_The Appendages of the Skin._--The _hair_ loses its gloss, becomes dry and brittle, and readily falls out, either as an exaggeration of the normal shedding of the hair, or in scattered areas over the scalp (_syphilitic alopœcia_). The hair is not re-formed in the scars which result from ulcerated lesions of the scalp. The _nail-folds_ occasionally present a pustular eruption and superficial ulceration, to which the name _syphilitic onychia_ has been applied; more commonly the nails become brittle and ragged, and they may even be shed. _The Mucous Membranes_, and especially those of the _mouth_ and _throat_, suffer from lesions similar to those met with on the skin. On a mucous surface the papular eruption assumes the form of _mucous patches_, which are areas with a congested base covered with a thin white film of sodden epithelium like wet tissue-paper. They are best seen on the inner aspect of the cheeks, the soft palate, uvula, pillars of the fauces, and tonsils. In addition to mucous patches, there may be a number of small, _superficial, kidney-shaped ulcers_, especially along the margins of the tongue and on the tonsils. In the absence of mucous patches and ulcers, the sore throat may be characterised by a bluish tinge of the inflamed mucous membrane and a thin film of shed epithelium on the surface. Sometimes there is an elongated sinuous film which has been likened to the track of a snail. In the _larynx_ the presence of congestion, œdema, and mucous patches may be the cause of persistent hoarseness. The _tongue_ often presents a combination of lesions, including ulcers, patches where the papillæ are absent, fissures, and raised white papules resembling warts, especially towards the centre of the dorsum. These lesions are specially apt to occur in those who smoke, drink undiluted alcohol or spirits, or eat hot condiments to excess, or who have irregular, sharp-cornered teeth. At a later period, and in those who are broken down in health from intemperance or other cause, the sore throat may take the form of rapidly spreading, penetrating ulcers in the soft palate and pillars of the fauces, which may lead to extensive destruction of tissue, with subsequent scars and deformity highly characteristic of previous syphilis. In the _Bones_, lesions occur which assume the clinical features of an evanescent periostitis, the patient complaining of nocturnal pains over the frontal bone, sternum, tibiæ, and ulnæ, and localised tenderness on tapping over these bones. In the _Joints_, a serous synovitis or hydrops may occur, chiefly in the knee, on one or on both sides.