sedentary position the equilibrium of the circulation is disturbed, the
blood is driven from the limbs to the internal organs and the dependent
portions of the trunk, hence to the pelvis; but almost equally to the
head, that is hanging down over the school-desk. Hence, the uterine
haemorrhages, that are necessarily confined to girls, are paralleled by
the nose-bleeding, common to girls and boys, and very frequent in such
circumstances. The cramped position of the chest interferes with
respiration; the bowels are generally constipated, and both conditions
again favor congestions of the visceral organs, including the uterus,
but not confined to it. To deficiency of physical exercise is due,
besides the disturbance in the equilibrium of the circulation, first, a
loss of heat that should be evolved during the chemical processes of
muscular action; second, a loss of stimulus to the spinal cord, which
has, therefore, less power to control ganglionic action. This latter,
therefore, becomes irregular, and the consequences of this irregularity
will be presently described. The influence of these two
conditions--cramped sedentary position, and deficiency of muscular
exercise--either sufficient to induce uterine haemorrhage, must,
therefore, be eliminated, before such accident can be attributed to any
other cause less simple and direct. The first criticism to be addressed
to the "statistics" contained in Dr. Clarke's clinical chapter, is, that
this necessary elimination has not been made, and one possible cause
arbitrarily selected out of an entire group of known causes.

As far as may be gathered from his book, Dr. Clarke's theory may be thus
formulated. Two intense nervous actions cannot, without detriment, be
sustained at the same time by the same organization. The mental labor
demanded by school studies on the one hand, and the physiological
process of menstruation on the other, are each connected with intense
action of different parts of the nervous system. They are, therefore,
incompatible with each other; and from the attempt to sustain them
simultaneously, results, first, the imperfect accomplishment of each;
second, the general exhaustion of the over-burdened nervous system. To
this exhaustion is to be attributed the uterine haemorrhages upon which
Dr. Clarke insists as the accident particularly liable to be induced by
any continuous, _i.e._, non-intermitting, system of education.

For non-medical readers it is important