The Spinal Cord, or spinal marrow, fills the spinal canal in the
vertebral column, or "backbone." It is a long mass of nerve tissue,
branching off at the several vertebrae to nerves communicating with
all parts of the body. The Spinal Cord is like a large telephone
cable, and the emerging nerves are like the private wires connecting
therewith.

The Sympathetic Nervous System consists of a double chain of Ganglia
on the side of the Spinal column, and scattered ganglia in the head,
neck, chest and abdomen. (A ganglion is a mass of nervous matter
including nerve cells.) These ganglia are connected with each other by
filaments, and are also connected with the Cerebro-Spinal System by
motor and sensory nerves. From these ganglia numerous fibers branch
out to the organs of the body, blood vessels, etc. At various points,
the nerves meet together and form what are known as plexuses. The
Sympathetic System practically controls the involuntary processes,
such as circulation, respiration and digestion.

The power or force transmitted from the brain to all parts of the body
by means of the nerves, is known to Western science as "nerve force,"
although the Yogi knows it to be a manifestation of Prana. In
character and rapidity it resembles the electric current. It will be
seen that without this "nerve force" the heart cannot beat; the blood
cannot circulate; the lungs cannot breathe; the various organs cannot
function; in fact the machinery of the body comes to a stop without
it. Nay more, even the brain cannot think without Prana be present.
When these facts are considered, the importance of the absorption of
Prana must be evident to all, and the Science of Breath assumes an
importance even greater than that accorded it by Western science.