M'l>m>RY OHVAX. :\\\\\ 



of the cochlear nerve pass. The number of these holes is 

 estimated as about 4000. The zone is known as the habenula 

 perforata. 



\Ve pass on to the second, more complicated part of the 

 tympanal wall, the lamina */>/m//x membranacea. The base 

 of this part forms the so-called membrana Ixtxilaris, which is a 

 process of the connective tissue occurring in the labium tym- 

 panicum of the limbus, and attaches itself to the crista basilaris 

 of the ligamentuni spirale. It has the form of a fine tightly 

 stretched membrane of a connective-tissue nature. The mem- 

 brana basilaris possesses on its lower (tympana!) surface a layer 

 which is a process of the periosteum of the lamina spiralis 

 ossea, and consists of an inner connective-tissue sheath and a 

 layer of flat epithelial cells. 



The surface directed toward the lumen of the ductus 

 cochlearis is covered with epithelium, which is in large part 

 differentiated into neuro-epithelium. It forms the so-called 

 <>i'</<i-non xfih'tili* or (hrfis or</<ui. in which lie the terminal 

 ramifications of the cochlear nerve. 



FK.. -J71. 



I'lif tin n iiex 



'cell* 



Flat prin-i'#-* 

 of unit'f 

 pillar 



Outer 

 'pi llnrs 



Inn<'r pillars, 



t of the oruan <!' Corti f a rabbit. l?<. 



Cortrs organ covers the inner part of the membrana basil- 

 aria. The part is called the zona tecta, as opposed to the 

 outer part, which is striated on its surface, and is known as 

 the zona pectinqta. 



If we observe the organ of Corti in a radial section of the 

 cochlea, we see that it is made up of an inner and an outer 

 part, which are made up of ainlUnni cell* and x//y; porting r< 



24 



