Sometimes at the site of the original chancre, which may have healed, there will be found one of the later lesions of the disease, which may be mistaken for another primary sore occupying the site of the first one. It may be distinguished by its central ulceration, its tendency to extend, and by the absence of the lymphatic involvement which is met with in the early stages of the disease. =Pathology of the Chancre.=--The chancre should be regarded as the first neoplastic evidence of a disease which is throughout characterized by its tendency toward new-cell formation. In the developed chancre there is a well-defined cell proliferation in the skin or mucous membrane, whose bloodvessels show the same character of change already mentioned, since in the walls, both of the minute arteries and veins, are found many new cells, some of which were originally leukocytes, but most of which are products of cell division, as shown by their numerous mitoses. All the coats of the vessels are involved and even the perivascular spaces are involved and obliterated. Essentially, then, the chancre consists of a local infiltration of the superficial tissues by cells, most of which are of the round type; the whole constitutes what may be spoken of as the initial sclerosis, which remains or disappears as such unless infected secondarily. This sclerosis should be carefully sought in every suspected region when the patient is first examined. It may range in bulk from a millet-seed to that of a good-sized grape; it is usually movable upon the tissues beneath; it may ulcerate deeply, and, should it persist for a long time, it may seem unusually active just before the outbreak of the so-called secondary symptoms. But little can be predicted with regard to the future course of the disease from the size, number, or appearance of the primary sores. The nature of the tissues upon which the virus has been implanted is a more important feature in the evolution of the disease than anything pertaining to its primary lesions, so far as appearances go. In patients of depraved habits or vitiated constitutions the chancre may often become gangrenous or phagedenic.