134 Irving Hardest}- 



may represent the individxial filiers^, while the heavier lines and dots 

 may consist of agglutinated bundles of them. 



The under surface of the main bod}' of the membrane is thus given a 

 transversely fibrous appearance when viewed on the flat, not by contin- 

 uous fibers coursing across it individua'.ly, but by the general direction 

 of the curved ends of many fibers. Beginning on the under surface, the 

 fibers first lie parallel with this surface and form it, and then curving 

 outward, upward and then inward, contribute to the upper surface. The 

 summation of the course of these ends gives to the under surface the 

 appearance of being striated in a direction oblique from the radial 

 and, like the upper surface, the slant is from the labium vestibulare 

 toward the apex of the cochlea. But the direction on the under 

 surface is more nearly radial than that on the upper, as may be 

 seen by comparing Fig. 4 with Figs. 2 and 3. On both surfaces, 

 the direction of the fibers in the inner or attached zone of the membrane 

 is inclined more toward the apex than that of the fibers in the main 

 body and especially the outer edge. An examination of the under 

 surface showed that the most nearly radial direction of the fibers occurs 

 in the second and third turns, and an attempt is made to show this in 

 Fig. 1. 



Fig. 4 represents a drawing of the l^roken end of a piece of mem- 

 brane from a cochlea fixed in Zenker's fluid. The preparation showed 

 that the fixed specimen, at least, in breaking, has a tendency to break 

 parallel with the direction of the fibers, and it suggests that the difference 

 in the course of the fibers above and below may contrymte to the 

 strength and elasticity of the membrane by a sort of interlocking ar- 

 rangement. In a break like this, the portion of the fibers intervening 

 between the under and upper surfaces must of necessity be broken 

 across. In the break pictured, there were evident clumps of fibers which 

 seemed to have been partly split off from the remainder before breaking, 

 and which appeared something as slivers, each a mass of fibers held in 

 a corresponding amount of the glassy matrix (Fig. 4, S). 



From a careful comparison of the surface views with the sections one 

 may conclude that the fibers contributing to the under surface of the 

 tectorial membrane make their immediate approach (or, rather, con- 

 sidered from the standpoint of their origin, they leave this surface) 

 from two general directions: (1) Most of those on the outer side of 

 Hensen's stripe contribute first to the striation of the upper surface, then 

 curve downward and then inward to contribute to the striation of the 



