Anna M. Galbraith, The Four Epochs of Woman's Life…
“ The purpose of menstruation is to keep the uterus in suitable condition for the reception of this product of conception at any time. It is now known that the menstrual flow is not the whole of menstruation, and that the changes going on in the uterus are almost as continuous as the process of digestion. The whole of the reproductive life of woman has been divided into cycles of twenty-eight days each ”
