570 SPECIAL HISTOLOGY. 



the usual manner into a very close elastic network ; which, however, 

 even where it is apparently most unmixed, contains some connective 

 tissue. The muscles of the larynx are all transversely striated with 

 fibres of 0*016-0-024 of a line, and present the same structure as those 

 of the trunk. They arise from the cartilages, and are inserted into them, 

 and also into their elastic ligaments; the latter being the case with the 

 thyreo-arytwnoideus, which is for the most part lost on the concave side 

 of the vocal ligaments. 



The mucous membrane of the larynx, the continuation of that of the 

 throat and mouth, is smooth, whitish red, and connected with the sub- 

 jacent parts by the ordinary, in some places abundant submucous con- 

 nective tissue. Except in the glottis, the mucous membrane, covered 

 only by a ciliated epithelium, and presenting no papillce, abounds in 

 finer elastic fibrous networks, particularly in its deeper portions ; whilst 

 the innermost layer, 0-03-0-04 of a line thick, consists principally of 

 connective tissue, and ceases in an inseparable, homogeneous border of 

 0*004 of a line. The ciliated epithelium, in the adult, commences at the 

 base of the epiglottis and, above the upper vocal ligaments, is composed 

 of several laminae (vide 21), on the whole 0-024-0-04 of a line thick; 

 with the exception of the vocal ligaments, which, as was discovered by 

 H. Rheiner and I can confirm, have a squaraose epithelium, it lines the 

 rest of the larynx throughout. The proper ciliated cylinders 0-015- 

 0-02 of a line long, and 0-0025-0-004 of a line broad in the mean, with 

 elongated round nuclei of 0-003-0-0045 of a line, and occasionally with 

 a few fat-granules, are mostly much acuminated, frequently even pro- 

 longed into slender filaments, which may attain such a length that the 

 entire cell may equal 0-024-0-027 of a line. The cilia are fine, trans- 

 parent, soft processes of the cell-membrane, 0-0016-0-0022 of a line 

 long, which arise from it with a rather broader basis, and terminate in 

 a pointed extremity. Most usually they are placed close together, over 

 the whole of the terminal surface of the cells, according to Valentin, on 

 the average, to the number of 10 to 22, which appears to be rather 

 under the mark ; more rarely they occur in smaller number, or even, as 

 it is said, singly upon a cell. But in this case, care must be taken not 

 to regard cohering cilia as single ones, as might happen, particularly in 

 the embryo. In their chemical relations the cells of the ciliated epithe- 

 lium correspond precisely with those of the cylinder-epithelium, and 

 especially, the separation of the cell membrane on the addition of water, 

 may also be remarked in them. The cilia are of much more delicate 

 consistence than the cell membrane and are very readily detached upon 

 any maceration of the epithelium ; more or less altered by almost all 

 reagents, they are, by many, at once destroyed ; in chromic acid, how- 

 ever, they may be preserved pretty well. In man, the ciliary motion is 

 directed, in the trachea, from below upwards and may often be perceived 



