I have, however, shown by the measurements of Luschka, on p. 64, that the proportions of the female voicebox are materially different from those of the male, and I have also pointed out differences in shape noticeable to any observer. Now, although I do not pretend that I have by these facts and figures sufficiently accounted for the difference in the registers of the male and the female voice; yet these facts and figures are nevertheless greatly in my favour, and they are certainly a sufficient answer to the above argument of those who differ from me. My case is further strengthened by the testimony of that eminent physiologist, Dr. Merkel, who says,[N] "In the male organ there are only two materially different registers to be noticed, the chest and the falsetto, ... on the other hand, in the female organ there are clearly to be distinguished three registers--a low, a medium, and a high." (From Dr. Merkel's definitions on pp. 148, 149, and 152, it will be seen that low, medium, and high, are but other names here employed for Thick, Thin, and Small.) Dr. Merkel, speaking of the chest (thick) register, goes on to observe, on p. 148, "It ceases, very curiously, in both sexes on one of the first four tones of the one-lined octave (der ein-gestrichenen Octave) [Illustration: musical notation] so that it is about one octave longer [deeper] in man than in woman." Let it be observed above all things that I am not propounding a theory, but explaining a fact; a fact, moreover, which I have before now demonstrated to men holding opposite opinions, thereby convincing them, and which I am willing at any moment to demonstrate again. A very striking proof that the distribution of the registers is in accordance with my explanations may be further found in the circumstance that it is often impossible to distinguish a male voice from a female when (other things such as power and quality being equal) both sing in the same registers. The similarity is, of course, greatest between tenor and contralto, and in case of a trial they must confine themselves to the compass easily belonging to both; neither should the singers be seen by the listeners. I have frequently by these experiments convinced sceptics; and it has happened more than once when the female voice was slightly more robust than the male, that, to the great amusement of those present, the judges emphatically and without the slightest hesitation pronounced the lady to be the tenor and the gentleman the contralto. * * * * *