30 



ANATOMICAL AND PHYSIOLOGICAL STUDIES ON 



As we know, the radial breadth of the membrane increases 

 gradually from the basal to the apical turn. Table 5 (charts 4, 

 5, and 6) shows how the breadth of the total and of each part 

 of the membrane changes in successive turns from base to apex 

 according to age. At birth it is broadest in the beginning of the 

 middle turn (turn II) decreasing gradually towards the apex. 

 From three to twenty days the greatest breadth is usually found 



TABLE 4 



Average radial breadth of the membrana tectoria and its thickness in radial-vertical 

 section. Averages of all four turns (charts 2 and 8) 



in turn III, but after this in turn IV. At the bottom of each 

 column are given the ratios of the radial breadth in each turn 

 between the several age limits. 



These show that after twelve days there is but little change 

 in the radial breadth of the entire membrane in any turn. 



On examining the growth in each zone of the membrane 

 through the several turns, we find that after three days the outer 

 zone of the membrane becomes at each age always broader 

 from base to apex. 



