FAVUS SQUARROSUS. 173 



more rhomboidal, the tubes of the mycelium and the spores are 

 seen, by the aid of a pocket-glass, before the yellow mass of favus 

 can be recognised, which is the result of the accumulation of 

 these cryptogamic elements. This hyper-secretion of the epi- 

 dermis may last six weeks before the yellow concretion of favus 

 manifests itself. The alteration of the hair progresses daily, but 

 the falling off of the hair takes place only after some years. 

 There is rarely but one spot of favus ; in most cases there are 

 several, sometimes only two, three, or four, distributed over 

 various regions of the head; they spring up simultaneously, or 

 one after the other, in the same parts ; they unite and form a 

 large crust, which occupies one third, two thirds, or even the 

 whole scalp. A small strip of hair remains frequently untouched 

 on the forehead, as well as the lower part of the occipital region 

 and of the nape of the neck. Half-circles are often found 

 around the diseased parts, which remind us of the first develop- 

 ment of the circular spots. The diseased spots are covered with 

 favi, more or less irregular, fragmentary crusts, often elevated 

 at the edges, pierced by hairs, and impregnated with dry blood, 

 possessing a faint, often stinking smell, and sometimes concealing 

 lice; although these guests are more frequently found in Im- 

 petigo granulata. The Tinea scutulata makes at this period its 

 appearance also in other parts of the body, called then Porrigo 

 favosa ; sometimes even at the same time with the first 

 species. The cure is, in this case, often accompanied by a 

 considerable contraction ; the hair grows, however, again very 

 easily. 



3. Favus squarrosus = Porrigo squarrosa. This species is often 

 mistaken for the preceding. They differ, however : the outer 

 development of the fungus does not proceed as regularly ; it 

 takes place on more or less prolonged, uneven, irregular surfaces, 

 which are limited, but very inaccurately. The mass of favi 

 spreads over the hair and forms sheaths for it, which adhere very 

 closely, producing thus distinct elevations on the surface of the 

 head, and small, prickly warts, with fragmentary, powdery crusts, 

 separated by deep furrows. 



Detailed description of the scabs of favi, according to Gudden and 

 Remak. The scabs form round or oval discs, measuring from 

 1 1J'" in diameter, and depressed towards the middle. They are 

 of a dirty yellow on the surface, changing to a dirty white towards 

 the centre, and raised a little above the level of the skin. These 



