40 



ANATOMICAL AND PHYSIOLOGICAL STUDIES ON 



In the growth of both zones we see about the same relation. 

 These increase rapidly from birth till nine (or twelve) days and 

 after that very slowly. These relations are shown clearly in 

 the ratios at 1 to 546, 12 to 546, and 20 to 546 days. While after 

 twelve days the ratios in total breadth and in each zone are 

 the same, 1:1.1, that for 1 to 546 days is smaller for the outer 

 zone than it is for the inner zone, thus the inner zone increases 



TABLE 9 



Radial breadth of Ihe membrana basilaris measured between the foramina nervina 

 and ligamentum spirale in radial sections on age (chart 7, fig. 2} 



considerably after birth, while the outer zone does not grow, 

 as some authors have imagined, as much as the inner zone. 

 I will discuss this point later. 



Comparing the growths of the radial breadth of the inner 

 and outer zones, we find that the inner zone is relatively narrow 

 at nine days; thus the ratios between them are 1:1. 4; after that 

 period the inner zone increases rapidly, and even at twelve 

 days the ratio becomes 1:1.1, which is almost the same as in 

 the adult, 1:1.2. 



