232 



ELEMENTS OF BIOLOGY 



certain definite frequencies. The length and number of nerve end- 

 ings on the organ of Corti provide for the recognition of a wide 

 range of sound frequencies. 



SUPERIOR 

 SEMICIRCULAR 

 CANAL 



LATERAL 



SEMICIRCULAR' 



CANAL 



UTRICULUS 

 AMPULLAE 



SACCULUS 

 NERVE 



COCHLEA 



ENDOLYMPHATIC 

 SAC 



— CPUS 



POSTERIOR 



SEMICIRCULAR 



CANAL 



NERVE 



AMPULLAE 



NERVES 



Fig. i6i. — The membranous labyrinth of the human ear. 



The membranous cochlea containing the organ of Corti is con- 

 tinuous with three membranous tubes roughly arranged as hori- 

 zontal, transverse, and perpendicular, called the semicircular 



