sect. 173.] MI'COUS MEMBRANE OF THE LARYNX. 



377 



mucous membrane of the buccal cavity and fauces, is smooth, 

 whitish-red, and connected with the subjacent parts by abundant 

 submucous tissue of the ordinary kind. Except at the aperture of 

 the glottis, the mucous membrane of the larynx possesses through- 

 out a ciliated epithelium, and is without papilla?. It abounds in 

 elastic fibres, which form a fine network, especially in its deeper 

 portions; the more superficial layer, c/03"' to 004'" in thickness, 

 consisting chiefly of connective tissue, and terminating with a ho- 

 mogeneous border, of about 0-004'" in thickness, that cannot be 

 isolated. In adults, according to Rheincr, the ciliated epithelium 

 begins at the base of the epiglottis and the upper 

 vocal cords 2'" to 3"' below the entrance of the 

 larynx, and thence extends downwards over the 

 whole interior (see fig. 10, p. 36). It consists of 

 several layers (see § 20, p. 36), and is, in the whole, 

 from 0-024'" to o - 04'" thick. According to the 

 discovery of H. Rheiner, which I can confirm, the 

 vocal cords possess a laminated pavement epi- 

 thelium, that extends as a narrow stripe upon the 

 arytenoid cartilages as far as the pharynx. The 

 proper cylinders, which cany the cilia, average 

 0-015'" to 0-02'" in length, and 00025'" to 0-004'" 

 in breadth; they contain oval nuclei, of 0-003'" 

 to 0-0043" m diameter, with occasionally some 

 fat-granules (fig. 156*). These cells are generally 

 sharply pointed, and are frequently prolonged into 

 a thin fibril, which may become so long that the 

 whole cell acquires a length of 0-024'" to 0-027'". The cilia 

 vibratilia are fine, clear, soft processes of the cells, o - ooi6"' to 

 0-0022'" in length, which arise from them by a somewhat broader 

 base, and terminate in a tapering point. They are mostly dis- 

 posed close to one another over the entire terminal surface of 

 the cells; according to Valentin, there are from ten to twenty- 

 two upon each cell, an estimate which appears to me rather 

 too low ; more rarely, they are met with in smaller numbers, or 

 even, as was previously mentioned, only a single one upon a cell. 

 Care must be taken, however, not to mistake several cilia glued 

 together for a single one, an appearance which is particularly likely 

 to deceive in the foetus. In a chemical point of view, the cells of 

 the ciliated epithelium agree throughout with those of the cylin- 

 drical epithelium, and the spontaneous elevation of the cell-mem- 

 brane, after the addition of water, is especially observable upon 



Isolated cells, from 

 the ciliated epithelium 

 of the larynx. 



