NERVOUS DISEASES

Division of Nerves.--1. Motor nerves or those in which irritation produces muscular contraction.

2. Sentitive nerves, or nerves of common sensibility, in which irritation is followed by an agreeable or painful feeling, according to the nature or degree of the stimulation.

3. Nevers of the special sense in which irritation excites the peculiar sensations of light, sound, taste, etc. Many sensitive nerves arise from nervous centres in such close proximity to motor nerves that a stimulus applied to the former will react upon the latter and produce not only a direct sensation, but what is technically called a reflex action. It is a remarkable fact that whatever part of a sentive nerve be irritated, whether it be the centre, the middle, or the extremity, the same sensation will be produced.

Nature of Nervous Force.--We can judge of the nature of the nervous force only by its effects. The muscular contraction caused by the irritation of a nerve is due to the deleopment of a peculiar vtal force in the nerve structure, which is unlike any of the known physical forces. It bears certain analogies to electricity.

  1. The identity of their effects on muscular fibre.
  2. The rapidity of heir action without producing any appreciable effect on the parts between the pointy of irritation and the point affected.
  3. The extreme sensibility of nerves to the electric current.
  4. The phenomena of electrical fishes.

CHOREA OR ST. VITUS' DANCE.

Causes.--From six to sixteen, in both sexes, especially often, however, in girls, chorea occurs. Nervous debility is almost always present before the attack. Fright is a frequent cause, overfatigue or mental excitement, blows or falls may produce it. Rheumatic fever is sometimes followed by it.

Symptoms.--Incessant and irregular movements of the voluntary muscles over which the will has but partial control. Walking in severe cases is difficult or unfacel the hands canot be regulated enough to write or work; speech may be affected; the muscles of the face often twitch grotequely. The pupil is, in some cases, unnaturally dialated; palpitation of the heart may occur, and also constipation and indigestion. The urine us if great density; the countenance assumes a blank and foolish expression, and the mind utsekf nat ub tune griw seruiysky ebfeevked.

Treatment.--Good diet, salt bathing and systematic gymnastic exercises will suffice for mild cases. Where marked anemia exists iron (citrate, phosphate or hypophosphatc, tincture of chloride, syrup of iodide) is important. Obstinate cases may be treated with Flower's solution of arsenic, in small doses, gradually increased. Cod-liver oil should be given if great debility exists. In chronic cases the tonies before mentioned with the addition of the hypophosphites should be resorted to, and change of climate is very likely to be of service.