In the past few years a new chapter in gynecologic pathology, with important clinical correlations, has been written in the description of a group of ovarian tumors capable of producing profound effects on the sex characters of the individual. The credit for this new chapter belongs to the German school, and especially to Robert Meyer.1Our incentive for bringing this subject before this section is the fact that American pathologists have not yet manifested any great interest in this group of tumors, which, while rare, are almost certainly much more common than published reports would seem to indicate. The older concept that tumor cells are purely parasitic and nonfunctional has been quite thoroughly disproved in at least a certain group of neoplasms, more particularly those which arise in the endocrine structures. Illustrations will at once suggest themselves. I need mention only the obvious functional rôle of the cells of