164 SPECIAL HISTOLOGY. 



ciliated cylinders are thrown off and expelled with the mucus 

 of the trachea, but of an extensive detachment of the ciliated 

 cells there is no indication. Even in diseases of the respi- 

 ratory passages, the detachment of the ciliated cells is by 

 no means so common a phenomenon as is believed by many, 

 and the epithelium may be frequently found uninjured under 

 puriform mucus, or even beneath croupose exudations. The 

 mode in which the ciliated cylinders that have been thrown off 

 are replaced, is probably simply this : that the deep cells mul- 

 tiply, perhaps by division {vide § 12), and succeed them, the 

 outermost again producing cilia. 



The laryngeal mucous membrane contains a considerable 

 number of glandules, all of which belong to the category of 

 minute racemose glands • and, like those of the oral cavity, 

 pharynx, &c, present rounded gland-vesicles of 0*003 — 004'", 

 with a tesselated epithelium, and excretory ducts lined with a 

 cylinder-epithelium. They are situated, in part scattered as 

 minute glandules of j^ — X" on * ne posterior surface of the epi- 

 glottis, where they are frequently imbedded in depressions, which 

 may even perforate the cartilage, and in the cavity of the larynx 

 itself, where their orifices, such as might be produced by a 

 needle, are easily seen; in part they occur at the entrance of 

 the larynx, in front of the arytenoid cartilages, forming a 

 large aggregate mass, a horizontal division of which envelopes 

 the cartilage of Wrisberg, whilst a second dips down into the 

 cavity of the larynx (glandulce arytcenoidece later ales). Glan- 

 dules are also placed upon the arytcenoideus transversus and a 

 considerable mass of them presents itself externally, in the ven- 

 tricles of Morgagni, behind and above the sacciform ligaments. 

 The secretion of these glands, as of the oral glands, is pure 

 mucus, without any morphological elements. 



The larynx is richly supplied with vessels and nerves. The 

 former, in the mucous membrane, present the same conditions 

 as in the pharynx and ultimately breaking up into capillaries, 

 0*003 — 0*004'", form a superficial plexus. The lymphatics are 

 numerous and are received by the deep cervical glands. Of the 

 nerves, we learn from Bidder- Volckmann, that the more sen- 

 sitive laryngeus superior contains a preponderance of fine fibres, 

 whilst the inferior, whose properties are more of a motor nature, 

 has more thick fibres. They terminate in the muscles, the peri- 



