Page:Popular Science Monthly Volume 45.djvu/399

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ON ACQUIRED FACIAL EXPRESSION.

the eyeball—i. e., the internal rectus, which rolls the eye inward toward the nose—gets its nerve supply partly from the same source as do the muscles for shortening the focus of the lens. The latter, in far-sighted persons, are constantly being urged to action by impulses proceeding from the brain along the nerve, and part of the impulse invariably finds its way, owing to the intimate relation of the parts, to the internal rectus muscle. This muscle does not at first respond to the stimulus sufficiently to turn the eye inward every time the lens is accommodated for near objects; but the result of this nervous stimulation is in the long run the same as if the internal rectus were constantly called into action by a deliberate exercise of the will. It greatly increases in bulk and strength, and outpulls its opponent on the outer side of the eye (which gets its nerve supply from a different source), and so the balance of power is destroyed and a hideous inward squint is produced.

From this we can understand the effect of a long-continued dominant emotion on the face, even although it may exist in an individual too well bred to allow his countenance to be easily distorted by the prevailing passion. Whenever the thoughts take their habitual direction, a stream of nervous influence from the brain to the hidden-expression muscles is the inevitable concomitant. The closest observer may not notice the least change of outline or the vaguest tremor of movement at the time, and the subject himself may be unwarned as to what is going on. Yet in the course of years the muscles so stimulated assert themselves over the others, and a permanent expression in accordance with the mental character comes out.

Close observation of almost any face under favorable circumstances supports this view. While engaged in studying the phenomena of sleep, I have repeatedly noticed that the apparent placidity of the features during slumber is deceptive. Even in dreams each fleeting emotion affects the facial muscles in some degree, and the apparent calm on the surface covers many little eddies and currents beneath, as one or other of them is thus provoked into partial activity. When the thoughts are all-absorbing and the owner of the face is off his guard, it does not require a very acute observer to see how the expression follows what is in the mind.

The other day, while traveling by train, I witnessed the parting of a pair of lovers. The damsel got into the carriage where we were seated, and until the train started there was an eloquent interchange of glances and smiles. As we steamed off, the last smile of parting gradually faded on the lassie's face. She shut her eyes and leaned back, so that she did not see that she was under observation, and at the same time the light showed her