diseased, the others do not continue to work and tax the strength of the ailing organ.
How the Sympathetic and Cerebro-spinal Nerves Differ.—The ganglionic nerves (1) contain mostly gray fibers; (2) pass through ganglia after leaving the spinal cord; (3) control the unconscious activities of the body; (4) pass to organs which contain slow-acting involuntary muscles, not to sense organs and quick-acting voluntary muscles; (5) transmit impulses slowly (about 20 ft. instead of 100 ft. per second). Crawfish and insects have hardly more than the ganglionic system of nerves (Animal Biology, Figs. 92, 132, 197).
Examples of the Supervisory Functions of the Sympathetic System.—Regulation of the heart beat and of the size of the blood vessels; secretion of sweat glands; contraction of pupils of eyes in a bright light; peristalsis.
Examples of Sympathetic Nerve Impulses reaching Consciousness.—Pain in colic and cramps; "heartburn" (pain in stomach from indigestion); backache (from nerves in organs prolapsed by tight clothing pulling upon their attachments at spine); hunger; thirst.
The Mind and Health.—A contented or peaceful mind is indispensable
to soundest health. Worry causes difficult breathing with bated
breath. Happiness brings full, easy breathing. Biological study of
physiology shows the futility of making health a care or anxiety, and
teaches "no meddling" with the body, whether by stimulating it, drugging
it, deforming it, overheating it, half smothering it in close rooms,
cultivating artificial instincts, etc. If the body degenerates through
wrong living, and disease ensues, a new way of living is needed, not
some quick and wonderful remedy. The new life will renew the body
and nothing else can.
Hygiene of the Nervous System
Necessity of Food, Fresh Air, and Rest for Sound Nerves.—The health of the nerves depends upon a free supply of
