476 



THE SPECIAL SENSES 



ing into the endolymph. These latter cells receive the 

 terminal brushes of the fibers and are supported below 

 by the layer of cells called the supporting ceUs. 



Fig. 225 — Diagram of cross section of a single coil of the cochlea. 



The action of this organ is not fully understood. All 

 that can be stated definitely of the action and the manner 

 in which sound impulses are interpreted may be summarized 

 as follows : 



Summary. — (a) The vibration of the perilymph being commu- 

 nicated to the endolymph through the membrane, sets up in it 

 similar vibrations. These vibrations, in turn, move the hairs of 

 the sensory cells and stimulate the fiber brushes, thus starting 

 impulses. 



