The tubercular syphilid may appear from one to forty years after the onset of the disease. Individual tubercles are pin-head to hazelnut sized nodules. Their evolution is like that of an ordinary boil, but without the signs of inflammation. They are firm, elastic, rounded, smooth or slightly scaly, brownish-red protuberances. Their most peculiar characteristic is a tendency to occur in segmental groups or to coalesce with the formation of circular or serpentine tracts, and the fusion is usually so intimate that individual tubercles are no longer able to be distinguished. Not uncommonly new tubercles continue to arise on the border of an old group or at the edge of a scar left by the dissipation of older tubercles, and thus a patch may grow from a fraction of an inch to four or five inches in diameter.