GROWTH OF THE INNER EAR OF ALBINO RAT 49 



Retzius ('84) studied this distance in the rabbit and cat and 

 gets the values given in Table 17. 



Comparing the values of these two authors with my own, 

 there are of course some differences. While in the rabbit the 

 interval is large at one day, it is greatly diminished at two days 

 of age. At three days the inner corner of the cell reaches the 

 habenula perforata. In the cat the values are nearer to mine. 

 The fact that the values increase from base toward apex is to 

 be seen here also. This peculiar phenomenon appears, therefore 

 not only in the albino rat, but also in the rabbit and the cat 

 during the earliest stage of postnatal life. 



4- 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 base. This measurement is difficult. As we 

 know, the inner and outer pillar cells in the albino are from birth 

 till nine days of age in contact with each other along their whole 

 length, and therefore they do not yet surround the space forming 

 the tunnel of Corti. At about nine days, however, the tunnel 

 appears while the cells remain in contact by their bases. It 

 is almost impossible to determine the line of contact on the 

 basilar membrane in my preparations. To get the radial distance 

 between the habenula perforata and the outer corner of the inner 

 pillar cell I have proceeded therefore as follows: 



First, I have measured this distance directly up to nine days 

 of age; after that this distance consists of the sum of the radial 

 basal breadth of the inner pillar (not pillar cell) and the breadth 

 of the inner basal cell on the basilar membrane. Since it is 

 impossible to get the latter value directly in my sections, I 

 considered that half of the radial distance between the outer 

 corner of the inner pillar and the inner corner of the outer pillar 

 would be equivalent to it. 



Of course, I do not know whether the value of the sum of 

 these two distances is at all ages, identical with the distance 

 between the habenula perforata and the outer corner of the inner 

 pillar cell at its base. I believe, however, that a systematic 

 study of the growth of this distance will be significant. 



