It may be stated in general that the descriptions in textbooks of erosion of the cervix are, for the most part, satisfactory. The histologic structure of this lesion has been understood for many years, and an attempt to describe it here will not be undertaken further than that presented in the accompanying illustrations. The descriptions referred to, however, often pass over the condition lightly and appear to disregard as unimportant, because they are so commonly seen, the varied cellular developments that characterize erosion in its several phases. On the other hand, erosion has been placed in the category of "precancerous" lesions by certain writers, without their stating in what way or under what circumstances these changes take place. Some erosions are simple and plainly enough lesions benign in nature; others show an extensive proliferation of cells, the development and arrangement of which clearly place the condition at the line bordering