Symptoms.—­They usually occur on the return to the surface of the water, or after a few hours have passed.  There are pains in the ears and joints and nose-bleed.  The pulse is slow and strong.  Neuralgia of the stomach and vomiting often occur.  Paralysis of one side, or of the lower extremities may occur.  Brain symptoms may develop and death may follow in a few hours.  In most cases recovery takes place in a few days or weeks.

Treatment.—­Persons who are engaged in such work should change very gradually from a great depth to the surface, and should not go into the outer air suddenly.

Myelitis.—­Myelitis is an inflammation of the spinal cord.

Causes.—­It may occur at any age, and is more common in male than in female.  The exciting causes are prolonged exposure to severe colds, too great mental and physical exertion, sexual excess, blows, bleeding into the cord, alcoholic excess, acute infectious diseases, syphilis, etc.

Symptoms.—­These depend upon the location of the inflammation and the severity.  The onset may be sudden or gradual—­when it is sudden, there may be a chill followed by a fever of 101 to 103 degrees—­general feeling of illness, loss of appetite, with coated tongue and constipation.  There may be over-sensitiveness to pain and touch.  Pain may radiate from the back into the limbs, with numbing and tingling of the limbs.  The urine may be retained or may dribble away.  Usually there is obstinate constipation.  There is frequently the feeling of a band around the body.  Paralysis may follow in the lower extremities and higher up, sometimes, depending upon how high up in the cord the inflammation exists.  This paralysis may cause no motion of the limbs or produce an exaggerated contracting of the affected muscles, the knees being drawn up on the abdomen and the heels touching the buttocks.

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Recovery.—­Chances for recovery depend upon the cause.  Most cases are chronic and may last for years.

Treatment.—­Treatment depends also upon the cause.  Rest in bed; counter-irritation, wet cupping, with care on account of bed sores.  A water-bed from the first may prevent bed-sores.  The urine must be drawn if it is retained.  The medical treatment must be carefully given and a physician of experience should be obtained.

Locomotor ataxia.  Tabes dorsalis.  Posterior Spinal Sclerosis).—­A hardening (sclerosis) affecting the posterior parts of the spinal cord and characterized by incoordination, which means a condition where a person is unable to produce voluntary muscular movements; for instance, of the legs, etc., loss of deep reflexes to bend them back; disturbances of nutrition and sensation, and various affections of sight.

Causes.—­This is a disease of adult life, persons under twenty-five being rarely affected, and is more common in men than women (ten to one).  Sometimes children suffering from hereditary syphilis have it.  The chief predisposing cause is syphilis which precedes it in from seventy to eighty-five of the cases according to various authorities.  Exposure to cold and wet, sexual and alcoholic excesses, mineral poisoning, and great physical exertion also exciting causes.