GROWTH OF THE INNER EAR OF ALBINO RAT 111 



age, as indicated in table 85 and chart 38. The ratios at the 

 bottom of the corresponding column show these relations. The 

 values for the volumes of the nuclei of the cells are given in the 

 last column. Here, also, the diameters in the upper turns tend to 

 be larger than in the basal turn. In table 87 are given the ratios 

 of the diameters of turn I to the three other turns. We see in 

 all the turns about the same ratios, 1:1.0. 



In the literature we find but two observations on the diameters 

 of the nuclei of the Dieters' cells. Kolmer ('07) reports in the 

 pig 5 [l, and von Ebner ('02) gives in man 7 jjl for. the diameter 

 of the round nucleus of the cells. 



In the rat, therefore, the diameter is larger than in these 

 two forms, but no significance can be attached to this difference 

 until correction has been made for the several techniques em- 

 ployed. This I am unable at present to do. 



On the nucleus-plasma ratio in Deiters' cells. In the condensed 

 table 88 are given the volumes of the cell bodies and of their 

 nuclei together with the respective nucleus-plasma ratios. This 

 shows that the ratio is progressive with age. While the ratio 

 is at birth only 0.05, that in the oldest group is 28.3. The absolute 

 increase is not great at earlier stages, but by eighteen days it 

 is marked 



The rapid change in the ratio is very interesting. Before 

 eight days of age the cells are still immature. Some time after 

 eight days they develop rapidly, seeming to play some important 

 part in the special functions of the cochlea. 



On the length of Deiters' cells. To measure the length of 

 Deiters' cells we divide them into two parts, the upper and the 

 lower, by the boundary line between the cell body and the pha- 

 langeal process. The sum of these two lengths makes the total 

 length of the cells. 



In table 89 are given the values for the total length and for 

 each part separately (chart 39). As in the volume of the cells, 

 we see an astonishing change in the development of the length. 

 The length of the cells increases through life, at earlier stages a 

 little, but at twelve days it becomes nearly twice as long as at nine 

 days. The ratios at the bottom of the last column show the 

 course of growth. 



