FAYUS. 171 



pierced with a hair in its centre. The yellow crust grows very 

 rapidly : its vertical diameter increasing \ 1"' during twenty- 

 four hours ; the ventral depression becomes daily more character- 

 istic, and may be compared to the alveoli of the honeycomb, or to 

 the depressions on beans, or to the small cups of the yellow lichens 

 on the branches of trees. Sometimes the inner surface of this de- 

 pression is quite smooth and even, such as is seen in the cnps of the 

 oak ; at other times uneven, and exhibiting a series of concentric 

 circular elevations, the number of which indicates to some extent 

 the age of the cup of the favus, and which resemble, from their 

 position, the circular prominences of the nests of swallows. The 

 younger these layers are the more saffron-coloured are they ; the 

 older, the whiter. The last layer raises sometimes the epidermis 

 several millimetres above the level of the surrounding skin. 

 The cup of the favus may even reach more than two centimetres 

 in breadth ; the fungus makes, however, its exit before it reaches 

 these dimensions by breaking through the epidermal covering 

 almost always some millimetres above the point where the crust is 

 pierced by the hair ; it makes a hernia through this opening, and 

 shows no longer any regular form during its growth. 



Complications. -The cups of favi run together and open a free 

 passage for the favus at another place. The patient often 

 scratches off the epidermal covering of the favi, causing- a few 

 drops of blood to flow, which dry on the crust. This increases 

 the irritation of the scalp, produced by the presence of the foreign 

 body, and leads to the formation of real impetigirious pustules and 

 crusts. If the alveolar crusts of the favus are removed, by the 

 nails of the patient, by poultices, or by the physician himself by 

 means of the spatula, the surfaces which lie underneath are found 

 to be depressed, red, bleeding, and covered with a thin epidermal 

 layer, above which are often seen the vessels and fibres of the 

 skin. If the crusts are carefully removed without injuring the 

 skin which lies underneath, a transparent lymph without blood 

 exudes. 



After removing the fungus, the depressed part dries and reaches 

 in a few days again the level of the surrounding skin. The 

 eruption of the favus daily covers more and more of the scalp ; 

 its progress is sometimes rapid, sometimes slow, according to the 

 cleanliness of the diseased persons attacked, and other conditions. 



After various intervals the patient arrives at the third period, 

 that of baldness. 



