resting on account of the
close relationship between sexual and vesical activity. After a minimum
point in autumn there is a rise through the early part of the year to a
height maintained through spring and summer, and reaching its maximum in
August.[171] This may be said to correspond with the general tendency
found in some cases of nocturnal seminal emissions from a winter minimum
to an autumn maximum.

There is an annual curve in voluntary muscle strength. Thus in Antwerp,
where the scientific study of children is systematically carried out by a
Pedological Bureau, Schuyten found that, measured by the dynamometer, both
at the ages of 8 and 9, both boys and girls showed a gradual increase of
strength from October to January, a fall from January to March and a rise
to June or July. March was the weakest month, June and July the
strongest.[172]

Schuyten also found an annual curve for mental ability, as tested by power
of attention, which for much of the year corresponded to the curve of
muscular strength, being high during the cold winter months. Lobsien, at
Kiel, seeking to test Schuyten's results and adopting a different method
so as to gauge memory as well as attention, came to conclusions which
confirmed those of Schuyten. He found a very marked increase of ability in
December and January, with a fall in April; April and May were the
minimum months, while July and October also stood low.[173] The inquiries
of Schuyten and Lobsien thus seem to indicate that the voluntary aptitudes
of muscular and mental force in children reach their maximum at a time of
the year when most of the more or less involuntary activities we have been
considering show a minimum of energy. If this conclusion should be
confirmed by more extended investigations, it would scarcely be matter for
surprise and would involve no true contradiction. It would, indeed, be
natural to suppose that the voluntary and regulated activities of the
nervous system should work most efficiently at those periods when they are
least exposed to organic and emotional disturbance.

So persistent a disturbing element in spring and autumn suggests that some
physiological conditions underlie it, and that there is a real metabolic
disturbance at these times of the year. So few continuous observations
have yet been made on the metabolic processes of the body that it is not
easy to verify such a surmise with absolute precision. Edward Smith's
investigations, so far as the