Without any question, all women have times of greater or less reproductive vitality, but in some women this is less marked than in others, and with some conception may take place at almost any date in the menstrual month; but with other women there is a group of days ranging from three or four to a dozen or more, in which conception seems to be impossible; while, on the other side of this group of neutral days, the days grade upwards towards a date of greater reproductive potency. Therefore, a woman and her husband who desire children, but have not after some years of marriage had the good fortune to attain parenthood, should choose for their acts of union those days on which conception is most likely. It is generally found that the most certain date for conception is--with very few exceptions--about the last day of the monthly period, or the day or two immediately after it; so that the husband who ardently desires his wife to conceive should, with her consent, concentrate their unions so far as possible on such dates. On the other hand, it must not be forgotten that the effect on the whole nervous system of the desire to conceive is very great. A too frantic desire, which leads to too frequently repeated unions, will probably defeat itself, because it is not the mere coalescence of the sperm with the ovum which completes conception, it is also the attachment of that impregnated ovum to the wall of the womb, and intense nervous excitement may prevent that. Indeed, it has been stated by a medical man of considerable weight in the last century that there are women among those races to whom sex-knowledge is not taboo who can voluntarily control conception at will and consciously expel an impregnated ovum by mere exercise of nervous force. A woman in modern society who is in a highly nervous condition, which may find expression in her constant need of cigarettes or excitement, may be (though this is by no means universally true) frequently impregnated and at the same time continually throwing off the impregnated ovum before the settling down of that ovum, which results in true conception, can take place. If, therefore, the woman who urgently desires to be a mother finds herself continuously smoking, or notes in herself any other indication of a lack of placidity in her nerves, she would do well--not merely to restrict her smoking, which is nothing but a symptom of a deeper need--but she would do well to restore so far as possible a calm poise to her whole system by longer sleep, more country air, plenty of fresh butter, or whatever simple remedy it may be that will supply her nerves with something lacking, and for which she is unconsciously craving.