GROWTH OF THE INNER EAR OF ALBINO RAT 



47 



in the increase of the total radial breadth of the membrane 

 according to turn. My results obtained from the albino rat 

 agree with these data. 



3. Radial distance between the habenula perforata and the 

 inner corner of the inner pillar cells at base. The measurements 

 of the radial distance from the habenula perforata to the bases of 

 the inner and outer pillar cells were taken to determine their 

 postnatal growth. As already stated, the cells from which the 

 arch of Corti arises stand at birth nearly vertically and have no 

 space between them (fig. 4). In the adult, however (fig. 10), 

 we see a space, the tunnel of Corti lying between them and 

 changes in the form of the arch occur. To follow these changes 



TABLE 14 

 Breadth of the inner zone of the membrana basilaris in n 



it seems at first necessary to study the growth of the pillar 

 cells and of the other elements in the organ of Corti. At the 

 same time we must take into consideration the inward shifting of 

 the organ of Corti, first studied by Hensen. This shift inward 

 of the organ is, according to Hensen, chiefly caused by the 

 wandering of the pillar cells, especially the inner pillar cell. 

 Therefore, it seemed necessary to determine the radial distance 

 of the pillar cells from the habenula perforata at different ages 

 before discussing this interesting problem. 



In table 15 are given the values for the radial distances between 

 the habenula perforata and the inner corner of the inner pillar 

 cell at its base according to age (figs. 4 to 9) . As we see, the 

 average value increases till three days of age, then vanishes 

 suddenly, though at six days we have a measurable interval 

 in the upper turns of the cochlea. Comparing these distances 

 according to the turn, they are smallest in turn I and increase 



