point of entrance of the motor nerve into the muscle (motor point); but in the case of large muscles with several motor points the whole muscle is best thrown into contraction by indirect stimulation—the electrode being over the nerve itself. A healthy muscular contraction is abrupt and sudden in its rise and fall.

Non-striated muscle reacts to both currents in its normal vermicular manner. The heart muscle does not react to the direct application of faradism, but does to galvanism; its rhythm may be increased or diminished by corresponding interruptions of the galvanic current. Percutaneous electrization of the brain, from before backward, causes a sickly sensation of cérebral disturbance; from side to side induces nausea and vertigo. Faradic currents do not affect the brain.

Although it is established that the spinal cord is penetrated by electrical currents, yet the effects produced are confounded with those resulting from the inevitable stimulation of the nerve roots, and cannot be distinguished.

It is still a disputed point whether the cervical sym

* See pages 92, 93.

pathetic can be influenced by electrical currents in the living subject.

A strong current passed through the pneumogastric nerve arrests the heart in diastole, and the respiratory movements during inspiration; a weak current increases the frequency of the heart's action.

Faradization of the pneumogastric causes vomiting and arrest of intestinal peristalsis; quiescence of the stomach is induced by galvanism.

Galvanization of the eye causes flashes of light upon current opening and closure, KC and AO producing one set of colors, and KO and AC another different set.

Subjective noises from electrization of the ear occur only on KC and AO. A current passing through the tongue causes the " 'galvanic taste ; through the nose, subjective odors.

All the abdominal organs containing muscular fibre may be acted on by percutaneous electrization.

CHAPTER IV.

ELECTRO-DIAGNOSIS.

IN certain diseases of the nervous system the neuromuscular apparatus does not respond in the usual manner; the normal polar formula is altered. Upon examination we may find:

I. Normal Reactions.-These indicate a healthy condition of the anterior spinal cornua and of the nerves arising from them, notwithstanding the part affected may be the seat of spasm or paralysis.

They occur 1. In all cerebral diseases unaccompanied by secondary changes in the cord.

2. In spinal diseases of the white matter only, at least in the early stages.

3. In circumscribed transverse spinal lesions in parts below, though degenerative reaction (De R) will be present in organs supplied directly by the seat of lesion.

4. In mild affections of peripheral nerves from cold or pressure.

II. Quantitative Changes.

1. Excitability augmented. In early stages of cerebral hemorrhages, locomotor ataxia, facial paralysis, etc., and in tetanilla. Also occur in first stage of De R.

2. Diminished excitability accompanies De R in some of its phases; occurs, also, in old cerebral paralyses with secondary degeneration, old leuco-myelitic diseases, certain cases of progressive muscular atrophy and pseudo-hypertrophy, in simple muscular atrophy from disuse, wasting diseases, and joint affections. Its occurrence excludes poliomyelitis, hysteria, purely cerebral disturbances, and shamming.

III. Quantitative and Qualitative (Serial and Modal) Changes: Reaction of Degeneration.

1. Alterations in nerve reactions.-A more or less rapid diminution, ending usually in loss of reaction equally to both currents. The duration of this period varies, but excitability usually reappears about the time that the nerve becomes capable of transmitting motor impulses.

Qualitative changes are rare.

2. Alterations in muscle reactions.-The changes in the reactions to faradism pursue exactly the same course as in the nerves, and are due to the degeneration of the intra-muscular nerve elements.

The galvanic reactions are characteristic :—

(a) QUANTITATIVE CHANGES.-A temporary diminution is followed by a rapid increase of excitability, reaching its maximum in the second week, and then gradually falling to or below normal.

(b) QUALITATIVE CHANGES.-A modal alteration consisting of increased sluggishness of muscular contraction with tendency to become tetanic.

SERIAL CHANGES.-These consist in reversal of the normal polar formulas, ACC occurring with a constantly diminishing current strength until it finally overtakes KCC; and in the same manner KOC overtakes AOC, but the opening contractions soon disappear.

De R may still be present after months have elapsed, and may persist after motility is restored, if this has been lost.

The presence of De R means a specific "degeneration atrophy" of the neuro-muscular apparatus, due to a cutting off of the trophic influence of the