It must be added that, especially among the lower social classes, the primitive belief of the savage that coitus during menstruation is bad for the man still persists.  Ploss and Bartels mention that among the peasants in some parts of Germany, where it is believed that impregnation is impossible during menstruation, coitus at that time would be frequent were it not thought dangerous for the man.[113] It has also been a common belief both in ancient and modern times that coitus during menstruation engenders monsters.[114]

Notwithstanding all the obstacles that are thus placed in the way of coitus during menstruation, there is nevertheless good reason to believe that the first coitus very frequently takes place at this point of least psychic resistance.  When still a student I was struck by the occurrence of cases in which seduction took place during the menstrual flow, though at that time they seemed to me inexplicable, except as evidencing brutality on the part of the seducer.  Negrier,[115] in the lying-in wards of the Hotel-Dieu at Angers, constantly found that the women from the country who came there pregnant as the result of a single coitus had been impregnated at or near the menstrual epoch, more especially when the period coincided with a feast-day, as St. John’s Day or Christmas.

Whatever doubt may exist as to the most frequent state of the sexual emotions during the period of menstruation, there can be no doubt whatever that immediately before and immediately after, very commonly at both times,—­this varying slightly in different women,—­there is usually a marked heightening of actual desire.  It is at this period (and sometimes during the menstrual flow) that masturbation may take place in women who at other times have no strong auto-erotic impulse.  The only women who do not show this heightening of sexual emotion seem to be those in whom sexual feelings have not yet been definitely called into consciousness, or the small minority, usually suffering from some disorder of sexual or general health, in whom there is a high degree of sexual anaesthesia.[116]

The majority of authorities admit a heightening of sexual emotion before or after the menstrual crisis.  See e.g., Krafft-Ebing, who places it at the post-menstrual period (Psychopathia Sexualis, Eng. translation of tenth edition, p. 27).  Adler states that sexual feeling is increased before, during and after menstruation (Die Mangelhafte Geschlechtsempfindung des Weibes, 1904, p. 88).  Kossmann (Senator and Kaminer, Health and Disease in Relation to Marriage, I, 249), advises intercourse just after menstruation, or even during the latter days of the flow, as the period when it is most needed.  Guyot says that the eight days after menstruation are the period of sexual desire in women (Breviaire de l’Amour Experimentale, p. 144).  Harry Campbell investigated the periodicity of sexual desire in healthy women of the working classes,