To describe the rôle of the female sex hormone ten years ago would have been a simple matter, as this hormone alone would have had to be considered, the main attention then being focused on the corpus luteum.1 Four years ago the situation became more complicated when Philip Smith,2 and almost simultaneously Zondek and Aschheim,3 showed that the prepituitary was necessary to activate the ovaries. A further complication was added when Hisaw4 discovered an aqueous corpus luteum factor which affected the pubic ligaments of the gopher, and Corner5 concentrated "progestin," the special lipoid extract of the corpus luteum.
Today, therefore, when analyzing the processes of the sex physiology in the female, it is necessary for one to consider all these chemical messengers. The structures to be analyzed now include the follicle,6 which excretes female sex hormone alone except in pregnancy, at which time prepituitary hormone also