The pathogenicity of Demodex folliculorum was discussed in a recent paper1 in which was described a clinical picture consisting of an irritation of the face, usually in women, with dryness, occasionally slight redness, sensations of burning or stinging, and a characteristic dry follicular scale ensheathing the base of the lanugo hairs or plugging the follicular opening. These rather inconspicuous follicular scales, when picked off and examined microscopically immediately after adding a drop or two of 40 per cent solution of potassium hydroxide, usually revealed large numbers of Demodex folliculorum, sometimes as many as sixteen organisms closely packed in a single scale. A majority of the patients admitted that they used soap and water infrequently, substituting instead various kinds of cleansing creams. The hypothesis was advanced that the lack of soap and water plus the rubbing in of the creams, by obstructing the sebaceous secretion, favored the abnormal proliferation