he recorded the results of detailed
observations of his dreams, and also of seminal emissions during sleep (by
him termed "gonekbole" or "ecbole"), during a period of something over two
years. Mr. Nelson found that both dreams and ecboles fell into a
physiological cycle of 28 days. The climax of maximum dreaming (as
determined by the number of words in the dream record) and the climax of
maximum ecbole fell at the same point of the cycle, the ecbolic climax
being more distinctly marked than the dream climax.

The question of cyclic physiological changes is considerably
complicated by our uncertainty regarding the precise length of
the cycle we may expect to find. Nelson finds a 28-day cycle
satisfactory. Perry-Coste, as we shall see, accepts a strictly
lunar cycle of 291/2 days. Fliess has argued that in both women and
men, many physiological facts fall into a cycle of 23 days, which
he calls male, the 28-day cycle being female. (W. Fliess, _Die
Beziehungen zwischen Nase und weiblichen Geschlechts-Organen_,
1897, pp. 113 et seq.) Although Fliess brings forward a number of
minutely-observed cases, I cannot say that I am yet convinced of
the reality of this 23-day cycle. It is somewhat curious,
however, that at the same time as Fliess, though in apparent
independence, and from a different point of view, another worker
also suggested that there is a 23-day physiological cycle (John
Beard, _The Span of Gestation and the Cause of Birth_, Jena,
1897). Beard approaches the question from the embryological
standpoint, and argues that there is what he terms an "ovulation
unit" of about 231/2 days, in the interval from the end of one
menstruation to the beginning of the next. Two "ovulation units"
make up one "critical unit," and the length of pregnancy,
according to Beard, is always a multiple of the "critical unit;"
in man, the gestation period amounts to six critical units. These
attempts to prove a new physiological cycle deserve careful study
and further investigation. The possibility of such a cycle should
be borne in mind, but at present we are scarcely entitled to
accept it.

So far as I am aware, Professor Nelson's very interesting series of
observations, which, for the first time, placed the question of a
menstrual rhythm in men on a sound and workable basis, have not directly
led to any further observations. I am, h