FALSE AND TRUE VOCAL CORDS. 43 



with, each other. In consequence of this disposition of the 

 fibres, large interspaces occur, which are occupied by numbers 

 of fat cells and considerable masses of glands. Both above and 

 below, a few isolated fasciculi run directly into the longitudi- 

 nal fibrous layer of the larynx. 



In the Dog the elastic tissue of the superior vocal cord not un- 

 frequently becomes converted into cartilage, the process of the 

 arytasnoid cartilage that runs forwards appearing to be prolonged into 

 it. In this animal also the horizontal direction of the fibres is much 

 more strongly marked, whilst the fasciculus, which in Man Curves 

 downward over the posterior angle of the ventricle of Morgagni, 

 becomes quite an independent structure, causing the mucous mem- 

 brane with which it is covered to project to a considerable extent, 

 and producing the impression that the superior vocal cord is inserted 

 along the floor of the ventricle. Where the above-mentioned conver- 

 sion into cartilage occurs, the glands, for the most part, lie behind 

 the cartilage, and traverse it to discharge their secretion into the 

 ventricle. 



A few small fasciculi of the external thyro-arytaenoid muscle, some- 

 times even in Man, enter into the composition of the superior vocal 

 cord, and then appear as an independent muscle (Muse., Santorini). 



The margins of the arytseno-epiglottidean folds, throughout 

 their whole extent, are covered with an epithelium composed 

 of tesselated cells, which is continued over the opposed sur- 

 faces of the arytsenoid cartilages, as far down as to the level 

 of the lower vocal cords. In animals the mucous membrane 

 presents papillary processes, similar to those that in Man are 

 only found on the folds of the mucous membrane produced by 

 the cartilagines corniculatse, and which sometimes measure 

 0'35 of a millimeter in height, and O'l in breadth. On the 

 other hand, the superior vocal cords, and in Man the walls of 

 the ventricle also, are lined by ciliated epithelium, similar to 

 that which has already been described as occurring at the base 

 of the epiglottis. The glands within the ventricle break up 

 into groups of much smaller size, all of which discharge their 

 secretion by just such separate straight excretory ducts as are 

 found on the opposed surfaces of the arytsenoid cartilages. 



In the true vocal cords, and especially at their free border, 



