TINEA is a term somewhat vaguely employed to designate certain parasitic diseases of the skin, and especially of the scalp. Three of the most important varieties of tinea, viz., tinea circinatus (ringworm of the body), tinea tonsurans (ringworm of the scalp), and nnea sycosis (ringworm of the beard), have been already described in the article Ring worm (q.v.). In these three varieties, which are included in the general term tinea ton dens, the vegetable parasite known as trichophyton tonsurans, figured in the above article, is always present. It now remains to notice the tinea decalvans of Bateman, known also as porrigo decalvans, alopecia circumscripta, etc. It is defined by Aitken as "a fungus disease, causing the formation of rounded or oval patches of baldness, some times solitary, more generally multiple. It affects the hairy scalp principally; but the beard and hairy portion of the skin may also suffer."—The Science and Practice of Medi cine, 2d ed. vol. i. p. 925. The fungus which causes these patches of baldness was detected by Gruby in 1843, and named the microsporon audonini. It differs from the ichophyton by its numerous waved filaments, and the extremely small size of its sporules, -and likewise by its position, not being found in the interior of the root of the hair, but forming a little tube round each hair, and thus causing it to soften and break down.
The hairs thus affected become dull and partially loose; the skin in which they are implanted becomes red, swollen, and slightly itchy; and a whitish matter (the sporules of the fungus) may soon be observed on the diseased skin and hairs. The hairs then suddenly fall off from the affected part, leaving a round bald patch of a very white color. The disease is capable of transmission from one person to another, although less readily than tinea tonsurans. It chiefly affects children. The treatment consists iu preventing the spread of the disease by extracting the hairs round the circumference of the patch, and washing the head daily with soft soap; and all the young hairs within the patch must be extracted till a healthy crop begins to appear. Moreover, a solution of sulphurous acid, as recommended for ringworm, should be applied. When by these means the fungus has been destroyed, stimulants must be applied to the bald patches. A mixture of equal parts of collodium and of ether cantharidalis (collodium vesicans) is, according to Dr. Aitken, the most useful stimulant in these eases.