Among the discoveries mentioned in my former publication one stands out most prominent, and it is the basis of all my other discoveries; namely, "that the voice is of a dual nature." I had ascertained that sounds circulate around the radix of the tongue; that they, or rather the air wave which carries them, enters either at the upper surface of the tip of the tongue and recedes back, to come out again from beneath its lower surface, or vice versa. I had also ascertained that the former process is the English, the latter the German, for breathing and vocal expression. I was convinced that this signified a circulation of vocal sounds; and though I had finally also reached this conclusion and intimated it, namely, "that we breathe and speak through the œsophagus," I did not express it in so many words, as I meant to leave this expression for a future publication. I was at first under the impression that both waves belonged to the trachea, the one that was ingoing as well as the one which was outgoing. Meantime I had discovered the "larynx or voice-box to the œsophagus," but considered this at first also as belonging to the trachea. I thought inspiration and ingoing sounds belonged to the vocal cords of the trachea, expiration and outgoing sounds to this "new" vocal cord located beneath the tongue. To study these first attempts, by which I was trying to find my way, and which culminated in these wonderful discoveries, I presume would be of interest to the student. I can here mention only the main points. I have found beyond a doubt, and my future statements will more fully establish this fact, that the frænum linguæ and the parts of the mucous membrane surrounding the same are relatively of the same nature in regard to the voice of the œsophagus that the vocal cords and other parts of the larynx are in relation to that of the trachea. In contradistinction to the larynx, I named these entire surroundings the "replica," as, in conjunction with the tip of the tongue resting upon the same, they conform to the shape of the oral cavity, of which in their general appearance they are almost a counterpart. In a similar manner I named the special part thereof, which "regulates" the intonation, the "vocal lip," in contradistinction to the vocal cords of the larynx, which perform the same service for the voice of the trachea. After making such positive assertions regarding the replica as I did in my previous publication--now more than four years ago--I was more than surprised that no one should have deemed it worth his while to look into the value of these assertions. If any one had, he could not have helped but acknowledge their correctness. It is but necessary to utter any vocal sound whatsoever, either vowel or consonant, and while doing so watch the vocal lip and the frænum, to become at once convinced that their motions are of precisely the same order as those of the larynx and the vocal cords.