The period of incubation of leprosy is peculiarly prolonged and is at any rate from two to five years and may extend over many years, Hallopeau having recorded a case where the disease did not develop for twenty-seven years after the patient left the infected district. The early manifestations are vague and indefinite, consisting chiefly of malaise, weariness and mental depression. There are often noted (_a_) irregular accessions of fever (leprotic fever), attended with rather profuse sweating, so that the onset may be mistaken for a malarial infection; (_b_) progressive weakness, the patient being easily fatigued with a tendency to somnolence; (_c_) alternating attacks of dryness and hypersecretion of the nasal mucous membrane, with frequent attacks of epistaxis, and (_d_) various neuralgic manifestations or paraesthesias as well as headache. These prodromal manifestations usually precede but may accompany the outbreak of the spots. It is the prominence of the nasal manifestations that has caused Sticker to insist that the primary lesion of leprosy is of the nasal mucosa, the general view, however, being that this view is without sufficient foundation and as a matter of fact some have recently suggested that the disease first manifests itself in the lymphatic glands, punctures of such structures showing bacilli rather frequently, although in less proportion than upon examination of the nasal mucosa. All authorities recognize two well-separated clinical types of leprosy, one the nodular, skin, hypertrophic or tubercular form and the other the smooth, nerve, maculo-anaesthetic or atrophic form. These fairly distinct types tend to run into one another and in such cases we have the mixed form of the disease. Following Manson I use the terms nodular and nerve leprosy. It is usually stated that in Northern climates nodular leprosy forms about 70% of cases while, in the tropics, the larger proportion is made up of nerve leprosy. At one time a classification of the 239 lepers at San Lazaro Hospital, Manila, P. I., showed 97 cases of nodular, 42 of nerve and 93 of mixed leprosy, with two cases of doubtful nature. NODULAR LEPROSY _A Typical Case._—After more or less indefinite and uncharacteristic prodromata the definite onset is by an outbreak of brownish red spots which later become pigmented and thickened. These spots are at first erythematous and tend to come out in crops, attended with attacks of irregular fever. They soon have the appearance of limited areas of sunburn. They vary in size from 1 or 2 millimeters to a blotch the size of the palm of the hand. They are raised and have a preference for appearing on the lobes of the ears, the nasal alae, the forehead, eyebrows, cheeks and chin.