16 ANATOMICAL AND PHYSIOLOGICAL STUDIES ON 



B. On the growth of the tympanic wall of the ductus cochkaris 



Figures 4 to 12 show the appearance in outline at birth, at 

 three six, nine (not hearing), nine (hearing), twelve, twenty one 

 hundred, and 546 days, respectively. These figures have been 

 drawn from the best corresponding sections at the beginning 

 of the middle turn of the cochlea, figure 3, turn n, which I have 

 selected as the type, as did Retzius. 



The fact, demonstrated by many authors, Bottcher ('69), 

 Retzius ('84), and others, that development progresses from 

 the basal to the apical turn is confirmed in the albino rat. 



In the albino rat the development of the cochlea, and es- 

 pecially of the ductus cochlearis, is somewhat retarded as compared 

 with man, and the papilla with its elements developed in a great 

 measure during the first ten days after birth. 



As we see in figure 4, the ductus cochlearis in the new-born 

 rat is very immature. It is remarkable that the space which 

 lies in adult rats axialward of the papilla spiralis between the 

 membrana tectoria and the limbus spiralis-sulcus spiralis internus 

 (fig. 10) is not yet to be seen. Instead of the space, there is the so- 

 called greater epithelial ridge (der grosse Epithelwulst of Bottcher) 

 figure 4, G. consisting of pseudostratified epithelial cells. These 

 long and narrow cells lie pressed very closely together with 

 their large oval nuclei at various heights. The surface of the 

 prominence sinks slightly in its center, and at the outer end of 

 the prominence more rapidly, where it passes over into the so- 

 called lesser epithelial ridge fig. 4, L. (der kleine Epithelwulst) 

 at an obtuse angle. 



The latter is, of course, a relatively small prominence, making 

 up the greater part of the papilla spiralis. The pillar cells of 

 Corti lie with their upper ends at the most inner part of the 

 surface of the lesser ridge just in the angle with the greater 

 ridge. They form two entirely separate rows of cells, the inner 

 and the outer, but so close together that we cannot detect any 

 space between them. Only the protoplasm of the inner pillar 

 cell is more transparent above the nucleus, and on the inward 

 side there is a thin rod passing from the upper end to the lower 



