among others to the supra-renal glands or adrenals, just over the
kidneys, and to the thyroid gland in the neck. Instantly these glands
pour forth adrenalin and thyroid secretion into the blood, and the
body responds. Blood pressure rises; brain cells speed up; the liver
pours forth glycogen, its ready-to-burn fuel; sweat-glands send forth
cold perspiration in order to regulate temperature; blood is pumped
out from stomach and intestines to the external muscles. As we have
seen, the body as a whole can respond to just one stimulus at a time.
The response to this stimulus has the right of way. The whole body is
integrated, set for this one thing. When fear holds the switchboard no
other messages are allowed on the line, and the creature is ready for
flight.

But after flight comes concealment with the opposite bodily need, the
need for absolute silence. This is why we sometimes get the opposite
result. The heart seems to stop beating, the breath ceases, the limbs
refuse to move, all because our ancestors needed to hide after they
had run, and because we are in a very real way a part of them.

=Old-Fashioned Fear.= There is one passage from Dr. Crile's book which
so admirably sums up these points that it seems worth while to insert
it at length.

We fear not in our hearts alone, not in our brains alone, not in
our viscera alone--fear influences every organ and tissue. Each
organ or tissue is stimulated or inhibited according to its use
or hindrance in the physical struggle for existence. By thus
concentrating all or most of the nerve force on the
nerve-muscular mechanism for defense, a greater physical power is
developed. Hence it is that under the stimulus of fear animals