54 



ANATOMICAL AND PHYSIOLOGICAL STUDIES ON 



and the inner corner of the pillar (not pillar cell) at the base, 

 on age. At the bottom of the last column are given the ratios 

 from 6 to 546, 12 to 546, and 20 to 546 days. As just stated, 

 the inner, and especially the outer rods, do not appear in the 

 respective pillar cells at the earliest stage, the latter becoming 

 evident a bit later than the former. After six days of age the 

 distance between them can be determined. 



As table 22 shows, this distance increases at first rapidly, 

 then more slowly with age. This agrees with the growth of the 

 membrana basilaris, as already noted. While the value at 546 

 days is over twice as large as at six days, it is but little larger 

 than at twenty days, as the ratios show. Moreover, the distance 

 increases from the base toward the apex rapidly up to turn 



TABLE 23 Condensed 



Ratios of the radial distance between the outer corner of the inner pillar and the 

 inner corner of the outer pillar, at base according to turns 

 of the cochlea on age 



III and less rapidly to turn IV. This relation is more concisely 

 presented in table 23. Retzius ('84) gives the value of this 

 distance in the rabbit and the cat as follows (table 24). 



The table 24 shows that there is no measurable distance 

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

 of the outer pillar at the very early stage in the rabbit, and this 

 result is like that for the albino rat. Later the distance is larger 

 in the rabbit than in the rat. The rate of increase of the values 

 from the base to the apex is, however, similar in both forms. 

 In the cat, on the other hand, there is already at birth a large 

 distance between the pillars. The cochlea of the cat is there- 

 fore at this period more advanced in this character than that of 

 the rabbit or rat, but in the cat also the distance tends to in- 

 crease from the base toward the apex. 



