236 An Introduction to Medical Mycology 



hydroxide, which tends to decolorize. The use of lactophenol, as first de- 

 scribed by Amann and later endorsed or modified by Langeron, Linder, 

 Henrici, Swartz and Conant, and others, is probably the best method of 

 staining fungi in fresh tissue. The following formula is used: 



The last ingredient is added after the other materials have been dissolved 

 with gentle warming. The fresh tissue is first partially digested on a glass 

 slide, using a 10 per cent solution of potassium hydroxide. When sufficiently 

 softened, the preparation is flooded with water which is then removed by 

 absorption, using blotting paper. When the hydroxide has been entirely 

 removed, the tissue is stained by the lactophenol solution and a cover slip 

 applied. If desired, cement may be placed around the edges of the cover 

 slip. 



When it is desired to hold for examination at a later time a slide prepared 

 with 10 per cent potassium hydroxide, a drop of a 50 per cent aqueous 

 solution of glycerin is placed at the edge of the cover slip. It will slowly mix 

 with the hydroxide, producing a homogeneous mount which may preserve 

 the specimen for several weeks or even months. Care must be used that the 

 cover slip is not disturbed. Such a method as this is useful when one does 

 not at first find the material which should be present or if a thorough search 

 must be delayed. 



Thin scales, such as those of tinea versicolor, erythrasma or pityriasis 

 capitis, may be placed on a slide, washed in acetone to remove fat and 

 mixed for three minutes with methylene blue, which is then drawn off with 

 blotting paper. The specimen is then dehydrated with a 95 per cent con- 

 centration of alcohol and xylene and is mounted in Canada turpentine. This 

 method gives a permanent stained mount, but it is not suitable for thick 

 sections. Huber and Caplin use a preparation of polyvinyl alcohol, a plastic, 

 for mounting thin tissue as well as for preserving material from cultures 

 (see section on binding agents, Chapter XXIV, p. 262). 



2. MAKING THE PREPARATION 



Place the material on one end of a clean glass slide and add a small 

 drop of a 10 per cent solution of potassium hydroxide. Put on a cover slip 

 and add almost enough hydroxide to fill in the 1 space between the cover slip 

 and the slide. Pass the slide through the (lame of a Bunsen burner three 



