mour is gradually infpiffated, till it forms a fcab.

DIFFERENCES. The Tinea is either dry or moift; the first has no flux of humour, but the second an abundant one, of a ferous, acrid humour, which cannot be dried. It is called Tinea favina, when it is like an honeycomb, Tinea ficofa, or oúxwors in Greek, when the tumours are like fmall figs. It is alfo called Tinea ulcerofa, when ulcers fenfibly appear; but thefe differences are of little moment. The Tinea miliaris, from its likeness to millet, is the firft degree of the diforder; the next is the fpecies called Tinea favina, which is full of ulcerated holes, like honey-combs, flowing with a yellow honeylike humour. The third degree is called oúnwois, or Tinea ficofa, wherein the tumours are larger, and are interspersed with several red points like fig-grains. The last degree of the disorder is called Tinea lupinofa, from the resemblance of the ulcerated tumours to lupins.

CAUSES. As moft authors who have treated as well of the diforders of children, as of those of adults, have given no satisfactory account of their genuine feat; fo others

others have been at a lofs for the feat of a gonorrhæa, the fmall-pox, measles, Crufta lactea, and many more; but in particular for the feat of the prefent diforder. All are perfuaded that the Cutis is affected by the Tinea. But the question is, what part of it? In order to discover the truth of the matter, let us observe, 1st. That in the Tinea the hair of the affected part is fhed for want of nourishment, through the corrofion of their roots. 2dly. That in order to cure it, all the hair of the part affected should be extracted. 3dly. That after the cure this part is smooth, and without hair, which commonly remains fo du ring the patient's life. From thefse observations we may conclude, that the evil is feated at the roots of the hair: now thefe roots, by one or many branches, are implanted in many fmall bulbs, or capfula, which correfpond to the number of hairs, the rest of their defcription, for brevity fake, I omit; obferving only, that they are fo nourished with their lymph, that they grow only by the root, which is propelled and continually advanced; for they do not grow equally in their whole length like all

other

other parts of the body. That the evil is feated in these capfulæ, or at the root of the hair, is plain from the gradation of the disorder, first manifefting itself by small tumours, or pimples, at the root of every hair, then by the small pores or iffues of the fame; the fhedding of the hair, till ulcers appear; and, finally, by the fcab. But what produces all these effects? Nothing certainly, but an acrid nutritious lymph, which corrodes the capfulæ and roots of the hair; wherefore, all things which are capable of rendering the blood or lymph acrid, may be esteemed caufes of this diforder; to which, add the local difpofition of the part which fhould concur with the former caufes to produce the evil, and the greater and more intense these difpofitions are, the greater the disorder will be, whether it be communicated by contagion, by the child's linnen, cap, or otherwife, which is very common, as the itch, &c. are communicated; or whether it proceeds from any o ther fource; for that medicinal or physical axiom, is very true in this cafe, that quidquid recipitur, ad difpofitionem recipientis recipitur. If the child's head be very

dirty,

dirty, feldom combed, and much neglected; the humour of transpiration being thus obftructed, renders the lymph of the above Capfula fo acrid, that it may alfo give room

to a Tinea.

SYMPTOMS. The Tinea begins to manifeft itself by several imperceptible pores or fmall orifices, at the roots of the hair, which emit, by compreffion, a ferous acrid humour, much like that which appears in the Epulis, or fuppuration, betwixt the gums and teeth,

from the caries of the latter. Soon after appear feveral fmall ulcers in the whole extent of the tinea, of a yellow, grey, or black colour, frequently fetid and dry. The cruft or scab is formed of the small drops tranfuded by the orifices of these small ulcers, which are reduced to a proper confiftence by the air, &c. The fcab is of the various colours above-mentioned, according to the quality of the humour. They fometimes fuppurate and fpread very much, till they meet each other, and create feveral furrows, or eminencies and depreflions, which according to their elevation, give ground for the appellations favi, fici, &c. If the ulcers be phagedenic, they fpread

ftill farther.

The hair is fhed, their roots being corroded; and confequently, are no longer nourished; this gives room to several bald places on the hairy-scalp, which are called area: if they fall off by locks, the diforder is called Alopecia; if the hair is fhed all over the affected part, it is called Calvities, and the evil is eafily communicated by contagion.

DIAGNOSTICS. What has been already faid of the symptoms of the tinea, is sufficient to discover its existence; for it can hardly be confounded with any other disorder; if with any, its only with the Crufta lactea, and a kind of fcabies, or itch of the hand but the last is tranfitory, void of danger, attended with very final tumours, or fuperficial fcab, rarely affecting any children but fuch as have too delicate and tender heads, too often expofed to the cold air; it is eafily cured, and frequently difappears of itself. As to the Crufta lactea, it is diftinguishable. from the Tinea, inafmuch as the former commonly affects only very young children, fix, ten, or fourteen months old, or thereabout, and fuch as are well nourished, and in good habit of body: it is also as apt to invade the

face