Volume VI n. August, l8g^. Number J. 



JOURNAL 



OF 



MORPHOLOGY. 



THE AUDITORY OR HAIR-CELLS OF THE EAR 

 AND THEIR RELATIONS TO THE AUDITORY 

 NERVE. 



HOWARD AYER.S. 



The present condition of this question, so far as the Golgi 

 method has influenced it, may be epitomized as follows : 



1. The hair-bearing or acoustic cells of the ear are not nerve 

 cells ; but they represent a secondary and higher differentia- 

 tion of the nerve end apparatus. 



2. All fibres of the auditory nerve are apparently out- 

 growths of the bipolar ganglion cells, one process reaching 

 to the periphery, the other into the central nervous system. 

 The peripheral processes sometimes terminate in small knobs 

 below or among the hair cells ; but more frequently they end 

 in numerous fine branches which pass up among the cells and 

 often reach quite to the surface of the epithelium. 



3. All the cells of the several auditory ganglia are simple 

 bipolar ganglion cells and are considered to retain a more 

 primitive condition than the ganglion cells of the spinal ganglia. 



4. The acoustic cells are not homologous with olfactive cells 

 since although hair-bearing they are not continuous with the 

 nerve fibres and are only secondarily brought into relation (not 

 more than a mere contact) to the free ends of the auditory 



445 



