the gland
is rudimentary or inadequate. All of which goes hand in hand with the
evidence that the skeleton stands directly under the domination of the
pituitary.

REGULATOR OF ORGANIC RHYTHMS

There are certain other singular by-effects of the gland in its
relation to the periodic phenomena of the organism like hibernation,
sleep, and the critical sex epochs of both sexes. In hibernation, or
winter sleep, the animal in cold weather passes into a cataleptic
state in which it continues to breathe, more deeply but more slowly
than when awake, but shows no other signs of consciousness or life.
A lowered blood pressure and a marked insensitivity to painful and
emotional stimuli go with it. There is a preliminary storage of starch
in the liver, and of fat throughout the fat depots of the body. These
are so like what happens after part of the pituitary is removed, that
a comparison of the two becomes inevitable. Common to both conditions
is a drop in the rate of tissue combustion or metabolism, which can
be relieved by injection of an extract of the pituitary, a rise of
temperature occuring simultaneously. Moreover, examination of the
glands of internal secretion of hibernating species, like the
woodchuck, during the period of hibernation, shows changes in all of
them, but most marked in the pituitary, the shrunken cells staining
as if they too were asleep, or in a resting stage. The characteristic
alive qualities of these cells return, without relation to food
or climate, when the animal comes to in the spring, at the vernal
equinox. Hibernation may, perhaps, be put down to a seasonal wave of
inactivity of the pituitary gland.

Now winter sleep may be looked upon as an exaggeration of ordinary
night sleep, the latter differing from the former only in its brevity.
In the natural sleep of non-hibernating species there occurs, too,
a fall in temperature. Moreover, they all, even man, have a certain
capacity for winter sleep, as the experiences of travellers and
explorers in the arctic regions indicate. In certain parts of Russia,
where there is a scarcity of food during the winter months, the
peasants pass weeks at a time in a somnolent state, arousing once a
day for a scant meal. Just as the sex glands influence the body and
mind profoundly with a certain cyclic periodicity of activity and
inactivity (rut, heat, menstrual period and so on), which has been
demonstrated to have a very close functional relationship with the