Ringworm
2 of the 7 encyclopedias on this shelf carry an entry for Ringworm. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
Important: Safety Warning This page presents medical treatment from an era before modern medicine. The remedies described are ineffective against the conditions named, and some of the ingredients or doses are harmful. Do not use them to treat any illness; consult a qualified medical professional. This information has been left in for historical purposes but should not be acted upon. a skin disease. It is caused by a minute parasitic plant which starts in small patches and spreads like a mold in every direction, thus forming rings. The name was given in a belief that the circles of inflammation were due to a minute worm burrowing in the skin. There are several kinds, all contagious and easily communicated. Although the disease is not dangerous, it is very annoying. One who is afflicted with it should have his own towel, sheets, and pillow cases. Like the itch, ringworm may be cured, usually by an application of mercurial ointment.
Collier's New Encyclopedia (1921)
an eruptive disease of the skin, more particularly on the head, and of which there are several kinds. The most common kind commences with clusters of small light yellow pustules which soon break and form thin scabs which, if neglected, become thick and hard by accumulation. When removed, they appear again in a few days; and by these repetitions the incrustations become thicker and the area of the patches extends, so as, if unchecked, to affect the whole head, and extend also to the forehead and neck. The patches are of an irregular circular form. This disease occurs generally in children of three or four years and upward. It is said to occur spontaneously in children ill-fed and uncleanly. The principal local treatment, when the patches are in an inflame flamed and irritable condition, consists in regular washing or or sponging with warm water or some emollient fomentation.