FACIAL EXPRESSION.
The facial nerve, which presides over the movements of the face, gives to the physiognomy its different expressions so as to reflect the passions and emotions of the soul. To prove this experimentally, Charles Bell took the most cunning and impressionable monkey he could find in the menagerie of Exeter Change, and divided its facial nerve on one side. Excited by pain, the poor monkey made faces with tenfold energy, but exactly and solely with one side of his face, while the other remained perfectly impassible.
Of course, no one would repeat this experiment on man; but nature sometimes takes the whim to make such a curiosity. All who saw the unfortunate monkey were struck with the strange analogy which its features presented with those of a comic actor then much in vogue in London, who could reproduce all sorts of expressions and mirror every passion with one side of his face, while he kept the other side in a state of perfect immobility. The experiment of Charles Bell gave the key to the enigma. The mimic was the victim of a facial hemiplegia, from some accident to the facial nerve; and he had the shrewdness to make people believe that voluntary which he could not prevent, and thus to profit by an otherwise mortifying affliction.