Pediculosis capitis (_pediculosis capillitii_), due to the presence of the pediculus capitis, occurs much more frequently in children than in adults. It is characterized by marked itching, and the formation of various inflammatory lesions, such as papules, pustules and excoriations--resulting from the irritation produced by the parasites and from the scratching to which the intense pruritus gives rise. In fact, an eczematous eruption of the pustular type soon results, attended with more or less crust formation. In consequence of the cutaneous irritation the neighboring lymphatic glands may become inflamed and swollen, and in rare cases suppurate. The occipital region is the part which is usually most profusely infested, more especially in young girls and women. In those of delicate skin, especially in children, scattered papules, vesico-papules, pustules, and excoriations may often be seen upon the forehead and neck. In some instances, however, especially in boys, there may be many pediculi present, with but little cutaneous disturbance, the itching being the sole symptom. [Illustration: Fig. 79. Pediculus Capitis x 25. (_After Duhring._) Female. Dorsal surface.] In addition to the pediculi, which, as a rule, may be readily found, their _ova_, or _nits_, are always to be seen upon the shaft of the hairs, quite firmly attached. #Describe the appearance of the ova.# They are dirty-white or grayish looking, minute, pear-shaped bodies, visible to the naked eye, and fastened upon the shaft of the hairs with the small end toward the root. [Illustration: Fig. 80. Ova of the head-louse attached to a hair. Magnified. (_After Kaposi._)] #Is there any difficulty in the diagnosis of pediculosis capitis?# No. The diagnosis is readily made, as the pediculi are usually to be found without difficulty, and even when they exist in small numbers and are not readily discovered, _the presence of the ova_ will indicate the nature of the affection. Pustular eruptions upon the scalp, especially posteriorly, should always arouse a suspicion of pediculosis. The possibility of the pediculosis being secondary to eczema must not be forgotten. #What is the treatment of pediculosis capitis?# Treatment consists in the application of some remedy destructive to the pediculi and their ova. Crude petroleum is effective, one or two thorough applications over night being usually sufficient; in order to lessen its inflammability, and also to mask its somewhat disagreeable odor, it may be mixed with an equal part of olive oil and a small quantity of balsam of Peru added. Tincture of cocculus indicus, pure or diluted, may also be applied with good results. When the parts are markedly eczematous, an ointment of ammoniated mercury or [beta]-naphthol, thirty to sixty grains to the ounce may be used.