110 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON 



irregular form and consist of three parts, the phalangeal process, 

 cell body, and foot. The phalangeal process is thin, somewhat 

 crooked in the adult though it runs straight at an earlier stage. 

 As the boundary between this process and the cell body, we 

 take a line running through the supporting cup ('Stutzkelch' of 

 Held) parallel to the plane of the basilar membrane (fig. 10). 

 The cell body in its upper part is wide, including here a round 

 nucleus. It then becomes thin and passes over to the foot. 

 Thus it is almost impossible to get the true volume of the cells. 

 Therefore, we have determined the volume of the cell body 

 only, excluding that of the phalangeal process. 



We think of the cell body as a cylinder having an average 

 diameter, which is calculated from four diameters measured at 

 four levels. The first level is just below the upper boundary 

 of the cell body, the second in the widest part, the third below at 

 about the middle of the cell body, and the last is at the narrowest 

 part near the foot. 



The height of the cylinder is the length of the cell body within 

 the limits just noted. Thus the volume obtained approximates 

 the value for the natural size of the cell body without the process. 



In table 85 (chart 38) are given the values for the volumes of 

 the Deiters' cells thus computed and the diameters and volumes 

 of the nuclei according to age. As there are in the radial section 

 three rows of cells, the values given are, of course, the average 

 of these. At the bottom of the last column appear the ratios at 

 1 to 12, 1 to 20, 1 to 546, and 12 to 546 days. As we see, the 

 volume of the cell body increases throughout life, slowly during 

 the first nine days, but from twelve to twenty days very rapidly, 

 and then less rapidly to old age. 



While the ratio from one to twelve days is 1:5.4, that from 

 1 to 546 days is 1:29.1, or more than five times as large. 



When we consider the volumes of the cells in each turn of 

 the cochlea, we see that it is smallest in turn I and largest in 

 turn I\ ', though there are some exceptions before nine days 

 of age. Table 86 shows these relations. 



The diameters of the nuclei of the cells grow, after some 

 fluctuations in the values at earlier stages, very slowly to old 



