58 IRVING HARDESTY 



SUMMARY 



1. The bony labyrinth of the adult pig, as well as that of the 

 pig fetus, is not fused with nor enveloped by the petrous part of 

 the temporal bone and thus may be readily removed. 



2. A fixing fluid which also slowly but sufficientlj^ decalcifies 

 is best used for normal appearances of the cochlear structures, 

 and, especially with cochleae of adult pigs, it is necessary to 

 make a small hole in the bony labyrinth to relieve pressure of gas 

 formed within during decalcification. 



3. Measured within the outer wall of the bony part of the 

 coil, the diameter of the basal coil of the cochlea of the adult 

 ox is 8.4 mm.; that of the adult pig, 5.8 mm.; and that of man, 

 6.7 mm. The height of the cochlea, from the apical side of the 

 scala vestibuH in the apical turn to the basal side of the scala 

 tympani in the basal turn, was found to be, for the adult ox, 

 6.7 mm. ; for the adult pig, 4.4 mm., and for the human, 4.9 mm. 

 The human cochlea seems to be slightly more flat than those of 

 the ox and pig. The cochlea of the pig at term, exclusive of 

 the outer bony wall, is slightly less in size than that of the adult 

 pig. The shght difference is apparently due to an increase in 

 the size of the two scalae in the adult. 



4. The length of the tectorial membrane of the adult pig is 

 estimated from measurements to be about 26 mm. or less than 

 1 mm. longer than in the fetus at term. 



5. The attached, axial zone of the tectorial membrane of the 

 adult pig is of practically the same width throughout the entire 

 length of the membrane. 



6. As to the proportions of the outspanning zone of the tec- 

 torial membrane of the adult, indicating its adaptedness to 

 serve as the chief vibratory structure of the auditory apparatus: 

 '(a) it is widest and thickest at its apical end, tapering gradually 

 and evenly to its basal end, which is its narrowest part ; (b) the 

 width of the apical end of the outspanning zone appears from 

 averages of measurements to be 6.8 times its width at the basal 

 end; (c) in thickness, the apical end of the outspanning zone 

 averages in sections of it 3 times its thickness at the 7th half 



