had initiated into the secret, to inhibit them voluntarily. "Up" and "down", "right" and "left", were expressed by movements of head or eye in those directions, "forward" by a forward movement of the head, "back" by a corresponding movement. "Yes" was accompanied by a slight nod of the head; "no" by two to four rapid turnings of the head to either side.[N] "Zero" was expressed by a movement of the head describing an oval in the air. Indeed, it was even possible to discover whether the subject had conceived of a printed or a written zero, for the characteristics of both were revealed in the head-movements. I was able later to verify this graphically. With Ch. as subject, I made 70% correct interpretations in a total of 20 tests; with von A. as subject, 72% in a total of 25 tests. And finally I was able to interpret the signs without any errors at all. It was not absolutely necessary to look directly at the subject's face. Even though I focussed a point quite to one side, so that the image of the subject's face would fall upon a peripheral portion of my retina, I still was able to make 89% correct interpretations in a total of 20 tests.--This is not astonishing after all, when we recall that the periphery of the retina possesses a relatively high sensitivity for movement impressions, although its chromatic sensitivity is very low.[O] [Footnote N: It was Charles Darwin[7] who first pointed out that the expressive movements (of the coarser sort) to be noted in nearly every race and people show a great, though by no means complete, similarity. The similarity is most pronounced in the shaking of the head to signify negation and nodding to denote affirmation. It will be noted that the former is essentially of the nature of a turning toward, and the latter a turning away.[8] These same movements have been reported in the case of the blind and deaf Laura Bridgman,[9] and we have been explicitly assured that they were a spontaneous development, and not acquired by imitation. For it is by imitation and never before the completion of the first year, that our children acquire these movements. On account of his unreliability, we can put but little stock in the statement of Garner,[10] a writer on the speech of monkeys, that these same gestures have been observed in the case of those animals. My experiments show that the same movements, greatly diminished in scope, as a rule accompany the mere thought of "yes," "no," etc. I cannot, however, regard the assertion as an established fact that every thought process whatsoever is connected with some form of muscular movement, as has been generalized by the French physiologist Fere,[11] and the American psychologist Wm. James.[12]]