Text: The cavity of the vestibule is prolonged anteriorly by the cochlea so called from its likeness to the shell of a snail. As a whole, it forms a blunt cone with its apex outwards; this cone is formed by a gradually tapering spiral tube, the first curve having a concavity upwards; it is coiled 2 1/2 times round a central column or "Modiolus" which sends an incomplete partion into the cavity of the tube. This partion is called "Lamina spiralis ossea" and winds in the cavity of the spiral cochlea like the thread of a screw or the staircase in a turret; it is wanting at the apex of the tube. Otoliths or otoconia (ear-dust) are found in the common sinus or utricle, in the saccule, and in the amullae of the semicircular canals; and besides them, the ampullae are lined with long, stiff, hair-like filaments, called "fila acustica". They are six-sided crystals of carbonate of lime, with pointed ends, and lie in the walls of these parts of the membranous labyrinth. They are occasionally absent. In these parts we find pigment cells, which seem in some mysterious manner to be essential to the sensitive parts of nearly all the special-sense organs; for they are present in the olfactory region of the nose, as well as in the globe of the eye, and only in the latter is their function known. It is a well known fact that white cats (cats which have no pigment) are deaf.

See Also: OTOLITH; BRAIN SAND

Source: 125