Since it is obvious that the number of discharges in any one year—­averaging, as they do, only 1.25 per day—­are far too few to yield a curve of any value, I have combined my data in two series.  The dotted curve on Chart 9 is obtained by combining the results of the years 1886-92:  two of these years are incompletely recorded, and there are no records for 1890; the total number of observations was 179.  The broken curve is obtained by combining those of the years 1893-97, the total number of observations being 185.  Even so, the data are far too scanty to yield a really characteristic curve; but the continuous curve, which sums up the results of the eleven years, is more reliable, and obviously more satisfactory.

If the two former curves be compared, it will be seen that, on the whole, they display a general concordance, such differences as exist being attributable chiefly to two facts:  (1) that the second curve is more even throughout, neither maximum nor minimum being so strongly marked as in the first; and (2) that the main maximum occurs in the middle of the month instead of on the second lunar day, and the absence of the marked initial maximum alters the character of the first week or so of this curve.  It is, however, scarcely fair to lay any great stress on the characters of curves obtained from such scanty data, and we will, therefore, pass to the continuous curve, the study of which will prove more valuable.[381]

Now, even a cursory examination of this continuous curve will yield the following results:—­

1.  The discharges occur most frequently on the second lunar day.

2.  The days of the next most frequent discharges are the 22d; the 13th; the 7th, 20th, and 26th; the 11th and 16th; so that, if we regard only the first six of these, we find that the discharges occur most frequently on the 2d, 7th, 13th, 20th, 22d, and 26th lunar days—­i.e., the discharges occur most frequently on days separated, on the average, by four-day intervals; but actually the period between the 20th and 22d days is that characterized by the most frequent discharges.

3.  The days of minimum of discharge are the 1st, 5th, 15th, 18th, and 21st.

4.  The curve is characterized by a continual see-sawing; so that every notable maximum is immediately followed by a notable minimum.  Thus, the curve is of an entirely different character from that representing the monthly rhythm of the pulse,[382] and this is only what one might have expected; for, whereas the mean pulsations vary only very slightly from day to day,—­thus giving rise to a gradually rising or sinking curve,—­a discharge from the sexual system relieves the tension by exhausting the stored-up secretion, and is necessarily followed by some days of rest and inactivity.  In the very nature of the case, therefore, a curve of this kind could not possibly be otherwise than most irregular if the discharges tended to occur most frequently upon definite days of the month; and thus the very irregularity of the curve affords us proof that there is a regular male periodicity, such that on certain days of the month there is greater probability of a spontaneous discharge than on any other days.