The wonderful diversity of expression in faces which structurally, as we may say, are almost identical, is due to minute differences in the arrangement of the little muscles which move the skin. The same thing holds good of the larynx." These are significant words. The distinguished physician who wrote them might just as well have said that the generally prevailing theory that in voice-production the muscles of the larynx exist solely to open and close the glottis and to regulate the tension and hence the vibration of the vocal cords, is incorrect. For they also exist in order to shape and reshape the entire larynx within itself according to the note to be produced, and the opening or closing of the glottis with the degree of tension of the vocal cords resulting therefrom is but one detail in the coördination of adjustments and readjustments which prepare the vocal tract to produce the tone the singer hears in his mind. Nearly every authority on the physiology of voice-production believes that the vocal tone is produced solely by the vibration of the vocal cords, and that the entire vocal tract situated above the vocal cords is concerned merely with augmenting the tone and determining its timbre or quality. Let us examine this theory and ascertain how tenable it is. To begin with, the term "cord" as applied to the vocal cords is misleading. It suggests a resemblance between the vocal cords and the strings of a violin, which are capable of great tension, or at least a resemblance between the vocal cords and the vibrating reed of a reed-instrument. In point of fact, the vocal cords are neither strings nor reeds, and are not even freely suspended from end to end or from one end like reeds, but are attached along their entire lower portion to the inner wall of the larynx. Therefore they are not cords, nor strings, nor reeds in any sense whatsoever. They are shelves composed of flesh and muscle, their substance resembles neither the catgut of which the strings of stringed instruments are made nor the cane, wood or metal of which the reeds of reed-instruments are formed; and the entire length of each cord is a trifle more than half an inch in men and a little less than half an inch in women. Almost every writer on voice appears to consider the term "cord" as applied to them a misnomer. They have been spoken of as membranous lips. "The vocal 'cord' is not a _string_, but the free edge of a projecting fold of membrane," says Mackenzie. Yet it is not only claimed but announced over and over again as a physiological fact that the human voice, sometimes sweet and mellow, sometimes tense and vibrant and with its great range, is produced solely by the vibration of two projecting folds of membrane, free only at their edges and at their longest only a little over half an inch in length.