ods of maximum spontaneous sexual disturbance, as far as I have been
able to obtain precise evidence of such disturbance. That the maximum of
physiological sexual excitement should tend to appear earlier than the
maximum of fecundation is a result that might be expected.

The considerations so far brought forward clearly indicate that among
primitive races there are frequently one or two seasons in the
year--especially spring and autumn--during which sexual intercourse is
chiefly or even exclusively carried on, and they further indicate that
these primitive customs persist to some extent even in Europe to-day. It
would still remain, to determine whether any such influence affects the
whole mass of the civilized population and determines the times at which
intercourse, or fecundation, most frequently takes place.

This question can be most conveniently answered by studying the seasonal
variation in the birthrate, calculating back to the time of conception.
Wargentin, in Sweden, first called attention to the periodicity of the
birthrate in 1767.[151] The matter seems to have attracted little further
attention until Quetelet, who instinctively scented unreclaimed fields of
statistical investigation, showed that in Belgium and Holland there is a
maximum of births in February, and, consequently, of conceptions in May,
and a minimum of births about July, with consequent minimum of conceptions
in October. Quetelet considered that the spring maximum of conceptions
corresponded to an increase of vitality after the winter cold. He pointed
out that this sexual climax was better marked in the country than in
towns, and accounted for this by the consideration that in the country
the winter cold is more keenly felt. Later, Wappaeus investigated the
matter in various parts of northern and southern Europe as well as in
Chile, and found that there was a maximum of conceptions in May and June
attributable to season, and in Catholic countries strengthened by customs
connected with ecclesiastical seasons. This maximum was, he found,
followed by a minimum in September, October, and November, due to
gradually increasing exhaustion, and the influence of epidemic diseases,
as well as the strain of harvest-work. The minimum is reached in the south
earlier than in the north. About November conceptions again become more
frequent, and reach the second maximum at about Christmas and New Year.
This second maximum is very slightly marked in southern c