USE OF ULTRAVIOLET LIGHT 77 



Conant.*'' Most authorities are now agreed that the mosaic fungus 

 is an artifact. 



Cornbleet * developed an alternative mounting fluid for hairs and 

 scales. Water is added to crystals of sodium sulphide in minimum 

 quantity to obtain complete solution. To this solution an equal 

 volume of alcohol is added. A cloudy precipitate is formed which is 

 redissolved by adding water drop by drop. This alcohol solution 

 makes possible a quicker and more complete wetting of the hair; the 

 sulphide serves to dissolve keratin. Swartz and Conant *° soften 

 scales of epidermis in 5 per cent potassium hydroxide, after which 

 they are washed in several changes of water and then mounted in 

 Amann's fluid with cotton blue (0.5 per cent cotton blue). This 

 method may also be used with hairs. Thus prepared, the mosaic 

 fungus does not appear in scales of epidermis. Clearer preparations 

 with much less (0.05 per cent) cotton blue are obtained but a longer 

 time is required for the stain to be absorbed by the fungi. Lewis 

 and Hopper -° have published numerous clear photographs of fungi 

 in hairs and scales, and of the artifacts which may be confused 

 with them. 



Use of Ultraviolet Light. The discovery by Margarot and 

 Deveze -" that hairs infected with species of Microsporum exhibit 

 a greenish fluorescence in ultraviolet light has led to a number of 

 studies of this phenomenon both in clinical diagnosis and in the 

 identification of cultures. If the patient is examined in a dark room 

 under filtered ultraviolet light, single infected hairs can be readily 

 seen although there may be no clinically apparent lesion. The 

 method is particularly useful in detecting small satellite lesions in 

 the scalp, infections of the eyebrows, and in checking the results of 

 treatment. Davidson and Gregory ^ showed that the Microsporum 

 species could be distinguished from species of Trichophyton in hairs, 

 the former giving a greenish fluorescence due to a water-soluble sub- 

 stance, the latter a bluish fluorescence due to a substance which could 

 not be extracted with water. Lewis ^^ applied this method to the 

 differentiation of dermatophytes in cultures and found that different 

 species gave fluorescent light of distinguishing color; in particular, 

 Microsporum Canis was said to be distinguished from M. Audouini. 

 Redaelli and Cortese ^^ studied a variety of sapprophytic and para- 

 sitic molds, yeasts, and actinomycetes, and found that, although 

 many of them fluoresced with different colors, the fluorescence varied 

 markedly with the medium and the age of the culture. The medium 

 itself usually gave some fluorescence. Non-pigmented molds were 

 most fluorescent, especially before spores were formed. Lewis and 



