How it is that we obtain voluntary muscular control is a problem of great interest and importance, for it helps to explain the origin and nature of the will. Bair has investigated the conditions and processes by which such control is gained in the case of a particular muscle. He selected the retrahens aurem because of its complete isolation from other muscles, the inability of most people to contract it, the comparative ease with which control can be learnt, and the definite movements attending contraction; moreover, this muscle is adequately supplied with motor and sensory nerves, and there is every reason to suppose that control over it is acquired in the same way as over any other muscle. Of the fourteen subjects on whom the experiments were made only two could move their ears at the beginning of the investigation, and then only by vigorously raising the brows.