It seems, however, when we look at these curves more closely, that they are not wholly without significance.  If I am justified in concluding that they scarcely demonstrate a monthly cycle, it may certainly be added that they show a rudimentary tendency for the ecboles to fall into a fortnightly rhythm, and a very marked and unmistakable tendency to a weekly rhythm.  The fortnightly rhythm is shown in the curve for the earlier period, but is somewhat disguised in the curve for the total period, because the first climax is spread over two days, the 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 entirely to obliterate the larger monthly rhythm.