GROWTH OF THE INNER EAR OF ALBINO RAT 25 



spiralis internus — which is deep and wide in the basal turn, 

 becomes gradually shallow and narrow as we pass upward, and 

 in the middle part of the middle turn is to be seen as a small 

 and flat space. In the apical turn it is not yet present. The 

 inner side of this space is made by the labium vestibulare of 

 the limbus laminae spiralis. 



As a result of this change in the greater ridge, the obtuse angle 

 between the greater and lesser ridge vanishes entirely, and the 

 two surfaces come to lie in the same place. The inner hair cell 

 becomes larger and inclines less outward. 



It is to be noted that the inner hair cell is supported on both 

 sides by long slender cells. These have been variously described 

 by several authors, but first Hans Held ('02) and afterwards 

 Kolmer ('07) have considered them as supporting cells, reaching 

 from the surface of the hair cell to the plane of the basilar 

 membrane. Held has termed the cell which lies outward the 

 ' Phalangenzelle. ' 



I have paid some attention to this cell and the changes in it. 

 It is long and slender and stands between the inner hair cell 

 and the inner pillar cell, with the upper end reaching to the 

 surface, and is attached at its base to the inner corner of the 

 inner pillar. The oblong oval nucleus lies in its basal portion. 

 On the inner side of the inner hair cell there is a group of two to 

 three cells of the same kind. These cells, termed ' Grenzzellen ' 

 by Held, stand near the habenula perforata, reach to the height 

 of epithelium, and have their bases in intimate relation to the 

 former. 



These are not neuro-epithelial cells nor in intimate relation with 

 the nerve fibers, but similar to the Deiters' cells which support 

 the outer hair cells. 



The developing pillar cells become progressively wider at their 

 bases. The inner pillar cell sends a long foot towards the habenula 

 perforata and in the basal turn it sometines reaches to it. The 

 outer pillar cell increases its length very rapidly and extends 

 its foot outward on the basilar membrane. Thus in the basal 

 turn the triangle made by the inner and outer pillar cells and 

 having a short base, in the upper turns changes to an equilateral 



