PLATE 4 



EXPLAXATIOX OF FIGURES 



8 Section across 3rd half turn of developing tectorial membrane and differ- 

 entiating spiral organ of pig of 19.5 cm. The recession of the cells of the axial 

 side of the greater epithelial ridge is well under way. 



9 Section across 3rd half turn of spiral organ and its tectorial membrane 

 of pig of 22 cm. The recession and disintegration of the cells of the outer part 

 of greater epithelial ridge is ncaring its completion, leaving the inner support- 

 ing cells of the spiral organ. 



70 



