GROWTH OF THE INNER EAR OF ALBINO RAT 



55 



In table 25 (chart 10) are given the values for the radial 

 distance between the habenula perforata and the outer corner 

 of the inner pillar cell (resp. the inner corner of the outer pillar 

 cell) at the base according to age. This table is derived from 

 tables 18, 19, and 22. The values from one to nine days of age 

 are from table 18. Those after twelve days consist of the sum 

 of the values in table 19 plus the one-half of those given in table 

 22 (fig. 2 value for bracket 3 plus one-half the value for bracket 

 6). 



TABLE 24 



Radial distance beliveen the outer corner of the inner pillar and inner corner of the 



outer -pillar — in n (Retzius) 



The values increase gradually after birth till nine days, when 

 they reach a maximum, and then decrease, but increase again 

 very gradually till old age. If this method of measurement is 

 accepted, then the inner corner of the inner pillar cell lengthens 

 inward at the base in the earlier stages. At the time when the 

 inner pillar reaches the habenula perforata, the outer corner 

 of the inner pillar has not yet moved inward, and thus the breadth 

 of the base is largest. After the inward wandering of the inner 

 pillar cell, the base diminishes a little in its breadth; then it 

 increases slightly with advancing age. 



When considered according to the turn of the cochlea, this 

 measurement generally increases from the base to the apex, 

 but more rapidly from turn I to turn III, and only slightly from 



