All the tones of the falsetto register are produced by vibrations only of the fine, inner, slender edges of the vocal ligaments. In this action the vocal ligaments are not so near together, but allow of a fine linear space between them, and the superior ligaments are pressed farther back than in the production of the tones of the chest register. The rest of the action of the glottis is, however, entirely the same. With the beginning of the falsetto register at fa♯ (f♯¹), the whole glottis appears again longer, and the vocal ligaments are much looser than in the highest tones of the chest register. The united action, already described, of the arytenoid cartilages and the ligaments in forming the deeper tones of the chest register, extends to do do♯ (c² c♯²) in the female voice, and in the male voice to mi♭ mi (e♭² e²) commonly written thus: mi♭ mi (e♭³ e³) but which only rarely occurs in composition, and then is sung by tenorists as I have given it; that is, one octave lower. With the do♯ (c♯²) in the female voice and the mi♭ mi (e♭² e²) in the male voice, the arytenoid cartilages cease again to act, and as before, at the second higher series of tones of the chest register, leave the formation of the sounds to the vocal ligaments alone, which at this change appear again longer and looser, but with every higher tone tighten up to fa fa♯ (f² f♯²) in the female voice, and in the male voice to sol (g²), or as it is commonly written: g³. In the falsetto register the larynx preserves its natural position, as in quiet breathing. THE HEAD REGISTER When in the observation of the falsetto register I had sung upwards to its highest tones, and then sang still higher, I became aware with the fa♯ (f♯²) of a change in the motions of the organ of singing, and the tones thus produced had a different timbre from the falsetto tones. It required long and patient practice before I finally succeeded in drawing back the epiglottis so that I could see the glottis in its whole length. Not until then was I able to observe the following: With the fa♯ (f♯²), the vocal ligaments suddenly closed firmly together to their middle, with their fine edges one over the other. [Representation in the mirror of the organ of singing in the formation of head tones.] a. The closing together of the vocal ligaments. b. Open part of the glottis. The oval opening of the anterior portion of the glottis is imperfectly shown, because it is hidden from view by the epiglottis at the extreme end. This closing appeared as a fine red line extending from the arytenoid cartilages at the back forward to the middle of the vocal ligaments, and leaving free only a third part of the whole glottis, immediately under the epiglottis, to the front wall of the larynx.