DISEASES OF THE HAIR AND NAILS 2283 , 



Canities is said to take place at a later ag^ in negroes than ip. 

 Europeans, but in our experience neither , in negroes nor in Indian 

 races is there any distinct difference. Alopecia of every origin is 

 met with in the tropics. Alopecia seborrhoeica is very frequent 

 among Europeans and educated natives. It is rare among the low 

 classes and coolies. Alopecia senilis is less frequent in natives than 

 in Europeans. Alopecia areata is apparently rare among natives, 

 but recently we have come across several cases; it is fairly frequent 

 among Europeans. We have seen a case of pseudo-pelade of Brocq 

 (folliculitis decalvans) in a Sinhalese man. 



All the diseases of the nails met with in temperate zones are 

 found also in the tropics. Brittle nails (onychorrhexis), ridged nails, 

 transverse furrowing, and thinning of the nails, eggshell nails, 

 shedding of the nails, are conditions occasionally seen. Leuco- 

 nychia, or whitening of the nails, either in spots (leuconychia 

 punctata), linear (leuconychia striata), or affecting the whole nail 

 (leuconychia totalis), is observed. We have described at p. 2236 a 

 peculiar black pigmentation of the nails. Onychia, or inflammation 

 of the nail matrix, is not rare. Ingrowing toenail is common. 

 So-called nail pterygium, or outgrowth of the posterior nail fold, is 

 occasionally seen, or the opposite condition, exposure of the root 

 of the nail (flcus unguium), may be met with. 



We have never observed a case of congenital atrophy, but we 

 have seen one case of supernumerary nails. We have noted with 

 comparative frequency a form of onychogryphosis affecting several 

 members of the same family, and apparently hereditary to a certain 

 ex:tent. The nails are enormously thickened, and much longer 

 than usual. All the nails may be affected, both those of the fingers 

 and those of the toes. 



Onychomycosis of various origin is a common affection, and has 

 already been considered (p. 2059). 



SOME COSMOPOLITAN DISEASES \0F MUCOUS 

 MEMBRANES. 



Patches of Leucoplakia of the tongue are common in natives, and 

 may be of various origin — syphilitic, frambcetic, or due to irritation 

 caused by smoking or chewing various substances. Cases of the 

 so-called circinate pityriasis linguse or annulus migrans are not 

 rare. Lingua nigra is occasionally seen. We have already called 

 attention to the dark patches found on the tongue in natives, and 

 which by some writers have been described as a sign of ankylo- 

 stomiasis. These pigmented patches are roundish or oval, and 

 may be found also on the gums, the mucosa of the lips, on the soft 

 and hard palate, and are apparently congenital. A condition 

 which might be called red or purple tongue, and which often puzzles 

 the newly arrived medical man, who does not know its origin, is 

 extremely common in Ceylon among the coolies and lower-class 



