16 IRVING HARDESTY 



For transverse sections of the tectorial membrane, and re- 

 mainder of the spiral organ, it is necessary that the edge of the 

 knife passes parallel with the axis of the cochlea, and for trans- 

 verse sections of the shortest or apical turn of the coil of the 

 membrane, only those sections can be used which pass through 

 the actual apex of the cochlea and the diameter of the cochlear 

 nerve at its base. Celloidin sections varying from 10 to 20 

 micra were studied. The 3.5, 5.5, and 9 cm. stages were also 

 embedded and sectioned in paraffin for thinner sections. 



For staining, the sections were passed through the gradually 

 decreasing grades of alcohol and the most generally satisfactory 

 results were given by Delafield's hematoxylin 6 hours or over- 

 night, washing in water, and both decolorizing and counter- 

 staining with Van Giesen's picric acid-fuchsin mixture. Thence 

 the sections were both washed and dehydrated with the increas- 

 ing grades of alcohol, cleared in creosote and mounted in balsam. 



All the drawings here given, except figures 10 and 11, were 

 first outlined in detail under the new Edinger drawing and pro- 

 jection apparatus. By it, inequality of magnification of parts 

 given by the camera lucida are avoided. The outlines of the 

 nuclei and those of many of the cells could be traced. All except 

 figures 10 and 11 were outlined with the same combination of 

 lenses and the same adjustment of the apparatus and thus they 

 are drawn to scale. The drawings were completed with the 

 identical section projected for the outline placed, in each case, 

 under the microscope and studied under high power for correc- 

 tions and insertion of details. 



PROPORTIONS OF THE ADULT TECTORIAL MEMBRANE 



. The hog, ox and man belong to those species of mammals 

 which possess the flat type of cochlea and the component 

 structures in their cochlea are remarkably similar in form and 

 character. 



Wiedersheim ('93) gives the coil of the cochlea of the hog 

 as having 4 turns, that of man as having nearly 3 turns and that 

 of the ox, 3^ turns. Gray ('07) gives the hog as having 3^ turns 



