In spite of the enormous amount of literature lately evolved on this subject, little has been presented that throws light on the true character of the growth. This statement was recently made by W. Risel, and I think we must all agree with him. Progress has been made in the study of the histology of these growths, and we have arrived at a more definite understanding of certain points in the histogenesis which were formerly much discussed. The term deciduoma malignum, introduced by S\l =a"\nger, has been abandoned, and it is generally conceded that this growth, composed as it is of Langhans'1 cells and syncytium, arises from the fetal ectoderm. But we seem to have been led into still greater confusion by the recent reports of cases of primary chorio-epitheliomatous growths arising outside of the placental site, and these not confined to the female, but found as well in the teratomata of the testicle. During the past seven years 20 cases of primary chorio-epitheliomata arising in woman outside the pla¬ cental site have been reported, and to this number I have added the report of a case that was primary in the uterine musculature. The following is a brief résumé of the 20 reported cases : Case 1.-Reported by L. Pick2 and Th. Landau, in 1897. Aged 22. Primipara ; no abortions. There developed a hydatidiform mole, which was expelled spontaneously. While the mole was yet in utero a vaginal tumor the size of a walnut ap¬ peared in the anterior wall of the vagina. The surface of the tumor was slightly ulcerated, and bled freely. No blood came from the uterus. The tumor was removed, and three days later the mole was expelled spontaneously. Three and one-half years later there was a normal birth, and a second normal birth the following year. There has been no recurrence of the growth. Histologie examination of the vaginal tumor showed villi re-* Read at the Fifty-fifth Annual Session of the American Medical Association. in the Section on Obstetrics and Diseases of Women, and approved for publication by the Executive Committee: