GROWTH OF THE INNER EAR OF ALBINO RAT 



105 



In table 77 are given the average ratios of turn I to the three 

 other turns. 



The comparison of the growth of the inner and outer hair 

 cells. As already stated, the growth of the inner and outer hair 

 .cells in volume proceeds in about the same way till they reach 

 their full size at twenty days. After that we note a difference 

 between them. While the outer hair cells maintain a nearly 

 constant volume, the volume of the inner hair cells diminishes 



TABLE 77 Condensed 



Ratios of the diameters of the nuclei of the outer hair cells according to the turns of 



the cochlea 



TABLE 78 Condensed 

 Comparison of the volumes of ike inner and the outer hair cells 



somewhat with age. When we consider the volume according 

 to the three age groups, it increases in both groups throughout 

 life (table 78). There are, however, large differences in the rate 

 of increase. The inner hair cell increases its volume at 11 days 

 by 80 per cent and between 11 and 213 days by less than 2 per cent. 

 For the outer hair cells the increase by 11 days is 120 per cent 

 and from 11 to 213 days, 19 per cent. At the same time the inner 

 are always larger than the outer hair cells, as the ratios in table 

 78 show. 



