quite suggestive of "mice," "putrid urine," or "an ill-kept menagerie," the diagnosis can be far more readily made from the characteristic appearances. In doubtful cases, moreover, in which there are no characteristic crusts, the peculiar favic odor is not likely to be perceived by ordinary olfactories. While typical cases of ringworm and favus are totally unlike in their clinical appearance, treatment often obscures the characteristic features, and hence, in cases where the crusts have
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Fig. 9.—Favus capitis.
been removed, the differential diagnosis may sometimes be attended with difficulty. In ringworm, however extensive and chronic the case may be, the hair is not apt to be permanently destroyed; while in favus the pressure of the crusts which develop in the epidermic layer around the orifices of the follicles tends to produce atrophy of the hair bulbs, and in all cases of long standing a few bald, depressed, and cicatricial areas are generally observed, and upon these the hair will never grow. In chronic cases, even after the disease has been cured, a num-
