488 IRVING HARDESTY 



same board, had been put on. The joints, cut as shown in figure 

 6, were coated with a fresh xylol solution of asphaltum immedi- 

 ately before screwing them together. The spiral lamina, with 

 its membranous portion and its vestibular and tympanic lips 

 was represented b}^ a piece of wood 2| inches wide and trimmed 

 out as indicated by SL, figure 5, C, and figure 6, the spiral sulcus, 

 SS, being attained by cutting a lateral groove in the wood. The 

 lamina was fitted as a water-tight partition along the trough, 

 so slanting that the space above it, representing the scala vestib- 

 uli, SV, figure 6, increased in passing from the basal toward the 

 apical end and thus the space below it, the scala tympani (ST) 

 was smallest at the apex and increased in passing toward the 

 basal end. At the basal end (BE, fig. 5) the lamina was fitted 

 water-tight against the inner side of the end of the trough, span- 

 ning between the openings in this end representing the fenestra 

 vestibuli above it and the fenestra cochleae below it. The 

 basal end of the model showing these openings, FV and FT, 

 closed by their respective membranes, is illustrated in figure 7, 

 A. At the apical end the lamina was cut about 1^ inches shorter 

 than the length of the trough, thus leaving a helicotrema or con- 

 tinuation here of the scala vestibuli with the scala tympani. 

 The top side of the trough could be closed water-tight by means 

 of a plate of glass {GP, fig. 6) cut to fit and placed upon strips of 

 India rubber upon which it was pressed down firmly by means 

 of wooden strips placed along its edges and held so pressed by 

 means of metal Japan buttons (MB, fig. 5, A, and fig. 6) set at 

 intervals along the wall of the trough. 



Even an approximate imitation of the tectorial membrane 

 was found verj^ difficult to attain. A material was desired with 

 low^ specific gravity and a texture sufficientl}^ tough to hold when 

 trimmed to the shape and proportions of the actual tectorial 

 membrane. Gelatin cast in the desired shape and fixed with 

 formaldehyde was tried but the thin, attached axial zone was 

 not sufficiently resistant for the purposes of the experiments 

 nor would the gelatin hold the wires which were decided to be 

 passed through it at intervals for making electrical contacts. 

 Chamois-skin has a specific gravity but little greater than water 



