The foremost part of the glottis formed an oval orifice, which, with each higher tone, seemed to contract more and more, and so became smaller and rounder. The fine edges of the vocal ligaments which formed this orifice were alone vibrating, and the vibrations seemed at first looser, but, with every higher tone, the ligaments were more stretched. The larynx remained in its natural state. Only after I had frequently repeated this observation of the head tones in myself and in others, and had always arrived at the same results, did I venture to publish it. The most various conjectures respecting the formation of the head voice had been previously proposed by the learned, and the existence, even, of the head voice had been denied by _Bataille_. It would lead us too far away to make mention here of all these different views, which, with the exception of those of _Dr. Merkel of Leipzig_, showed themselves to be really without a sound foundation. It was objected to the results of my observations, that such an action of the glottis “was only possible by means of cartilages and muscles, but that such cartilages and muscles as could render an action of that kind possible were not known, nor was there any reference to them to be found in any manual of anatomy.” While I fully admitted the soundness of this objection, I was, after repeated observations, more and more convinced of the correctness of my own statements. But as I found nothing to support them in any anatomical work, either German or French, I began anew to study the anatomy of the larynx in dissected subjects. My renewed efforts were rewarded by the discovery, within the membranes of the vocal ligaments, of those filaments or fibres of muscle which in the anatomical Appendix to this book I mention as _arytenoid-thyroid interna_, and which have also been found by other observers. They are found in all larynxes, and consist of muscular fibres, sometimes finer, sometimes thicker.[3] At the same time I satisfied myself of the existence of a pair of cartilages--the cuneiform cartilages described in the Appendix. I found these always in the female larynx, but only now and then in the male. As these cartilages, also found within the membranes of the vocal ligaments and reaching from their junction with the arytenoid cartilages to the middle of the ligaments, are only now and then fully formed in the male larynx, but undeniably work the shutting part of the glottis, it follows plainly that only a few male voices are capable of producing the head tones. But observation with the microscope revealed in those larynxes in which the cuneiform cartilages were wanting, parts of a cartilaginous mass, or the rudiments of a cartilage, in the place indicated.