100 CLINICAL BACTERIOLOGY ANG HEMATOLOGY 



remains intact, and the inner portion of the hair is packed with 

 long waving filaments, whilst the outside (under the cuticle) is 

 covered with short "elements" — the exact nature of which is 

 doubtful — of every shape and size. 



The identification of the variety of organism which is present 

 is not usually difficult. The first point to be looked to is the 

 arrangement of the spores. If these form an irregular mosaic, 

 the microsporon is present ; if they form filaments somewhat 

 resembling those of a streptococcus, the organism is a tricho- 

 phyton. Then look to see whether the cuticle is intact, and 

 whether the fungus invades the interior of the hair. This 

 can usually be determined by focussing up and down until 

 you see an " optical section " of the hair in question. It is 

 important not to be deluded by the fact that the fungus which 

 lies on the outside of the hair will appear to be inside it if a 

 surface view only is taken. 



Ringworm of the Nails. 



The nails may be affected by either of the trichophytons or by 

 favus. The diagnosis of the presence of ringworm may usually 

 be made by the examination of pieces of the nails after soaking in 

 liuqor potassee, but a prolonged examination of many pieces must 

 be made before their absence is assumed. The diagnosis of the 

 variety present can only be made by cultures, and is not of clinical 

 importance (Plate VI„ Fig. 3). 



OTHER SKIN DISEASES 



In seborrhoeic affections the bottle bacillus of Unna is constantly 

 present, and as it does not occur at all frequently in other diseases, 

 if at all, it is a useful test between seborrhceic dermatitis and 

 psoriasis, especially on the scalp. It is a moderately large 

 organism which consists of an oval, spore-like body attached to a 

 short neck or handle. The former stains faintly, especially in the 

 middle, where it seems to have a clear vacuole, whilst the handle 

 stains deeply. It is very easily recognised after it has once been 

 seen ; it is perhaps the only bacterium which can be positively 

 identified by microscopic means alone. It stains by Gram. 



To search for it, take a scale or two from the affected region and 

 grind it in a drop of water between two slides until reduced to a 



