The work of a great number of American and European investigators during the past few years has focused the attention of the medical profession on the problem of ovarian function. Many theories have arisen, but so far there has been little unanimity in the acceptance of any one of them. The one piece of work with which this communication is concerned is that of Frank1 and his co-workers in isolating from the blood of women an active estrus-producing substance. Frank has used the vaginal smear reaction of Stockard and Paponicolaou2 as the criterion of the activity of his extracts.
Frank's work includes also theories of ovarian physiology, but this paper is concerned only with the reliability of the test as an index of ovarian activity. Theoretical considerations will not be taken into account at this time. The test in itself offers an extremely promising weapon for the investigation