From the National Institute of Child Health and Human Development, Bethesda, Md.; the Department of Obstetrics and Gynecology, College of Physicians and Surgeons, Columbia University, and the Obstetrical and Gynecological Service (The Sloane Hospital) of the Presbyterian Hospital, New York City, N. Y.

Supported in part by the Josiah Macy, Jr. Foundation.

The study was greatly facilitated by the cooperation of Dr. Anna Southam, members of the Infertility Clinic, and Dr. Theodore King and associates.

The illustration at the top of the page is from a 16th-century German engraving.