No. I.] THE VERTEBRATE EAR. 



123 



form the thickened border of the band. In structure this film 

 was very like some of Loewenberg's nets that I had studied 

 before, and when it was removed from the surface of the hair 

 band no net was found below it. From this I concluded that 

 the net of Loewenberg is only the loosened and displaced plate 

 or film of cell caps of the ridge of Corti outside of the outer 

 row of hair cells. There is nothing unusual in the process, as 

 those might suppose who are not familiar with the old and 

 highly reverenced mysteries of cochlear anatomy ; for in the 

 membrana reticularis, discovered and originally described by 

 Kolliker, I believe in the first edition of his GeiuebeleJire, we 

 have just such a film split off the tops of the cochlear cells 

 betzveen the hair cell of both rows and among the rows. Recall, 

 for the moment, the relation of the parts of the organ of Corti 

 as I have previously described them. A long ridge of more or 

 less even surface, of unequal side slopes, with a crest of waving 

 hairs fixed near the apex of the ridge. The surface of the ridge 

 is continuous from side to side as a matter of course, and, since 

 the body of the ridge is composed of columnar epithelial cells, 

 the surface is made up of the mosaic of their ends, and as I 

 have stated, this surface is quite smooth, the only inequalities 

 being the thickened rims of the cell ends. The whole surface 

 of the ridge is liable to artificial ecdysis under the influence of 

 reagents, but owing to the insertion of the crest of auditory 

 hairs, the whole surface cannot be removed intact. 



Beginning on the outside in the bottom of the sulcus spiralis 

 externus, let us follow the progress of such an artificial ecdysis. 

 The cell-cap film is thinnest in the bottom of the sulcus exter- 

 nus, where the cells are smallest and least differentiated. It 

 gradually thickens upwards as we ascend the slope. All over 

 this free slope, which has no surface growths or projections, 

 the film peels off freely, and is a continuous membrane until it 

 reaches the outer row of hair cells. Since this film is more 

 delicate and more exposed than the hair band, as regards its 

 attachments, it is acted on more quickly, and, consequently, in 

 preparations where the hair band is ultimately raised from the 

 surface of the ridge of Corti, this thin film has already been dis- 

 placed by the curling, distorting action of the reagent and taken 

 its place upon the surface of the hair band as Loewenberg's net. 

 As it curls upward the holes made in this sheet by the hair cells 



