as brought forward much evidence in confirmation
of this view. It may be added that there is considerable significance in
the fact that the erotic hallucinations, which are not infrequently
experienced by women under the influence of nitrous oxide gas, are more
likely to appear at the monthly period than at any other time. (D.W.
Buxton, _Anesthetics_, 1892, p. 61.)

[112] Gehrung considers that in healthy young girls amorous sensations are
normal during menstruation, and in some women persist, during this period,
throughout life. More usually, however, as menstrual period after
menstrual period recurs, without the natural interruption of pregnancy,
the feeling abates, and gives place to sensations of discomfort or pain.
He ascribes this to the vital tissues being sapped of more blood than can
be replaced in the intervals. "The vital powers, being thus kept in
abeyance, the amative sensations are either not developed, or destroyed.
This, superadded by the usual moral and religious teachings, is amply
sufficient, by degrees, to extinguish or prevent such feelings with the
great majority. The sequestration as 'unclean,' of women during their
catamenial period, as practiced in olden times, had the same tendency."
(E.C. Gehrung, "The Status of Menstruation," _Transactions American
Gynecology Society_, 1901, p. 48.)

[113] It is possible there may be an element of truth in this belief.
Diday, of Lyons, found that chronic urethorrhoea is an occasional result
of intercourse during menstruation. Raciborski (_Traite de la
Menstruation_, 1868, p. 12), who also paid attention to this point, while
confirming Diday, came to the conclusion that some special conditions must
be present on one or both sides.

[114] See, e.g., Ballantyne, "Teratogenesis," _Transactions of the
Edinburgh Obstetrical Society_, 1896, vol. xxi, pp. 324-25.

[115] As quoted by Icard, _La Femme_, etc., p. 194. I have not been able
to see Negrier's work.

[116] I deal with the question of sexual anaesthesia in women in the third
volume of these _Studies_: "The Sexual Impulse in Women."

II.

The Question of a Monthly Sexual Cycle in Men--The Earliest Suggestions of
a General Physiological Cycle in Men--Periodicity in Disease--Insanity,
Heart Disease, etc.--The Alleged Twenty-three Days' Cycle--The
Physiological Periodicity of Seminal Emissions during Sleep--Original
Observations--Fortnightly and Weekly Rhythms.

For some centuries, at least, inqu