 examined. The parasite is clearly seen as described 

 above. The spores are round or oval. A stained specimen 

 may be made by teasing in a distilled water drop, exposing 

 to dry, fixing by heat or absolute alcohol, and staining 

 with thionin. To isolate in culture, inoculate on gelatin, 

 and incubate at a low temperature (15 to 20 C.) for 48 

 hours. By that time white or creamy colonies appear, 

 which are pure cultures of the thrush fungus. The ordinary 

 microbes of the mouth are unable to develop at that 

 temperature in the same time. 



Ringworm Fungi. The study of these is very complex. 

 The mode of demonstration of them in the various parts 

 affected is the same for all, and is summarized thus by 

 Agasse-Lafont : 



Hairs. Prepare a solution of caustic potash of 30 per 

 cent strength. Extract some of the diseased hairs, and 

 put them in a drop of this solution on a slide. Put 

 on a cover-glass, and heat moderately for several seconds 

 over the flame of a spirit lamp, until the hairs can be 

 crushed by gentle pressure on the cover-glass. Examine 

 directly without staining, with a dry lens and medium 

 light ; or first mount in glycerin or glycerin jelly. 



Epidermal Scales. Tease out with two sterile needles, 

 and treat in the same manner. 



Nails. Reduce to powder with a nail file, and treat as 

 above. 



Pus. Dry on slide, and examine directly without 

 staining. 



Favus Crusts. Tease out, crush between two slides, and 

 thereafter treat as for hairs. 



They are best cultivated on Sabouraud's medium 

 Agar, 18 grm. ; peptone, 10 grm. ; maltose, 40 grm ; and 

 water to 1000 c.c. Heat to dissolve, fill into tubes, and 

 sterilize on three successive days. To inoculate tubes, 

 take an infected hair, rinse it for a few seconds in absolute 

 alcohol, and wash thoroughly with sterile water. Then 

 stab it into medium at several places, and grow at 18 C 

 If first growth is not pure, remove plug, and inverting tube 



