The fact that the body temperature varies during the menstrual cycle has been known for many years. The alteration in temperature which takes place at the time of ovulation has been employed as an aid in trying to overcome the infertility of certain couples. Tompkins,1in reference to the work of others, said: All this literature may be summed up thus: A record of body temperatures taken daily under standard conditions shows a typical curve during the menstrual cycle. The temperature is relatively low during the first part of the month, drops to a minimum about the time that ovulation occurs and rises definitely thereafter to a relatively high level, which is maintained until the next menses, when the temperature drops abruptly. Tompkins1stated: If the temperature shows a rise of 2 or 3 fifths of a degree, and if this rise corresponds with a similar rise in the