THE AUDITORY APPARATUS 



125 



essential and very important part of the human induction 

 coil — the organ of Corti. 



Before, however, going into that let us inspect a vertical 

 section through the middle of the cochlea, taken from 

 Schafer's Essentials of Histology. 



Vermcai, Section through the MiddIvE of the Human 



CocHi<EA. {After Schafer.) 



a, Basilar membrane ; b. Canal of the Cochlea ; c, Scala Vestibuli ; d. 



Membrane of Reissner ; e. Ganglia ; /, Membrana Tectoria ; g, Scala 



Tympani. 



It is quite evident that in the cochlea — ^the only part of 

 the labyrinth really spiral in form — the endolymph occupies 

 a much smaller space than the perilymph ; the latter filling 

 the scalse vestibuli and tympani, and the former the cochlear 

 duct only. 



Stretching across the scala vestibuli at an angle, and 

 separating it from the cochlear duct, is a piece of connective 

 tissue of the pavement variety, called the Membrane of 

 Reissner. This tissue is non-conductive of the nervous 

 impulse, is, from an electro-ph37siological point of view, 

 dielectric in character and therefore capable, when between 

 two conducting bodies, of transmitting neuro-electricity by 

 induction. 



We can now see that instead of the neuro-electrical waves 

 set up in the endolymph going direct to the brain, they pass 

 first to the organ of Corti, but before we proceed any further 

 it is desirable to consider what is called the Acoustic Nerve ; 



