54 



IRVING HARDESTY 



pleted, the pressure must not only be relieved, but, from the 

 marked decrease in number of cells, there may result an almost 

 negative pressure. 



Measurements show that the space occupied by the width 

 of the greater epithehal ridge increases throughout the coils 

 of the cochlea up to pigs of 15 to 16 cm. (when the ridge is widest) 

 and thereafter it begins to decrease very perceptibly. The 

 measurements were taken from the membrana propria of the 

 epithelium of the greater ridge, at its most axial extension under 

 Huschke's teeth (S, figs. 1 and 7), to the apical end of the inner 



TABLE 6 



Giving in micra averages of the width of the developing and developed internal spiral 

 sulcus, measured from the membrana propria of the epithelium under Huschke's 

 teeth to the apical ends of the inner hair cells of the spiral organ, in the different 

 pigs and the different regions of the cochlea specified 



hair cell of the spiral organ. The averages of the measurements 

 are recorded in table 6. As in the other tables, some of 

 the variations in width of the greater ridge, and internal spiral 

 sulcus, evident in the 1st and 7th half turns are due to 

 the varying distances from the apical and basal ends of the 

 cochlear duct at which the knife passed. In the specimens 

 from pigs of 9 to 11.4 cm., the 1st half turn was not completed, 

 and in those from 13 to 14 cm., the differentiation of the vestib- 

 ular lip of the spiral hmbus in this turn was not sufficient 

 for the measurement. In the 3rd half turn of the 9 cm. pig 

 (see fig. 6) this differentiation had not taken place, and thus this 



