f the carotid and cavernous plexuses; other branches pass to the
pharynx, and a branch enters the formation of the cardiac plexuses. From
the carotid and cavernous plexuses pass many nerves, only a few of which
need special mention; one unites with the great superficial petrosal to
form the Vidian nerve which goes to _Meckel's_ ganglion, branches pass
to the Gasserian ganglion, while we have others passing to the third,
fourth, the ophthalmic division of the fifth and the sixth nerve, also
we have derived from the nerve the sympathetic root of the lenticular
ganglion.

ONE OF ITS FUNCTIONS.

Physiologically we know that one of the special functions of the
sympathetic nervous system is to control the tone of non-striate
muscular tissue, and that we have filaments distributed from the
sympathetic system in the muscular wall of every blood vessel, duct and
organ throughout the body. We also know that the sympathetic is the
accelerator nerve of the heart, being opposed in its action by the vagus
which, is inhibitory; further, that the vagus is constant in its
brake-like action, while the sympathetic only acts when stimulated
either directly or reflexly. While the vagus is inhibitory to the heart
it is motor to the lungs. Nerve force is not generated in the
sympathetic system; the cerebro-spinal nerve force is conveyed to the
ganglia by the rami communicantes and in the ganglia is transformed into
sympathetic nerve force. We might compare the ganglia to electrical
transformers. Such being the case it is not difficult to see that if the
superior cervical ganglion receives the nerve-force for transformation
from the upper four cervical nerves and we can prevent, or lessen, the
passage of nerve-force from the spinal cord through those nerves to the
ganglion, that we will, to a corresponding degree, lessen the amount of
sympathetic nerve-force transformed in the ganglion and transmitted from
it by its branches.

STIMULATION OR INHIBITION.

We can produce stimulation or inhibition of a nerve at will; press
suddenly and with a little violence upon the ulnar nerve where it lies
in relation with the internal condyle of the humerus and we will find a
manifestation of its physiological action, evidenced by a sense of pain
in the ulnar and radial sides of the fifth finger and the ulnar side of
the fourth, together with contraction of the muscles supplied by that
nerve. But if our pressure be less intense and more prolonged we w