158 THE AUDITORY NERVE AND COCHLEA, BY W. WALDEYER. 



laminge projects like a phalanx between every pair of hair cells 

 (see fig. 326). But since the internal hair cells are much broader 

 than the internal pillars, and at the point corresponding to each 

 hair cell a rounded gap occurs in the margin of the capitular 

 lamina, the capitular lamina existing on each of the internal 

 pillars must present a different aspect, according to whether 

 one of these pillars is exactly opposite a hair cell, or is situated 

 between two of them. And thus it occurs that, on isolation of 

 the internal pillars, differently formed internal appendices are 

 seen, which in general, as has been already mentioned, resem- 

 ble a little hook in profile. (See the careful description given 

 by Deiters, 13.) 



By their juxtaposition the opposite pillars overarch a kind 

 of tunnel extending along the whole length of the lamina 

 spiralis, as far almost as to the end of the hamulus. The lu- 

 men of the tunnel is triangular on section,* the longest side 

 of which is in general formed by the membrana basilaris, 

 and the shortest by the internal pillars. The smaller the 

 species of animal, the narrower becomes the membrana basi- 

 laris; the shorter the pillars, the steeper their rise from the 

 membrana basilaris, and consequently the greater the relative 

 height of the arches ; the difference in size between the exter- 

 nal and internal pillars then almost entirely disappears. The 

 larger animals have very long pillars, forming an arch of con- 

 siderable span. Man presents the flattest form of arch, the 

 transverse section resembling a low trapezium. (Compare 

 fig. 321, from Man, with fig. 322, from Vesperugo.) Other 

 peculiarities result from differences in the form of the pillars. 

 In Cheiroptera and Mice they are short and compressed; in Man, 

 slender and strongly arched, as they are also in the Dog and 

 Ox. Man possesses the longest capitular laminae. The size of 

 the pillars, as well as the height and span of the arches, differs 

 in different parts of the lamina spiralis. As a general rule, 



* The term lumen may be used with perfect propriety, since, with the 

 exception of the above-mentioned remains of protoplasm attached to the 

 pillars, the supporting fibrous bands of Deiters on the floor, and the nerve 

 fibres running through the tunnel, only endolymphatic fluid is contained 

 in its interior. (See also Reichert, 44.) 



