7th and 8th
of the month. If we readjust the curve for the total period by presenting
the days in pairs, the fortnightly tendency is more clearly brought out
(Chart I).

A more pronounced tendency still is traceable to a weekly rhythm. This is,
indeed, the most unquestionable fact brought out by these curves. All the
maxima occur on Saturday or Sunday, with the minima on Tuesday, Wednesday,
Thursday, or Friday. This very pronounced weekly rhythm will serve to
swamp more or less completely any monthly rhythm on a 28-day basis.
Although here probably seen in an exaggerated form, it is almost certainly
a characteristic of the ecbolic curve generally.[123] I have been told by
several young men and women, especially those who work hard during the
week, that Saturday, and especially Sunday afternoon, are periods when the
thoughts spontaneously go in an erotic direction, and at this time there
is a special tendency to masturbation or to spontaneous sexual excitement.
It is on Friday, Saturday, Sunday, and Monday, according to Guerry's
tables,[124] that the fewest suicides are committed, Tuesday, Wednesday,
and Thursday, with, however, a partial fall on Wednesday, those on which
most suicides are committed, so that there would appear to be an
antagonism between sexual activity and the desire to throw off life. It
also appears (in the reports of the Bavarian factory inspectors) that
accidents in factories have a tendency to occur chiefly at the beginning
of the week, and toward the end rather than in the middle.[125] Even
growth, as Fleischmann has shown in the case of children, tends to fall
into weekly cycles. It is evident that the nervous system is profoundly
affected by the social influences resulting from the weekly cycle.

The analysis of this series of ecbolic curves may thus be said to recall
the suggestion of Laycock, that the menstrual cycle is really made up of
four weekly cycles, the periodic unit, according to Laycock, being three
and one-half days. I think it would, however, be more correct to say that
the menstrual cycle, perhaps originally formed with reference to the
influence of the moon on the sexual and social habits of men and other
animals, tends to break up by a process of segmentation into fortnightly
and weekly cycles. If we are justified in assuming that there is a male
menstrual cycle, we must conclude that in such a case as that just
analyzed, the weekly rhythm has become so marked as almost entirel