1911 Encyclopædia Britannica/Ringworm

RINGWORM (or Tinea Tonsurans), a disease of the scalp (especially common within the tropics); it consists of bald patches, usually round, and varying in diameter from half an inch up to several inches, the surface showing the broken stumps of hairs and a iine whitish powdering of desquamated epidermic scales. In scrofulous subjects matter is sometimes produced, which forms crusts, or glues the hair together, or otherwise obscures the characteristic appearance. The disease is due to a parasite, Trichophyton tonsurans, which exists mostly in the form of innumerable spores (with hardly any mycelium), and is most abundant within the substance of the hairs, especially at their roots. If a piece of the hair near the root be soaked for a time in dilute liquor potassae and pressed flat under a cover-glass, the microscope will show it to be occupied by long rows of minute oval spores, very uniform in size, and each bearing a nucleus.

The same fungus sometimes attacks the hairs of the -beard, producing a disease called “ sycosis.” Sometimes it invades the hairless regions of skin, forming “ tinea circinata ”; circular patches of skin disease, if they be sharply defined by a margin of papules or vesicles, may be suspected of depending on the tinea-fungus. Interesting varieties of tinea are found in some of the Pacific and East Indian islands, Among the best remedial agents are various mercurial preparations. But in modern practice much success has been found in X-raying the patch in order to remove the dead and diseased hairs, thus leaving a free channel for the passage of antiseptic applications to the follicles. The exposures are followed by in unction of a mercurial preparation or of a lotion of tincture of iodine with methylated spirit.

See also Favus.